Sample records for high-angle thrust faults

  1. Seismic reflection profiles from offshore central California: evidence for post-Miocene imbricate thrust faulting

    Energy Technology Data Exchange (ETDEWEB)

    Crouch, J.K.; Bachman, S.


    High-resolution, 36-fold seismic reflection data with penetration to 3 sec have been collected recently in the northeastern offshore Santa Maria basin, the northern Santa Barbara Channel, and off Point Conception, California. These profiles reveal major east-over-west thrust in areas previously interpreted as being characterized by strike-slip faults and/or high-angle normal or reverse faults. Like those in well known foreland thrust belts, these faults typically from an imbricate system in which they curve asymptotically downward to a common basal sole thrust. ''Soling out'' generally occurs at depths of 1.5-3km (5000-10,000 ft). Detailed mapping of faults and folds associated with these thrust systems coupled with fault-plane solutions suggest that: these thrust formed within the last 5 m.y.,; many have modern activity; and compressive forces causing them are normal to the strike of the San Andreas fault. These observations agree with present-day plate motion studies which require that Pacific-North American relative plate motion include a component of compression orthogonal to the San Andreas fault. These overthrust regions are all sites of recent major petroleum discoveries. However, these discoveries have all been made on obvious anticlinal structures that generally are attributed to wrench tectonics. Recognition of thrust faulting in these areas may lead to additional discoveries from more subtle geologic traps associated with overthrusting.

  2. Geometry and evolution of low-angle normal faults (LANF) within a Cenozoic high-angle rift system, Thailand: Implications for sedimentology and the mechanisms of LANF development (United States)

    Morley, Chris K.


    At least eight examples of large (5-35 km heave), low-angle normal faults (LANFs, 20°-30° dip) occur in the Cenozoic rift basins of Thailand and laterally pass into high-angle extensional fault systems. Three large-displacement LANFs are found in late Oligocene-Miocene onshore rift basins (Suphan Buri, Phitsanulok, and Chiang Mai basins), they have (1) developed contemporaneous with, or after the onset of, high-angle extension, (2) acted as paths for magma and associated fluids, and (3) impacted sedimentation patterns. Displacement on low-angle faults appears to be episodic, marked by onset of lacustrine conditions followed by axial progradation of deltaic systems that infilled the lakes during periods of low or no displacement. The Chiang Mai LANF is a low-angle (15°-25°), high-displacement (15-35 km heave), ESE dipping LANF immediately east of the late early Miocene Doi Inthanon and Doi Suthep metamorphic core complexes. Early Cenozoic transpressional crustal thickening followed by the northward motion of India coupled with Burma relative to east Burma and Thailand (˜40-30 Ma) caused migmatization and gneiss dome uplift in the late Oligocene of the core complex region, followed by LANF activity. LANF displacement lasted 4-6 Ma during the early Miocene and possibly transported a late Oligocene-early Miocene high-angle rift system 35 km east. Other LANFs in Thailand have lower displacements and no associated metamorphic core complexes. The three LANFs were initiated as low-angle faults, not by isostatic rotation of high-angle faults. The low-angle dips appear to follow preexisting low-angle fabrics (thrusts, shear zones, and other low-angle ductile foliations) predominantly developed during Late Paleozoic and early Paleogene episodes of thrusting and folding.

  3. Evolution of the Puente Hills Thrust Fault (United States)

    Bergen, K. J.; Shaw, J. H.; Dolan, J. F.


    This study aims to assess the evolution of the blind Puente Hills thrust fault system (PHT) by determining its age of initiation, lateral propagation history, and changes in slip rate over time. The PHT presents one of the largest seismic hazards in the United States, given its location beneath downtown Los Angeles. The PHT is comprised of three fault segments: the Los Angeles (LA), Santa Fe Springs (SFS), and Coyote Hills (CH). The LA and SFS segments are characterized by growth stratigraphy where folds formed by uplift on the fault segments have been continually buried by sediment from the Los Angeles and San Gabriel rivers. The CH segment has developed topography and is characterized by onlapping growth stratigraphy. This depositional setting gives us the unique opportunity to measure uplift on the LA and SFS fault segments, and minimum uplift on the CH fault segment, as the difference in sediment thicknesses across the buried folds. We utilize depth converted oil industry seismic reflection data to image the fold geometries. Identifying time-correlative stratigraphic markers for slip rate determination in the basin has been a problem for researchers in the past, however, as the faunal assemblages observed in wells are time-transgressive by nature. To overcome this, we utilize the sequence stratigraphic model and well picks of Ponti et al. (2007) as a basis for mapping time-correlative sequence boundaries throughout our industry seismic reflection data from the present to the Pleistocene. From the Pleistocene to Miocene we identify additional sequence boundaries in our seismic reflection data from imaged sequence geometries and by correlating industry well formation tops. The sequence and formation top picks are then used to build 3-dimensional surfaces in the modeling program Gocad. From these surfaces we measure the change in thicknesses across the folds to obtain uplift rates between each sequence boundary. Our results show three distinct phases of

  4. Initiation of a thrust fault revealed by analog experiments (United States)

    Dotare, Tatsuya; Yamada, Yasuhiro; Adam, Juergen; Hori, Takane; Sakaguchi, Hide


    To reveal in detail the process of initiation of a thrust fault, we conducted analog experiments with dry quartz sand using a high-resolution digital image correlation technique to identify minor shear-strain patterns for every 27 μm of shortening (with an absolute displacement accuracy of 0.5 μm). The experimental results identified a number of "weak shear bands" and minor uplift prior to the initiation of a thrust in cross-section view. The observations suggest that the process is closely linked to the activity of an adjacent existing thrust, and can be divided into three stages. Stage 1 is characterized by a series of abrupt and short-lived weak shear bands at the location where the thrust will subsequently be generated. The area that will eventually be the hanging wall starts to uplift before the fault forms. The shear strain along the existing thrust decreases linearly during this stage. Stage 2 is defined by the generation of the new thrust and active displacements along it, identified by the shear strain along the thrust. The location of the new thrust may be constrained by its back-thrust, generally produced at the foot of the surface slope. The activity of the existing thrust falls to zero once the new thrust is generated, although these two events are not synchronous. Stage 3 of the thrust is characterized by a constant displacement that corresponds to the shortening applied to the model. Similar minor shear bands have been reported in the toe area of the Nankai accretionary prism, SW Japan. By comparing several transects across this subduction margin, we can classify the lateral variations in the structural geometry into the same stages of deformation identified in our experiments. Our findings may also be applied to the evaluation of fracture distributions in thrust belts during unconventional hydrocarbon exploration and production.

  5. Foreland normal fault control on northwest Himalayan thrust front development (United States)

    Blisniuk, Peter M.; Sonder, Leslie J.; Lillie, Robert J.


    In the Trans-Indus Ranges along the western part of the northwest Himalayan thrust front, unconformities, changes in paleocurrent directions, and locally derived conglomerates in synorogenic foreland basin deposits provide evidence for major local deformation at ≥3.5 Ma. The tectonic history of the Trans-Indus Ranges has previously been described in terms of a single episode of major thrusting at ≤1 Ma, thus our work implies that there were two distinct phases of deformation. In conjunction with published evidence in the Salt Range to the east for two phases of deformation (˜6 to 5 Ma, and ˜2.5 Ma to present), this study demonstrates that these two phases of deformation are regionally significant and probably correlative along the entire present-day NW Himalayan thrust front. Reconstruction of possible source areas for the locally derived conglomerates shows that the earlier deformation is probably related to normal faulting. These results suggest that the tectonic evolution of the area along the present-day thrust front is characterized by (1) latest Miocene to early Pliocene formation of north dipping normal fault zones (total throw ≥ 600 m) within the foreland basin, related to syn-orogenic flexure of the Indian plate, and (2) late Pliocene to early Pleistocene initiation of south directed thrusting along the present-day thrust front, related to outward growth of the NW Himalayan thrust wedge. The location of the present-day thrust front appears to be controlled by north dipping normal faults and monoclines that formed during the earlier deformation and subsequently localized structural ramps during later thrusting.

  6. Flight-Determined Subsonic Longitudinal Stability and Control Derivatives of the F-18 High Angle of Attack Research Vehicle (HARV) with Thrust Vectoring (United States)

    Iliff, Kenneth W.; Wang, Kon-Sheng Charles


    The subsonic longitudinal stability and control derivatives of the F-18 High Angle of Attack Research Vehicle (HARV) are extracted from dynamic flight data using a maximum likelihood parameter identification technique. The technique uses the linearized aircraft equations of motion in their continuous/discrete form and accounts for state and measurement noise as well as thrust-vectoring effects. State noise is used to model the uncommanded forcing function caused by unsteady aerodynamics over the aircraft, particularly at high angles of attack. Thrust vectoring was implemented using electrohydraulically-actuated nozzle postexit vanes and a specialized research flight control system. During maneuvers, a control system feature provided independent aerodynamic control surface inputs and independent thrust-vectoring vane inputs, thereby eliminating correlations between the aircraft states and controls. Substantial variations in control excitation and dynamic response were exhibited for maneuvers conducted at different angles of attack. Opposing vane interactions caused most thrust-vectoring inputs to experience some exhaust plume interference and thus reduced effectiveness. The estimated stability and control derivatives are plotted, and a discussion relates them to predicted values and maneuver quality.

  7. Paleoseismic investigations at the Cal thrust fault, Mendoza, Argentina (United States)

    Salomon, Eric; Schmidt, Silke; Hetzel, Ralf; Mingorance, Francisco


    Along the active mountain front of the Andean Precordillera between 30°S and 34°S in western Argentina several earthquakes occurred in recent times, including a 7.0 Ms event in 1861 which destroyed the city of Mendoza and killed two thirds of its population. The 1861 event and two other earthquakes (Ms = 5.7 in 1929 and Ms = 5.6 in 1967) were generated on the Cal thrust fault, which extends over a distance of 31 km north-south and runs straight through the center of Mendoza. In the city, which has now more than 1 million inhabitants, the fault forms a 3-m-high fault scarp. Although the Cal thrust fault poses a serious seismic hazard, the paleoseismologic history of this fault and its long-term slip rate remains largely unknown (Mingorance, 2006). We present the first results of an ongoing paleoseismologic study of the Cal thrust at a site located 5 km north of Mendoza. Here, the fault offsets Late Holocene alluvial fan sediments by 2.5 m vertically and exhibits a well developed fault scarp. A 15-m-long and 2-3-m-deep trench across the scarp reveals three east-vergent folds that we interpret to have formed during three earthquakes. Successive retrodeformation of the two youngest folds suggests that the most recent event (presumably the 1861 earthquake) caused ~1.1 m of vertical offset and ~1.8 m of horizontal shortening. For the penultimate event we obtain a vertical offset of ~0.7 m and a horizontal shortening of ~1.9 m. A vertical displacement of ~0.7 m observed on a steeply west-dipping fault may be associated with an older event. The cumulative vertical offset of 2.5 m for the three inferred events is in excellent agreement with the height of the scarp. Based on the retrodeformation of the trench deposits the fault plane dips ~25° to the west. In the deepest part of the trench evidence for even older seismic events is preserved beneath an angular unconformity that was formed during a period of erosion and pre-dates the present-day scarp. Dating of samples to

  8. Experimental evidence that thrust earthquake ruptures might open faults. (United States)

    Gabuchian, Vahe; Rosakis, Ares J; Bhat, Harsha S; Madariaga, Raúl; Kanamori, Hiroo


    Many of Earth's great earthquakes occur on thrust faults. These earthquakes predominantly occur within subduction zones, such as the 2011 moment magnitude 9.0 eathquake in Tohoku-Oki, Japan, or along large collision zones, such as the 1999 moment magnitude 7.7 earthquake in Chi-Chi, Taiwan. Notably, these two earthquakes had a maximum slip that was very close to the surface. This contributed to the destructive tsunami that occurred during the Tohoku-Oki event and to the large amount of structural damage caused by the Chi-Chi event. The mechanism that results in such large slip near the surface is poorly understood as shallow parts of thrust faults are considered to be frictionally stable. Here we use earthquake rupture experiments to reveal the existence of a torquing mechanism of thrust fault ruptures near the free surface that causes them to unclamp and slip large distances. Complementary numerical modelling of the experiments confirms that the hanging-wall wedge undergoes pronounced rotation in one direction as the earthquake rupture approaches the free surface, and this torque is released as soon as the rupture breaks the free surface, resulting in the unclamping and violent 'flapping' of the hanging-wall wedge. Our results imply that the shallow extent of the seismogenic zone of a subducting interface is not fixed and can extend up to the trench during great earthquakes through a torquing mechanism.

  9. Experimental evidence that thrust earthquake ruptures might open faults (United States)

    Gabuchian, Vahe; Rosakis, Ares J.; Bhat, Harsha S.; Madariaga, Raúl; Kanamori, Hiroo


    Many of Earth’s great earthquakes occur on thrust faults. These earthquakes predominantly occur within subduction zones, such as the 2011 moment magnitude 9.0 eathquake in Tohoku-Oki, Japan, or along large collision zones, such as the 1999 moment magnitude 7.7 earthquake in Chi-Chi, Taiwan. Notably, these two earthquakes had a maximum slip that was very close to the surface. This contributed to the destructive tsunami that occurred during the Tohoku-Oki event and to the large amount of structural damage caused by the Chi-Chi event. The mechanism that results in such large slip near the surface is poorly understood as shallow parts of thrust faults are considered to be frictionally stable. Here we use earthquake rupture experiments to reveal the existence of a torquing mechanism of thrust fault ruptures near the free surface that causes them to unclamp and slip large distances. Complementary numerical modelling of the experiments confirms that the hanging-wall wedge undergoes pronounced rotation in one direction as the earthquake rupture approaches the free surface, and this torque is released as soon as the rupture breaks the free surface, resulting in the unclamping and violent ‘flapping’ of the hanging-wall wedge. Our results imply that the shallow extent of the seismogenic zone of a subducting interface is not fixed and can extend up to the trench during great earthquakes through a torquing mechanism.

  10. Fault Characteristics in Longmen Mountain Thrust Belt,Western Sichuan Foreland Basin,China

    Institute of Scientific and Technical Information of China (English)

    Wan Guimei; Tang Liangjie; Yang Keming; Jin Wenzheng; LU Zhizhou; Yu Yixin


    Through field geological survey,the authors found that abundant thrust faults developed in the Longmen (龙门) Mountain thrust belt.These faults can be divided into thrust faults and strike-slip faults according to their formation mechanisms and characteristics.Furthermore,these faults can be graded into primary fault,secondary fault,third-level fault,and fourth-level fault according to their scale and role in the tectonic evolution of Longmen Mountain thrust belt.Each thrust fault is composed of several secondary faults,such as Qingchuan (青川)-Maowen (茂汶) fault zone is composed of Qiaozhuang (乔庄) fault,Qingxi (青溪) fault,Maowen fault,Ganyanggou (赶羊沟) fault,etc..The Longmen Mountain thrust belt experienced early Indosinian movement,Anxian (安县) movement,Yanshan (燕山)movement,and Himalayan movement,and the faults formed gradually from north to south.

  11. Was Himalayan normal faulting triggered by initiation of the Ramgarh-Munsiari Thrust? (United States)

    Robinson, Delores M.; Pearson, Ofori N.


    The Ramgarh–Munsiari thrust is a major orogen-scale fault that extends for more than 1,500 km along strike in the Himalayan fold-thrust belt. The fault can be traced along the Himalayan arc from Himachal Pradesh, India, in the west to eastern Bhutan. The fault is located within the Lesser Himalayan tectonostratigraphic zone, and it translated Paleoproterozoic Lesser Himalayan rocks more than 100 km toward the foreland. The Ramgarh–Munsiari thrust is always located in the proximal footwall of the Main Central thrust. Northern exposures (toward the hinterland) of the thrust sheet occur in the footwall of the Main Central thrust at the base of the high Himalaya, and southern exposures (toward the foreland) occur between the Main Boundary thrust and Greater Himalayan klippen. Although the metamorphic grade of rocks within the Ramgarh–Munsiari thrust sheet is not significantly different from that of Greater Himalayan rock in the hanging wall of the overlying Main Central thrust sheet, the tectonostratigraphic origin of the two different thrust sheets is markedly different. The Ramgarh–Munsiari thrust became active in early Miocene time and acted as the roof thrust for a duplex system within Lesser Himalayan rocks. The process of slip transfer from the Main Central thrust to the Ramgarh–Munsiari thrust in early Miocene time and subsequent development of the Lesser Himalayan duplex may have played a role in triggering normal faulting along the South Tibetan Detachment system.

  12. Formation of chlorite during thrust fault reactivation. Record of fluid origin and P-T conditions in the Monte Perdido thrust fault (southern Pyrenees) (United States)

    Lacroix, B.; Charpentier, D.; Buatier, M.; Vennemann, T.; Labaume, P.; Adatte, T.; Travé, A.; Dubois, M.


    The chemical and isotopic compositions of clay minerals such as illite and chlorite are commonly used to quantify diagenetic and low-grade metamorphic conditions, an approach that is also used in the present study of the Monte Perdido thrust fault from the South Pyrenean fold-and-thrust belt. The Monte Perdido thrust fault is a shallow thrust juxtaposing upper Cretaceous-Paleocene platform carbonates and Lower Eocene marls and turbidites from the Jaca basin. The core zone of the fault, about 6 m thick, consists of intensely deformed clay-bearing rocks bounded by major shear surfaces. Illite and chlorite are the main hydrous minerals in the fault zone. Illite is oriented along cleavage planes while chlorite formed along shear veins (<50 μm in thickness). Authigenic chlorite provides essential information about the origin of fluids and their temperature. δ18O and δD values of newly formed chlorite support equilibration with sedimentary interstitial water, directly derived from the local hanging wall and footwall during deformation. Given the absence of large-scale fluid flow, the mineralization observed in the thrust faults records the P-T conditions of thrust activity. Temperatures of chlorite formation of about 240°C are obtained via two independent methods: chlorite compositional thermometers and oxygen isotope fractionation between cogenetic chlorite and quartz. Burial depth conditions of 7 km are determined for the Monte Perdido thrust reactivation, coupling calculated temperature and fluid inclusion isochores. The present study demonstrates that both isotopic and thermodynamic methods applied to clay minerals formed in thrust fault are useful to help constrain diagenetic and low-grade metamorphic conditions.

  13. Evaluation of thrusting and folding of the Deadman Creek Thrust Fault, Sangre de Cristo range, Saguache County, Colorado (United States)

    Weigel, Jacob F., II

    The Deadman Creek Thrust Fault was mapped in a structural window on the west side of the Sangre de Cristo Range. The study area, located in southern Colorado, is a two square mile area halfway between the town of Crestone and the Great Sand Dunes National Park. The Deadman Creek Thrust Fault is the center of this study because it delineates the fold structure in the structural window. The fault is a northeast-directed low-angle thrust folded by subsequent additional compression. This study was directed at understanding the motion of the Deadman Creek Thrust Fault as affected by subsequent folding, and the driving mechanism behind the folding of the Pole Creek Anticline as part of a broader study of Laramide thrust faulting in the range. This study aids in the interpretation of the geologic structure of the San Luis Valley, which is being studied by staff of the United States Geological Survey (USGS), to understand Rio Grande Rift basin evolution by focusing on rift and pre-rift tectonic activity. It also provides a geologic interpretation for the Saguache County Forest Service, Great Sand Dunes National Park, and its visitors. The Sangre de Cristo Mountain Range has undergone tectonic events in the Proterozoic, Pennsylvanian (Ancestral Rocky Mountains), Cretaceous-Tertiary (Laramide Orogeny) and mid-Tertiary (Rio Grande Rift). During the Laramide Orogeny the Deadman Creek Thrust Fault emplaced Proterozoic gneiss over Paleozoic sedimentary rocks and Proterozoic granodiorite in the area. Continued deformation resulted in folding of the fault to form the Pole Creek Anticline. The direction of motion of both the fault and fold is northeastward. A self-consistent net of cross-sections and stereonet plots generated from existing and new field data show that the anticline is an overturned isoclinal fold in Pole Creek Canyon, which shows an increasing inter-limb angle and a more vertical axial surface northwestward toward Deadman Creek Canyon. Southwest-directed apparent

  14. Syntectonic fluid-flow along thrust faults: Example of the South Pyrenean fold-and-thrust belt (United States)

    Lacroix, B.; Travé, A.; Buatier, M.; Labaume, P.


    Estimation of the P-T conditions during evolution of sedimentary basins and characterization of petrophysical properties of fault zone are of major interests to oil companies, since they could allow to understand paleohydrological characteristics of potential reservoirs. In fold-and-thrust belts, faults are supposed to constitute channelized pathways for fluids coming from external, either deep or meteoric sources. However, the different available studies suggest that fluid flow through such discontinuities is not so evident. In order to constrain the paleofluid flow through the south Pyrenean fold-and-thrust belt we focus on thrust faults located at different structural levels. The microstructures observed in the different studied fault zones are similar and consist of pervasive cleavage, calcite shear and extension veins (respectively SV1 and EV1) and late dilatation veins (EV3). Thus, the presence of veins attests to the involvement of fluids during deformation. In order to characterize the nature and origin of fluid, petrological and geochemical (stable isotopes and trace elements) analyses were performed on calcite veins. The results suggest a high complexity in the hydrological behaviours of thrust faults evidencing a reservoir compartmentalization in the South-Pyrenean fold-and-thrust belt. In the southern part of the Axial Zone, different studies evidence the contribution of deep metamorphic water, probably derived from the Paleozoic basement, along Gavarnie related fault zones during deformation. In the Jaca basin, during the Monte Perdido thrust fault activity, we evidence the contribution of formation water. These data suggest a very closed hydrological fluid system where fluid flow didn't exceeded 70 m. In the other hand, the Jaca and Cotiella thrust faults located in the southern part of the basin, are characterized by a composite fluid-flow system. Indeed, stable isotopes and trace elements compositions of the first generation of calcite veins

  15. Application of three fault growth criteria to the Puente Hills thrust system, Los Angeles, California, USA (United States)

    Olson, Erik L.; Cooke, Michele L.


    Three-dimensional mechanical models are used to evaluate the performance of different fault growth criteria in predicting successive growth of three échelon thrust faults similar to the segments of the Puente Hills thrust system of the Los Angeles basin, California. Four sequential Boundary Element Method models explore the growth of successive échelon faults within the system by simulating snapshots of deformation at different stages of development. These models use three criteria, (1) energy release rate, (2) strain energy density, and (3) Navier-Coulomb stress, to characterize the lateral growth of the fault system. We simulate the growth of an échelon thrust fault system to evaluate the suitability of each of these criteria for assessing fault growth. Each of these three factors predicts a portion of the incipient fault geometry (i.e. location or orientation); however, each provides different information. In each model, energy release rate along the westernmost (leading) tip of the Puente Hills thrust drops with growth of the next neighboring fault; this result supports the overall lateral development of successive échelon segments. Within each model, regions of high strain energy density and Navier-Coulomb stress envelope at least a portion of the next fault to develop, although the strain energy density has stronger correlation than Navier-Coulomb stress to the location of incipient faulting. In each model, one of the two predicted planes of maximum Navier-Coulomb stress ahead of the leading fault tip matches the strike but not the dip of the incipient fault plane recreating part of the fault orientation. The incipient fault dip is best predicted by the orientation of the strain energy density envelopes around the leading fault tip. Furthermore, the energy release rate and pattern of strain energy density can be used to characterize potential soft linkage (overlap) or hard linkage (connection) of échelon faults within the system.

  16. Recent movements along the Main Boundary Thrust of the Himalayas: Normal faulting in an over-critical thrust wedge? (United States)

    Mugnier, Jean-Louis; Huyghe, Pascale; Chalaron, Edouard; Mascle, Georges


    The Main Boundary Thrust (MBT) is one of the major Himalayan thrusts occurring during the Cainozoic, and it is presently incorporated within the Himalayan thrust wedge (Lesser and Outer Himalayas) displaced above the Indian lithosphere. Nonetheless the MBT shows recent normal displacement along most of its length. We suggest that the orientation of the major principal stress within the Himalayan thrust wedge deviates significantly from the horizontal and when this deviation exceeds the dip of the vectors normal to back-tilted thrusts, the normal component of displacement may act along these faults. Steep north-dipping segments of the MBT therefore show a normal component of displacement if a geometrical definition is used, but they are faults in a compressional regime where the major principal stress axis has deviated from the horizontal. Micro-structural data recorded along the Surkhet-Ghorahi segment of the MBT are consistent with a strong deviation of the state of stress. The presence of such peculiar normal faulting along the MBT is used to calibrate the mechanical characteristics of the belt considered as a Coulomb wedge. The following characteristics are suggested: (a) very poor strength contrast between basal decollement and rocks in the wedge body, (b) a high pore fluid pressure ratio (probably close to 0.8-0.9) and a higher fluid pressure ratio (close to 1.0) along the active normal faults if a high internal friction angle (close to the Byerlee value) is considered. The strong deviation in principal stress direction may have recently increased, due to a taper of the Himalayan wedge exceeding the stability boundary and may be controlled by erosion and isostatic uplift rebound of the Himalayan range.

  17. Displacement transfer from fault-bend to fault-propagation fold geometry: An example from the Himalayan thrust front (United States)

    Qayyum, Mazhar; Spratt, Deborah A.; Dixon, John M.; Lawrence, Robert D.


    The leading edge of the ENE-trending Himalayan thrust front in Pakistan exhibits along-strike changes in deformational style, ranging from fault-bend to fault-propagation folds. Although the structural geometry is very gently deformed throughout the Salt Range, it becomes progressively more complex to the east as the leading edge of the emergent Salt Range Thrust becomes blind. Surface geology, seismic reflection, petroleum well, and chronostratigraphic data are synthesized to produce a 3-D kinematic model that reconciles the contrasting structural geometries along this part of the Himalayan thrust front. We propose a model whereby displacement was transferred, across a newly-identified lateral ramp, from a fault-bend fold in the west to fault-propagation folds in the east and comparable shortening was synchronously accommodated by two fundamentally different mechanisms: translation vs. telescoping. However, substantially different shortening distribution patterns within these structurally contrasting segments require a tear fault, which later is reactivated as a thrust fault. The present geometry of this S-shaped displacement transfer zone is a combined result of the NW-SE compression of the lateral culmination wall and associated tear fault, and their subsequent modification due to mobilization of underlying ductile salt.

  18. Fault-related fold styles and progressions in fold-thrust belts: Insights from sandbox modeling (United States)

    Yan, Dan-Ping; Xu, Yan-Bo; Dong, Zhou-Bin; Qiu, Liang; Zhang, Sen; Wells, Michael


    Fault-related folds of variable structural styles and assemblages commonly coexist in orogenic belts with competent-incompetent interlayered sequences. Despite their commonality, the kinematic evolution of these structural styles and assemblages are often loosely constrained because multiple solutions exist in their structural progression during tectonic restoration. We use a sandbox modeling instrument with a particle image velocimetry monitor to test four designed sandbox models with multilayer competent-incompetent materials. Test results reveal that decollement folds initiate along selected incompetent layers with decreasing velocity difference and constant vorticity difference between the hanging wall and footwall of the initial fault tips. The decollement folds are progressively converted to fault-propagation folds and fault-bend folds through development of fault ramps breaking across competent layers and are followed by propagation into fault flats within an upper incompetent layer. Thick-skinned thrust is produced by initiating a decollement fault within the metamorphic basement. Progressive thrusting and uplifting of the thick-skinned thrust trigger initiation of the uppermost incompetent decollement with formation of a decollement fold and subsequent converting to fault-propagation and fault-bend folds, which combine together to form imbricate thrust. Breakouts at the base of the early formed fault ramps along the lowest incompetent layers, which may correspond to basement-cover contacts, domes the upmost decollement and imbricate thrusts to form passive roof duplexes and constitute the thin-skinned thrust belt. Structural styles and assemblages in each of tectonic stages are similar to that in the representative orogenic belts in the South China, Southern Appalachians, and Alpine orogenic belts.

  19. Using laterally compatible cross sections to infer fault growth and linkage models in foreland thrust belts (United States)

    Watkins, Hannah; Butler, Robert W. H.; Bond, Clare E.


    We investigate changes in shortening, displacement and fold geometry to understand the detailed along-strike structural variation within fold-thrust belts, and infer thrust growth and linkage mechanisms. Field observations from the Vercors in SE France are used to characterise deformation style in the region. Parallel cross sections are constructed, analysed and used to create shortening and thrust displacement profiles from the northern to southern Vercors. Sections show changes in structural style and shortening accommodation from thrust-dominated in the north to fold-dominated in the south. The total shortening distance in the Vercors does not change significantly along strike (3400-4650 m), however displacements along individual thrust zones do vary significantly and displacement profiles show a range in displacement gradients (16-107 m/km). Despite relatively simple shortening patterns in the Vercors, sections show a more complex 3D internal structure of the fold-thrust belt. Thrust displacements and geometries suggest both large-scale thrust zones and small-scale thrusts are soft linked, transferring displacement along strike through transfer zones. Short, soft-linked thrust segments indicate an intermediate stage of thrust growth and linkage, well documented for normal fault systems, which form prior to the formation of thrust branches and hard-linked displacement transfer.

  20. Thrust fault segmentation and downward fault propagation in accretionary wedges: New Insights from 3D seismic reflection data (United States)

    Orme, Haydn; Bell, Rebecca; Jackson, Christopher


    The shallow parts of subduction megathrust faults are typically thought to be aseismic and incapable of propagating seismic rupture. The 2011 Tohoku-Oki earthquake, however, ruptured all the way to the trench, proving that in some locations rupture can propagate through the accretionary wedge. An improved understanding of the structural character and physical properties of accretionary wedges is therefore crucial to begin to assess why such anomalously shallow seismic rupture occurs. Despite its importance, we know surprisingly little regarding the 3D geometry and kinematics of thrust network development in accretionary prisms, largely due to a lack of 3D seismic reflection data providing high-resolution, 3D images of entire networks. Thus our current understanding is largely underpinned by observations from analogue and numerical modelling, with limited observational data from natural examples. In this contribution we use PSDM, 3D seismic reflection data from the Nankai margin (3D Muroto dataset, available from the UTIG Academic Seismic Portal, Marine Geoscience Data System) to examine how imbricate thrust fault networks evolve during accretionary wedge growth. We unravel the evolution of faults within the protothrust and imbricate thrust zones by interpreting multiple horizons across faults and measuring fault displacement and fold amplitude along-strike; by doing this, we are able to investigate the three dimensional accrual of strain. We document a number of local displacement minima along-strike of faults, suggesting that, the protothrust and imbricate thrusts developed from the linkage of smaller, previously isolated fault segments. Although we often assume imbricate faults are likely to have propagated upwards from the décollement we show strong evidence for fault nucleation at shallow depths and downward propagation to intersect the décollement. The complex fault interactions documented here have implications for hydraulic compartmentalisation and pore

  1. Fold-to-Fault Progression of a Major Thrust Zone Revealed in Horses of the North Mountain Fault Zone, Virginia and West Virginia, USA


    Orndorff, Randall C.


    The method of emplacement and sequential deformation of major thrust zones may be deciphered by detailed geologic mapping of these important structures. Thrust fault zones may have added complexity when horse blocks are contained within them. However, these horses can be an important indicator of the fault development holding information on fault-propagation folding or fold-to-fault progression. The North Mountain fault zone of the Central Appalachians, USA, was studied in order to better und...

  2. Thrust fault growth within accretionary wedges: New Insights from 3D seismic reflection data (United States)

    Orme, H.; Bell, R. E.; Jackson, C. A. L.


    The shallow parts of subduction megathrust faults are typically thought to be aseismic and incapable of propagating seismic rupture. The 2011 Tohoku-Oki earthquake, however, ruptured all the way to the trench, proving that in some locations rupture can propagate through the accretionary wedge. An improved understanding of the structural character and physical properties of accretionary wedges is therefore crucial to begin to assess why such anomalously shallow seismic rupture occurs. Despite its importance, we know surprisingly little regarding the 3D geometry and kinematics of thrust network development in accretionary prisms, largely due to a lack of 3D seismic reflection data providing high-resolution, 3D images of entire networks. Thus our current understanding is largely underpinned by observations from analogue and numerical modelling, with limited observational data from natural examples. In this contribution we use PSDM, 3D seismic reflection data from the Nankai margin (3D Muroto dataset, available from the UTIG Academic Seismic Portal, Marine Geoscience Data System) to examine how imbricate thrust fault networks evolve during accretionary wedge growth. Previous studies have reported en-echelon thrust fault geometries from the NW part of the dataset, and have related this complex structure to seamount subduction. We unravel the evolution of faults within the protothrust and imbricate thrust zones by interpreting multiple horizons across faults and measuring fault displacement and fold amplitude along-strike; by doing this, we are able to investigate the three dimensional accrual of strain. We document a number of local displacement minima along-strike of faults, suggesting that, the protothrust and imbricate thrusts developed from the linkage of smaller, previously isolated fault segments. We also demonstrate that the majority of faults grew upward from the décollement, although there is some evidence for downward fault propagation. Our observations

  3. Shallow seismic imaging of folds above the Puente Hills blind-thrust fault, Los Angeles, California (United States)

    Pratt, Thomas L.; Shaw, John H.; Dolan, James F.; Christofferson, Shari A.; Williams, Robert A.; Odum, Jack K.; Plesch, Andreas


    High-resolution seismic reflection profiles image discrete folds in the shallow subsurface (Puente Hills blind-thrust fault system, Los Angeles basin, California. The profiles demonstrate late Quaternary activity at the fault tip, precisely locate the axial surfaces of folds within the upper 100 m, and constrain the geometry and kinematics of recent folding. The Santa Fe Springs segment of the Puente Hills fault zone shows an upward-narrowing kink band with an active anticlinal axial surface, consistent with fault-bend folding above an active thrust ramp. The Coyote Hills segment shows an active synclinal axial surface that coincides with the base of a 9-m-high scarp, consistent with tip-line folding or the presence of a backthrust. The seismic profiles pinpoint targets for future geologic work to constrain slip rates and ages of past events on this important fault system.

  4. Thrust-wrench fault interference in a brittle medium: new insights from analogue modelling experiments (United States)

    Rosas, Filipe; Duarte, Joao; Schellart, Wouter; Tomas, Ricardo; Grigorova, Vili; Terrinha, Pedro


    We present analogue modelling experimental results concerning thrust-wrench fault interference in a brittle medium, to try to evaluate the influence exerted by different prescribed interference angles in the formation of morpho-structural interference fault patterns. All the experiments were conceived to simulate simultaneous reactivation of confining strike-slip and thrust faults defining a (corner) zone of interference, contrasting with previously reported discrete (time and space) superposition of alternating thrust and strike-slip events. Different interference angles of 60°, 90° and 120° were experimentally investigated by comparing the specific structural configurations obtained in each case. Results show that a deltoid-shaped morpho-structural pattern is consistently formed in the fault interference (corner) zone, exhibiting a specific geometry that is fundamentally determined by the different prescribed fault interference angle. Such angle determines the orientation of the displacement vector shear component along the main frontal thrust direction, determining different fault confinement conditions in each case, and imposing a complying geometry and kinematics of the interference deltoid structure. Model comparison with natural examples worldwide shows good geometric and kinematic similarity, pointing to the existence of matching underlying dynamic process. Acknowledgments This work was sponsored by the Fundação para a Ciência e a Tecnologia (FCT) through project MODELINK EXPL/GEO-GEO/0714/2013.

  5. Contemporary tectonics of the Himalayan frontal fault system: folds, blind thrusts and the 1905 Kangra earthquake (United States)

    Yeats, Robert S.; Lillie, Robert J.

    The Sub-Himalayan fold-thrust belt consists of deformed late Cenozoic and older deposits south of the Main Boundary thrust (MBT). In Pakistan, east of the Indus River, the Sub-Himalaya comprises the Potwar Plateau and the Salt Range, which is thrust southward over the Jhelum River floodplain along the Salt Range thrust. Although an estimated 9-14 mm a -1 shortening has been taken up on the Salt Range thrust during the last 2 Ma, the range-front scarp does not show signs of recent faulting. Shortening may be shifting southward to the Lilla overpressured anticline, which rises from the Jhelum floodplain as a fault-propagation fold. Farther east, shortening is partitioned among several anticlines underlain by foreland- and hinterland-dipping blind thrusts. Southeast of the main deformation zone, the Pabbi Hills overpressured anticline is best explained as a fault-propagation fold. Throughout the Potwar Plateau and Salt Range, thrusts and folds rise from a basal décollement horizon in Eocambrian evaporites. The Pakistani part of the décollement horizon could generate large earthquakes only if these evaporites die out northward at seismogenic depths. In India and Nepal, the Sub-Himalaya is narrower, reflecting the absence of evaporites and a steeper slope of the basement towards the hinterland. The southern boundary of the Sub-Himalaya is the Himalayan Front fault, discontinuous because part of the shortening is expressed at the surface by folding. Broad, alluvial synclinal valleys (dun valleys) are bounded on the south by rising barrier anticlines of Siwalik molasse. The 1905 Kangra earthquake (M8) produced uplift on the Mohand anticline and the Dehra Dun Valley, suggesting that this earthquake occurred on a décollement horizon above basement, downdip from the fold. If so, the Kangra event is the largest known earthquake on a blind thrust expressed at the surface as a fold.

  6. An experimental investigation of thrust vectoring two-dimensional convergent-divergent nozzles installed in a twin-engine fighter model at high angles of attack (United States)

    Capone, Francis J.; Mason, Mary L.; Leavitt, Laurence D.


    An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine thrust vectoring capability of subscale 2-D convergent-divergent exhaust nozzles installed on a twin engine general research fighter model. Pitch thrust vectoring was accomplished by downward rotation of nozzle upper and lower flaps. The effects of nozzle sidewall cutback were studied for both unvectored and pitch vectored nozzles. A single cutback sidewall was employed for yaw thrust vectoring. This investigation was conducted at Mach numbers ranging from 0 to 1.20 and at angles of attack from -2 to 35 deg. High pressure air was used to simulate jet exhaust and provide values of nozzle pressure ratio up to 9.

  7. Recognition of Paleoearthquakes on the Puente Hills Blind Thrust Fault, California (United States)

    Dolan, James F.; Christofferson, Shari A.; Shaw, John H.


    Borehole data from young sediments folded above the Puente Hills blind thrust fault beneath Los Angeles reveal that the folding extends to the surface as a discrete zone (-145 meters wide). Buried fold scarps within an upward- narrowing zone of deformation, which extends from the upward termination of the thrust ramp at 3 kilometers depth to the surface, document the occurrence of at least four large (moment-magnitude 7.2 to 7.5) earthquakes on this fault during the past 11,000 years. Future events of this type pose a seismic hazard to metropolitan Los Angeles. Moreover, the methods developed in this study can be used to refine seismic hazard assessments of blind thrusts in other metropolitan regions.

  8. Earth tides can trigger shallow thrust fault earthquakes. (United States)

    Cochran, Elizabeth S; Vidale, John E; Tanaka, Sachiko


    We show a correlation between the occurrence of shallow thrust earthquakes and the occurrence of the strongest tides. The rate of earthquakes varies from the background rate by a factor of 3 with the tidal stress. The highest correlation is found when we assume a coefficient of friction of mu = 0.4 for the crust, although we see good correlation for mu between 0.2 and 0.6. Our results quantify the effect of applied stress on earthquake triggering, a key factor in understanding earthquake nucleation and cascades whereby one earthquake triggers others.

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

    Directory of Open Access Journals (Sweden)

    Lorenzo ePetracchini


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

  10. Deformation Mechanism and Petroleum Accumulation of the High Angle Faults in the Western Circle Zone of Mahu Depression, Junggar Basin%玛湖西环带高角度断裂成因与控藏作用

    Institute of Scientific and Technical Information of China (English)

    郭文建; 吴孔友; 任本兵; 裴仰文; 黄立良


    According to the high-resolution 3D seismic interpretation,a series of high angle faults are developed in the western circle zone of Mahu depression.In section view,these high angle faults present single or combination distribution;while in plain view,they present oblique or parallel distribution. The large shearing fault branches several splays to form flower structures in section view; whereas the smaller shearing fault usually presents single fault development. It is sug-gested that the high angle faults are accommodation structures of the Daerbute fault, corresponding to the R’shearing in the Sylvester shearing model,which is also verified by the physical experiments. These high angle faults can be good con-duits for the vertical migration of petroleum, as the deformation timing is properly matched with the hydrocarbon genera-tion timing. During stable period, the high angle faults present good sealing properties to form effective hydrocarbon traps. Therefore, the fault blocks and fault noses constrained by these high angle faults can be emphasizes in the follow-ing petroleum exploration.%通过高密度三维地震资料精细解释,在准噶尔盆地玛湖凹陷西环带发现众多高角度断层,断层剖面组合为复合型与单一型,平面组合为斜交式与平行式。规模大、压扭强的断层,分支多,剖面组合呈“花状”构造;规模小、压扭性弱的断层,常单独发育。成因机理分析表明,高角度断层是达尔布特断裂的派生构造,属Sylvester简单剪切模式中R’剪裂面,并得到物理模拟实验证实。高角度断层与油气运聚关系极密切,形成期与油气生成期匹配合理,构成油气垂向运移的良好通道。静止期形成有效的油气圈闭,高角度断层围限的断块、断鼻是下一步油气勘探的重点目标。

  11. Length-Displacement Scaling of Lunar Thrust Faults and the Formation of Uphill-Facing Scarps (United States)

    Hiesinger, Harald; Roggon, Lars; Hetzel, Ralf; Clark, Jaclyn D.; Hampel, Andrea; van der Bogert, Carolyn H.


    Lobate scarps are straight to curvilinear positive-relief landforms that occur on all terrestrial bodies [e.g., 1-3]. They are the surface manifestation of thrust faults that cut through and offset the upper part of the crust. Fault scarps on planetary surfaces provide the opportunity to study the growth of faults under a wide range of environmental conditions (e.g., gravity, temperature, pore pressure) [4]. We studied four lunar thrust-fault scarps (Simpelius-1, Morozov (S1), Fowler, Racah X-1) ranging in length from 1.3 km to 15.4 km [5] and found that their maximum total displacements are linearly correlated with length over one order of magnitude. We propose that during the progressive accumulation of slip, lunar faults propagate laterally and increase in length. On the basis of our measurements, the ratio of maximum displacement, D, to fault length, L, ranges from 0.017 to 0.028 with a mean value of 0.023 (or 2.3%). This is an order of magnitude higher than the value of 0.1% derived by theoretical considerations [4], and about twice as large as the value of 0.012-0.013 estimated by [6,7]. Our results, in addition to recently published findings for other lunar scarps [2,8], indicate that the D/L ratios of lunar thrust faults are similar to those of faults on Mercury and Mars (e.g., 1, 9-11], and almost as high as the average D/L ratio of 3% for faults on Earth [16,23]. Three of the investigated thrust fault scarps (Simpelius-1, Morozov (S1), Fowler) are uphill-facing scarps generated by slip on faults that dip in the same direction as the local topography. Thrust faults with such a geometry are common ( 60% of 97 studied scarps) on the Moon [e.g., 2,5,7]. To test our hypothesis that the surface topography plays an important role in the formation of uphill-facing fault scarps by controlling the vertical load on a fault plane, we simulated thrust faulting and its relation to topography with two-dimensional finite-element models using the commercial code ABAQUS

  12. Role of low angle normal faulting and basement thrusting on the structural architecture of the Northern Apennines (Italy) (United States)

    Molli, Giancarlo; Carlini, Mirko; Vescovi, Paolo; Artoni, Andrea; Balsamo, Fabrizio; Camurri, Francesca; Clemenzi, Luca; Storti, Fabrizio; Torelli, Luigi


    The Northern Apennines of Italy are a classical site for studying fundamental issues in thrust wedges, such as ophiolite formation and emplacement, interplay between tectonics and sedimentation, role of out-of-sequence thrusting, syn-orogenic versus post-orogenic extension, along strike segmentation, etc. Accordingly, the Northern Apennines have been extensively studied since more than two centuries ago. Despite the huge amount of available data with different resolution, a 3D comprehensive regional view combining in a modern framework all available surface and subsurface information for contiguous sectors of the chain is still lacking. We performed such an attempt in the area framed between the Taro valley to the north and the northern termination of the Alpi Apuane to the south. The region includes the main morphostructural zones of the North-West Apennines from the Tyrrhenian coast West-Northwest of La Spezia, through the main topographic divide of the Apennines, to the external frontal part of the chain. The area has been investigated through a multidisciplinary approach that integrated: 1) surface geological data collected during the last two decades of structural and stratigraphic field works in the internal as well as external sectors of the chain; 2) subsurface geological data including: a) interpretation of 1200 Km of seismic reflection profiles tied to surface geology and b) analysis of 39 boreholes stratigraphies. The construction of two regional NE-SW trending cross-sections (the Levanto-Pontremoli-Parma to the North and the La Spezia-Sarzana-North Apuane-Cerreto to the South), connected by the NW-SE trending Taro River-Lunigiana Area-Alpi Apuane composite section, allowed us to illustrate (i) the role of out-of-sequence blind thrusting in the basement, (ii) the presence of low angle normal faulting and its relationships with recent to active high angle normal faulting. Both extensional and contractional systems have relevant implications for the

  13. Kinematical and Structural Patterns of the Yingjing-Mabian-Yanjin Thrust Fault Zone,Southeast of the Qinghai-Xizang (Tibet) Plateau and Its Segmentation from Earthquakes

    Institute of Scientific and Technical Information of China (English)

    Zhang Shimin; Nie Gaohong; Liu Xudong; Ren Junjie; Su Gang


    Segmentation of the thrust fault zone is a basic problem for earthquake hazard evaluation. The Yingjing-Mabian-Yanjin thrust fault zone is an important seismic belt NW-trending in the southeast margin of the Qinghai-Xizang (Tibet) plateau. The longitudinal faults in the thrust zone are mainly of the thrust slipping type. The late Quaternary motion modes and displacement rates are quite different from north to south. Investigation on valleys across the fault shows that the transverse faults are mainly of dextral strike-slipping type with a bit dip displacement. Based on their connections with the longitudinal faults, three types of transverse faults are generalized, namely: the separate fault, the transform fault and the tear fault, and their functions in the segmentation of the thrust fault zone are compared. As the result, the Yingjing-Mabian-Yanjin thrust fault zone is divided into three segments, and earthquakes occurring in these three segments are compared. The tri-section of the Yingjing-Mabian-Yanjin thrust fault zone identified by transverse fault types reflects, on the one hand, the differences in slip rate, earthquake magnitude and pace from each segment, and the coherence of earthquake rupturing pace on the other hand. It demonstrates that the transverse faults control the segmentation to a certain degree, and each type of the transverse faults plays a different role.

  14. Recent tectonic activity on Mercury revealed by small thrust fault scarps (United States)

    Watters, Thomas R.; Daud, Katie; Banks, Maria E.; Selvans, Michelle M.; Chapman, Clark R.; Ernst, Carolyn M.


    Large tectonic landforms on the surface of Mercury, consistent with significant contraction of the planet, were revealed by the flybys of Mariner 10 in the mid-1970s. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission confirmed that the planet's past 4 billion years of tectonic history have been dominated by contraction expressed by lobate fault scarps that are hundreds of kilometres long. Here we report the discovery of small thrust fault scarps in images from the low-altitude campaign at the end of the MESSENGER mission that are orders of magnitude smaller than the large-scale lobate scarps. These small scarps have tens of metres of relief, are only kilometres in length and are comparable in scale to small young scarps on the Moon. Their small-scale, pristine appearance, crosscutting of impact craters and association with small graben all indicate an age of less than 50 Myr. We propose that these scarps are the smallest members of a continuum in scale of thrust fault scarps on Mercury. The young age of the small scarps, along with evidence for recent activity on large-scale scarps, suggests that Mercury is tectonically active today and implies a prolonged slow cooling of the planet's interior.

  15. The Dauki Fault in NE India: A crustal scale thrust-fold reactivating the continental margin (United States)

    Ferguson, E. K.; Seeber, L.; Akhter, S. H.; Steckler, M. S.; Biswas, A.; Mukhopadhyay, B. P.


    New structural data along the central part of the Dauki topographic front supports the hypothesis that the Shillong Plateau is a highly asymmetric south-verging Quaternary anticline driven by a north-dipping blind thrust fault that projects into Bangladesh, south of the topographic front. This thrust-fold is tectonically more important than it appears from the relatively modest accumulated deformation, and may represent a reorganization of the eastern Himalayan front. The Dauki Fault is the most likely source of the 1897 Great Indian Earthquake and poses a hazard to densely populated areas on the Ganges-Brahmaputra Delta region. The sharp linear topographic feature often mapped as the Dauki fault is instead a contact between competent Eocene limestone and much less competent younger clastic units. This contact may be depositional or locally a secondary back thrust. While the Sylhet basin has been rapidly subsiding in the Late Quaternary, the topographic front is marked by raised and eroded river fanglomerates, thus still on the hangingwall side of the fault. Samples from these raised terraces will be dated using optically stimulated luminescence. The exposed structural relief is primarily accounted for by folding, very broad at the culmination on the "plateau," but much sharper at the southern front. In the central and steepest Cherrapunji segment of the Dauki front, the fold is marked by the erosion resistant Cretaceous-Paleocene passive-margin sequence overlying the Sylhet Traps with evidence that the Cretaceous rifting was parallel to the Dauki front. The Dauki fault, therefore, could be a passive margin-related normal fault reactivated as a thrust. The part of the forelimb exposed in the ~20 km Cherrapunji segment exhibits two sharp kinks, suggesting blind imbricates above the main blind fault. The Shillong Plateau is characterized by a two-level drainage morphology. The well-preserved Precambrian surface and its Cretaceous cover along the southern edge of the

  16. Permian magmatism, Permian detachment faulting, and Alpine thrusting in the Orobic Anticline, southern Alps, Italy (United States)

    Pohl, Florian; Froitzheim, Niko; Geisler-Wierwille, Thorsten; Schlöder, Oliver


    Lombardo. It is therefore an Alpine structure. (4) Several south-directed Alpine thrusts duplicate the lithostratigraphy, including the detachment, and are related to the Orobic thrust further north. They also offset the Biandino Fault. U-Pb zircon ages measured with LA-ICP-MS (work in progress) will further clarify the temporal relations between the intrusions, volcanics, and the shear zones. Froitzheim, N., Derks, J.F., Walter, J.M. & Sciunnach, D. 2008. Evolution of an Early Permian extensional detachment fault from synintrusive, mylonitic flow to brittle faulting (Grassi Detachment Fault, Orobic Anticline, southern Alps, Italy) Geological Society, London, Special Publications, 298; 69-82. doi:10.1144/SP298.4 Thöni, M., Mottana, A., Delitala, M. C., De Capitani, L. & Liborio, G. 1992. The Val Biandino composite pluton: A late Hercynian intrusion into the South-Alpine metamorphic basement of the Alps (Italy). Neues Jahrbuch für Mineralogie-Monatshefte, 12, 545-554. Sciunnach, D. 2001. Early Permian palaeofaults at the western boundary of the Collio Basin (Valsassina, Lombardy). Natura Bresciana. Annuario del Museo Civico di Scienze Naturali, Brescia, Monografia, 25, 37-43.

  17. The 2013, Mw 7.7 Balochistan earthquake, energetic strike-slip reactivation of a thrust fault (United States)

    Avouac, Jean-Philippe; Ayoub, Francois; Wei, Shengji; Ampuero, Jean-Paul; Meng, Lingsen; Leprince, Sebastien; Jolivet, Romain; Duputel, Zacharie; Helmberger, Don


    We analyse the Mw 7.7 Balochistan earthquake of 09/24/2013 based on ground surface deformation measured from sub-pixel correlation of Landsat-8 images, combined with back-projection and finite source modeling of teleseismic waveforms. The earthquake nucleated south of the Chaman strike-slip fault and propagated southwestward along the Hoshab fault at the front of the Kech Band. The rupture was mostly unilateral, propagated at 3 km/s on average and produced a 200 km surface fault trace with purely strike-slip displacement peaking to 10 m and averaging around 6 m. The finite source model shows that slip was maximum near the surface. Although the Hoshab fault is dipping by 45° to the North, in accordance with its origin as a thrust fault within the Makran accretionary prism, slip was nearly purely strike-slip during that earthquake. Large seismic slip on such a non-optimally oriented fault was enhanced possibly due to the influence of the free surface on dynamic stresses or to particular properties of the fault zone allowing for strong dynamic weakening. Strike-slip faulting on thrust fault within the eastern Makran is interpreted as due to eastward extrusion of the accretionary prism as it bulges out over the Indian plate. Portions of the Makran megathrust, some thrust faults in the Kirthar range and strike-slip faults within the Chaman fault system have been brought closer to failure by this earthquake. Aftershocks cluster within the Chaman fault system north of the epicenter, opposite to the direction of rupture propagation. By contrast, few aftershocks were detected in the area of maximum moment release. In this example, aftershocks cannot be used to infer earthquake characteristics.

  18. Regional post-late Miocene thrust faulting in offshore central California-implications for wrench-style tectonics

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    Crouch, J.K.; Bachman, S.


    High-resolution, deep-penetration seismic reflection data have recently been collected in the offshore Santa Maria basin, northern Santa Barbara Channel, and off Point Conception, California. These data reveal major post-late Miocene east-over-west thrust faulting in offshore central California. Recognizable on both dip and strike lines, the thrust faults are generally imbricate and curve downward to a basal sole thrust at depths of 1.5-3 km (4900-9800 ft). The offshore Santa Maria basin is generally regarded as a wrench-style basin. However, the Hosgri and other northwest-trending faults with the basin appear to be predominantly thrust rather than strike-slip faults. Also, detailed mapping within the basin indicates that the overall structural pattern does not fit accepted models of wrench tectonics; for example, folds have a preferred asymmetry and their axes closely paralleled faults rather than lie en echelon to them. It is concluded that the folds and faults as well as the present morphology of the offshore Santa Maria basin are largely due to post-late Miocene northeast-southwest compression. Similar conclusions can be drawn from the onshore Santa Maria basin on the basis of field relations and well data. These data, and the conclusions drawn from them, raise questions as to the validity of the generally accepted notion that all California Neogene basins are products of wrench-style tectonics.

  19. Fold-to-fault progression of a major thrust zone revealed in horses of the North Mountain fault zone, Virginia and West Virginia, USA (United States)

    Orndorff, Randall C.


    The method of emplacement and sequential deformation of major thrust zones may be deciphered by detailed geologic mapping of these important structures. Thrust fault zones may have added complexity when horse blocks are contained within them. However, these horses can be an important indicator of the fault development holding information on fault-propagation folding or fold-to-fault progression. The North Mountain fault zone of the Central Appalachians, USA, was studied in order to better understand the relationships of horse blocks to hanging wall and footwall structures. The North Mountain fault zone in northwestern Virginia and eastern panhandle of West Virginia is the Late Mississippian to Permian Alleghanian structure that developed after regional-scale folding. Evidence for this deformation sequence is a consistent progression of right-side up to overturned strata in horses within the fault zone. Rocks on the southeast side (hinterland) of the zone are almost exclusively right-side up, whereas rocks on the northwest side (foreland) of the zone are almost exclusively overturned. This suggests that the fault zone developed along the overturned southeast limb of a syncline to the northwest and the adjacent upright limb of a faulted anticline to the southeast.

  20. Fold-to-Fault Progression of a Major Thrust Zone Revealed in Horses of the North Mountain Fault Zone, Virginia and West Virginia, USA

    Directory of Open Access Journals (Sweden)

    Randall C. Orndorff


    Full Text Available The method of emplacement and sequential deformation of major thrust zones may be deciphered by detailed geologic mapping of these important structures. Thrust fault zones may have added complexity when horse blocks are contained within them. However, these horses can be an important indicator of the fault development holding information on fault-propagation folding or fold-to-fault progression. The North Mountain fault zone of the Central Appalachians, USA, was studied in order to better understand the relationships of horse blocks to hanging wall and footwall structures. The North Mountain fault zone in northwestern Virginia and eastern panhandle of West Virginia is the Late Mississippian to Permian Alleghanian structure that developed after regional-scale folding. Evidence for this deformation sequence is a consistent progression of right-side up to overturned strata in horses within the fault zone. Rocks on the southeast side (hinterland of the zone are almost exclusively right-side up, whereas rocks on the northwest side (foreland of the zone are almost exclusively overturned. This suggests that the fault zone developed along the overturned southeast limb of a syncline to the northwest and the adjacent upright limb of a faulted anticline to the southeast.

  1. Influence of mobile shale on thrust faults: Insights from discrete element simulations (United States)

    Dean, S. L.; Morgan, J. K.


    thrusts are listric, similar to those in the Niger Delta, steepening updip and curving near the intersection with the mobile shale layer. The décollements in our simulations, however, are much more diffuse then interpreted in nature. Discrete thrust faults within the pre-delta layer sole into broader zones of distributed strain within the mobile shale layer. In the frontal fold and thrust belt, both backthrusts and forethrusts were observed, also seen in the western lobe of the Niger Delta. In our simulations, this dual vergence is caused by the rotation of the principal stress in the pre-delta layer from sub-vertical under the sediment wedge, to nearly horizontal in front of the wedge. This rotation is thought to be due to a basinward 'push' created by updip extension along normal faults, which slide within the mobile layer and along the base of the model. This rotation of stresses is not found in the underlying weak mobile layer. The amount of contraction in the fold and thrust belt was about half the amount of extension accommodated beneath the sediment wedge, indicating that a large amount of contraction was distributed throughout the models, including in front of the toe thrusts, rather than being concentrated solely in the fold and thrust belt.

  2. Accelerating slip rates on the puente hills blind thrust fault system beneath metropolitan Los Angeles, California, USA (United States)

    Bergen, Kristian J; Shaw, John H.; Leon, Lorraine A; Dolan, James F; Pratt, Thomas L.; Ponti, Daniel J.; Morrow, Eric; Barrera, Wendy; Rhodes, Edward J.; Murari, Madhav K.; Owen, Lewis


    Slip rates represent the average displacement across a fault over time and are essential to estimating earthquake recurrence for proba-bilistic seismic hazard assessments. We demonstrate that the slip rate on the western segment of the Puente Hills blind thrust fault system, which is beneath downtown Los Angeles, California (USA), has accel-erated from ~0.22 mm/yr in the late Pleistocene to ~1.33 mm/yr in the Holocene. Our analysis is based on syntectonic strata derived from the Los Angeles River, which has continuously buried a fold scarp above the blind thrust. Slip on the fault beneath our field site began during the late-middle Pleistocene and progressively increased into the Holocene. This increase in rate implies that the magnitudes and/or the frequency of earthquakes on this fault segment have increased over time. This challenges the characteristic earthquake model and presents an evolving and potentially increasing seismic hazard to metropolitan Los Angeles.

  3. Length-displacement scaling of thrust faults on the Moon and the formation of uphill-facing scarps (United States)

    Roggon, Lars; Hetzel, Ralf; Hiesinger, Harald; Clark, Jaclyn D.; Hampel, Andrea; van der Bogert, Carolyn H.


    Fault populations on terrestrial planets exhibit a linear relationship between their length, L, and the maximum displacement, D, which implies a constant D/L ratio during fault growth. Although it is known that D/L ratios of faults are typically a few percent on Earth and 0.2-0.8% on Mars and Mercury, the D/L ratios of lunar faults are not well characterized. Quantifying the D/L ratios of faults on the Moon is, however, crucial for a better understanding of lunar tectonics, including for studies of the amount of global lunar contraction. Here, we use high-resolution digital terrain models to perform a topographic analysis of four lunar thrust faults - Simpelius-1, Morozov (S1), Fowler, and Racah X-1 - that range in length from 1.3 km to 15.4 km. First, we determine the along-strike variation of the vertical displacement from ≥ 20 topographic profiles across each fault. For measuring the vertical displacements, we use a method that is commonly applied to fault scarps on Earth and that does not require detrending of the profiles. The resulting profiles show that the displacement changes gradually along these faults' strike, with maximum vertical displacements ranging from 17 ± 2 m for Simpelius-1 to 192 ± 30 m for Racah X-1. Assuming a fault dip of 30° yields maximum total displacements (D) that are twice as large as the vertical displacements. The linear relationship between D and L supports the inference that lunar faults gradually accumulate displacement as they propagate laterally. For the faults we investigated, the D/L ratio is ∼2.3%, an order of magnitude higher than theoretical predictions for the Moon, but a value similar for faults on Earth. We also employ finite-element modeling and a Mohr circle stress analysis to investigate why many lunar thrust faults, including three of those studied here, form uphill-facing scarps. Our analysis shows that fault slip is preferentially initiated on planes that dip in the same direction as the topography, because

  4. Lateral structural variation along the Kalabagh Fault Zone, NW Himalayan foreland fold-and-thrust belt, Pakistan (United States)

    Khan, Shuhab D.; Chen, Lize; Ahmad, Sajjad; Ahmad, Irshad; Ali, Fayaz


    The NW Himalayan fold-and-thrust belt in Pakistan is of gentler regional slope and wider extent than the other parts of the convergent plate boundary between India and the rest of Asia. Large scale structural re-entrants typify the Main Frontal Thrust (MFT) of the NW Himalayan fold-and-thrust belt in Pakistan. Understanding dynamics of the formation of these structural variations has been hampered by the lack of information about the lateral structures bounding the re-entrants. Our mapping of the Kalabagh Fault Zone, a lateral ramp linking the Salt and the Surghar Ranges, advanced spaceborne thermal emission and reflection radiometer (ASTER) data, field investigations and the interpreted reprocessed 2D seismic data. This integration of surface and subsurface geology provides new insights on the geometry and evolution of the Kalabagh Fault Zone, by showing that it forms an oblique ramp to the Main Frontal Thrust, and at north a lateral ramp with right-lateral strike slip movement. Our results indicate that the presence and areal extent of the evaporates is the dominant factor controlling lateral structural variation in the NW Himalayan fold-and-thrust belt of Pakistan. The Kalabagh Fault Zone acts as a zone that accommodates differential shortening and structural variation along the orogenic trend.

  5. Wave characteristics and tectonic-sedimentation evolution of foreland thrust fault of Micang Mountain

    Institute of Scientific and Technical Information of China (English)


    In this paper,the technology of wave process method for sedimentation is first adopted in the research of the foreland thrust fault of Micang Mountain with respect of oil and reservoir’s formation and tectonic and sedimentary evolution. From the fluctuation characteristics,we could make conclusions in the foreland thrust belt of Micang Mountain that,there existed 2 first-order sedimentary cycles (220 Ma),corresponding to Caledonian-Hercynian and Indo-Chinese-Yanshan-Himalayan tectonic cycles respec-tively; there existed 4 second-order sedimentary cycles (10 Ma),corresponding to two sedimentation peak period and two denudation peak periods in research zone; there existed 12 third-order sedimen-tary cycles (35 Ma) and 21 fourth-sedimentary cycles (20 Ma). These 33 cycles in the research zone corresponded to the sedimentation-denudation process in different periods,furthermore,their fluctua-tion characteristics bore the genetic relationship with the development law of source,reservoir and cap rocks: the source rock had the tendency to develop at the turning part between wave crest and wave trough,or at the superposition of wave turning part in different periods,presenting like "X"; most res-ervoir rocks developed at the place of wave peak; the development of cap rock was located in the wave trough on the right of sedimentation-denudation datum line. As a result,through the application of wave process method for sedimentation,we could rediscover the understanding of the tectonic and sedimentary evolution from another prospective,meanwhile,it enables to make prediction about the development rule of source,reservoir and cap rocks,which means a significant importance to the re-search of oil and reservoir’s forming condition.

  6. Role of Fault Dilatancy in Subduction Zone Aseismic Deformation Transients and Thrust Earthquakes (United States)

    Liu, Y.; Rubin, A. M.; Rice, J. R.; Segall, P.


    -dipping subduction fault model using recently reported hydrothermal gabbro gouge friction data [He et al., Tectonophys., 2006, 2007]. The along-dip elevated p is constrained by seismological observations and by thermal and petrological models for the northern Cascadia margin (p near-lithostatic around stability transition and lower in the seismogenic zone). Similarly, aseismic transients can exist for a much broader range of W / h★, making it plausible to produce transients with total slips of a few centimeters and recurrence periods of a couple years while using lab values for L of 10s of microns in the low σ× zone. Inclusion of dilatancy also reduces the speed and spatial extent of coseismic rupture. For a fixed T = 1 and ɛ / β = 0.2 MPa, rupture stops ~ 50 km up-dip of the lower stability transition and causes nearly no coseismic slip at the trench. The depth of complete interseismic locking also varies with parameters E and T in the seismogenic zone. This suggests that a subduction fault extending well down-dip of the limit of seismogenesis could be frictionally unstable (a-b<0) but undergo no seismic slip due to effective dilatancy stabilization. This has implications for the relative depths of slow slip events and thrust earthquakes and for the total slip budget in an earthquake cycle.

  7. Lithologic Controls on Structure Highlight the Role of Fluids in Failure of a Franciscan Complex Accretionary Prism Thrust Fault (United States)

    Bartram, H.; Tobin, H. J.; Goodwin, L. B.


    Plate-bounding subduction zone thrust systems are the source of major earthquakes and tsunamis, but their mechanics and internal structure remain poorly understood and relatively little-studied compared to faults in continental crust. Exposures in exhumed accretionary wedges present an opportunity to study seismogenic subduction thrusts in detail. In the Marin Headlands, a series of thrusts imbricates mechanically distinct lithologic units of the Mesozoic Franciscan Complex including pillow basalt, radiolarian chert, black mudstone, and turbidites. We examine variations in distribution and character of structure and vein occurrence in two exposures of the Rodeo Cove thrust, a fossil plate boundary exposed in the Marin Headlands. We observe a lithologic control on the degree and nature of fault localization. At Black Sand Beach, deformation is localized in broad fault cores of sheared black mudstone. Altered basalts, thrust over greywacke, mudstone, and chert, retain their coherence and pillow structures. Veins are only locally present. In contrast, mudstone is virtually absent from the exposure 2 km away at Rodeo Beach. At this location, deformation is concentrated in the altered basalts, which display evidence of extensive vein-rock interaction. Altered basalts exhibit a pervasive foliation, which is locally disrupted by both foliation-parallel and cross-cutting carbonate-filled veins and carbonate cemented breccia. Veins are voluminous (~50%) at this location. All the structures are cut by anastomosing brittle shear zones of foliated cataclasite or gouge. Analyses of vein chemistry will allow us to compare the sources of fluids that precipitated the common vein sets at Rodeo Beach to the locally developed veins at Black Sand Beach. These observations lead us to hypothesize that in the absence of a mechanically weak lithology, elevated pore fluid pressure is required for shear failure. If so, the vein-rich altered basalt at Rodeo Beach may record failure of an

  8. Determination of a Holocene Slip Rate on the Puente Hills Blind-Thrust Fault, Los Angeles Basin, California (United States)

    Christofferson, S. A.; Dolan, J. F.; Shaw, J. H.; Pratt, T. L.


    Paleoseismologic observations of slip histories and slip rates of faults that break the surface are available at an ever-increasing rate, but the nature of blind-thrust faults has kept paleoearthquake information on these faults out of reach. The complex network of blind thrust faults beneath the Los Angeles metropolitan region includes the Puente Hills thrust fault (PHT), which extends southeastward for >35 km from beneath downtown Los Angeles into northern Orange County. This thrust is active, as demonstrated by the occurrence of the 1987 Mw 6.0 Whittier Narrows earthquake (Shaw and Shearer 1999). Despite our awareness of the hazard posed by this fault, we do not know its current slip rate or its earthquake history prior to the 1987 event. To determine these critical data, we have begun a two-phase project in which we will acquire high-resolution seismic reflection data and excavate paleoseismologic boreholes and trenches across the zone of active folding associated with major earthquakes on the PHT. We have acquired high-resolution seismic reflection profiles along two transects across the zone of active folding. In our eastern most profile, along Trojan Way in La Mirada, the seismic reflection data show that the locus of active folding extends to 1.5- 2-m-thick reddish-brown argillic horizon. This soil indicates that the geomorphic surface atop the scarp is late Pleistocene in age. The 9 m height of the scarp provides a minimum estimate of total structural relief since stabilization of the ground surface. These observations yield an approximate uplift rate on the order of a few tenths of a mm/yr. Assuming simple hangingwall block translation and given the 19° -22° N dip of the PHT beneath the site, we calculate a minimum average late Pleistocene-Recent dip-slip rate of \\sim 0.2 to 1.1 mm/yr. This slip-rate range is based on our crude age estimates of the late Pleistocene soil. 14C dating of detrital charcoal recovered from the borehole will allow us to

  9. Active faulting within a megacity: the geometry and slip rate of the Pardisan thrust in central Tehran, Iran (United States)

    Talebian, M.; Copley, A. C.; Fattahi, M.; Ghorashi, M.; Jackson, J. A.; Nazari, H.; Sloan, R. A.; Walker, R. T.


    Tehran, the capital city of Iran with a population of over 12 million, is one of the largest urban centres within the seismically active Alpine-Himalayan orogenic belt. Although several historic earthquakes have affected Tehran, their relation to individual faults is ambiguous for most. This ambiguity is partly due to a lack of knowledge about the locations, geometries and seismic potential of structures that have been obscured by dramatic urban growth over the past three decades, and which have covered most of the young geomorphic markers and natural exposures. Here we use aerial photographs from 1956, combined with an ˜1 m DEM derived from stereo Pleiades satellite imagery to investigate the geomorphology of a growing anticline above a thrust fault-the Pardisan thrust-within central Tehran. The topography across the ridge is consistent with a steep ramp extending from close to the surface to a depth of ˜2 km, where it presumably connects with a shallow-dipping detachment. No primary fault is visible at the surface, and it is possible that the faulting dissipates in the near surface as distributed shearing. We use optically stimulated luminescence to date remnants of uplifted and warped alluvial deposits that are offset vertically across the Pardisan fault, providing minimum uplift and slip-rates of at least 1 mm yr-1. Our study shows that the faults within the Tehran urban region have relatively rapid rates of slip, are important in the regional tectonics, and have a great impact on earthquake hazard assessment of the city and surrounding region.

  10. Fault Geometry beneath the Chittagong-Myanmar Fold and Thrust Belt, Bangladesh, and Implications for Earthquake Hazard (United States)

    Burgi, P.; Hubbard, J.; Peterson, D. E.; Akhter, S. H.


    Bangladesh sits on the seismically active Chittagong-Myanmar Fold and Thrust Belt (CMFB), a partially exposed accretionary prism on the eastern margin of the India-Eurasia collision. Earthquakes on the basal décollement and emergent thrusts beneath and within the CMFB present a potential hazard to Bangladesh, one of the most densely populated countries in the world. Geodetic data suggest that the faults associated with the CMFB may be locked and accumulating 13 mm/yr of elastic strain (Steckler et al., 2016). However, accurate inversion of geodetic data requires data-constrained fault geometries to produce elastic loading models, particularly because of the shallow nature of these faults. In this study, we use both published and unpublished seismic reflection profiles and velocity data to locate the shallow décollement below east Bangladesh and the Indian state of Tripura. We then fit a surface to this data to constrain the overall geometry of the décollement. Seismic data reveal that the décollement is located at 9-10 km depth in northeast and southeast Bangladesh, but shallows to 5-6 km in the central portion of east Bangladesh. This shallow portion of the décollement is located in the region beneath the western-most exposed anticlines, as well as the northern extent of the Bay of Bengal. An important implication of this configuration is that the corrugated nature of this fault could act as a rupture barrier, were a large earthquake to occur on the basal décollement. The thrust faults that rise from the décollement and produce the anticlines within the CMFB may also be capable of slipping in earthquakes. The outermost folds in the CMFB appear to be detachment folds, whereas folds in the inner CMFB are cored by faults. This implies that deformation begins as distributed shearing and evolves into brittle deformation as the fold grows over time. Further efforts to invert geodetic data and model earthquakes on this large, subaerial fault system are necessary

  11. Study of blind thrust faults underlying Tokyo and Osaka urban areas using a combination of high-resolution seismic reflection profiling and continuous coring

    Directory of Open Access Journals (Sweden)

    K. Miura


    Full Text Available We acquired high-resolution seismic reflection profiles and continuously cored boreholes to evaluate active flexures produced by major blind thrust fault systems within two densely populated Neogene-Quaternary sedimentary basins in Japan: the Fukaya Fault System near Tokyo in the Kanto Basin and the Uemachi Fault System in the Osaka Basin. The high-resolution seismic reflection survey made clear the length, geometry and growth history of fault-related folds, or flexures formed above the two blind thrusts. Continuously cored boreholes linked with high-resolution seismic profiles enabled us to estimate the uplift rate as defined by shallow stratigraphic horizons and constrain the age of the most recent growth of the flexures during earthquakes on the Fukaya and Uemachi fault systems. Even with the high quality of the data we collected, it is still not possible to exactly constrain the age of the most recent blind thrust earthquake recorded by flexure of these fault-related folds. Data presented in this paper form the basis for future efforts aimed at mechanical and kinematic models for fault growth to evaluate the activity of blind thrusts underlying urban areas.

  12. Near-Surface & High Resolution Seismic Imaging of the Bennett Thrust Fault in the Indio Mountains of West Texas (United States)

    Vennemann, A.; Karplus, M. S.; Kaip, G.; Harder, S. H.


    We investigate the crustal structure of the Indio Mountains in southwest Texas, 34 km southwest of Van Horn at the University of Texas at El Paso (UTEP) field station using newly acquired active-source seismic data. These new data are the first active-source seismic data acquired at the UTEP field station. The dominant regional lithologies in this area comprise a transgressive sequence nearly 2 km in total stratigraphic thickness, formed by extensional processes. The area is highly faulted with multiple fault generations. I will show images of the Bennett Thrust Fault, a northwest-striking, northeast-dipping fault associated with the Laramide Orogeny and discuss the near-surface geometries of this fault and adjacent rock units. This region is a pre-salt analog for similar areas that are ideal for petroleum reservoirs, such are reservoirs off the coasts of Brazil and Angola. While there are no petroleum plays in the Indio Mountains region, imaging and understanding subsurface structural and lithological geometries and how that geometry directs potential fluid flow has implications for other regions with petroleum plays. I will present processed data and interpretation of a 1 km 2-D near-surface, high-resolution seismic reflection line. Along the 1 km line, we collected a lower frequency dataset using 100 third-pound explosions and a higher frequency dataset produced from 500 sledge-hammer blows at the same 100 source points (5 blows will be stacked at each source point). The lower frequency data set will be the focus of this presentation. The data will be processed using standard seismic reflection practices using ProMAX. This image will be imported into Petrel to create a model of the faults' geometries and the sedimentary layers. My research will identify near-surface structures, fault geometries and lithologies.

  13. Holocene internal shortening within the northwest Sub-Himalaya: Out-of-sequence faulting of the Jwalamukhi Thrust, India (United States)

    Dey, Saptarshi; Thiede, Rasmus C.; Schildgen, Taylor F.; Wittmann, Hella; Bookhagen, Bodo; Scherler, Dirk; Strecker, Manfred R.


    The southernmost thrust of the Himalayan orogenic wedge that separates the foreland from the orogen, the Main Frontal Thrust, is thought to accommodate most of the ongoing crustal shortening in the Sub-Himalaya. Steepened longitudinal river profile segments, terrace offsets, and back-tilted fluvial terraces within the Kangra reentrant of the NW Sub-Himalaya suggest Holocene activity of the Jwalamukhi Thrust (JMT) and other thrust faults that may be associated with strain partitioning along the toe of the Himalayan wedge. To assess the shortening accommodated by the JMT, we combine morphometric terrain analyses with in situ 10Be-based surface-exposure dating of the deformed terraces. Incision into upper Pleistocene sediments within the Kangra Basin created two late Pleistocene terrace levels (T1 and T2). Subsequent early Holocene aggradation shortly before 10 ka was followed by episodic reincision, which created four cut-and-fill terrace levels, the oldest of which (T3) was formed at 10.1 ± 0.9 ka. A vertical offset of 44 ± 5 m of terrace T3 across the JMT indicates a shortening rate of 5.6 ± 0.8 to 7.5 ± 1.1 mm a-1 over the last 10 ka. This result suggests that thrusting along the JMT accommodates 40-60% of the total Sub-Himalayan shortening in the Kangra reentrant over the Holocene. We speculate that this out-of-sequence shortening may have been triggered or at least enhanced by late Pleistocene and Holocene erosion of sediments from the Kangra Basin.

  14. Multidisciplinary approach to constrain kinematics of fault zones at shallow depths: a case study from the Cameros-Demanda thrust (North Spain) (United States)

    Casas-Sainz, A. M.; Román-Berdiel, T.; Oliva-Urcia, B.; García-Lasanta, C.; Villalaín, J. J.; Aldega, L.; Corrado, S.; Caricchi, C.; Invernizzi, C.; Osácar, M. C.


    Thrusting at shallow depths often precludes analysis by means of structural indicators effective in other geological contexts (e.g., mylonites, sheath folds, shear bands). In this paper, a combination of techniques (including structural analysis, magnetic methods, as anisotropy of magnetic susceptibility and paleomagnetism, and paleothermometry) is used to define thrusting conditions, deformation, and transport directions in the Cameros-Demanda thrust (North Spain). Three outcrops were analyzed along this intraplate, large-scale major structure having 150 km of outcropping length, 30 km of maximum horizontal displacement, and 5 km of vertical throw. Results obtained by means of the different techniques are compared with data derived from cross sections and stratigraphic analysis. Mixed-layer illite-smectite and vitrinite reflectance indicating deep diagenetic conditions and mature stage of hydrocarbon generation suggests shallow depths during deformation, thus confirming that the protolith for most of the fault rocks is the footwall of the main thrust. Kinematic indicators (foliation, S/C structures, and slickenside striations) indicate altogether a dominant NNW movement of the hanging wall in the western zone and NE in the eastern zone of the thrust, thus implying strain partitioning between different branches of the main thrust. The study of AMS in fault rocks (nearly 400 samples of fault gouge, breccia, and microbreccia) indicates that the strike of magnetic foliation is oblique to the transport direction and that the magnetic lineation parallelizes the projection of the transport direction onto the k max/ k int plane in sites with strong shear deformation. Paleomagnetism applied to fault rocks indicates the existence of remagnetizations linked to thrusting, in spite of the shallow depth for deformation, and a strong deformation or scattering of the magnetic remanence vectors in the fault zone. The application of the described techniques and consistency of

  15. The Relationship Between the Surface Expression of Blind Thrust Faults and Crustal-Scale Deformation in the Eastern Precordillera, San Juan, Argentina (United States)

    Schiffman, C. R.; Meigs, A. J.


    Large earthquakes (M w 6.5+) are often accompanied by surface rupture that has a predictable relationship with the magnitude. However, in large thrust earthquakes that have a deep (30+ km) hypocenter or fault tip, coseismic surface deformation is expressed primarily by folding rather than as rupture along the fault surface. Knowledge of source characteristics and surficial geology are required to characterize the relationship between earthquake fault slip and coseismic folding. By fully identifying and characterizing the fault plane of the M w 7.4 earthquake that occurred in 1944 in the eastern Precordillera of the Andes, destroying the city of San Juan in northwestern Argentina, we seek to relate active folding in the near-surface structures to the blind-thrust fault at depth. Coseismic deformation associated with the 1944 earthquake are secondary fault-related folding features, and there is a large discrepancy between the amount of surface rupture and the magnitude. Subtle fold-related clues at the surface represent the only potential for recognition of the occurrence of past earthquakes. This two-part study employs seismology and structural mapping to provide a new image of the Eastern Precordillera at the crustal scale. Source parameter inversion of teleseismic seismograms from the 1944 event place the hypocenter on a west-dipping plane approximately 30 km deep, which has previously been defined by microseismicity, as opposed to a surface-rupturing event in the Neogene sedimentary strata. Preliminary results from field mapping show two types of folding due to a west-dipping thrust fault with a tip at 5 km depth: a broad long-wavelength fold (~8 km) in deformed strath terraces cut into previously deformed bedrock, and short wavelength folding and faulting in the bedrock in the form of reactivation of older thrust planes. As of now, we cannot uniquely tie any one of these surficial structure to the thrust fault at depth because the pre-existing deformation in the

  16. Stress transfer among en echelon and opposing thrusts and tear faults: Triggering caused by the 2003 Mw = 6.9 Zemmouri, Algeria, earthquake (United States)

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


    The essential features of stress interaction among earthquakes on en echelon thrusts and tear faults were investigated, first through idealized examples and then by study of thrust faulting in Algeria. We calculated coseismic stress changes caused by the 2003 Mw = 6.9 Zemmouri earthquake, finding that a large majority of the Zemmouri afterslip sites were brought several bars closer to Coulomb failure by the coseismic stresses, while the majority of aftershock nodal planes were brought closer to failure by an average of ~2 bars. Further, we calculated that the shallow portions of the adjacent Thenia tear fault, which sustained ~0.25 m slip, were brought >2 bars closer to failure. We calculated that the Coulomb stress increased by 1.5 bars on the deeper portions of the adjacent Boumerdes thrust, which lies just 10–20 km from the city of Algiers; both the Boumerdes and Thenia faults were illuminated by aftershocks. Over the next 6 years, the entire south dipping thrust system extending 80 km to the southwest experienced an increased rate of seismicity. The stress also increased by 0.4 bar on the east Sahel thrust fault west of the Zemmouri rupture. Algiers suffered large damaging earthquakes in A.D. 1365 and 1716 and is today home to 3 million people. If these shocks occurred on the east Sahel fault and if it has a ~2 mm/yr tectonic loading rate, then enough loading has accumulated to produce a Mw = 6.6–6.9 shock today. Thus, these potentially lethal faults need better understanding of their slip rate and earthquake history.

  17. Assessing Fault Slip Behavior and the History of Fluid-Rock Interaction of The Rodeo Cove Thrust, Franciscan Complex (United States)

    Bartram, H.; Goodwin, L. B.; Tobin, H. J.


    Internal mechanical properties and stress conditions in subduction megathrusts remain poorly understood. We present a study of fault rocks and veins to elucidate controls on fault slip behavior in the Rodeo Cove thrust zone, a fossil plate boundary exposed in two coastal outcrops of the Mesozoic Franciscan accretionary complex: Rodeo Beach (RB) and Black Sand Beach (BSB). Thrusts imbricate mechanically distinct lithologic units including pillow basalt, radiolarian chert, black shale, and greywacke. Locally large vein-to-rock ratios record significant fluid flux and mineral precipitation during deformation. Cross-cutting relations at outcrop- and micro-scale reveal a complex history of fluid-rock interaction followed by brittle shearing. At RB, fault-related deformation is commonly concentrated in altered basalts in which original, isotropic igneous microstructures are preserved but rocks are more commonly foliated. These structures are locally disrupted by foliation-parallel and cross-cutting calcite veins as well as calcite-cemented breccia. Veins are less common at BSB, where they are found in altered basalt and greywacke near black shales. Stable isotope chemistry of calcite records differing fluid sources at these two locations. At RB, δ18O values range from 17.5—22.4‰ SMOW compared to 16.9—21.4‰ SMOW at BSB. These relatively high δ18O values may reflect upward movement of metamorphic fluids along the fault. The RB δ13C values (-2.0—+2.9‰ VPDB) are similar to those of marine carbonates precipitated from seawater and are considerably higher than the BSB values (-16.8—+3.0‰ VPDB), which suggest a possible biogenic source of carbon consistent with fluid interaction with black shale. Optical cathodoluminescence of calcite reveals complex internal structures that will be correlated with quantitative chemical analysis using an electron microprobe. Anastomosing localized brittle shear zones of foliated cataclasite or gouge cut veins at RB and

  18. Non-linear Flight Dynamics at High Angles of Attack

    DEFF Research Database (Denmark)

    Granasy, P.; Sørensen, C.B.; Mosekilde, Erik


    The methods of nonlinear dynamics are applied to the longitudinal motion of a vectored thrust aircraft, in particular the behavior at high angles of attack. Our model contains analytic nonlinear aerodynamical coefficients based on NASA windtunnel experiments on the F-18 high-alpha research vehicle...... (HARV). When the aircraft is forced with small thrust deflections whilst in poststall equilibrium, chaotic motion is observed at certain frequencies. At other frequencies, several limiting states coexist....

  19. Three-dimensional Geometry of Buried Fold Scarps Associated With Ancient Earthquakes on the Puente Hills Blind Thrust Fault (United States)

    Leon, L. A.; Dolan, J. F.; Hoeft, J. S.; Shaw, J. H.; Hartleb, R. D.


    The Puente Hills thrust fault (PHT) is a large blind thrust fault that extends east-west beneath the heart of the metropolitan Los Angeles region (Shaw and Shearer, 1999; Shaw et al., 2003). Christofferson (2002; in prep.) and Dolan et al. (2003) identified four buried fold scarps associated with large (Mw greater than or equal to 7), ancient earthquakes on the PHT beneath the City of Bellflower, in northern Orange County. One of the major outstanding questions regarding this research concerns the subsurface, three-dimensional geometry of these buried scarps. Specifically, we want to determine the extent to which the subsurface geometry of these scarps is controlled by tectonic versus fluvial processes. In order to begin addressing these questions, we drilled a north-south transect of hollow-stem, continuously cored boreholes across the buried fold scarps. This new borehole transect, which comprises six, 20-m-deep boreholes, was drilled parallel to, and ˜ 100 m west of, the original Carfax Avenue transect of Christofferson (2002) and Dolan et al. (2003). The overall pattern of progressive southward thickening of sedimentary units observed in the Carfax borehole transect extends westward to the new transect. Moreover, several key sedimentary contacts that are traceable laterally between the two transects occur at approximately the same depths at all locations along both transects. This three-dimensional data set thus defines several buried fold scarps that extend east-west beneath the study site. These observations confirm that the buried scarps are primarily tectonic, rather than fluvial features.

  20. Precise timing of the Early Paleozoic metamorphism and thrust deformation in the Eastern Kunlun Orogen

    Institute of Scientific and Technical Information of China (English)


    In Dulan County, Qinghai Province NW China, the arc volcanic sequences in the northern side of the Central Fault of the East Kunlun were metamorphosed progressively from upper greenschist facies in the south to epidote-amphibolite facies in the north. High-angle thrust deforma-tion was developed synchronously with the peak metamor-phim and superimposed with later low-angle striking-slip deformation. Zircon U-Pb dating yields a concordant age of (448 ± 4) Ma for the metavolcanics. Syn-kinematic horn-blende and muscovite separated from the high-angle thrust-ing belt give 40Ar-39Ar plateau age of (427 ± 4) Ma and 408 Ma, respectively. These results precisely constrain the timing of the closure of early Paleozoic volcanic basin (Proto-Tethys) over the eastern portion of the East Kunlun Orogen, and the thrust tectonic slice had a cool rate of ca. 9℃/Ma.

  1. Thrust fault modeling and Late-Noachian lithospheric structure of the circum-Hellas region, Mars (United States)

    Egea-Gonzalez, Isabel; Jiménez-Díaz, Alberto; Parro, Laura M.; López, Valle; Williams, Jean-Pierre; Ruiz, Javier


    The circum-Hellas area of Mars borders Hellas Planitia, a giant impact ∼4.0-4.2 Ga old making the deepest and broadest depression on Mars, and is characterized by a complex pattern of fracture sets, lobate scarps, grabens, and volcanic plains. The numerous lobate scarps in the circum-Hellas region mainly formed in the Late Noachian and, except Amenthes Rupes, have been scarcely studied. In this work, we study the mechanical behavior and thermal structure of the crust in the circum-Hellas region at the time of lobate scarp formation, through the modeling of the depth of faulting beneath several prominent lobate scarps. We obtain faulting depths between ∼13 and 38 km, depending on the lobate scarp and accounting for uncertainty. These results indicate low surface and mantle heat flows in Noachian to Early Hesperian times, in agreement with heat flow estimates derived from lithospheric strength for several regions of similar age on Mars. Also, faulting depth and associate heat flows are not dependent of the local crustal thickness, which supports a stratified crust in the circum-Hellas region, with heat-producing elements concentrated in an upper layer that is thinner than the whole crust.

  2. Thrust faulting and 3D ground deformation of the 3 July 2015 Mw 6.4 Pishan, China earthquake from Sentinel-1A radar interferometry (United States)

    Sun, Jianbao; Shen, Zheng-Kang; Li, Tao; Chen, Jie


    Boosted by the launch of Sentinel-1A radar satellite from the European Space Agency (ESA), we now have the opportunity of fast, full and multiple coverage of the land based deformation field of earthquakes. Here we use the data to investigate a strong earthquake struck Pishan, western China on July 3, 2015. The earthquake fault is blind and no ground break features are found on-site, thus Synthetic Aperture Radar (SAR) data give full play to its technical advantage for the recovery of coseismic deformation field. By using the Sentinel-1A radar data in the Interferometric Wide Swath mode, we obtain 3 tracks of InSAR data over the struck region, and resolve the 3D ground deformation generated by the earthquake. Then the Line-of-Sight (LOS) InSAR data are inverted for the slip-distribution of the seismogenic fault. The final model shows that the earthquake is completely blind with pure-thrust motion. The maximum slip is 0.48 m at a depth of 7 km, consistent with the depth estimate from seismic reflection data. In particular, the inverted model is also compatible with a south-dipping fault ramp among a group of fault interfaces detected by the seismic reflection profile over the region. The seismic moment obtained equals to a Mw 6.4 earthquake. The Pishan earthquake ruptured the frontal part of the thrust ramps under the Slik anticline, and unloaded the coulomb stress of them. However, it may have loaded stress to the back-thrust above the thrust ramps by 1-4 bar, and promoted it for future failure. Moreover, the stress loading on the west side of the earthquake fault is much larger than that on the east side, indicating a higher risk for failure to the west of the Zepu fault.

  3. Development of deep-seated joint sets in the early stage of mountain building and its role on subsequent micro faulting during thrust stacking: a case study in the northern fold-and-thrust belt of Taiwan (United States)

    Lee, J.; CHU, H.; Angelier, J.


    Systematic joint sets are one of the most common and persistent features within a brittle deformation regime, usually found in intact rocks, such as massive sandstone. However, joint occurrence can take place under different circumstances from very shallow to rather deep crust, which pose challenges for understanding the mechanisms of its development and thus provokes debates in past decades. In this study, we characterize the deformation structures, including micro fault and joint, by comparing their geometric relation with stratigraphic bedding plane. We intend not only to differentiate the relative chronology of different structures but also to determine the chronological orders and stages during thrust stacking processes in which rocks exhume from depths to surface. We take the northern fold-and-thrust belt of Taiwan as our case study area. It is composed of Pleistocene to Oligocene, terrestrial to shallow marine sedimentary deposits, which was exhumed accompanied with a series of imbricate thrusts during the Plio-Pleistocene orogeny of arc-continent collision between the Philippine Sea and Eurasian plates. We study four cross sections from little deformed rock formations in the foreland to intense folded and even slightly metamorphosed terrains in the slate belt, in order to characterize and distinguish different brittle structures at different depths. Particular attention is paid to the development of the joint sets at different depths and their relationship with the bedding plane where joints happen to occur. We found that 1) the most predominant joint sets are deep-seated and tectonics related, in comparison with shallow released joints, although their relation with tectonic stress orientation remains inconclusive; 2) the onset depths of development of joint sets can be as shallow as 1-2 km and as deep as 10-15 km. As to whether the development occurs during burial or exhumation, it remains questionable; 3) micro faults with striated slip, mainly under NW

  4. In-situ Stresses, Pore-fluid Pressures and Uplift Erosion in Relation to Active Thrust Faulting in western Taiwan (United States)

    Hung, J.; Yen, P.; Wang, L.


    We have studied the in-situ stresses, pore-fluid pressures and amounts of uplift erosion (UE) from petroleum wells drilled in the Hsinchu-Taichung area of western Taiwan Fold-thrust Belt. The average gradient of regional vertical stress (Sv) calculated from formation density logs is about 23 MPa/km. The magnitude of pore pressure (Pp) is estimated from mud pressure, gas cut and repeat formation test (RFT) in reservoir sandstone, and sonic logs. P-wave travel time in shale (STT) is used to determine the fluid-retention depth (ZFRD) which defines current fully compacted sediments with hydrostatic pressures above and undercompacted, overpressured zones below. Regional ZFRD is ~ 3 km except in the Chuhuangkeng anticline, where ZFRD is at shallower depth (~ 2.2 km) and extremely high pore pressure (λ=0.8) is also observed.. Calculated amounts of UE increase from 0.6 to 4.6 km eastward from outer to inner Foothills belt and correspond to stratigraphy downward and depth upward migration of the ZFRD. Along-strike variation of UE is insignificant. Hydraulic fracturing data including leak-off tests (LOTs) and mini-fracs, as well as qualitative data such as mud loss, are used to constrain the minimum horizontal stress (Shmin). The linear gradient of Shmin is about 17~19 MPa/km, relatively less than that of Sv (~23.60 MPa/km). This implies the in-situ stresses are at strike-slip (SHmax>SV>Shmin) to reverse fault considering focal mechanisms of seismicity are dominant by these two stress regimes in the study area. An upper-bound value of the maximum horizontal stress (SHmax) constrained by frictional limits and the coefficient of friction (μ=0.6) can be estimated from Anderson (1951) faulting criterion. Caliper logs from 8 wells are used to calculate the orientations of the maximum horizontal stresses following the definitions of borehole breakout in World Stress Map. The maximum horizontal stress axis is oriented in NW-SE but local variations occur when passing through

  5. Continuity of slip rates over various time scales on the Puente Hills Blind-thrust Fault, Los Angeles, California (United States)

    Bergen, Kristian J.; Shaw, John H.; Leon, Lorraine A.; Dolan, James F.; Pratt, Thomas L.; Ponti, Daniel J.; Barrera, Wendy; Rhodes, Edward J.; Murari, Madhav K.; Owen, Lewis A.


    Our study seeks to assess the history of slip on the Los Angeles segment of the Puente Hills blind-thrust fault system (PHT) from its inception through the Holocene by integrating a suite of geological and geophysical datasets. The PHT presents one of the largest seismic hazards in the United States, given its location beneath downtown Los Angeles. It is also well suited to slip rate studies, as fold scarps formed by slip on the PHT at depth have been continually buried by flood deposits from the Los Angeles and San Gabriel Rivers, preserving a record of uplift in the form of growth stratigraphy. We determined uplift from the growth stratigraphy by measuring the difference in sediment thickness across the folded layers. At our study site above the western segment of the PHT, the fold structure was imaged by industry seismic reflection data and a pair of high-resolution (100 to 700 m depth) seismic reflection profiles acquired by the authors for this study using weight drop and small vibrator sources. The industry and high-resolution profiles were stacked, migrated and depth converted using a velocity model based on the stacking velocities and the Southern California Earthquake Center Community Velocity Model. The shallowest layers of growth stratigraphy were geometrically constrained by lithological correlations across a series of cone penetration tests and continuously cored boreholes. Age control was provided by radiocarbon dating, optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) dating, and sequence-stratigraphic boundaries. Radiocarbon dating was used to constrain individual earthquake event ages in the borehole transect. Using a novel coring procedure, light-protected samples for quartz OSL and feldspar IRSL dating were acquired from a 171-m-deep borehole that we drilled within the growth fold. These samples provided age constraints on growth strata that were tied to prominent seismic reflections and were combined with

  6. 准南逆冲褶皱带超压与逆冲断层持续活动%Activity thrust faults and overpressure in the thrust and fold belt of southern Junggar Basin

    Institute of Scientific and Technical Information of China (English)

    杨庚; 李伟; 李本亮; 王晓波


    天山北缘准南地区的褶皱带为自新生代以来一直持续活动的逆冲构造带,由于逆冲断层的持续活动,形成了现今断层和相关褶皱.钻井资料显示,准南逆冲褶皱带内的超压层主要发育在古近纪安集海河组泥岩和紫泥泉子组泥岩之中,而该泥岩同时又成为逆冲断层发育的主滑脱面.通过多年来对准南地区地面地质调查、二维地震和三维地震资料的解释以及钻井证实,我们统计出准南逆冲褶皱带现存的逆冲断层倾角分别集中在两个区间:30±5°和50±5°区间.应力分析表明,在持续挤压应力作用下,超压层(泥岩、页岩和煤系地层)中和超压层之下地层中发育的早期逆冲断层与晚期最大主压应力之间的夹角处在30±5°之间时,作用在断层面上的最大主应力与最小主应力比达到最小值,因此该断层最容易再次活动,形成最大的流体压力,因而断层周围的流体就会沿着最大主应力方向发生流动,断层本身就会成为流体运移的主要通道;而早期逆冲断层与晚期最大主压应力之间的夹角处在50±5°之间时,作用在断层面上的最大主应力与最小主应力比较大,断层重新活动所需要的流体压力较高,导致断层作为流体运移的通道因被挤压而闭合.应力分析和钻井实测应力均指出,准南逆冲褶皱带发育的超压为挤压构造应力形成的超压.这些研究表明,准南逆冲褶皱带的逆冲断层持续活动,导致早期发育的断层在晚期应力作用下,断层倾角聚集在两个优势区间,油气沿最大主压应力方向运移,聚集油气则沿断层滑动面发育形成构造超压,导致该区域油气长期处于运移与聚集的动平衡状态.%The thrust and fold belt of south Junggar Basin, north Tianshan, is still activity since Cenozoic time, and the development of an activity fault and fault-related folds. Well data show that overpressures are developed in the

  7. Characterization of Fluid Transfer Properties in a Transpressive Fault System: Chaîne des Matheux Fold-and-Thrust Belt and Enriquillo-Plantain Garden Fault Zone - Haiti (United States)

    Wessels, R.; Ellouz-Zimmermann, N.; Rosenberg, C.; Hamon, Y.; Battani, A.; Bellahsen, N.; Deschamps, R.; Leroy, S. D.; Momplaisir, R.


    The NW - SE trending Chaîne des Matheux (CdM) comprises the onshore frontal thrust sheet of the SW-verging Haitian fold-and-thrust belt (HFTB). The HFTB's active deformation front is covered by sediments of the Cul-de-Sac plain and is bounded on the south by the E - W trending left-lateral Enriquillo-Plantain Garden fault zone (EPGFZ). Seismicity down to the junction between the two systems has been recorded during the 12 January 2010 Mw 7.0 Léogâne earthquake. Stratigraphic, structural and kinematic field data on a transect from the CdM to the EPGFZ indicate (N)NE - (S)SW oriented shortening, which is partitioned over 1) (N)NE-dipping oblique thrusts rooted in Cretaceous basement, 2) decollement levels in both latest Cretaceous and Paleogene limestones, and 3) by strike-slip and positive flower structures along the EPGFZ. We investigated the geometry and kinematics of both fault and fracture systems, which was coupled with sampling and analysis of fluid-derived mineralizations to constrain the timing and geological evolution. C & O isotope and whole-rock analyses have been performed to characterize the geochemistry of the source of these fluids. Raman spectroscopy and fluid-inclusion analyses has been applied to selected samples to comprehend the local burial history. Fluid and gas seepages along fault planes are qualitative indicators for transfer properties between different fault segments and their connectivity with deeper crustal or mantle reservoirs. Relative timing of structures in the CdM coupled with cathodoluminescence (CL) microscopy reveals three deformation phases, characterized by associated calcite veins that precipitated from oxidizing meteoric fluids. The deeply rooted frontal CdM thrust lacks mineralization, but fluids expelled from along-strike natural springs registered He and Ne isotope ratios suggesting a strong mantle-derived component. CL microscopy results on calcite veins from the EPGFZ's fault core imply fluid circulation in an

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

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


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

  9. Rock magnetic expression of fluid infiltration in the Yingxiu-Beichuan fault (Longmen Shan thrust belt, China)

    NARCIS (Netherlands)

    Yang, T.; Yang, Xiaosong; Duan, Qingbao; Chen, J.; Dekkers, M.J.


    Fluid infiltration within fault zones is an important process in earthquake rupture. Magnetic properties of fault rocks convey essential clues pertaining to physicochemical processes in fault zones. In 2011, two shallow holes (134 and 54 m depth, respectively) were drilled into the Yingxiu-Beichuan

  10. Earthquake-by-earthquake fold growth above the Puente Hills blind thrust fault, Los Angeles, California: Implications for fold kinematics and seismic hazard (United States)

    Leon, L.A.; Christofferson, S.A.; Dolan, J.F.; Shaw, J.H.; Pratt, T.L.


    Boreholes and high-resolution seismic reflection data collected across the forelimb growth triangle above the central segment of the Puente Hills thrust fault (PHT) beneath Los Angeles, California, provide a detailed record of incremental fold growth during large earthquakes on this major blind thrust fault. These data document fold growth within a discrete kink band that narrows upward from ???460 m at the base of the Quaternary section (200-250 m depth) to 82% at 250 m depth) folding and uplift occur within discrete kink bands, thereby enabling us to develop a paleoseismic history of the underlying blind thrust fault. The borehole data reveal that the youngest part of the growth triangle in the uppermost 20 m comprises three stratigraphically discrete growth intervals marked by southward thickening sedimentary strata that are separated by intervals in which sediments do not change thickness across the site. We interpret the intervals of growth as occurring after the formation of now-buried paleofold scarps during three large PHT earthquakes in the past 8 kyr. The intervening intervals of no growth record periods of structural quiescence and deposition at the regional, near-horizontal stream gradient at the study site. Minimum uplift in each of the scarp-forming events, which occurred at 0.2-2.2 ka (event Y), 3.0-6.3 ka (event X), and 6.6-8.1 ka (event W), ranged from ???1.1 to ???1.6 m, indicating minimum thrust displacements of ???2.5 to 4.5 m. Such large displacements are consistent with the occurrence of large-magnitude earthquakes (Mw > 7). Cumulative, minimum uplift in the past three events was 3.3 to 4.7 m, suggesting cumulative thrust displacement of ???7 to 10.5 m. These values yield a minimum Holocene slip rate for the PHT of ???0.9 to 1.6 mm/yr. The borehole and seismic reflection data demonstrate that dip within the kink band is acquired incrementally, such that older strata that have been deformed by more earthquakes dip more steeply than younger

  11. Earthquake-by-earthquake fold growth above the Puente Hills blind thrust fault, Los Angeles, California: Implications for fold kinematics and seismic hazard (United States)

    Leon, Lorraine A.; Christofferson, Shari A.; Dolan, James F.; Shaw, John H.; Pratt, Thomas L.


    Boreholes and high-resolution seismic reflection data collected across the forelimb growth triangle above the central segment of the Puente Hills thrust fault (PHT) beneath Los Angeles, California, provide a detailed record of incremental fold growth during large earthquakes on this major blind thrust fault. These data document fold growth within a discrete kink band that narrows upward from ˜460 m at the base of the Quaternary section (200-250 m depth) to 82% at 250 m depth) folding and uplift occur within discrete kink bands, thereby enabling us to develop a paleoseismic history of the underlying blind thrust fault. The borehole data reveal that the youngest part of the growth triangle in the uppermost 20 m comprises three stratigraphically discrete growth intervals marked by southward thickening sedimentary strata that are separated by intervals in which sediments do not change thickness across the site. We interpret the intervals of growth as occurring after the formation of now-buried paleofold scarps during three large PHT earthquakes in the past 8 kyr. The intervening intervals of no growth record periods of structural quiescence and deposition at the regional, near-horizontal stream gradient at the study site. Minimum uplift in each of the scarp-forming events, which occurred at 0.2-2.2 ka (event Y), 3.0-6.3 ka (event X), and 6.6-8.1 ka (event W), ranged from ˜1.1 to ˜1.6 m, indicating minimum thrust displacements of ≥2.5 to 4.5 m. Such large displacements are consistent with the occurrence of large-magnitude earthquakes (Mw > 7). Cumulative, minimum uplift in the past three events was 3.3 to 4.7 m, suggesting cumulative thrust displacement of ≥7 to 10.5 m. These values yield a minimum Holocene slip rate for the PHT of ≥0.9 to 1.6 mm/yr. The borehole and seismic reflection data demonstrate that dip within the kink band is acquired incrementally, such that older strata that have been deformed by more earthquakes dip more steeply than younger strata

  12. Near-Surface Seasonal Creeping and Subsurface Repeated Seismicity on the Plate-Suture Thrust Fault in Chihshang, Eastern Taiwan (United States)

    Lee, J.; Chu, H.; Angelier, J.; Hu, J.; Rau, R.


    The Chihshang fault is one of the most active segments of the Longitudinal Valley Fault, the plate suture between the converging Philippine and Eurasian plates. A destructive earthquake of M 6.2 with substantial surface scarps resulted from rupturing of the Chihshang fault in 1951. From that on, no big earthquake greater than M 6 occurred in this area. Instead, the Chihshang fault reveals a creeping behavior at least during the past 18 observation years. The creepmeter data of daily basis at Chihshang since 1998 revealed different behaviors of surface fault motion at two sites but similar annual shortening rates, 16.2 mm at Tapo site and 15.0 mm at Chinyuan site. Four of five creepmeters showed a seasonal variation, in which the fault only moved, as steadily rapid creeping, during the rainy season, generally from April to October, and remained quite during the rest of year. The only exception is due to the creepmeter located on the mélange-composed slope, where local gravitational landslide played a significant role combined with the tectonic faulting. Comparing to the precipitation data, we inferred that the relatively moderate rainfall is seemingly enough for triggering or facilitating slippages on the surface fault, one or two months before the heavy rains dropped in the wet season. During this observation period from 1998 to 2001, the subsurface seismicity exhibited clusters of micro-earthquakes occurred on the Chihshang fault at the depth of 15-25 km. The repeated earthquakes continuously occurred regardless the wet or the dry seasons, indicating the stress on the Chihshang fault in the shallow crust level of less than 10 km released only by creeping during the wet season. Combination of the near-surface creeping and the subsurface repeated earthquakes provided insights on the mechanical behaviors of the Chihshang fault, which are likely related to the geological materials of the converging island-arc: week mélange in the near-surface fault zone and strong

  13. Inversion of inherited thrusts by wastewater injection induced seismicity at the Val d’Agri oilfield (Italy) (United States)

    Buttinelli, M.; Improta, L.; Bagh, S.; Chiarabba, C.


    Since 2006 wastewater has been injected below the Val d’Agri Quaternary basin, the largest on-land oilfield in Europe, inducing micro-seismicity in the proximity of a high-rate injection well. In this study, we have the rare opportunity to revise a massive set of 2D/3D seismic and deep borehole data in order to investigate the relationship between the active faults that bound the basin and the induced earthquakes. Below the injection site we identify a Pliocene thrusts and back-thrusts system inherited by the Apennines compression, with no relation with faults bounding the basin. The induced seismicity is mostly confined within the injection reservoir, and aligns coherently with a NE-dipping back-thrust favorably oriented within the current extensional stress field. Earthquakes spread upwards from the back-thrust deep portion activating a 2.5-km wide patch. Focal mechanisms show a predominant extensional kinematic testifying to an on-going inversion of the back-thrust, while a minor strike-slip compound suggests a control exerted by a high angle inherited transverse fault developed within the compressional system, possibly at the intersection between the two fault sets. We stress that where wastewater injection is active, understanding the complex interaction between injection-linked seismicity and pre-existing faults is a strong requisite for safe oilfield exploitation.

  14. Magnetic fabrics in fault-related fold and its relation with finite strain: an example from Mingjiang thrust structures in Western Sichuan

    Institute of Scientific and Technical Information of China (English)

    Jia Dong; Chen Zhuxin; Luo Liang; Hu Qianwei; Jia Qiupeng


    The anisotropy of magnetic susceptibility (AMS) is a quick, effective and sensitive technique used to measure the weakly deformed sedimentary rocks, and also a reliable method to reveal the deforming mechanisms of fault-related folds. In Longmenshan front belt, a typical cross-section of fault-related folds is chosen to study the AMS. A total of 224 oriented specimens have been drilled at 23 different sampling sites which were distributed at the key structural positions of this structural section developed in the Xujiahe formation of the upper Triassic. Six elementary types of magnetic fabrics are recognized and established through this AMS study: 1 ) a sedimentary fabric; 2) an initial deformation fabric; 3) a pencil structure fabric; 4) a weak cleavage fabric; 5) a strong cleavage fabric; 6) a stretching lineation fabric. It has been found that most of magnetic fabrics are characterized by fabrics of weak deformation which belong to the pureshear results of a pre-folding layer parallel shortening (LPS). In the fault-bend fold, almost all magnetic fabrics are the initial deformation fabrics of weak deformation, and denote that the deformation in the forelimb is stronger than that in the backlimb and no finite strain is shown in the footwall. While in the fault-propagation fold, finite strains are concentrated in the trishear zone where magnetic fabric results are approximately consistent with the estimated consequences of the kinematic model. The tectonic stress field indicated by the magnetic fabrics is basically the same along the whole structural section and shows a NW to SE compression and shortening which is accordant with the regional compressive stress field of the Longmenshan fold-thrust belt.

  15. Faults (United States)

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

  16. Field study and three-dimensional reconstruction of thrusts and strike-slip faults in the Central Andes: implications for deep-seated geothermal circulation and ore deposits exploration (United States)

    Norini, Gianluca; Groppelli, Gianluca; Giordano, Guido; Baez, Walter; Becchio, Raul; Viramonte, Jose; Arnosio, Marcelo


    The Puna plateau (NW Argentina), located in the back-arc of the Central Andes, is a plateau characterized by both orogen-parallel and orogen-oblique deformation styles, extensive magmatic and geothermal activity, and the broad occurrence of igneous and hydrothermal ore-forming minerals. In this area, like in other convergent margins, the behaviour of the magma-tectonics interplay can affect the circulation of hydrothermal fluids, so that the full comprehension of the tectonic control on the magmas and fluids paths in the continental crust is crucial to plan the geothermal and ore exploration. In this study, we present a structural analysis of the back-arc portion of the orogen-oblique Calama-Olacapato-El Toro fault system and the surrounding orogen-parallel thrust faults in the central-eastern Puna Plateau, comprising the Cerro Tuzgle-Tocomar geothermal volcanic area, with high geothermal potential, and silicic calderas and domes associated with epithermal ore deposits. We also focused on the tectonic and volcanotectonic structures of the Chimpa and Tuzgle stratovolcanoes, two of the most important polygenetic volcanic centres of the plateau. Morphostructural analysis and field mapping reveal the geometry, kinematics and dynamics of the tectonic structures of the studied area. These data and the available stratigraphic and geophysical data have been integrated with the software MOVE and PETREL in a three-dimensional reconstruction of the main fault planes, showing their attitude and intersections at depth. As a result of our study, we show that despite different geometry and kinematics of the Calama-Olacapato-El Toro fault system and the thrust faults, they formed and evolved under the same progressive evolving dynamic state, forming a single tectonic system and accommodating crustal shortening of a thickened crust. In this frame, the crust underwent simultaneous deformation along both the low-angle thrust faults and the vertical transcurrent strike-slip faults

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

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


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

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

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


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

  19. Discussion on the Seismogenic Fault of the 1976 Tangshan Earthquake

    Institute of Scientific and Technical Information of China (English)


    The opinions of two papers carried in the journal "Seismology and Geology" are discussed in the paper. One is that the Tangshan fault is a high-angle, west-dipping and thrust with strikeslip fault. The other is that the Fuzhuang-Xihe fault distributed on the east side of Tangshan city is the seismogenic fault that caused the Tangshan earthquake. For the former opinion, it needs to explain the relationship between the active style of the thrust Tangshan fault and the formation genesis of a Quaternary depression along the west side of Tangshan city. For the latter opinion, if the Fuzhuang-Xihe fault is the seismogenic fault of the Tangshan earthquake,it needs to explain the genesis relationship between this west-dip slip fault zone and the strikeslip surface fissure zone that extends through Tangshan city. And it needs more evidence exclude the possibility that the surface rupture belongs to the rupturing of a secondary structure. This paper suggests doing more work on the active fault that controls the Caobo Quaternary depression.

  20. Stress sensitivity of fault seismicity: A comparison between limited-offset oblique and major strike-slip faults (United States)

    Parsons, Tom; Stein, Ross S.; Simpson, Robert W.; Reasenberg, Paul A.


    We present a new three-dimensional inventory of the southern San Francisco Bay area faults and use it to calculate stress applied principally by the 1989 M = 7.1 Loma Prieta earthquake and to compare fault seismicity rates before and after 1989. The major high-angle right-lateral faults exhibit a different response to the stress change than do minor oblique (right-lateral/thrust) faults. Seismicity on oblique-slip faults in the southern Santa Clara Valley thrust belt increased where the faults were undamped. The strong dependence of seismicity change on normal stress change implies a high coefficient of static friction. In contrast, we observe that faults with significant offset (>50-100 km) behave differently; microseismicity on the Hayward fault diminished where right-lateral shear stress was reduced and where it was undamped by the Loma Prieta earthquake. We observe a similar response on the San Andreas fault zone in southern California after the Landers earthquake sequence. Additionally, the offshore San Gregorio fault shows a seismicity rate increase where right-lateral/oblique shear stress was increased by the Loma Prieta earthquake despite also being clamped by it. These responses are consistent with either a low coefficient of static friction or high pore fluid pressures within the fault zones. We can explain the different behavior of the two styles of faults if those with large cumulative offset become impermeable through gouge buildup; coseismically pressurized pore fluids could be trapped and negate imposed normal stress changes, whereas in more limited offset faults, fluids could rapidly escape. The difference in behavior between minor and major faults may explain why frictional failure criteria that apply intermediate coefficients of static friction can be effective in describing the broad distributions of aftershocks that follow large earthquakes, since many of these events occur both inside and outside major fault zones.

  1. Detecting and Characterizing Active Thrust Fault and Deep-Seated Landslides in Dense Forest Areas of Southern Taiwan Using Airborne LiDAR DEM

    Directory of Open Access Journals (Sweden)

    Rou-Fei Chen


    Full Text Available Steep topographic reliefs and heavy vegetation severely limit visibility when examining geological structures and surface deformations in the field or when detecting these features with traditional approaches, such as aerial photography and satellite imagery. However, a light detection and ranging (LiDAR-derived digital elevation model (DEM, which is directly related to the bare ground surface, is successfully employed to map topographic signatures with an appropriate scale and accuracy and facilitates measurements of fine topographic features. This study demonstrates the efficient use of 1-m-resolution LiDAR for tectonic geomorphology in forested areas and to identify a fault, a deep-seated landslide, and the regional cleavage attitude in southern Taiwan. Integrated approaches that use grayscale slope images, openness with a tint color slope visualization, the three-dimensional (3D perspective of a red relief image map, and a field investigation are employed to identify the aforementioned features. In this study, the previously inferred Meilongshan Fault is confirmed as a NE–SW-trending, eastern dipping thrust with at least a 750 m-wide deformation zone. The site where future paleoseismological studies should be performed has been identified, and someone needs to work further on this site. Signatures of deep-seated landslides, such as double ridges, trenches, main escarpments, and extension cracks, are successfully differentiated in LiDAR DEM images through the use of different visualization techniques. Systematic parallel and continuous lineaments in the images are interpreted as the regional cleavage attitude of cleavage, and a field investigation confirms this interpretation.

  2. Stress history and fracture pattern in fault-related folds based on limit analysis: application to the Sub-Andean thrust belt of Bolivia (United States)

    Barbe, Charlotte; Leroy, Yves; Ben Miloud, Camille


    A methodology is proposed to construct the stress history of a complex fault-related fold in which the deformation mechanisms are essentially frictional. To illustrate the approach, fours steps of the deformation of an initially horizontally layered sand/silicone laboratory experiment (Driehaus et al., J. of Struc. Geol., 65, 2014) are analysed with the kinematic approach of limit analysis (LA). The stress, conjugate to the virtual velocity gradient in the sense of mechanicam power, is a proxy for the true statically admmissible stress field which prevailed over the structure. The material properties, friction angles and cohesion, including their time evolution are selected such that the deformation pattern predicted by the LA is consistent with the two main thrusting events, the first forward and the second backward once the layers have sufficiently rotated. The fractures associated to the stress field determined at each step are convected on today configuration to define the complete pattern which should be observed. The end results are presented along virtual vertical wells and could be used within the oil industry at an early phase of exploration to prepare drealing operations.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  4. Refolding of thin-skinned thrust sheets by active basement-involved thrust faults in the Eastern Precordillera of western Argentina Replegamiento de láminas de corrimiento epidérmicas mediante fallas inversas de basamento activas en la Precordillera Oriental del oeste de Argentina

    Directory of Open Access Journals (Sweden)

    A. Meigs


    Full Text Available Devastating earthquakes like the 1944 San Juan earthquake reflect active deformation in western Argentina. Although the earthquake caused considerable damage to San Juan, the source of the earthquake remains uncertain. Potential source faults occur in the thin-skinned fold-and-thrust belt Precordillera province and in the thick-skinned Sierras Pampeanas province, to the west and east, respectively of Sierra de Villicum, a thrust sheet in the eastern Precordillera northwest of San Juan. Sierra de Villicum is a west-vergent thrust sheet bound on the northwest by the Villicum thrust, which juxtaposes a southeast dipping panel of Cambro-Ordovician and Neogene strata in the hanging wall with Neogene red beds in the footwall. A series of Late Pleistocene fluvial terraces developed across the Villicum thrust show no evidence of active fold or fault deformation. Terraces are deformed by active folds and faults in the middle of the southeastern flank of the Sierra de Villicum thrust sheet. A southeast-facing, southwest-plunging monocline characterizes the Neogene red beds in the region of active folding. Co- and post-seismic surface rupture along roughly 6 km of the La Laja fault in 1944 occurred in the limb of the monocline. Evidence that surface deformation in the 1944 earthquake was dominated by folding includes terrace´s fold geometry, which is consistent with kink-band models for fold growth, and bedding-fault relationships that indicate that the La Laja fault is a flexural slip fault. A blind basement reverse fault model for the earthquake source and for active deformation reconciles the zone of terrace deformation, coseismic surface rupture on the La Laja fault, refolding of the Villicum thrust sheet, a basement arch between the Precordillera and eastern Precordillera, and microseismicity that extends northwestward from a depth of ~5 km beneath Sierra de Villicum to ~35 km depth. Maximum horizontal shortening rate is estimated to be ~3.0 mmyr-1

  5. Structure of a normal seismogenic fault zone in carbonates: The Vado di Corno Fault, Campo Imperatore, Central Apennines (Italy) (United States)

    Demurtas, Matteo; Fondriest, Michele; Balsamo, Fabrizio; Clemenzi, Luca; Storti, Fabrizio; Bistacchi, Andrea; Di Toro, Giulio


    The Vado di Corno Fault Zone (VCFZ) is an active extensional fault cutting through carbonates in the Italian Central Apennines. The fault zone was exhumed from ∼2 km depth and accommodated a normal throw of ∼2 km since Early-Pleistocene. In the studied area, the master fault of the VCFZ dips N210/54° and juxtaposes Quaternary colluvial deposits in the hangingwall with cataclastic dolostones in the footwall. Detailed mapping of the fault zone rocks within the ∼300 m thick footwall-block evidenced the presence of five main structural units (Low Strain Damage Zone, High Strain Damage Zone, Breccia Unit, Cataclastic Unit 1 and Cataclastic Unit 2). The Breccia Unit results from the Pleistocene extensional reactivation of a pre-existing Pliocene thrust. The Cataclastic Unit 1 forms a ∼40 m thick band lining the master fault and recording in-situ shattering due to the propagation of multiple seismic ruptures. Seismic faulting is suggested also by the occurrence of mirror-like slip surfaces, highly localized sheared calcite-bearing veins and fluidized cataclasites. The VCFZ architecture compares well with seismological studies of the L'Aquila 2009 seismic sequence (mainshock MW 6.1), which imaged the reactivation of shallow-seated low-angle normal faults (Breccia Unit) cut by major high-angle normal faults (Cataclastic Units).

  6. Raman spectra of carbonaceous materials in a fault zone in the Longmenshan thrust belt, China; comparisons with those of sedimentary and metamorphic rocks (United States)

    Kouketsu, Yui; Shimizu, Ichiko; Wang, Yu; Yao, Lu; Ma, Shengli; Shimamoto, Toshihiko


    We analyzed micro-Raman spectra of carbonaceous materials (CM) in natural and experimentally deformed fault rocks from Longmenshan fault zone that caused the 2008 Wenchuan earthquake, to characterize degree of disordering of CM in a fault zone. Raman spectral parameters for 12 samples from a fault zone in Shenxigou, Sichuan, China, all show low-grade structures with no graphite. Low crystallinity and δ13C values (-24‰ to -25‰) suggest that CM in fault zone originated from host rocks (Late Triassic Xujiahe Formation). Full width at half maximum values of main spectral bands (D1 and D2), and relative intensities of two subbands (D3 and D4) of CM were variable with sample locations. However, Raman parameters of measured fault rocks fall on established trends of graphitization in sedimentary and metamorphic rocks. An empirical geothermometer gives temperatures of 160-230 °C for fault rocks in Shenxigou, and these temperatures were lower for highly sheared gouge than those for less deformed fault breccia at inner parts of the fault zone. The lower temperature and less crystallinity of CM in gouge might have been caused by the mechanical destruction of CM by severe shearing deformation, or may be due to mixing of host rocks on the footwall. CM in gouge deformed in high-velocity experiments exhibits slight changes towards graphitization characterized by reduction of D3 and D4 intensities. Thus low crystallinity of CM in natural gouge cannot be explained by our experimental results. Graphite formation during seismic fault motion is extremely local or did not occur in the study area, and the CM crystallinity from shallow to deep fault zones may be predicted as a first approximation from the graphitization trend in sedimentary and metamorphic rocks. If that case, graphite may lower the friction of shear zones at temperatures above 300 °C, deeper than the lower part of seismogenic zone.

  7. Identification of High Angle Structures Controlling the Geothermal System at Rye Patch, Nevada. (United States)

    Ehni, W. J.


    The successful completion of a recent well in the Rye Patch Geothermal field, located in Pershing County, Nevada, supports the geologic and geophysical interpretation that high angle structures control this geothermal system. Although lower angle structures are present, hot water migrates up from deeper sources along high angle faults more efficiently than structures with a shallower dip. Earlier attempts to develop the resource focused on structures that dipped at an angle between 60 and 70 degrees from horizontal. Recently acquired geophysical data indicated that numerous high angle structures were present in the area, with dips between 80 and 90 degrees. Original drilling targets focused on the subsurface projection of a surface structure, mapped as the Rye Patch fault, with an erroneously low angle. These early attempts at drilling were discouraging and might have been more successful if additional geology and geophysics were used to evaluate the geothermal system and map the Rye Patch fault more accurately. The successful completion of the most recent well can be attributed to the incorporation of the geology of previous wells with additional geology and geophysics. Temperature gradient holes were used to confirm that the Rye Patch fault provided the primary plumbing for this geothermal system, and 3D seismic data indicated that most of the structures had dips between 80 and 90 degrees. Geothermometry at Rye Patch indicates that the resource has a relatively high quartz equilibrium temperature and it is speculated that the higher the angle of the structural control, the higher the resource temperature. The dip of Basin and Range normal faults varies considerably and the interpretation of these structures for geothermal, fossil geothermal mineral prospects, and or oil and gas prospects is important. At Rye Patch, the high angle structure feeds geothermal fluids into cavernous limestone beds, dipping to the west usually between 40 and 60 degrees, which is a

  8. The Quaternary thrust system of the northern Alaska Range (United States)

    Bemis, Sean P.; Carver, Gary A.; Koehler, Richard D.


    The framework of Quaternary faults in Alaska remains poorly constrained. Recent studies in the Alaska Range north of the Denali fault add significantly to the recognition of Quaternary deformation in this active orogen. Faults and folds active during the Quaternary occur over a length of ∼500 km along the northern flank of the Alaska Range, extending from Mount McKinley (Denali) eastward to the Tok River valley. These faults exist as a continuous system of active structures, but we divide the system into four regions based on east-west changes in structural style. At the western end, the Kantishna Hills have only two known faults but the highest rate of shallow crustal seismicity. The western northern foothills fold-thrust belt consists of a 50-km-wide zone of subparallel thrust and reverse faults. This broad zone of deformation narrows to the east in a transition zone where the range-bounding fault of the western northern foothills fold-thrust belt terminates and displacement occurs on thrust and/or reverse faults closer to the Denali fault. The eastern northern foothills fold-thrust belt is characterized by ∼40-km-long thrust fault segments separated across left-steps by NNE-trending left-lateral faults. Altogether, these faults accommodate much of the topographic growth of the northern flank of the Alaska Range.Recognition of this thrust fault system represents a significant concern in addition to the Denali fault for infrastructure adjacent to and transecting the Alaska Range. Although additional work is required to characterize these faults sufficiently for seismic hazard analysis, the regional extent and structural character should require the consideration of the northern Alaska Range thrust system in regional tectonic models.

  9. Style and rate of quaternary deformation of the Hosgri Fault Zone, offshore south-central coastal California (United States)

    Hanson, Kathryn L.; Lettis, William R.; McLaren, Marcia; Savage, William U.; Hall, N. Timothy; Keller, Mararget A.


    alternative tectonic models by evaluating (1) the cumulative effects of multiple deformational episodes that can produce complex, difficult-to-interpret fault geometries, patterns, and senses of displacement; (2) the difficult imaging of high-angle fault planes and horizontal fault separations on seismic reflection data; and (3) the effects of strain partitioning that yield coeval strike-slip faults and associated fold and thrust belts.

  10. Kinematics of syn- and post-exhumational shear zones at Lago di Cignana (Western Alps, Italy): constraints on the exhumation of Zermatt-Saas (ultra)high-pressure rocks and deformation along the Combin Fault and Dent Blanche Basal Thrust (United States)

    Kirst, Frederik; Leiss, Bernd


    Kinematic analyses of shear zones at Lago di Cignana in the Italian Western Alps were used to constrain the structural evolution of units from the Piemont-Ligurian oceanic realm (Zermatt-Saas and Combin zones) and the Adriatic continental margin (Dent Blanche nappe) during Palaeogene syn- and post-exhumational deformation. Exhumation of Zermatt-Saas (U)HP rocks to approximately lower crustal levels at ca. 39 Ma occurred during normal-sense top-(S)E shearing under epidote-amphibolite-facies conditions. Juxtaposition with the overlying Combin zone along the Combin Fault at mid-crustal levels occurred during greenschist-facies normal-sense top-SE shearing at ca. 38 Ma. The scarcity of top-SE kinematic indicators in the hanging wall of the Combin Fault probably resulted from strain localization along the uppermost Zermatt-Saas zone and obliteration by subsequent deformation. A phase of dominant pure shear deformation around 35 Ma affected units in the direct footwall and hanging wall of the Combin Fault. It is interpreted to reflect NW-SE crustal elongation during updoming of the nappe stack as a result of underthrusting of European continental margin units and the onset of continental collision. This phase was partly accompanied and followed by ductile bulk top-NW shearing, especially at higher structural levels, which transitioned into semi-ductile to brittle normal-sense top-NW deformation due to Vanzone phase folding from ca. 32 Ma onwards. Our structural observations suggest that syn-exhumational deformation is partly preserved within units and shear zones exposed at Lago di Cignana but also that the Combin Fault and Dent Blanche Basal Thrust experienced significant post-exhumational deformation reworking and overprinting earlier structures.

  11. The August 1st, 2014 ( M w 5.3) Moderate Earthquake: Evidence for an Active Thrust Fault in the Bay of Algiers (Algeria) (United States)

    Benfedda, A.; Abbes, K.; Bouziane, D.; Bouhadad, Y.; Slimani, A.; Larbes, S.; Haddouche, D.; Bezzeghoud, M.


    On August 1st, 2014, a moderate-sized earthquake struck the capital city of Algiers at 05:11:17.6 (GMT+1). The earthquake caused the death of six peoples and injured 420, mainly following a panic movement among the population. Following the main shock, we surveyed the aftershock activity using a portable seismological network (short period), installed from August 2nd, 2014 to August 21st, 2015. In this work, first, we determined the main shock epicenter using the accelerograms recorded by the Algerian accelerograph network (under the coordination of the National Center of Applied Research in Earthquake Engineering-CGS). We calculated the focal mechanism of the main shock, using the inversion of the accelerograph waveforms in displacement that provides a reverse fault with a slight right-lateral component of slip and a compression axis striking NNW-SSE. The obtained scalar seismic moment ( M o = 1.25 × 1017 Nm) corresponds to a moment magnitude of M w = 5.3. Second, the analysis of the obtained aftershock swarm, of the survey, suggests an offshore ENE-WSW, trending and NNW dipping, causative active fault in the bay of Algiers, which may likely correspond to an offshore unknown segment of the Sahel active fault.

  12. Evidence for distributed clockwise rotation of the crust in the northwestern United States from fault geometries and focal mechanisms (United States)

    Brocher, Thomas M.; Wells, Ray E.; Lamb, Andrew P.; Weaver, Craig S.


    Paleomagnetic and GPS data indicate that Washington and Oregon have rotated clockwise for the past 16 Myr. Late Cenozoic and Quaternary fault geometries, seismicity lineaments, and focal mechanisms provide evidence that this rotation is accommodated by north directed thrusting and right-lateral strike-slip faulting in Washington, and SW to W directed normal faulting and right-lateral strike-slip faulting to the east. Several curvilinear NW to NNW trending high-angle strike-slip faults and seismicity lineaments in Washington and NW Oregon define a geologic pole (117.7°W, 47.9°N) of rotation relative to North America. Many faults and focal mechanisms throughout northwestern U.S. and southwestern British Columbia have orientations consistent with this geologic pole as do GPS surface velocities corrected for elastic Cascadia subduction zone coupling. Large Quaternary normal faults radial to the geologic pole, which appear to accommodate crustal rotation via crustal extension, are widespread and can be found along the Lewis and Clark zone in Montana, within the Centennial fault system north of the Snake River Plain in Idaho and Montana, to the west of the Wasatch Front in Utah, and within the northern Basin and Range in Oregon and Nevada. Distributed strike-slip faults are most prominent in western Washington and Oregon and may serve to transfer slip between faults throughout the northwestern U.S.

  13. 40Ar/39Ar dating of Daqingshan thrust

    Institute of Scientific and Technical Information of China (English)

    LIU Zhenghong; XU Zhongyuan; YANG Zhensheng


    The Daqingshan thrust system, to the south of the Shiguai Mesozoic basin, is a complex system of top-to- the-north thrusting tectonic sheets. The thrust system has a complicated evolution due to multi-stage thrusting. In order to date the thrusting events, syntectonic muscovite and biotite grains are respectively analyzed with normal 40Ar/39Ar dating and laser 40Ar/39Ar dating, which yield 2 isochron ages, i.e. 193.74 ± 3.88 Ma and 121.6 ± 1.6 Ma. These ages suggest that faults within the Daqingshan thrust system formed during 2 stages of thrusting, one the early Indosinian and the other the late Yanshanian. The isotopic dating is consistent with field geological relations. Indosinan deformation is evidenced by top-to-the-north thrusting, with the occurrence of a series of large-scale east-west trending thrust faults and folds, while the Yanshanian thrusting is characterized by top-to-the-NNW thrusting. It is superposed on and modifies early Indosinian thrust faults.

  14. The 2015 April 25 Gorkha (Nepal) earthquake and its aftershocks: implications for lateral heterogeneity on the Main Himalayan Thrust (United States)

    Kumar, Ajay; Singh, Shashwat K.; Mitra, S.; Priestley, K. F.; Dayal, Shankar


    The 2015 Gorkha earthquake (Mw 7.8) occurred by thrust faulting on a ˜150 km long and ˜70 km wide, locked downdip segment of the Main Himalayan Thrust (MHT), causing the Himalaya to slip SSW over the Indian Plate, and was followed by major-to-moderate aftershocks. Back projection of teleseismic P-wave and inversion of teleseismic body waves provide constraints on the geometry and kinematics of the main-shock rupture and source mechanism of aftershocks. The main-shock initiated ˜80 km west of Katmandu, close to the locking line on the MHT and propagated eastwards along ˜117° azimuth for a duration of ˜70 s, with varying rupture velocity on a heterogeneous fault surface. The main-shock has been modelled using four subevents, propagating from west-to-east. The first subevent (0-20 s) ruptured at a velocity of ˜3.5 km s- 1 on a ˜6°N dipping flat segment of the MHT with thrust motion. The second subevent (20-35 s) ruptured a ˜18° W dipping lateral ramp on the MHT in oblique thrust motion. The rupture velocity dropped from 3.5 km s- 1 to 2.5 km s- 1, as a result of updip propagation of the rupture. The third subevent (35-50 s) ruptured a ˜7°N dipping, eastward flat segment of the MHT with thrust motion and resulted in the largest amplitude arrivals at teleseismic distances. The fourth subevent (50-70 s) occurred by left-lateral strike-slip motion on a steeply dipping transverse fault, at high angle to the MHT and arrested the eastward propagation of the main-shock rupture. Eastward stress build-up following the main-shock resulted in the largest aftershock (Mw 7.3), which occurred on the MHT, immediately east of the main-shock rupture. Source mechanisms of moderate aftershocks reveal stress adjustment at the edges of the main-shock fault, flexural faulting on top of the downgoing Indian Plate and extensional faulting in the hanging wall of the MHT.

  15. The geometry of a deformed carbonate slope-basin transition: The Ventoux-Lure fault zone, SE France (United States)

    Ford, Mary; Stahel, U.


    The Ventoux-Lure fault zone (VLFZ) is a 70 km-long, E-W trending triangle zone of folds and thrusts in the Alpine foreland of SE France. The VLFZ corresponds to the site of a Lower Cretaceous carbonate slope-basin transition and it provides a good example of a deformed basin margin where, (1) compression was at a high angle to the basin margin; (2) deformation was mainly controlled by the mechanical stratigraphy and not by fault reactivation; and (3) inversion was a gradual process (from Middle Cretaceous) with deformation concentrated mainly in the basin to the north (as evidenced by growth strata) until the last (post-Burdigalian) stages when the slope carbonates to the south were thrust northward on the Ventoux-Lure Thrust (VLT). Within the eastern half of this zone structural geometries become increasingly complex from east to west, showing a progression from triangle zone to tectonic wedging geometries in which erosion of the emergent thrust sheets played an important role. This lateral variation was due to the obliquity of the eastern VLT to the Vocontian folds and the increase in displacement westward from a tip point south of Sisteron. The western sector of the VLFZ shows less N-S shortening and evidence of strike slip. On a regional scale, Late Cretaceous N-S shortening, contemporaneous with reactivation of NE-SW faults, may have been caused by the eastward migration of the Iberian-Briançonnais plate to the south of the European plate. The post-Burdigalian displacement of the VLT is correlated with the late Alpine SW emplacement on the Digne Thrust to the east. Within the French Alpine foreland the dextral NE-SW Durance Fault separated a zone where SW directed displacement was accommodated principally on the Digne Thrust from an area to the west, including the VLFZ, of more diffuse SW-NE shortening.

  16. Analecta of structures formed during the 28 June 1992 Landers-Big Bear, California earthquake sequence (including maps of shear zones, belts of shear zones, tectonic ridge, duplex en echelon fault, fault elements, and thrusts in restraining steps)

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, A.M.; Johnson, N.A.; Johnson, K.M.; Wei, W. [Purdue Univ., West Lafayette, IN (United States). Dept. of Earth and Atmospheric Sciences; Fleming, R.W. [Geological Survey, Denver, CO (United States); Cruikshank, K.M. [Portland State Univ., OR (United States). Dept. of Geology; Martosudarmo, S.Y. [BPP Technologi, Jakarta (Indonesia)


    The June 28, 1992, M{sub s} 7.5 earthquake at Landers, California, which occurred about 10 km north of the community of Yucca Valley, California, produced spectacular ground rupturing more than 80 km in length (Hough and others, 1993). The ground rupturing, which was dominated by right-lateral shearing, extended along at least four distinct faults arranged broadly en echelon. The faults were connected through wide transfer zones by stepovers, consisting of right-lateral fault zones and tension cracks. The Landers earthquakes occurred in the desert of southeastern California, where details of ruptures were well preserved, and patterns of rupturing were generally unaffected by urbanization. The structures were varied and well-displayed and, because the differential displacements were so large, spectacular. The scarcity of vegetation, the aridity of the area, the compactness of the alluvium and bedrock, and the relative isotropy and brittleness of surficial materials collaborated to provide a marvelous visual record of the character of the deformation zones. The authors present a series of analecta -- that is, verbal clips or snippets -- dealing with a variety of structures, including belts of shear zones, segmentation of ruptures, rotating fault block, en echelon fault zones, releasing duplex structures, spines, and ramps. All of these structures are documented with detailed maps in text figures or in plates (in pocket). The purpose is to describe the structures and to present an understanding of the mechanics of their formation. Hence, most descriptions focus on structures where the authors have information on differential displacements as well as spatial data on the position and orientation of fractures.

  17. Fault rock texture and porosity type in Triassic dolostones (United States)

    Agosta, Fabrizio; Grieco, Donato; Bardi, Alessandro; Prosser, Giacomo


    Preliminary results of an ongoing project aimed at deciphering the micromechanics and porosity evolution associated to brittle deformation of Triassic dolostones are presented. Samples collected from high-angle, oblique-slip, 10's to 100's m-throw normal faults crosscutting Mesozoic carbonates of the Neo Tethys (Campanian-Lucanian Platform) are investigated by mean of field geological mapping, optical microscopy, SEM and image analyses. The goal is to characterize in detail composition, texture and porosity of cataclastic rocks in order to assess the structural architecture of dolomitic fault cores. Moreover, the present study addresses the time-space control exerted by several micro-mechanisms such as intragranular extensional fracturing, chipping and shear fracturing, which took place during grain rolling and crushing within the evolving faults, on type, amount, dimensions and distribution of micropores present within the cataclastic fault cores. Study samples are representative of well-exposed dolomitic fault cores of oblique-slip normal faults trending either NW-SE or NE-SW. The high-angle normal faults crosscut the Mesozoic carbonates of the Campanian-Lucanian Platform, which overrode the Lagonegro succession by mean of low-angle thrust faults. Fault throws are measured by considering the displaced thrust faults as key markers after large scale field mapping (1:10,000 scale) of the study areas. In the field, hand samples were selected according to their distance from main slip surfaces and, in some case, along secondary slip surfaces. Microscopy analysis of about 100 oriented fault rock samples shows that, mostly, the study cataclastic rocks are made up of dolomite and sparse, minute survivor silicate grains deriving from the Lagonegro succession. In order to quantitatively assess the main textural classes, a great attention is paid to the grain-matrix ratio, grain sphericity, grain roundness, and grain sorting. By employing an automatic box-counting technique

  18. Seismological evidence of an active footwall shortcut thrust in the Northern Itoigawa-Shizuoka Tectonic Line derived by the aftershock sequence of the 2014 M 6.7 Northern Nagano earthquake (United States)

    Panayotopoulos, Yannis; Hirata, Naoshi; Hashima, Akinori; Iwasaki, Takaya; Sakai, Shin'ichi; Sato, Hiroshi


    A destructive M 6.7 earthquake struck Northern Nagano prefecture on November 22, 2014. The main shock occurred on the Kamishiro fault segment of the northern Itoigawa-Shizuoka Tectonic Line (ISTL). We used data recorded at 41 stations of the local seismographic network in order to locate 2118 earthquakes that occurred between November 18 and November 30, 2014. To estimate hypocenters, we assigned low Vp models to stations within the Northern Fossa Magna (NFM) basin thus accounting for large lateral crustal heterogeneities across the Kamishiro fault. In order to further improve accuracy, the final hypocenter locations were recalculated inside a 3D velocity model using the double-difference method. We used the aftershock activity distribution and focal mechanism solutions of major events in order to estimate the source fault area of the main shock. Our analysis suggests that the shallow part of the source fault corresponds to the surface trace of the Kamishiro fault and dips 30°-45° SE, while the deeper part of the source fault corresponds to the downdip portion of the Otari-Nakayama fault, a high angle fault dipping 50°-65° SE that formed during the opening of the NFM basin in the Miocene. Along its surface trace the Otari-Nakayama fault has been inactive during the late Quaternary. We verified the validity of our model by calculating surface deformation using a simple homogeneous elastic half-space model and comparing it to observed surface deformation from satellite interferometry, assuming large coseismic slip in the areas of low seismicity and small coseismic slip in the areas of high seismicity. Shallowing of the source fault from 50°-65° to 30°-45° in the upper 4 km, in the areas where both surface fault traces are visible, is a result of footwall shortcut thrusting by the Kamishiro fault off the Otari-Nakayama fault.

  19. Earthquake Surface Rupture of the Salt Range Thrust at the Himalayan Thrust Front in Pakistan (United States)

    Meigs, A.; Yule, J. D.; Madden, C.; Yeats, R.; Hussain, A.; Akhtar, S. S.; Latif, A.; Waliullah, A.; Ashraf, M.; Ramzan, S.; Dasti, N.


    Considerable evidence from Nepal and India now indicates that the basal detachment of the Himalaya produces great earthquakes that result in large coseismic displacements at the thrust front in India and Nepal (the Main Frontal thrust). In contrast, knowledge of the earthquake potential of the Salt Range thrust in Pakistan (SRT) is virtually absent. It has been clear since the publication of the Salt Range maps of Gee (1989) that the SRT deforms young surficial deposits and is an active fault. What remains uncertain is whether surface rupturing events occur on the SRT, with what frequency those events occur, and what is the size of the associated earthquakes. In a field reconnaissance of the SRT in Spring, 2007, we were able to confirm that this thrust is an active fault, and we discovered numerous localities where the fault nearly reaches the surface, cutting all but the youngest few meters of colluvial deposits. Whereas our observations suggest that surface rupturing events occur on the SRT, a number of characteristics of the Pakistani Himalaya suggests the earthquake behavior of the basal detachment and thrust front may be substantially different than it is in India and Nepal to the southeast. Key differences include an uncertain, but lower, convergence rate at the thrust front (5 to 13 mm/yr), a low tapered thrust wedge, and localization of the basal detachment in a weak evaporite unit. In this sense, the front of the Zagros fold-and-thrust belt in Iran may be a more appropriate analog for the thrust front in Pakistan than the Himalayan thrust front to the southeast. Future mapping of deformed geomorphic surfaces and paleoseismic trenching along the SRT will provide the first direct evidence of the earthquake potential and recurrence of plate- boundary earthquakes in Pakistan. This knowledge is critical for hazard assessment in north-central Pakistan where more than 7 million people are likely to be affected by a great earthquake on the plate boundary.

  20. Clocked Thrust Reversers (United States)

    Suciu, Gabriel L. (Inventor); Chandler, Jesse M. (Inventor)


    An aircraft includes a fuselage including a propulsion system supported within an aft portion. A thrust reverser is mounted proximate to the propulsion system for directing thrust in a direction to slow the aircraft. The thrust reverser directs thrust at an angle relative to a vertical plane to reduce interference on control surfaces and reduce generation of underbody lift.

  1. Atomistic aspects of crack propagation along high angle grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, D. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Science and Engineering


    The author presents atomistic simulations of the crack tip configuration near a high angle {Sigma} = 5 [001](210) symmetrical tilt grain boundary in NiAl. The simulations were carried out using molecular statics and embedded atom (EAM) potentials. The cracks are stabilized near a Griffith condition involving the cohesive energy of the grain boundary. The atomistic configurations of the tip region are different in the presence of the high angle grain boundary than in the bulk. Three different configurations of the grain boundary were studied corresponding to different local compositions. It was found that in ordered NiAl, cracks along symmetrical tilt boundaries show a more brittle behavior for Al rich boundaries than for Ni-rich boundaries. Lattice trapping effects in grain boundary fracture were found to be more significant than in the bulk.

  2. The 2008 Nura Mw6.7 earthquake: A shallow rupture on the Main Pamir Thrust revealed by GPS and InSAR

    Directory of Open Access Journals (Sweden)

    Xuejun Qiao


    Full Text Available The 2008 Nura Mw6.7 earthquake occurred in front of the Trans-Alai Range, central Asia. We present Interferometric Synthetic Aperture Radar (InSAR measurements of its coseismic ground deformation that are available for a major earthquake in the region. Analysis of the InSAR data shows that the earthquake ruptured a secondary fault of the Main Pamir Thrust for about 20 km. The fault plane striking N46°E and dipping 48°SE is dominated by thrust slip up to 3 m, most of which is confined to the uppermost 2–5 km of the crust, similar to the nearby 1974 Mw7.0 Markansu earthquake. The elastic model of interseismic deformation constrained by GPS measurements suggests that the two earthquakes may have resulted from the failures of two high-angle reverse faults that are about 10 km apart and rooted in a locked décollement at depths of 5–6 km. The elastic strain is built up by a freely creeping décollement at about 16 mm/a.

  3. High angle of attack aerodynamics subsonic, transonic, and supersonic flows

    CERN Document Server

    Rom, Josef


    The aerodynamics of aircraft at high angles of attack is a subject which is being pursued diligently, because the modern agile fighter aircraft and many of the current generation of missiles must perform well at very high incidence, near and beyond stall. However, a comprehensive presentation of the methods and results applicable to the studies of the complex aerodynamics at high angle of attack has not been covered in monographs or textbooks. This book is not the usual textbook in that it goes beyond just presenting the basic theoretical and experimental know-how, since it contains reference material to practical calculation methods and technical and experimental results which can be useful to the practicing aerospace engineers and scientists. It can certainly be used as a text and reference book for graduate courses on subjects related to high angles of attack aerodynamics and for topics related to three-dimensional separation in viscous flow courses. In addition, the book is addressed to the aerodynamicist...

  4. Seafloor expression and shallow structure of a fold-and-thrust system, Isfjorden, west Spitsbergen

    Directory of Open Access Journals (Sweden)

    Maria Blinova


    Full Text Available A detailed map of the structure of the west Spitsbergen fold-and-thrust belt in the Isfjorden area, Spitsbergen, is presented. The map was constructed from a dense grid of two-dimensional multichannel reflection seismic and bathymetric data. Joint interpretation of two data sets allowed a comparison of tectonic structures detected along the uppermost parts of the seismic sections and those reflected in the morphology of the seafloor. Three major, predominantly north-west–south-east striking faults were identified. The westernmost fault (T1 is a hinterland-directed (most likely out of sequence thrust, while the central and easternmost faults (T2 and T3 are foreland-directed (in-sequence thrusts. The thrusts divide Isfjorden into three subareas. Subarea 1 is bounded by thrust faults T1 and T2 and comprises Tertiary rocks surrounded by Jurassic–Cretaceous strata. The structural signature of Subarea 1 is that of a system of hinterland- and foreland-directed thrust faults, resulting in a seafloor relief characterized by parallel ridges and troughs. Subarea 2 is limited by thrust faults T2 and T3 and shows Jurassic–Cretaceous outcrops on the seafloor. Subarea 3 is situated east of the main thrust fault T3 and mainly involves outcrops of Triassic–Jurassic rocks. Together, Subareas 2 and 3 are dominated by foreland-directed, north-west–south-east and NNW–SSE-striking thrusts that are hardly detectable in bathymetric data.

  5. The Formation of a Retroarc Fold-Thrust Belt by the Closure and Inversion of a Back-Arc Basin; Patagonian-Fuegian Fold-Thrust Belt, Chile (United States)

    Betka, P.; Klepeis, K. A.; Mosher, S.


    margin. A low taper triangle zone formed at the tip of the thrust wedge where Late Cretaceous strata of the foreland basin are backthrust (top-SE) above the shale decollement. Several NE-vergent thrusts sole into the shale decollement and imbricate foreland basin strata. Shortening in the basement beneath the lower decollement is detached from the cover and accommodated by polyphase folding and penetrative strain. A minimum of ~9 km (15%) of shortening is transferred into the FTB during this stage. The second stage is marked by basement involved, steeply dipping (>60°) reverse faults that cut the initial decollements. One high-angle reverse fault places basement and RVB rocks above the foreland basin strata and can be traced for >100 km along strike. Two other basement involved reverse faults cut early phase structures of the retroarc FTB. On the basis of steep dip, and the cross cutting relationship with the early decollements, basement-involved reverse faults are interpreted to reactivate Jurassic normal faults. Thick-skinned faulting accounts for a minimum of ~4 km (7%) shortening. The Patagonian-Fuegian FTB provide an important example of how decollement levels and structural style of a retroarc FTB can be controlled by the inherited stratigraphic architecture and structure of a back-arc basin in a noncollisional setting.

  6. A 3-D Model of Stacked Thrusts in the Sevier Thrust Belt, Eastern Idaho (United States)

    Clayton, R. W.; Clayton, S. R.


    Using published and new geologic map data and two exploratory wells for control, we constructed a three-dimensional geological model of the Pine Creek area in the Big Hole Mountains of eastern Idaho, where stacked Sevier thrust sheets are exposed at the surface. In this area, Cretaceous crustal shortening displaced and folded strata from Cambrian to Cretaceous in age. Using geologic map data as a primary input to a 3-D model presents a number of challenges, especially representing fault geometries at depth and maintaining strata thicknesses. The highly variable attitudes measured at the surface are also difficult to represent in a subsurface model because they require extensive extrapolation to depth. To overcome these challenges we EarthVision software, which has tools for model construction with minimal data inputs and uses a minimum tension algorithm to create geologically realistic surfaces. We also constructed two primary cross-sections to constrain strata and fault geometries according to structural principles, and used these to guide construction of fault and horizon surfaces. We then designated horizons with the best control as reference horizons to constrain strata geometries, and built the remaining horizons using isochores to add or subtract from those surfaces. The model shows classic flat-ramp thrust geometries as seen farther southeast in the Wyoming section of the thrust belt. The model also shows uniform southwestward tilting of faults and strata in the north end above younger thrusts, but strong effects from a duplex on a younger thrust fault encountered in the southern well, which rotated the strata and older faults above it.

  7. Seismic hazard in low slip rate crustal faults, estimating the characteristic event and the most hazardous zone: study case San Ramón Fault, in southern Andes (United States)

    Estay, Nicolás P.; Yáñez, Gonzalo; Carretier, Sebastien; Lira, Elias; Maringue, José


    Crustal faults located close to cities may induce catastrophic damages. When recurrence times are in the range of 1000-10 000 or higher, actions to mitigate the effects of the associated earthquake are hampered by the lack of a full seismic record, and in many cases, also of geological evidences. In order to characterize the fault behavior and its effects, we propose three different already-developed time-integration methodologies to define the most likely scenarios of rupture, and then to quantify the hazard with an empirical equation of peak ground acceleration (PGA). We consider the following methodologies: (1) stream gradient and (2) sinuosity indexes to estimate fault-related topographic effects, and (3) gravity profiles across the fault to identify the fault scarp in the basement. We chose the San Ramón Fault on which to apply these methodologies. It is a ˜ 30 km N-S trending fault with a low slip rate (0.1-0.5 mm yr-1) and an approximated recurrence of 9000 years. It is located in the foothills of the Andes near the large city of Santiago, the capital of Chile (> 6 000 000 inhabitants). Along the fault trace we define four segments, with a mean length of ˜ 10 km, which probably become active independently. We tested the present-day seismic activity by deploying a local seismological network for 1 year, finding five events that are spatially related to the fault. In addition, fault geometry along the most evident scarp was imaged in terms of its electrical resistivity response by a high resolution TEM (transient electromagnetic) profile. Seismic event distribution and TEM imaging allowed the constraint of the fault dip angle (˜ 65°) and its capacity to break into the surface. Using the empirical equation of Chiou and Youngs (2014) for crustal faults and considering the characteristic seismic event (thrust high-angle fault, ˜ 10 km, Mw = 6.2-6.7), we estimate the acceleration distribution in Santiago and the hazardous zones. City domains that are under

  8. Role of detachments and thrust kinematics in Structural evolution of Kohat and Potwar fold thrust belt in Pakistan (United States)

    Ghani, Humaad; Zeilinger, Gerold; Sobel, Edward; Heidarzadeh, Ghasem


    The Kohat and Potwar fold thrust belts in Pakistan represent the outermost external zone of the Himalayan fold and thrust system. The Main Boundary thrust marks their northern extent, showing that they are genetically linked; however, both exhibit a distinct contrast between the structural style at the surface and subsurface. This contrast becomes more conspicuous at the leading edge of the thrust belt where the Potwar allochothon extends further south, linked to Kohat in the north via an active strike-slip fault. Previous workers explained the structural evolution of the two belts separately, disregarding the influence of similar fold and thrusts developed in both belts. This research focuses on the preparation of a 3D structural model at the boundary of the two thrust belts to understand similarities and differences in their structural style and evolution. The model is constrained by integrating field, seismic and well data for better subsurface interpretation. Cross sections show that Potwar evolved on thrust faults originating from a basal detachment in Precambrian (pC) salt and terminating in Miocene Molasse forming duplexes of pre Himalayan strata. To the south, the Potwar allochothon is glided over a salt detachment with rare internal deformation toward its leading edge, forming fault bend fold thrust structure known as Salt range. The structural evolution towards the west in Kohat results from deformation on multiple detachment horizons at the pC salt, Eocene evaporites and Miocene Molasse. Disharmonic folding over Eocene evaporites is evident from their presence in the cores of outcropping folds. In the subsurface, closely spaced thrusts cut up section from basal detachment terminates in Eocene evaporites forming duplex in northern part of area. In south change of lithological facies from evaporites to limestone shift detachment level upward in to molasse strata which resemble structural style in northern Potwar. Thrusts at the surface evolved from the

  9. Interplay of thrust, back-thrust, strike-slip and salt tectonics in a fold and thrust belt system: an example from Zakynthos Island, Greece (United States)

    Zelilidis, A.; Papatheodorou, G.; Maravelis, A. G.; Christodoulou, D.; Tserolas, P.; Fakiris, E.; Dimas, X.; Georgiou, N.; Ferentinos, G.


    The southwestern flank of the Hellenic fold and thrust belt, situated along the southern edge of the Dinarides-Albanides-Hellenides continental convergent zone, was examined for reconstructing the tectonic deformation. This investigation presents an integrated study of onshore sedimentological and structural analyses, as well as offshore seismic lines, across the Pliocene-Pleistocene sedimentary succession in Zakynthos Island. Back-thrust faults, using the Triassic evaporites as decollement surface, during the Pliocene, and coeval diapiric intrusions formed three sub-basins on the hangingwall of the Kalamaki back-thrust fault. This interaction is responsible for the growth of the Skopos Mountain and the soft sediment deformation that formed synclines and slumps, respectively. Back-thrust and strike-slip faults were active during the early Pleistocene, and diapiric intrusions modified the bathymetry on the sea floor, giving rise to slumps and recumbent folds. At least five events of synsedimentary diapiric intrusions have been recognized and are marked by five slump horizons. During the Holocene, the diapiric intrusions between the Kalamaki back-thrust and the Vrachionas anticline could be either related to normal faults or gravitationally driven.

  10. Out-of-sequence thrusting in polycyclic thrust belts: An example from the Mesozoic Yanshan belt, North China Craton (United States)

    Li, Chengming; Zhang, Changhou; Cope, Tim D.; Lin, Yi


    The EW trending Yanshan belt, an intraplate fold-thrust belt located in the northern North China Craton that has experienced several episodes of deformation widely separated in time, is characterized by out-of-sequence thrusts. According to detailed mapping in the central Yanshan belt, five geometric and stratigraphic criteria used to aid in determining whether a thrust has an out-of-sequence geometry or not can be recognized. They are (1) unconformable relationships, (2) inclination of fault surfaces, (3) irregular changes in apparent offset along strike, (4) short fault length relative to apparent offset, and (5) in-sequence geometry. With the help of these criteria, two generations of out-of-sequence thrusts that postdate the original in-sequence thrusting in the central Yanshan belt are recognized. The ancestral southward verging fold-and-thrust belt that formed prior to 180 Ma was deformed and cut by two younger generations of faults that are probably more deeply rooted and are constrained to between 172-165 Ma and 152-135 Ma. A series of thrusts with opposite vergence formed during the last period, resulting in abundant abnormal field relationships such as younger-on-older thrust relations, fold truncation, and cutting down-section. The nature and occurrence of faults in the Yanshan belt implies that superimposed deformation, a common feature in polycyclic orogenic belts, is a mechanism for the generation of out-of-sequence thrusting. This adds to mechanisms already described in the literature, such as maintaining constant critical taper at an orogenic scale, inhibition of the deformation front, and lateral changes in the nature of the décollement horizons.

  11. Normal Faulting at the Western Margin of the Altiplano Plateau, Southern Peru (United States)

    Schildgen, T. F.; Hodges, K. V.; Whipple, K. X.; Perignon, M.; Smith, T. M.


    Although the western margin of the Altiplano Plateau is commonly used to illustrate the marked differences in the evolution of a mountain range with strong latitudinal and longitudinal precipitation gradients, the nature of tectonism in this semi-arid region is poorly understood and much debated. The western margin of the Altiplano in southern Peru and northern Chile marks an abrupt transition from the forearc region of the Andes to the high topography of the Cordillera Occidental. This transition has been interpreted by most workers as a monocline, with modifications due to thrust faulting, normal faulting, and gravity slides. Based on recent fieldwork and satellite image analysis, we suggest that, at least in the semi-arid climate of southern Peru, this transition has been the locus of significant high-angle normal faulting related to the block uplift of the Cordillera Occidental. We have focused our initial work in the vicinity of 15\\deg S latitude, 71\\deg W longitude, where the range front crosses Colca Canyon, a major antecedent drainage northwest of Arequipa. In that area, Oligocene to Miocene sediments of the Moquegua Formation, which were eroded from uplifted terrain to the northeast, presently dip to the northeast at angles between 2 and 10º. Field observations of a normal fault contact between the Moquegua sedimentary rocks and Jurassic basement rocks, as well as 15-m resolution 3-D images generated from ASTER satellite imagery, show that the Moquegua units are down-dropped to the west across a steeply SW-dipping normal fault of regional significance. Morphology of the range front throughout southern Peru suggests that normal faulting along the range front has characterized the recent tectonic history of the region. We present geochronological data to constrain the timing of movement both directly from the fault zone as well as indirectly from canyon incision that likely responded to fault movement.

  12. Tectonic analysis on Tumuxiuke fault belt in the western Tarim Basin%塔里木盆地吐木休克构造带断裂构造分析

    Institute of Scientific and Technical Information of China (English)

    刘亚雷; 文磊; 杨海军; 齐英敏; 胡秀芳; 王月然; 李曰俊; 王海燕; 赵岩; 张强


    吐木休克断裂位于塔里木盆地西部,是一条大型基底卷入型断裂构造带,构成塔里木盆地次级构造单元阿瓦提凹陷和巴楚断隆的分界.根据系统的地震资料解释,可以将吐木休克断裂分为西段、中段和东段3部分,各段构造特征有所差异.西段,为单一的基底卷入型高角度逆冲断层,倾向巴楚断隆;中段,除倾向巴楚断隆的主冲断层外,倾向相反的反冲断层越来越清晰,楔状冲断构造的轮廓逐渐显现出来.同时,在断层上盘还发育第四纪正断层;东段,倾向巴楚断隆的主冲断层,向上断至中寒武统,未断开中寒武统以上的地层,其冲断位移量完全为倾向阿瓦提凹陷的反冲断层所吸收,形成典型的楔状冲断构造.根据地震资料解释,认为吐木休克断裂带主要存在两期断裂构造:深部高角度基底卷入型逆冲断裂带和其上叠加的浅部正断层.前者形成于库车组沉积前,在库车组沉积期间持续活动,并在新近纪晚期定型;后者是本次研究首次发现的,形成于第四纪早中期,仅发育在吐木休克断裂带的中部.%The Tumuxiuke fault belt, which locates in the western Tarim Basin, is a large-scale basement-involved fault zone and forms the boundary between the Awati Sag and Bachu fault-uplift (sub tectonic units of Tarim Basin) . Based on systematic interpretation on seismic data, three sections of different tectonic features can be divided: the west, the middle and the east section. In the west section, there only develops a basement-involved high-angle thrust fault which dips towards the Bachu fault-uplift; while in the middle section, besides the main Bachu-inclining fault mentioned above, a reversed-inclination recoil fault becomes increasingly clear and gradually draws the outline of wedge-shaped thrust structures. Meantime, on the upper plate of the recoil fault,a series of Quaternary normal faults develop; however,in the east section

  13. Evaluation of faults and their effect on ground-water flow southwest of Frenchman Flat, Nye and Clark counties, Nevada: a digital database (United States)

    McKee, Edwin H.; Wickham, Thomas A.; Wheeler, Karen L.


    Ground-water flow through the region south and west of Frenchman Flat, in the Ash Meadows subbasin of the Death Valley ground-water flow system, is controlled mostly by faults which arrange the distribution of permeable and impermeable rocks. In addition, most permeability is along fractures caused by faulting in carbonate rocks. Large faults are more likely to reach the potentiometric surface as deep as 325 meters below the ground surface and are more likely to effect the flow path than small faults. This study concentrated on identifying large faults, especially where they cut carbonate rocks. Small faults, however, may develop as much permeability as large faults if they are penetrative and are part of an anastomosing fault_zone. The overall pattern of faults and joints at the ground surface in the Spotted and Specter Ranges is an indication of the fracture system at the depth of the water table. Most of the faults in these ranges are west-southwest-striking, high-angle faults, 100 to 3,500 meters long, with 10 to 300 meters of displacement. Many of them, such as those in the Spotted Range and Rock Valley are left-lateral strike-slip faults that are conjugate to the NW-striking right-lateral faults of the Las Vegas Valley shear zone. These faults control the ground-water flow path, which runs west-southwest beneath the Spotted Range, Mercury Valley and the Specter Range. The Specter Range thrust is a significant geologic structure with respect to ground- water flow. This regional thrust fault emplaces siliceous clastic strata into the north central and western parts of the Specter Range. These rocks act as a barrier that confines ground- water flow to the southern part of the range, directing it southwestward toward springs at Ash Meadows. These siliceous clastic aquitard rocks and overlying Cenozoic deposits probably also block westward flow of ground-water in Rock Valley, diverting it southward to the flow path beneath the southern part of the Specter Range.

  14. PPT Thrust Stand (United States)

    Haag, Thomas W.


    A torsional-type thrust stand has been designed and built to test Pulsed Plasma Thrusters (PPT's) in both single shot and repetitive operating modes. Using this stand, momentum per pulse was determined strictly as a function of thrust stand deflection, spring constant, and natural frequency. No empirical corrections were required. The accuracy of the method was verified using a swinging impact pendulum. Momentum transfer data between the thrust stand and the pendulum were consistent to within 1%. Following initial calibrations, the stand was used to test a Lincoln Experimental Satellite (LES-8/9) thruster. The LES-8/9 system had a mass of approximately 7.5 kg, with a nominal thrust to weight ratio of 1.3 x 10(exp -5). A total of 34 single shot thruster pulses were individually measured. The average impulse bit per pulse was 266 microN-s, which was slightly less than the value of 300 microN-s published in previous reports on this device. Repetitive pulse measurements were performed similar to ordinary steady-state thrust measurements. The thruster was operated for 30 minutes at a repetition rate of 132 pulses per minute and yielded an average thrust of 573 microN. Using average thrust, the average impulse bit per pulse was estimated to be 260 microN-s, which was in agreement with the single shot data. Zero drift during the repetitive pulse test was found to be approximately 1% of the measured thrust.

  15. Thick-skinned tectonics within the intracontinental easternmost Atlas foreland-and-thrust belt (Tunisia): Meso-Cenozoic kinematics and implications for regional geodynamics (United States)

    Belkhiria, W.; Boussiga, H.; Inoubli, M. H.


    The transition zone between western and central Mediterranean domains presents a key area to investigate kinematic interactions within the adjacent orogen systems such as the easternmost Atlas foreland-and-thrust belt. Gravity and seismic data revealed a highly structured basement, characterizing a series of structural highs and lows delimited by high-angle N-S, E-W, and NW-SE extensional faults. This basement architecture is inherited from successive extensional events related to the openings of the Triassic-Early Cretaceous Tethys oceans (i.e., Alpine Tethys, Ligurian Tethys, and Mesogea). Throughout this period, this mosaic of continental blocks significantly controlled the thickness and facies distributions. Early stages of diapirism took place along these basement faults and allowed maximum subsidence in minibasins revealed by the development of growth strata. In response to the Late Cretaceous-Eocene shortenings, these extensional faults have been reactivated as trasnpressional shear zones, giving rise to narrow pop-up structures. In addition, gravity modeling indicates crustal thinning and deep-rooted faults affecting the crust south of the Zaghouan Thrust and along E-W transfer zones. From the late Miocene, a drastic change in the stress regime is attributed to the effect of the adjacent Sicily channel on the study area. This promotes crustal thinning, basin subsidence, and channeling up of mantle-derived helium along lithospheric-scale weak zones. Our results give rise to new insights into the reactivation of inherited weakness zones of southern Tethys margin in response to the complex interaction between African and Eurasian plates accommodated by subduction, rollback, collision, and slab segmentation.

  16. Structural style of the Marathon thrust belt, West Texas (United States)

    Hickman, Robert G.; Varga, Robert J.; Altany, Robert M.


    The Marathon portion of the Ouachita thrust belt consists of a highly deformed allochthonous wedge of Cambrian-Pennsylvanian slope strata (Marathon facies) that was transported to the northwest and emplaced over Pennsylvanian foredeep sediments. The foredeep strata in turn overlie early-middle Paleozoic shelfal sediments which are deformed by late Paleozoic basement-involved reverse faults. The Dugout Creek thrust is the basal thrust of the allochthon. Shortening in this sheet and overlying sheets is ˜80%. Steep imbricate faults link the Dugout Creek thrust to upper level detachments forming complex duplex zones. Progressive thrusting and shortening within the allochthon folded the upper level detachments and associated thrust sheets. The Caballos Novaculite is the most competent unit within the Marathon facies and controlled development of prominent detachment folds. Deeper imbricate sheets composed of the Late Pennsylvanian foredeep strata, and possibly early-middle Paleozoic shelfal sediments developed concurrently with emplacement of the Marathon allochthon and folded the overlying allochthon. Following termination of thrusting in the earliest Permian, subsidence and deposition shifted northward to the Delaware, Midland and Val Verde foreland basins.

  17. Structural evidence for northeastward movement on the Chocolate Mountains thrust, southeasternmost Calfornia

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, J.T. (Alaska Div. of Geological and Geophysical Surveys, Fairbanks (USA)); Haxel, G.B. (Geological Survey, Flagstaff, AZ (USA)); Tosdal, R.M. (Geological Survey, Menlo Park, CA (USA))


    The Late Cretaceous Chocolate Mountains thrust of southeastern California and southwestern Arizona places a block of Proterozoic and Mesozoic continental crust over the late Mesozoic continental margin oceanic sedimentary and volcanic rocks of the regionally distinctive Orocopia Schist. The Chocolate Mountains thrust is interpreted as a thrust (burial, subduction) fault rather than a low-angle normal (exhumation, unroofing, uplift) fault. The Chocolate Mountains thrust zone contains sparse to locally abundant mesoscopic asymmetric folds. Fabric relations indicate that these folds are an integral part of and coeval with the thrust zone. On a lower hemisphere equal-area plot representing the orientation and sense of asymmetry of 80 thrust zone folds from 36 localities, spread over an area 60 by 10 km, Z folds plot northwest of and S folds plot southeast of a northeast-southwest striking vertical plane of overall monoclinic symmetry. The only sense of movement consistent with the collective asymmetry of the thrust zone folds is top to the northeast. Paleomagnetic data suggest that the original sense of thrusting, prior to Neogene vertical axis tectonic rotation related to the San Andreas fault system, was northward. The essential point is that movement of the upper plate of the Chocolate Mountains thrust evidently was continentward. Continentward thrusting suggests a tectonic scenario in which an insular or peninsular microcontinental fragment collided with mainland southern California. Alternative tectonic models involving subduction of the Orocopia Schist eastward beneath continental southern California circumvent the suture problem but are presently not supported by any direct structural evidence.

  18. Thrust stand for low-thrust liquid pulsed rocket engines. (United States)

    Xing, Qin; Zhang, Jun; Qian, Min; Jia, Zhen-yuan; Sun, Bao-yuan


    A thrust stand is developed for measuring the pulsed thrust generated by low-thrust liquid pulsed rocket engines. It mainly consists of a thrust dynamometer, a base frame, a connecting frame, and a data acquisition and processing system. The thrust dynamometer assembled with shear mode piezoelectric quartz sensors is developed as the core component of the thrust stand. It adopts integral shell structure. The sensors are inserted into unique double-elastic-half-ring grooves with an interference fit. The thrust is transferred to the sensors by means of static friction forces of fitting surfaces. The sensors could produce an amount of charges which are proportional to the thrust to be measured. The thrust stand is calibrated both statically and dynamically. The in situ static calibration is performed using a standard force sensor. The dynamic calibration is carried out using pendulum-typed steel ball impact technique. Typical thrust pulse is simulated by a trapezoidal impulse force. The results show that the thrust stand has a sensitivity of 25.832 mV/N, a linearity error of 0.24% FSO, and a repeatability error of 0.23% FSO. The first natural frequency of the thrust stand is 1245 Hz. The thrust stand can accurately measure thrust waveform of each firing, which is used for fine control of on-orbit vehicles in the thrust range of 5-20 N with pulse frequency of 50 Hz.

  19. The Pinning by Particles of Low and High Angle Grain Boundaries during Grain Growth

    DEFF Research Database (Denmark)

    Tweed, C.J.; Ralph, B.; Hansen, Niels


    and coworkers. These estimates of local driving pressures have shown that they are similar for both the low and the high angle boundaries encountered in the samples. The pinning effects by particles at high angle boundaries are in general accord with the model due to Zener whilst those at low angle boundaries...

  20. Sandbox modeling of evolving thrust wedges with different preexisting topographic relief: Implications for the Longmen Shan thrust belt, eastern Tibet (United States)

    Sun, Chuang; Jia, Dong; Yin, Hongwei; Chen, Zhuxin; Li, Zhigang; Shen, Li; Wei, Dongtao; Li, Yiquan; Yan, Bin; Wang, Maomao; Fang, Shaozhi; Cui, Jian


    To understand the effects of substantial topographic relief on deformation localization in the seismically active mountains, like the Longmen Shan thrust belt in the eastern Tibet, sandbox experiments were performed based on the framework of the critical taper theory. First, a reference experiment revealed that the critical taper angle was 12° for our experimental materials. Subsequently, different proto wedges (subcritical (6° in taper angle), critical (12°), and supercritical (20°)) were introduced to cover the range of natural topographic relief, and we used two setups: setup A considered only across-strike topographic relief, whereas setup B investigated along-strike segmentation of topography, consist of two adjacent proto wedges. In all experiments, thrust wedges grew by in-sequence accretion of thrust sheets. Setup A revealed an alternating mode of slip partitioning on the accreted thrusts, with large-displacement thrust and small-displacement thrust developing in turn. And contrasting wedge evolutions occurred according to whether the proto wedge was subcritical or critical-supercritical. In setup B, the differential deformation along the strike produced transverse structures such as tear fault and lateral ramp during frontal accretion. The observed tear fault and its associated thrust system resemble the seismogenic fault system of the 2008 Mw7.9 Wenchuan earthquake. Our experimental results could also explain first-order deformation features observed in the Longmen Shan. Consequently, we conclude that topographic features, including topographic relief across the range and along-strike segmentation of topography, contribute significantly to the kinematics and deformation localization in such active mountains.

  1. Early history and reactivation of the rand thrust, southern California (United States)

    Postlethwaite, Clay E.; Jacobson, Carl E.

    The Rand thrust of the Rand Mountains in the northwestern Mojave Desert separates an upper plate of quartz monzonite and quartzofeldspathic to amphibolitic gneiss from a lower plate of metagraywacke and mafic schist (Rand Schist). The Rand thrust is considered part of the regionally extensive Vincent/Chocolate Mountain thrust system, which is commonly believed to represent a Late Cretaceous subduction zone. The initial direction of dip and sense of movement along the Vincent/Chocolate Mountain thrust are controversial. Microfabrics of mylonites and quartzites from the Rand Mountains were analyzed in an attempt to determine transport direction for this region, but the results are ambiguous. In addition, the southwestern portion of the Rand thrust was found to have been reactivated as a low-angle normal fault after subduction. Reactivation might have occurred shortly after subduction, in which case it could account for the preservation of high-pressure mineral assemblages in the Rand Schist, or it could be related to mid-Tertiary extension in the western United States. In either event, the reactivation might be responsible for the complicated nature of the microfabrics. The Rand Schist exhibits an inverted metamorphic zonation. Isograds in the schist are not significantly truncated by the reactivated segment of the Rand thrust. This indicates that other segments of the Vincent/Chocolate Mountain thrust should be re-evaluated for the possibility of late movement, even if they show an apparently undisturbed inverted metamorphic zonation.

  2. How the structure of a continental margin affects the development of a fold and thrust belt. 3: evidences from field mapping and geological cross-sections in south-central Taiwan (United States)

    Alvarez-Marron, Joaquina; Biete, Cristina; Brown, Dennis; Camanni, Giovanni; Kuo-Chen, Hao; Ho, Chun-Wei


    The Eurasian Margin is obliquely colliding with the Luzon Arc to form the Taiwan orogen. This configuration is particularly apparent in south-central part of the island providing a case example to investigate the effects of structural inheritance in the development of the thrust and fold belt. The Eurasian Margin evolved from a pre-Cenozoic continental basement that underwent rifting in the Early Eocene and subsequent sea-floor spreading to form the South China Sea during the late Early Oligocene. The margin underwent localized extension in the Middle Miocene, before the initiation of collision with the Luzon Arc by the Early Miocene. The important along-strike changes in structure and topography of south-central Taiwan thrust and fold belt are evidenced in the detailed geological map and 3 balanced geological cross sections. A 3D tomography model is integrated in this study to help constrain the structure at depth. Major along-strike changes seem to be related to structures oriented at a high angle to the thrust system. These include changes in strike of thrusts and fold traces, the changing elevation of thrusts and stratigraphic contacts, and the growing importance of Middle Miocene sediments within the thrust system that take place from north to south. Horizontal slices of the tomography model illustrate that N-S changes in velocity have the orientation of the inherited structural grain of the Eurasian margin. In particular, the inherited location of the Mesozoic margin's shelf-slope transition affects the distribution of seismicity and the location of lateral stratigraphic and structural changes. Also, it appears to be associated with the inversion of Eocene- and Miocene-age extensional faults, deeply rooted in the pre-Cenozoic basement that trend oblique to the thrust belt. The inversion of inherited structures affects the uplift of Miocene syn-extensional and syn-tectonic Plio-Pleistocene foreland basin sediments, and of the pre-Cenozoic basement. Section A

  3. The TR method: A new graphical method that uses the slip preference of the faults to separate heterogeneous fault-slip data in extensional and compressional stress regimes (United States)

    Tranos, Markos


    stress regimes into "real" and "hybrid" ones. The "real" compressional regimes are the RC, RC-PC and PC, where the activated faults dip at angles up to 50° and their slip deviation from the reverse activation is no more than 30°. The "hybrid" compressional stress regimes are PC-TRP and TRP, where the activated faults can dip with even higher angles than 50° and their slip deviation from the reverse activation increases with the dip angle and the decrease of the stress ratio. In these stress regimes, the steeply dipping faults behave as contractional oblique strike-slip and strike-slip faults when their dip direction shifts at high angles away from the σ1 trend. Examples of the application of the TR method indicate that the method not only succeeds in separating heterogeneous fault-slip data into homogeneous groups, but it can (a) distinguish stress regimes whose horizontal principal stress axes trend close to each other, (b) distinguish faults driven by either tectonic or magmatic stresses, e.g., along the South Aegean Volcanic Arc, and (c) partition the contemporary stress regime related with the plate convergence between the Philippines Sea and Eurasia due to the different orientation of the activated structures, e.g., the inherited N-S striking Chelungpu Thrust and NE-SW striking Shihkang-Shangchi fault zone that have been activated during the 1999 Chi Chi earthquake, Taiwan.

  4. Fault Diagnosis and Fault Handling for Autonomous Aircraft

    DEFF Research Database (Denmark)

    Hansen, Søren

    Unmanned Aerial vehicles (UAVs) or drones are used increasingly for missions where piloted aircraft are unsuitable. The unmanned aircraft has a number of advantages with respect to size, weight and manoeuvrability that makes it possible for them to solve tasks that an aircraft previously has been...... that the fault is discovered in time such that appropriate actions can be taken. That could either be the aircraft controlling computer taking the fault into account or a human operator that intervenes. Detection of faults that occur during flight is exactly the subject of this thesis. Safety towards faults...... to another type of aircraft with different parameters. Amongst the main findings of this research project is a method to handle faults on the UAV’s pitot tube, which measures the aircraft speed. A set of software redundancies based on GPS velocity information and engine thrust are used to detect abnormal...

  5. 库车坳陷前陆冲断带断源储盖组合样式及其对成藏的控制%Fault-source-reservoir-cap combinations and their control on accumulation in foreland thrust belt of Kuqa Depression

    Institute of Scientific and Technical Information of China (English)



    在前陆冲断带天然气成藏的诸多控制因素中,断裂的发育决定着圈闭的形成、油气的运移聚集以及盖层的封闭性,以断层发育为核心的断源储盖的空间组合样式决定了油气的输导能力、圈闭的封闭性和充满度,从而最终控制了天然气的成藏。根据库车坳陷前陆冲断带不同地区的构造特点、生储盖组合关系以及成藏主控因素的不同,解剖已知油气藏的成藏特征,构建了库车坳陷前陆冲断带断源储盖组合样式,并阐述了4种不同断源储盖组合对天然气成藏的控制作用。其中,克深型断源储盖组合为最佳,向下既沟通侏罗系气源,向上又未断开库姆格列姆膏盐岩盖层,既是天然气运聚的良好通道,又未破坏盖层的封闭性,从而造成天然气的连片分布。克拉苏型由于断层不仅断开了巴什基奇克储层,而且还断开了膏盐岩盖层,因此圈闭的侧向封堵性是其成藏的关键。大宛齐型是盐上成藏,穿盐断层的输导以及盐上圈闭的有效性是其成藏的关键。依其克里克型则是自生自储,其成藏的关键是上倾控圈断层是否封闭以及断层两盘的岩性对接关系。%Fault development plays a vital role in all the factors controlling gas accumulation in foreland thrust belt, which determines the migration and accumulation of oil and gas, the formation of trap, and the sealing capacity of caprocks. Therefore, the combinations of fault-source-reservoir-cap, of which fault development is the core, determine the channel capacity of oil and gas, the sealing features and the fullness degree of traps, and ultimately control the accumulation of gas. According to the structure characteristics, the association of source-reservoir-cap, the main controlling factors of accumulation and the analysis of the known hydrocarbon reservoirs in different regions of the foreland thrust belt in Kuqa Depression, the

  6. Deformation in thrust-ramp anticlines and duplexes: implications for geometry and porosity

    Energy Technology Data Exchange (ETDEWEB)

    Groshong, R.H. Jr.; Usdansky, S.I.


    A computerized kinematic model of thrust-ramp anticline geometry allows workers to predict the zones of greatest deformation in ramp anticlines and fault duplexes. The model assumes a constant cross-section area, symmetrical fold hinges, and slip in the hanging wall parallel to the ramp and forelimb. Assuming that the collapse of original porosity or the generation of secondary fracture porosity is proportional to deformation, the model can be used to predict porosity changes. Deformation in a single ramp anticline is greatest in the forelimb and backlimb, and may be absent in the crest. A duplex structure results from comparatively closely spaced thrusts that have a common upper detachment horizon. Relatively wide spacing between the duplex faults yields a bumpy roofed duplex as in the central Appalachians. Forelimbs may be deformed twice and should show greater porosity modification. Relatively close spacing between ramp-and-flat thrusts can produce a listric-fault, snakehead anticline geometry because younger faults deform the preexisting thrust slices. The resulting geometry is here called a snakehead duplex and appears to be fairly common, as in the Jumpingpound field in the Canadian Rockies. Each thrust slice within the duplex is deformed six times or more, providing the maximum opportunity for deformation-related porosity changes. Maximum fracture porosity should occur in thrusts having listric-fan or snakehead duplex geometry. Structures involving duplexes generally should be better than isolated ramp anticlines.

  7. Recommended Practices in Thrust Measurements (United States)

    Polk, James E.; Pancotti, Anthony; Haag, Thomas; King, Scott; Walker, Mitchell; Blakely, Joseph; Ziemer, John


    Accurate, direct measurement of thrust or impulse is one of the most critical elements of electric thruster characterization, and one of the most difficult measurements to make. The American Institute of Aeronautics and Astronautics has started an initiative to develop standards for many important measurement processes in electric propulsion, including thrust measurements. This paper summarizes recommended practices for the design, calibration, and operation of pendulum thrust stands, which are widely recognized as the best approach for measuring micro N- to mN-level thrust and micro Ns-level impulse bits. The fundamentals of pendulum thrust stand operation are reviewed, along with its implementation in hanging pendulum, inverted pendulum, and torsional balance configurations. Methods of calibration and recommendations for calibration processes are presented. Sources of error are identified and methods for data processing and uncertainty analysis are discussed. This review is intended to be the first step toward a recommended practices document to help the community produce high quality thrust measurements.

  8. Interseismic Strain Accumulation Across Metropolitan Los Angeles: Puente Hills Thrust (United States)

    Argus, D.; Liu, Z.; Heflin, M. B.; Moore, A. W.; Owen, S. E.; Lundgren, P.; Drake, V. G.; Rodriguez, I. I.


    Twelve years of observation of the Southern California Integrated GPS Network (SCIGN) are tightly constraining the distribution of shortening across metropolitan Los Angeles, providing information on strain accumulation across blind thrust faults. Synthetic Aperture Radar Interferometry (InSAR) and water well records are allowing the effects of water and oil management to be distinguished. The Mojave segment of the San Andreas fault is at a 25° angle to Pacific-North America plate motion. GPS shows that NNE-SSW shortening due to this big restraining bend is fastest not immediately south of the San Andreas fault across the San Gabriel mountains, but rather 50 km south of the fault in northern metropolitan Los Angeles. The GPS results we quote next are for a NNE profile through downtown Los Angeles. Just 2 mm/yr of shortening is being taken up across the San Gabriel mountains, 40 km wide (0.05 micro strain/yr); 4 mm/yr of shortening is being taken up between the Sierra Madre fault, at the southern front of the San Gabriel mountains, and South Central Los Angeles, also 40 km wide (0.10 micro strain/yr). We find shortening to be more evenly distributed across metropolitan Los Angeles than we found before [Argus et al. 2005], though within the 95% confidence limits. An elastic models of interseismic strain accumulation is fit to the GPS observations using the Back Slip model of Savage [1983]. Rheology differences between crystalline basement and sedimentary basin rocks are incorporated using the EDGRN/EDCMP algorithm of Wang et al. [2003]. We attempt to place the Back Slip model into the context of the Elastic Subducting Plate Model of Kanda and Simons [2010]. We find, along the NNE profile through downtown, that: (1) The deep Sierra Madre Thrust cannot be slipping faster than 2 mm/yr, and (2) The Puente Hills Thrust and nearby thrust faults (such as the upper Elysian Park Thrust) are slipping at 9 ±2 mm/yr beneath a locking depth of 12 ±5 km (95% confidence limits

  9. Geomorphic evidence of unrecognized Balapur fault segment in the southwest Kashmir basin of northwest Himalayas (United States)

    Ahmad, Shabir; Alam, Akhtar; Ahmad, Bashir; Bhat, M. I.; Sultan Bhat, M.


    The Balapur fault (BF) is a high angle thrust fault (reverse), dipping ~ 60° NE, with an established length of ~ 40 km striking NW-SE of the Kashmir basin. However, geomorphic traces suggest that the strike of the BF propagates beyond what has been documented previously. The present investigation aims to identify the unrecognized segment of the BF in the SW of the Kashmir basin using hypsometric variability in longitudinal profiles (knickpoints/zones), followed by validation through stream gradient index (SL) calculations of the rivers draining the area. The longitudinal profiles of all the streams indicate prominent and consistent anomalies in the upper and mid-reaches even on the coarse resolution data (Survey of India topographic maps - 1:50,000/40 m, DEM-SRTM 90 m). The profile anomalies in the upper reaches (hard rock zone) of the streams may be attributed to lithological contacts, i.e., Panjal trap agglomeratic slate-shale-limestone. However, the river profile convex segments and course deflection specifically in the mid-reaches (soft rock zone) are most likely associated with recent tectonic activity. Geomorphic signatures suggest that these anomalies coincide with the strike of the recognized segment of the BF. Moreover, the SL values of each stream express a clear agreement with the anomalies shown by the long profiles of the rivers. Hence, we infer that the strike of the BF extends for a significant distance (~ 95 km) over the northeastern flank of the Pir Panjal range in the NW-SE direction.

  10. Structural setting of the Apennine-Maghrebian thrust belt

    Institute of Scientific and Technical Information of China (English)

    PieroElter; MarioGrasso; MaurizioParotto; LivioVezzani


    The Apennine-Maghrebian fold-and-thrust belt devel-oped from the latest Cretaceous to Early Pleistocene at the subduction-collisional boundary between the Euro-pean and the westward-subducted Ionian and Adria plates. Large parts of the Mesozoic oceanic lithosphere were subducted during an Alpine phase from the Late Cretaceous to Middle Eocene. The chain developed through the deformation of major paleogeographic internal domains (tectono-sedimentary sequences of the Ligurian-Piedmont Ocean) and external domains (sedi-mentary sequences derived from the deformation of the continental Adria-African passive mareinL The continu-ity of the Apennine chain is abruptly interrupted in the Calabrian Arc by the extensive klippe of Kabylo-Calabrian crystalline exotic terranes, derived from deformation of the European passive margin.Major complexities (sharp deflections in the arcuate configuration of the thrust belt, out-of-sequence propagation of the thrusts) are referred to contrasting rheology and differential buoyancy of the subducted lithosphere (transitional from conti-nental to oceanic) and consequent differential roll-back of the Adria plate margin, and to competence contrasts in the Mesozoic stratigraphic sequences,where multiple décollement horizons at different stratigraphic levels may have favored significant differential shortening.From the Late Miocene, the geometry of the thrust belt was strongly modified by extensional fault-ing, volcanic activity, crustal thinning and formation of oceanic crust correlated with the development of the Tyrrhenian Basin.

  11. Investigation of the High Angle of Attack Dynamics of the F-15B Using Bifurcation Analysis (United States)


    region via limit points should not be expected due to asymmetric thrust alone. A large I perturbation may push the F-15 away from the stable branch and...engine thrust setting of 25,000 lbf was then tried in the simu- 3 lation. Fig. 5-16 shows that using the higher thrust asym- metry, the F-15 pushes ...ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION Air Force Institute of Tecnology REPORT NUMBER I WPAFB, OH 45433-6583 AFIT/GAE/ENY/90D-16 9

  12. Reducing Thrusts In Solid-Fuel Rockets (United States)

    Bement, Laurence J.


    Thrust-terminating system conceived to reduce thrust of solid-propellant rocket motor in controlled manner such that thrust loads not increased or decreased beyond predictable levels. Concept involves explosively cutting opposing venting pairs in case of rocket motor above nozzles to initiate venting of chamber and reduction of thrust. Vents sized and numbered to control amount and rate of reduction in thrust.

  13. Lattice Boltzmann Method used for the aircraft characteristics computation at high angle of attack

    Institute of Scientific and Technical Information of China (English)


    Traditional Finite Volume Method(FVM)and Lattice Boltzmann Method(LBM)are both used to compute the high angle attack aerodynamic characteristics of the benchmark aircraft model named CT-1.Even though the software requires flow on the order of Ma<0.4,simulation at Ma=0.5 is run in PowerFLOW after theoretical analysis.The consistency with the wind tunnel testing is satisfied,especially for the LBM which can produce perfect results at high angle attack.PowerFLOW can accurately capture the detail of flows because it is inherently time-dependent and parallel and suits large-scale computation very well.

  14. Recent faulting in the Gulf of Santa Catalina: San Diego to Dana Point (United States)

    Ryan, H.F.; Legg, M.R.; Conrad, J.E.; Sliter, R.W.


    fault zone is more discontinuous and in places has no strong physiographic expression. The San Diego Trough fault zone consists of one or two well-defined linear fault strands that cut through the center of the San Diego Trough and strike N30??W. North of the La Jolla fan valley, this fault zone steps to the west and is composed of up to four fault strands. At the base of the continental slope, faults that show recency of movement include the San Onofre fault and reverse, oblique-slip faulting associated with the San Mateo and Carlsbad faults. In addition, the low-angle Oceanside detachment fault is imaged beneath much of the continental slope, although reflectors associated with the detachment are more prominent in the area directly offshore of San Mateo Point. North of San Mateo Point, the Oceanside fault is imaged as a northeast-dipping detachment surface with prominent folds deforming hanging-wall strata. South of San Mateo point, reflectors associated with the Oceanside detachment are often discontinuous with variable dip as imaged in WesternGeco MCS data. Recent motion along the Oceanside detachment as a reactivated thrust fault appears to be limited primarily to the area between Dana and San Mateo Points. Farther south, offshore of Carlsbad, an additional area of folding associated with the Carlsbad fault also is imaged near the base of the slope. These folds coincide with the intersection of a narrow subsurface ridge that trends at a high angle to and intersects the base of the continental slope. The complex pattern of faulting observed along the base of the continental slope associated with the San Mateo, San Onofre, and Carlsbad fault zones may be the result of block rotation. We propose that the clockwise rotation of a small crustal block between the Newport-Inglewood-Rose Canyon and Coronado Bank fault zones accounts for the localized enhanced folding along the Gulf of Santa Catalina margin. Prominent subsurface basement ridges imaged offshore of Dana Point

  15. Why style matters - uncertainty and structural interpretation in thrust belts. (United States)

    Butler, Rob; Bond, Clare; Watkins, Hannah


    Structural complexity together with challenging seismic imaging make for significant uncertainty in developing geometric interpretations of fold and thrust belts. Here we examine these issues and develop more realistic approaches to building interpretations. At all scales, the best tests of the internal consistency of individual interpretations come from structural restoration (section balancing), provided allowance is made for heterogeneity in stratigraphy and strain. However, many existing balancing approaches give misleading perceptions of interpretational risk - both on the scale of individual fold-thrust (trap) structures and in regional cross-sections. At the trap-scale, idealised models are widely cited - fault-bend-fold, fault-propagation folding and trishear. These make entirely arbitrary choices for fault localisation and layer-by-layer deformation: precise relationships between faults and fold geometry are generally invalidated by real-world conditions of stratigraphic variation and distributed strain. Furthermore, subsurface predictions made using these idealisations for hydrocarbon exploration commonly fail the test of drilling. Rarely acknowledged, the geometric reliability of seismic images depends on the assigned seismic velocity model, which in turn relies on geological interpretation. Thus iterative approaches are required between geology and geophysics. The portfolio of commonly cited outcrop analogues is strongly biased to examples that simply conform to idealised models - apparently abnormal structures are rarely described - or even photographed! Insight can come from gravity-driven deep-water fold-belts where part of the spectrum of fold-thrust complexity is resolved through seismic imaging. This imagery shows deformation complexity in fold forelimbs and backlimbs. However, the applicability of these, weakly lithified systems to well-lithified successions (e.g. carbonates) of many foreland thrust belts remains conjectural. Examples of

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

    Betka, Paul; Klepeis, Keith; Mosher, Sharon


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

  17. Active fault survey on the Tanlu fault zone in Laizhou Bay

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-cai; YANG Xi-ha; LI Chang-chuan; DENG Qi-dong; DU Xian-song; CHAO Hong-tai; WU Zi-quan; XIAO Lan-xi; SUN Zhao-ming; MIN Wei; LING Hong


    Shallow-depth acoustic reflection profiling survey has been conducted on the Tanlu fault zone in Laizhou Bay. It is found that the Tanlu fault zone is obviously active during the late Quaternary and it is still the dominating structure in this region. The Tanlu fault zone consists of two branches. The KL3 fault of the western branch is composed of several high angle normal faults which had been active during the period from the latest Pleistocene to early Holocene, dissected by a series of northeast or approximate east-west trending fault which leaped sediment of the late Pleistocene. The Longkou fault of the eastern branch consists of two right-laterally stepped segments. Late Quaternary offsets and growth strata developed along the Tanlu fault zone verify that the fault zone retained active in the latest Pleistocene to the early Holocene. The Anqiu-Juxian fault that passes through the middle of Shandong and corresponds to the Longkou fault is composed of a series of right-laterally stepped segments. The active faults along the eastern branch of the Tanlu fault zone from the Laizhou bay to the north of Anqiu make up a dextral simple shear deformation zone which is characterized by right-lateral strike-slip movement with dip-slip component during the late Quaternary.

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

    Altintas, Ali Can

    either side of the fault are Proterozoic - Cretaceous metamorphic or/and plutonic rocks. Previous work based on geologic mapping hypothesized the existence of a shallow, low angle Abel Mountain Thrust in which crystalline rocks were thrust over Miocene sedimentary rocks, near Apache Saddle. However, gravity models indicate the crystalline rocks are vertically extensive and form a positive flower structure bounded by high angle faults. Also, based on the thickness of fault adjacent sedimentary cover, the gravity models suggest a minimum exhumation of 5-6 km for crystalline rocks in the south. Assuming exhumation began with the switch from the transtensional San Gabriel Fault to transpressional San Andreas Fault at approximately 5 Ma, this indicates exhumation rates of 1 km/Ma. Overall, the broad gravity highs observed along the southern transects are due to uplift of basement rocks in this area.

  19. Low-thrust rocket trajectories

    Energy Technology Data Exchange (ETDEWEB)

    Keaton, P.W.


    The development of low-thrust propulsion systems to complement chemical propulsion systems will greatly enhance the evolution of future space programs. Two advantages of low-thrust rockets are stressed: first, in a strong gravitational field, such as occurs near the Earth, freighter missions with low-thrust engines require one-tenth as much propellant as do chemical engines. Second, in a weak gravitational field, such as occurs in the region between Venus and Mars, low-thrust rockets are faster than chemical rockets with comparable propellant mass. The purpose here is to address the physics of low-thrust trajectories and to interpret the results with two simple models. Analytic analyses are used where possible - otherwise, the results of numerical calculations are presented in graphs. The author has attempted to make this a self-contained report. 57 refs., 10 figs.

  20. Low-thrust rocket trajectories

    Energy Technology Data Exchange (ETDEWEB)

    Keaton, P.W.


    The development of low-thrust propulsion systems to complement chemical propulsion systems will greatly enhance the evolution of future space programs. Two advantages of low-thrust rockets are stressed: first, in a strong gravitational field, such as occurs near the Earth, freighter missions with low-thrust engines require one-tenth as much propellant as do chemical engines. Second, in a weak gravitational field, such as occurs in the region between Venus and Mars, low-thrust rockets are faster than chemical rockets with comparable propellant mass. The purpose here is to address the physics of low-thrust trajectories and to interpret the results with two simple models. Analytic analyses are used where possible - otherwise, the results of numerical calculations are presented in graphs. The author has attempted to make this a self-contained report.

  1. Navy and the HARV: High angle of attack tactical utility issues (United States)

    Sternberg, Charles A.; Traven, Ricardo; Lackey, James B.


    This presentation will highlight results from the latest Navy evaluation of the HARV (March 1994) and focus primarily on the impressions from a piloting standpoint of the tactical utility of thrust vectoring. Issue to be addressed will be mission suitability of high AOA flight, visual and motion feedback cues associated with operating at high AOA, and the adaptability of a pilot to effectively use the increased control power provided by the thrust vectoring system.

  2. Development of the Himalayan frontal thrust zone: Salt Range, Pakistan (United States)

    Baker, Dan M.; Lillie, Robert J.; Yeats, Robert S.; Johnson, Gary D.; Yousuf, Mohammad; Zamin, Agha Sher Hamid


    The Salt Range is the active frontal thrust zone of the Himalaya in Pakistan. Seismic reflection data show that a 1 km offset of the basement acted as a buttress that caused the central Salt Range-Potwar Plateau thrust sheet to ramp to the surface, exposing Mesozoic and Paleozoic strata. The frontal part of the thrust sheet was folded passively as it overrode the subthrust surface on a ductile layer of Eocambrian salt. Lack of internal deformation of the rear part of the thrust sheet is due to decoupling of sediments from the basement along this salt layer. Early to middle Pliocene (˜4.5 Ma) conglomerate deposition in the southern Potwar Plateau, previously interpreted in terms of compressional deformation, may instead document uplift related to basement normal faulting. Stratigraphic evidence, paleomagnetic dating of unconformities, and sediment-accumulation rates suggest that the thrust sheet began to override the basement offset from 2.1 to 1.6 Ma. Cross-section balancing demonstrates at least 20 to 23 km of shortening across the ramp. The rate of Himalayan convergence that can be attributed to underthrusting of Indian basement beneath sediments in the Pakistan foreland is therefore at least 9-14 mm/yr, about 20%-35% of the total plate convergence rate.

  3. Fluid storage and transport in thrust belts: the Gavarnie Thrust system revisited (United States)

    McCaig, Andrew


    There has been renewed interest in the pressure and movement of fluids in thrust systems in recent years with the discovery and increasing importance of slow slip earthquakes. Unfortunately the overpressured regime thought to be the source region for both normal and slow-slip earthquakes is inaccessible to direct observation, so information about the actual water content, flow regimes and permeability structure at the time of thrusting can only be obtained in exhumed rocks. The Gavarnie Thrust System in the Pyrenees (including the immediate footwall of the thrust and overlying thrust sheets) is exceptionally well studied in terms of structural and microstructural work, fluid inclusions, and isotopic tracing of fluid flow. Southward thrusting by 12-15 km occurred during the Eocene, and the current geometry of the thrust is a broad dome, allowing sampling at many locations. There is abundant evidence for near-lithostatic fluid pressures at depths of 8-15 km in the crust and temperatures of 300-400 °C, and fluids at these levels are dominated by hypersaline brines with Cl/Br ratios indicating evaporation of seawater. They are inferred to be derived from widespread Triassic evaporates, and stored in underlying redbeds and fractured basement rocks. There is also evidence from fluid inclusions for periodic pressure cycling down to near-hydrostatic values. This is thought to be related to co-seismic fault valve behaviour with release of fluid both into the shallow thrust and into steeply dipping shear zones in the hangingwall. Isotopic studies of carbonate mylonites along the Gavarnie thrust indicate unidirectional southward (structurally upward) flow of fluid , again probably mainly during transient veining events. These relatively slow moving fluids appear to have fed into a hydrostatic regime with topographically driven flow at higher levels. If time averaged permeability was high, most of the fluid would have rapidly escaped, since there is little opportunity to

  4. Bifurcation analysis of polynomial models for longitudinal motion at high angle of attack

    Institute of Scientific and Technical Information of China (English)

    Shi Zhongke; Fan Li


    To investigate the longitudinal motion stability of aircraft maneuvers conveniently,a new stability analysis approach is presented in this paper.Based on describing longitudinal aerodynamics at high angle-of-attack (α < 50°) motion by polynomials,a union structure of two-order differential equation is suggested.By means of nonlinear theory and method,analytical and global bifurcation analyses of the polynomial differential systems are provided for the study of the nonlinear phenomena of high angle-of-attack flight.Applying the theories of bifurcations,many kinds of bifurcations,such as equilibrium,Hopf,homoclinic (heteroclinic) orbit and double limit cycle bifurcations are discussed and the existence conditions for these bifurcations as well as formulas for calculating bifurcation curves are derived.The bifurcation curves divide the parameter plane into several regions; moreover,the complete bifurcation diagrams and phase portraits in different regions are obtained.Finally,our conclusions are applied to analyzing the stability and bifurcations of a practical example of a high angle-of-attack flight as well as the effects of elevator deflection on the asymptotic stability regions of equilibrium.The model and analytical methods presented in this paper can be used to study the nonlinear flight dynamic of longitudinal stall at high angle of attack.

  5. Wing-Alone Aerodynamic Characteristics to High Angles of Attack at Subsonic and Transonic Speeds. (United States)


    indicators of symmetry since the wings were unbanked within the limits of tolerances and flow angularity. Longitudinal, spanwise, and vertical... unbanked wings at subsonic and transonic speeds from low to high angles of attack. The wing planforms varied in aspect ratio and taper ratio with

  6. Improved Rhenium Thrust Chambers (United States)

    O'Dell, John Scott


    Radiation-cooled bipropellant thrust chambers are being considered for ascent/ descent engines and reaction control systems on various NASA missions and spacecraft, such as the Mars Sample Return and Orion Multi-Purpose Crew Vehicle (MPCV). Currently, iridium (Ir)-lined rhenium (Re) combustion chambers are the state of the art for in-space engines. NASA's Advanced Materials Bipropellant Rocket (AMBR) engine, a 150-lbf Ir-Re chamber produced by Plasma Processes and Aerojet Rocketdyne, recently set a hydrazine specific impulse record of 333.5 seconds. To withstand the high loads during terrestrial launch, Re chambers with improved mechanical properties are needed. Recent electrochemical forming (EL-Form"TM") results have shown considerable promise for improving Re's mechanical properties by producing a multilayered deposit composed of a tailored microstructure (i.e., Engineered Re). The Engineered Re processing techniques were optimized, and detailed characterization and mechanical properties tests were performed. The most promising techniques were selected and used to produce an Engineered Re AMBR-sized combustion chamber for testing at Aerojet Rocketdyne.



  8. Structural features and petroleum geology of the fold-thrust belt in the southern Tarim basin, China

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xinyuan; LUO Jinhai; WANG Qinghua


    The west Kunlun fold-thrust belt (WKFTB) and the Altun fold-thrust belt (AFTB) are respectively located in the southern margin of the Tarim basin, NW China. The analyses of typical structures and regional dynamics of the fold-thrust belts reveal their different structural and petroleum features and mechanisms. WKFTB differs from AFTB by abundant fault-related folds and triangles zones, and was formed by northward extrusion of the west Kunlun orogen. AFTB was affected synchronously by northward extrusion of the Altun orogen and the sinistral strike-slipping of the Altun Fault, so it is characterized by the minor scale and the monotonous structural styles. The Aqike anticline and the Aqike fault, of which the strikes are orthogonal to the strike of the fold-thrust belts, are regarded as the adjustive structures between both of the fold-thrust belts. The oil-gas pools of WKFTB develop mainly in the faulted-related anticline traps, but the oil-gas pools of AFTB develop mainly in the low fault-block and anticlines traps related with the paleo-uplifts. There are different exploration countermeasures for both of the fold-thrust belts.

  9. Fault Estimation

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, H.


    This paper presents a range of optimization based approaches to fault diagnosis. A variety of fault diagnosis prob-lems are reformulated in the so-called standard problem setup introduced in the literature on robust control. Once the standard problem formulations are given, the fault diagnosis pr...... problems can be solved by standard optimization tech-niques. The proposed methods include: (1) fault diagnosis (fault estimation, (FE)) for systems with model uncertainties; (2) FE for systems with parametric faults, and (3) FE for a class of nonlinear systems.......This paper presents a range of optimization based approaches to fault diagnosis. A variety of fault diagnosis prob-lems are reformulated in the so-called standard problem setup introduced in the literature on robust control. Once the standard problem formulations are given, the fault diagnosis...


    Institute of Scientific and Technical Information of China (English)

    LIAO Zhongli; DENG Yongfu; LIAO Guangyu


    The Jinping orogenic belt in Sichuan, China consists mainly of the Jinpingshan intracontinental thrust-nappe belt, foreland thrust-nappe belt and foreland uplift belt. Based on analyses about the characteristics of the structural units in this area, the authors propose in this paper that Chapuzi-Bazhe revival fault belt is the regional boundary fault, and points out that after the formation of the Pre-Sinian basement, the western edge of the Yangtze paraplatform was turned into the passive continental margin in Sinian to Triassic, then into the Mesozoic collision orogenic belt, and finally into the Cenozoic orogenic belt through intracontinental orogeny.

  11. Seismic profile analysis of the Kangra and Dehradun re-entrant of NW Himalayan Foreland thrust belt, India: A new approach to delineate subsurface geometry

    Indian Academy of Sciences (India)

    Joyjit Dey; R Jayangonda Perumal; Subham Sarkar; Anamitra Bhowmik


    In the NW Sub-Himalayan frontal thrust belt in India, seismic interpretation of subsurface geometry of the Kangra and Dehradun re-entrant mismatch with the previously proposed models. These procedures lack direct quantitative measurement on the seismic profile required for subsurface structural architecture. Here we use a predictive angular function for establishing quantitative geometric relationships between fault and fold shapes with ‘Distance–displacement method’ (D–d method). It is a prognostic straightforward mechanism to probe the possible structural network from a seismic profile. Two seismic profiles Kangra-2 and Kangra-4 of Kangra re-entrant, Himachal Pradesh (India), are investigated for the fault-related folds associated with the Balh and Paror anticlines. For Paror anticline, the final cut-off angle β=35∘ was obtained by transforming the seismic time profile into depth profile to corroborate the interpreted structures. Also, the estimated shortening along the Jawalamukhi Thrust and Jhor Fault, lying between the Himalayan Frontal Thrust (HFT) and the Main Boundary Thrust (MBT) in the frontal fold-thrust belt, were found to be 6.06 and 0.25 km, respectively. Lastly, the geometric method of fold-fault relationship has been exercised to document the existence of a fault-bend fold above the Himalayan Frontal Thrust (HFT). Measurement of shortening along the fault plane is employed as an ancillary tool to prove the multi-bending geometry of the blind thrust of the Dehradun re-entrant.

  12. Aircraft Horizontal Thrust Measurement Facility (United States)

    Federal Laboratory Consortium — This facility is designed to support the DoD mission by providing unique air vehicle installed engine performance (thrust output) measurements. This system consists...

  13. Active faulting in the Birjand region of NE Iran (United States)

    Walker, R. T.; Khatib, M. M.


    We use satellite imagery and field observations to investigate the distribution of active faults around Birjand in eastern Iran to determine how the transition between conjugate zones of faulting can be accommodated by diffuse active faulting. In the south of the study area, right-lateral strike-slip faults of the Sistan Suture Zone end in thrusts which die away westward from the strike-slip faults. These thrust terminations appear to allow a northward change to E-W thrusting in central parts of the study area. The introduction of E-W thrusting is, in turn, likely to facilitate a change to E-W left-lateral faulting north of the study region. The relatively diffuse pattern of active faulting at Birjand relates to the regional transition between N-S and E-W strike-slip faulting in northeast Iran, which involves a change from nonrotational to rotational deformation. The change from N-S to E-W faulting is likely to result from the orientation of preexisting structures in Iran and western Afghanistan, which are roughly parallel to the active fault zones. The features described at Birjand also show the influence of preexisting structure on the location and style of active faulting at a local scale, with the position of individual faults apparently controlled by inherited geological weaknesses. Very few modern earthquakes have occurred in the region of Birjand and yet destructive events are known from the historical record. The large number of active faults mapped in this study pose a substantial seismic hazard to Birjand and surrounding regions.

  14. Potential earthquake faults offshore Southern California, from the eastern Santa Barbara Channel south to Dana Point (United States)

    Fisher, M.A.; Sorlien, C.C.; Sliter, R.W.


    Urban areas in Southern California are at risk from major earthquakes, not only quakes generated by long-recognized onshore faults but also ones that occur along poorly understood offshore faults. We summarize recent research findings concerning these lesser known faults. Research by the U.S. Geological Survey during the past five years indicates that these faults from the eastern Santa Barbara Channel south to Dana Point pose a potential earthquake threat. Historical seismicity in this area indicates that, in general, offshore faults can unleash earthquakes having at least moderate (M 5-6) magnitude. Estimating the earthquake hazard in Southern California is complicated by strain partitioning and by inheritance of structures from early tectonic episodes. The three main episodes are Mesozoic through early Miocene subduction, early Miocene crustal extension coeval with rotation of the Western Transverse Ranges, and Pliocene and younger transpression related to plate-boundary motion along the San Andreas Fault. Additional complication in the analysis of earthquake hazards derives from the partitioning of tectonic strain into strike-slip and thrust components along separate but kinematically related faults. The eastern Santa Barbara Basin is deformed by large active reverse and thrust faults, and this area appears to be underlain regionally by the north-dipping Channel Islands thrust fault. These faults could produce moderate to strong earthquakes and destructive tsunamis. On the Malibu coast, earthquakes along offshore faults could have left-lateral-oblique focal mechanisms, and the Santa Monica Mountains thrust fault, which underlies the oblique faults, could give rise to large (M ??7) earthquakes. Offshore faults near Santa Monica Bay and the San Pedro shelf are likely to produce both strike-slip and thrust earthquakes along northwest-striking faults. In all areas, transverse structures, such as lateral ramps and tear faults, which crosscut the main faults, could

  15. Structural evolution of the Yeongwol thrust system, northeastern Okcheon fold-thrust belt, Korea: Insights from structural interpretations and SHRIMP U-Pb and K-Ar geochronology (United States)

    Jang, Yirang; Kwon, Sanghoon


    The NE-trending Okcheon Belt is a prominent fold-thrust belt preserved in the Korean Peninsula. In the Yeongwol area, the northeastern Okcheon Belt, the Cambrian-Ordovician (possibly to Silurian) Joseon Supergroup overlies the Carboniferous-Permian (possibly to early Triassic) Pyeongan Supergroup and/or Jurassic Bansong Group by N-S trending thrust faults, having highly connected traces in map view. To understand the structural geometry of these thrust faults and their evolution history, we have conducted structural analyses, together with SHRIMP U-Pb zircon and K-Ar illite age datings. The results show that (1) the thrusts in the Yeongwol area, carrying the lower Paleozoic strata over the upper Paleozoic or Mesozoic strata, are defined as the Yeongwol thrust system. The closed-loops map patterns of this system can further be interpreted by alternative duplex models in terms of a hinterland dipping duplex vs. a combination of major thrusts and connecting splays; (2) newly obtained SHRIMP U-Pb zircon ages from a dike and synorogenic sediments and K-Ar illite ages from fault gouges, together with previously reported evidences form the Yeongwol area, suggest multiple events after Permo-Triassic to early Neogene. The SHRIMP U-Pb detrital zircon ages from the lower Paleozoic rocks of the Yeongwol area can provide tectono-stratigraphic information of this area before the Permian. These further indicate the broader implications in that how detailed structural interpretations supported by the geochronological data can help to understand the tectonic evolution of the Okcheon Belt as well as the fold-thrust belts in general.

  16. Study of thrust and nappe tectonics in the eastern Jiaodong Peninsula, China

    Institute of Scientific and Technical Information of China (English)

    ZHANG HongYuan; HOU QuanLin; CAO DaiYong


    Thrust and nappe tectonics have affected the eastern Jiaodong Peninsula, the easternmost terminal of the Sulu Ultra-high Pressure Metamorphic Belt. Four nappes have been mapped, named respectively the Shidao, Rongcheng, Mishan and Mouping nappes. The methods used included multi-scale structural analysis and structural chronology analysis. These nappes define four deep level slip-thrust shear zones that were mainly active in the Mesozoic. The amount of ductile deformation decreases from the Shidao to Rongcheng to Mouping to Mishan shear zones, and shows an inverse relationship with temperature. 40Ar/39Ar chronological analysis and the chronological results of former workers reveal four movement steps defined by the development of thrusts and nappes in the late Triassic (210-180 Ma), extensional movement from the Jurassic to early Cretaceous (180-130 Ma), slip-thrust movement in the Early Cretaceous (130-120 Ma), and extensional movement since the Late Cretaceous (120 Ma). The order of boundary shear zone motion in the period of slip-thrust movement during the Early Cretaceous (130-120 Ma) was along the Shidao, Rongcheng, Mouping and finally the Mishan shear zone. This resulted in clockwise rotation of the nappes relative to block west to the Tan-Lu Faults. Because of the similar evolutionary history of the Tan-Lu Faults and the thrust and nappe structure in the eastern Jiaodong Peninsula, slip dislocation along the Tan-Lu Faults might have been absorbed by thrust and nappe tectonics in the Jiaodong area in the Mesozoic era, resulting in much less dislocation on the Tan-Lu faults in North Eastern China than that in south along the Jiaodong Peninsula.

  17. Study of thrust and nappe tectonics in the eastern Jiaodong Peninsula, China

    Institute of Scientific and Technical Information of China (English)


    Thrust and nappe tectonics have affected the eastern Jiaodong Peninsula, the easternmost terminal of the Sulu Ultra-high Pressure Metamorphic Belt. Four nappes have been mapped, named respectively the Shidao, Rongcheng, Mishan and Mouping nappes. The methods used included multi-scale struc- tural analysis and structural chronology analysis. These nappes define four deep level slip-thrust shear zones that were mainly active in the Mesozoic. The amount of ductile deformation decreases from the Shidao to Rongcheng to Mouping to Mishan shear zones, and shows an inverse relationship with temperature. 40Ar/39Ar chronological analysis and the chronological results of former workers reveal four movement steps defined by the development of thrusts and nappes in the late Triassic (210-180 Ma), extensional movement from the Jurassic to early Cretaceous (180-130 Ma), slip-thrust movement in the Early Cretaceous (130-120 Ma), and extensional movement since the Late Cretaceous (120 Ma). The order of boundary shear zone motion in the period of slip-thrust movement during the Early Cre- taceous (130-120 Ma) was along the Shidao, Rongcheng, Mouping and finally the Mishan shear zone. This resulted in clockwise rotation of the nappes relative to block west to the Tan-Lu Faults. Because of the similar evolutionary history of the Tan-Lu Faults and the thrust and nappe structure in the eastern Jiaodong Peninsula, slip dislocation along the Tan-Lu Faults might have been absorbed by thrust and nappe tectonics in the Jiaodong area in the Mesozoic era, resulting in much less dislocation on the Tan-Lu faults in North Eastern China than that in south along the Jiaodong Peninsula.

  18. Economic Recovery of Oil Trapped at Fan Margins Using High Angle Wells and Multiple Hydraulic Fractures

    Energy Technology Data Exchange (ETDEWEB)

    Mike L. Laue


    The distal fan margin in the northeast portion of the Yowlumne field contains significant reserves but is not economical to develop using vertical wells. Numerous interbedded shales and deteriorating rock properties limit producibility. In addition, extreme depths (13,000 ft) present a challenging environment for hydraulic fracturing and artificial lift. Lastly, a mature waterflood increases risk because of the uncertainty with size and location of flood fronts. This project attempts to demonstrate the effectiveness of exploiting the distal fan margin of this slope-basin clastic reservoir through the use of a high-angle well completed with multiple hydraulic-fracture treatments. The combination of a high-angle (or horizontal) well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore. The equivalent production rate and reserves of three vertical wells are anticipated at one-half to two-thirds the cost.

  19. Unraveling the deformational history of faults from AMS (United States)

    Calvín, Pablo; Casas-Sainz, Antonio; Román-Berdiel, Teresa; Oliva-Urcía, Belén; García-Lasanta, Cristina; Pocoví, Andrés; Gil-Imaz, Andrés; Pueyo-Anchuela, Oscar; Izquierdo-Llavall, Esther; Osácar, Cinta; José Villalaín, Juan; Corrado, Sveva; Invernizzi, Chiara; Aldega, Luca; Caricchi, Chiara; Antolín-Tomás, Borja


    The faults chosen for this study belong to the Iberian Chain (Northeastern Iberian Plate) and include two kinematically different kinds of structures (thrusts and strike-slip), with well-developed fault gouges several tens or hundreds of meters thick (Datos Fault System and Daroca Fault) and thinner clayey layers linked to thrust surfaces (Cameros-Demanda Thrust). The Cameros-Demanda Thrust has a relatively simple history of Mesozoic extension and Tertiary inversion. Along the thrust several areas with fault rocks include weakly oriented breccias, deformed conglomerates and clayey fault gouge with S/C structures. The Datos and Daroca faults show a more complex history of movement and are of key importance in the Variscan and Alpine evolution of the Iberian microplate. They show fault rocks with thickness of up to hundreds of meters, consisting of fault gouges, microbreccias and fault breccias with large blocks of stratified Paleozoic and Mesozoic blocks. Anisotropy of Magnetic Susceptibility (AMS) can be an useful tool in order to discriminate the tectonic evolution of such faults, remembering the different behaviors as part of different stages in northern Gondwana (Variscan cycle) and the Iberian microplate (Alpine cycle). Samples for the AMS study were collected from 56 sites, 29 (434 specimens) belonging to three areas of the Cameros-Demanda Thrust, 17 (196 specimens) in the Datos Fault System, and 10 (114 specimens) at the Daroca Fault. AMS results at the Cameros-Demanda Thrust show a main NW-SE magnetic lineation (Matute and Prejano areas), a secondary NE-SW magnetic lineation (Matute area) and a girdle distribution from NE to SW in the Panzares area. These results suggest a main NW movement for the Cameros-Demanda Thrust, consistent with kinematic indicators, but also evidence a NE-directed minor contribution, especially in the easternmost outcrops. Daroca and Datos Faults show a grater variability, both in plunge and azimuth, and magnetic lineation can be

  20. Methods of evaluating segmentation characteristics and segmentation of major faults

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kie Hwa; Chang, Tae Woo; Kyung, Jai Bok [Seoul National Univ., Seoul (Korea, Republic of)] (and others)


    Seismological, geological, and geophysical studies were made for reasonable segmentation of the Ulsan fault and the results are as follows. One- and two- dimensional electrical surveys revealed clearly the fault fracture zone enlarges systematically northward and southward from the vicinity of Mohwa-ri, indicating Mohwa-ri is at the seismic segment boundary. Field Geological survey and microscope observation of fault gouge indicates that the Quaternary faults in the area are reactivated products of the preexisting faults. Trench survey of the Chonbuk fault Galgok-ri revealed thrust faults and cumulative vertical displacement due to faulting during the late Quaternary with about 1.1-1.9 m displacement per event; the latest event occurred from 14000 to 25000 yrs. BP. The seismic survey showed the basement surface os cut by numerous reverse faults and indicated the possibility that the boundary between Kyeongsangbukdo and Kyeongsannamdo may be segment boundary.

  1. Integrated geomorphic and geodynamic modeling of a potential blind thrust in the San Francisco Bay area, California (United States)

    Johnson, Courtney B.; Furlong, Kevin P.; Kirby, Eric


    Geometries and slip budgets of the faults in the San Francisco Bay area imply previously unrecognized fault linkages, including examples of blind thrust structures that appear to connect segments of strike-slip faults and accommodate along-strike variations in slip rate along these structures. Displacement along linking faults may be associated with the development of topography and also may serve as earthquake sources. In Marin County, California, systematic spatial patterns in landscape topography and geomorphic indices suggest that the region north of Mt. Tamalpais is experiencing differential rock uplift. We suggest that a blind thrust underlies the elevated area, creating the observed topography and possibly resolving a slip discrepancy between the Hayward and San Andreas Fault in this region. We have developed and implemented an integrative approach that combines observations from tectonic deformation and geomorphic properties to identify a potential blind thrust beneath Marin County. Elastic displacement modeling has been tested for compatibility with the blind thrust hypothesis and to assess the sensitivity of observables to fault geometry and orientation; from this, a set of plausible blind thrust structures are defined. We use a range of empirical relationships between channel steepness index and erosion rate to estimate spatial variations in erosion rate along Bolinas Ridge. By coupling these erosion estimates with elastic displacement fault modeling, we can use the resulting topographic envelopes to constrain the rate and duration of deformation. These constraints, along with spatial bounds on the possible fault models, are used to calculate potential seismic moment and moment magnitude. With an assumed recurrence interval of ~ 100 years, such blind thrusts can produce a Mw ~ 6.3 earthquake, while a longer recurrence time (~ 1000 years) results in a maximum Mw ~ 7.0 earthquake. Although such events are not likely to be catastrophic, they are large

  2. Army (MANTECH) Thrust Area Concept: Optics Thrust Area (United States)

    Kopacz, Stanley P.


    With the shrinking of the U.S. Army's material needs and the compression of defense requirements, the Army Manufacturing Technology (MANTECH) Program has the opportunity to advance the manufacturing state-of-the-art and solve near term production problems of the U.S. industrial base. To exploit this opportunity, the Army restructured its MANTECH efforts in FY 90 based on a thrust area concept. Each of the ten current thrusts, directed by a thrust area manager, has a broad technical objective selected to improve specific manufacturing processes. The manager is charged with setting objectives, selecting tasks, monitoring execution, leveraging external resources, and establishing microfactories to promote technology transfer. The Optics Manufacturing Thrust is an example of the concept. It is currently directed at revitalizing the domestic precision optics manufacturing base, now characterized by high labor costs and 1940's technology, through introduction of revolutionary machines, new processes, and Computer Integrated Manufacturing (CIM) principles. Leveraging of MANTECH dollars with those of industry, academia, and state governments led to the establishment of the center for Optics Manufacturing and plans for regional centers. Recognition of the U.S. as a world leader in precision optics manufacturing and a dramatic reduction of both manufacturing time and cost should accrue from thrust area efforts.

  3. Evaluation of fluidic thrust vectoring nozzle via thrust pitching angle and thrust pitching moment (United States)

    Li, L.; Hirota, M.; Ouchi, K.; Saito, T.


    Shock vector control (SVC) in a converging-diverging nozzle with a rectangular cross-section is discussed as a fluidic thrust vectoring (FTV) method. The interaction between the primary nozzle flow and the secondary jet is examined using experiments and numerical simulations. The relationships between FTV parameters [nozzle pressure ratio (NPR) and secondary jet pressure ratio (SPR)] and FTV performance (thrust pitching angle and thrust pitching moment) are investigated. The experiments are conducted with an NPR of up to 10 and an SPR of up to 2.7. Numerical simulations of the nozzle flow are performed using a Navier-Stokes solver with input parameters set to match the experimental conditions. The thrust pitching angle and moment computed from the force-moment balance are used to evaluate FTV performance. The experiment and numerical results indicate that the FTV parameters (NPR and SPR) directly affect FTV performance. Conventionally, FTV performance evaluated by the common method using thrust pitching angle is highly dependent on the location of evaluation. Hence, in this study, we show that the thrust pitching moment, a parameter which is independent of the location, is the appropriate figure of merit to evaluate the performance of FTV systems.

  4. Tectonothermal history of an exhumed thrust-sheet-top basin: An example from the south Pyrenean thrust belt (United States)

    Labaume, Pierre; Meresse, Florian; Jolivet, Marc; Teixell, Antonio; Lahfid, Abdeltif


    This paper presents a new balanced structural cross section of the Jaca thrust-sheet-top basin of the southern Pyrenees combined with paleothermometry and apatite fission track (AFT) thermochronology data. The cross section, based on field data and interpretation of industrial seismic reflection profiles, allows refinement of previous interpretations of the south directed thrust system, involving the identification of new thrust faults, and of the kinematic relationships between basement and cover thrusts from the middle Eocene to the early Miocene. AFT analysis shows a southward decrease in the level of fission track resetting, from totally reset Paleozoic rocks and lower Eocene turbidites (indicative of heating to Tmax > ~120°C), to partially reset middle Eocene turbidites and no/very weak resetting in the upper Eocene-lower Oligocene molasse (Tmax < ~60°C). AFT results indicate a late Oligocene-early Miocene cooling event throughout the Axial Zone and Jaca Basin. Paleomaximum temperatures determined by vitrinite reflectance measurements and Raman spectroscopy of carbonaceous material reach up to ~240°C at the base of the turbidite succession. Inverse modeling of AFT and vitrinite reflectance data with the QTQt software for key samples show compatibility between vitrinite-derived Tmax and the AFT reset level for most of the samples. However, they also suggest that the highest temperatures determined in the lowermost turbidites correspond to a thermal anomaly rather than burial heating, possibly due to fluid circulation during thrust activity. From these results, we propose a new sequential restoration of the south Pyrenean thrust system propagation and related basin evolution.

  5. Tsunamis and splay fault dynamics (United States)

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


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

  6. Growth and seismic hazard of the Montserrat anticline in the North Canterbury fold and thrust belt, South Island, New Zealand (United States)

    VanderLeest, R. A.; Fisher, D. M.; Oakley, D. O. S.; Gardner, T. W.


    Fault-related fold growth is a seismic hazard in North Canterbury, New Zealand. The North Canterbury fold and thrust belt (NCFTB) is located at the southern end of the Hikurangi subduction zone, South Island, New Zealand where the Pacific plate transitions from subduction to transpression along the Alpine fault. Transpression causes shortening beneath the South Island, resulting in basement thrusts generating folds such as the Montserrat anticline. We focus on fault geometry and seismic hazard associated with this structure, exposed along the coast where Pleistocene marine terraces on the backlimb record tectonic uplift. To constrain parameters associated with evolution of this fault-related fold, we model the fold using several trishear kinematic models. A listric fault is most compatible with field and regional geophysical studies. Ages of marine terraces and inner edge elevations constrain uplift rate due to slip on the Glendhu fault to 1.1 ± 0.1 m(ka)-1. An ∼800 year recurrence interval is calculated for the Glendhu fault. Listric fault geometry lengthens the recurrence interval relative to other fault geometry models. An accurate understanding of subsurface fault geometry and kinematics is important for estimating seismic hazard in regions of fault-related folding such as the NCFTB because it affects recurrence interval estimations.

  7. Post-burnout thrust measurements (United States)

    McKenna, E. F.; Smith, H. T.


    Research was conducted into the problems of avoiding collision between separated payloads and spent rocket motors due to post burnout thrust, and the problem of contamination of scientific instrumentation due to outgassing of the smoldering insulation. The post burnout thrust was measured using a payload instrument module separated from an instrumented Black Brant VC Rocket in the exoatmosphere. In addition to measuring acceleration and velocities the spent motor was observed by a TV camera on board the command attitude controlled payload module. Analysis shows that the payload separated cleanly from the vehicle at a relative separation velocity of 0.69 m/sec, however the residual thrust of the spent motor overcame this differential, catching up to the payload 37 sec after separation and continuing on a parallel velocity vector at about 1.03 m/sec.

  8. Do faults stay cool under stress? (United States)

    Savage, H. M.; Polissar, P. J.; Sheppard, R. E.; Brodsky, E. E.; Rowe, C. D.


    Determining the absolute stress on faults during slip is one of the major goals of earthquake physics as this information is necessary for full mechanical modeling of the rupture process. One indicator of absolute stress is the total energy dissipated as heat through frictional resistance. The heat results in a temperature rise on the fault that is potentially measurable and interpretable as an indicator of the absolute stress. We present a new paleothermometer for fault zones that utilizes the thermal maturity of extractable organic material to determine the maximum frictional heating experienced by the fault. Because there are no retrograde reactions in these organic systems, maximum heating is preserved. We investigate four different faults: 1) the Punchbowl Fault, a strike-slip fault that is part of the ancient San Andreas system in southern California, 2) the Muddy Mountain Thrust, a continental thrust sheet in Nevada, 3) large shear zones of Sitkanik Island, AK, part of the proto-megathrust of the Kodiak Accretionary Complex and 4) the Pasagshak Point Megathrust, Kodiak Accretionary Complex, AK. According to a variety of organic thermal maturity indices, the thermal maturity of the rocks falls within the range of heating expected from the bounds on burial depth and time, indicating that the method is robust and in some cases improving our knowledge of burial depth. Only the Pasagshak Point Thrust, which is also pseudotachylyte-bearing, shows differential heating between the fault and off-fault samples. This implies that most of the faults did not get hotter than the surrounding rock during slip. Simple temperature models coupled to the kinetic reactions for organic maturity let us constrain certain aspects of the fault during slip such as fault friction, maximum slip in a single earthquake, the thickness of the active slipping zone and the effective normal stress. Because of the significant length of these faults, we find it unlikely that they never sustained

  9. Bivergent thrust wedges surrounding oceanic island arcs: Insight from observations and sandbox models of the northeastern caribbean plate (United States)

    ten Brink, U.S.; Marshak, S.; Granja, Bruna J. L.


    At several localities around the world, thrust belts have developed on both sides of oceanic island arcs (e.g., Java-Timor, Panama, Vanuatu, and the northeastern Caribbean). In these localities, the overall vergence of the backarc thrust belt is opposite to that of the forearc thrust belt. For example, in the northeastern Caribbean, a north-verging accretionary prism lies to the north of the Eastern Greater Antilles arc (Hispaniola and Puerto Rico), whereas a south-verging thrust belt called the Muertos thrust belt lies to the south. Researchers have attributed such bivergent geometry to several processes, including: reversal of subduction polarity; subduction-driven mantle flow; stress transmission across the arc; gravitational spreading of the arc; and magmatic inflation within the arc. New observations of deformational features in the Muertos thrust belt and of fault geometries produced in sandbox kinematic models, along with examination of published studies of island arcs, lead to the conclusion that the bivergence of thrusting in island arcs can develop without reversal of subduction polarity, without subarc mantle flow, and without magmatic inflation. We suggest that the Eastern Greater Antilles arc and comparable arcs are simply crustalscale bivergent (or "doubly vergent") thrust wedges formed during unidirectional subduction. Sandbox kinematic modeling suggests, in addition, that a broad retrowedge containing an imbricate fan of thrusts develops only where the arc behaves relatively rigidly. In such cases, the arc acts as a backstop that transmits compressive stress into the backarc region. Further, modeling shows that when arcs behave as rigid blocks, the strike-slip component of oblique convergence is accommodated entirely within the prowedge and the arc-the retrowedge hosts only dip-slip faulting ("frontal thrusting"). The existence of large retrowedges and the distribution of faulting in an island arc may, therefore, be evidence that the arc is

  10. Surface pressure model for simple delta wings at high angles of attack

    Indian Academy of Sciences (India)

    A A Pashilkar


    A new aerodynamic modelling approach is proposed for the longitudinal static characteristics of a simple delta wing. It captures the static variation of normal force and pitching moment characteristics throughout the angle of attack range. The pressure model is based on parametrizing the surface pressure distribution on a simple delta wing. The model is then extended to a wing/body combination where body-alone data are also available. The model is shown to be simple and consistent with experimental data. The pressure model can be used as a first approximation for the load estimation on the delta wing at high angles of attack.

  11. Prediction of forces and moments on finned bodies at high angle of attack in transonic flow

    Energy Technology Data Exchange (ETDEWEB)

    Oberkampf, W. L.


    This report describes a theoretical method for the prediction of fin forces and moments on bodies at high angle of attack in subsonic and transonic flow. The body is assumed to be a circular cylinder with cruciform fins (or wings) of arbitrary planform. The body can have an arbitrary roll (or bank) angle, and each fin can have individual control deflection. The method combines a body vortex flow model and lifting surface theory to predict the normal force distribution over each fin surface. Extensive comparisons are made between theory and experiment for various planform fins. A description of the use of the computer program that implements the method is given.

  12. Magnus effects at high angles of attack and critical Reynolds numbers (United States)

    Seginer, A.; Ringel, M.


    The Magnus force and moment experienced by a yawed, spinning cylinder were studied experimentally in low speed and subsonic flows at high angles of attack and critical Reynolds numbers. Flow-field visualization aided in describing a flow model that divides the Magnus phenomenon into a subcritical region, where reverse Magnus loads are experienced, and a supercritical region where these loads are not encountered. The roles of the spin rate, angle of attack, and crossflow Reynolds number in determining the boundaries of the subcritical region and the variations of the Magnus loads were studied.

  13. East-west faults due to planetary contraction

    CERN Document Server

    Beuthe, Mikael


    Contraction, expansion and despinning have been common in the past evolution of Solar System bodies. These processes deform the lithosphere until it breaks along faults. The type and orientation of faults are usually determined under the assumption of a constant lithospheric thickness, but lithospheric thinning can occur at the equator or at the poles due either to latitudinal variation in solar insolation or to localized tidal dissipation. Using thin elastic shells with variable thickness, I show that the equatorial thinning of the lithosphere transforms the homogeneous and isotropic fault pattern caused by contraction/expansion into a pattern of faults striking east-west, preferably formed in the equatorial region. By contrast, lithospheric thickness variations only weakly affect the despinning faulting pattern consisting of equatorial strike-slip faults and polar normal faults. If contraction is added to despinning, the despinning pattern first shifts to thrust faults striking north-south and then to thrus...

  14. The Altun Fault: Its Geometry, Nature and Mode of Growth

    Institute of Scientific and Technical Information of China (English)

    崔军文; 李莉; 杨经绥; 岳永军; 李朋武; 张建新; 陈文


    The Altun (or Altyn Tagh) fault displays a geometry of overlapping of linear and arcuate segments and shows strong inhomogeneity in time and space. It is a gigantic fault system with complex mechanical behaviours including thrusting, sinistral strike slip and normal slip. The strike slip and normal slip mainly occurred in the Cretaceous–Cenozoic and Plio–Quaternary respectively, whereas the thrusting was a deformation event that has played a dominant role since the late Palaeozoic (for a duration of about 305 Ma). The formation of the Altun fault was related to strong inhomogeneous deformation of the massifs on its two sides (in the hinterland of the Altun Mountains contractional deformation predominated and in the Qilian massif thrust propagation was dominant). The fault experienced a dynamic process of successive break-up and connection of its segments and gradual propagation, which was synchronous with the development of an overstep thrust sequence in the Qilian massif and the uplift of the Qinghai-Tibet plateau. With southward propagation of the thrust sequence and continued uplift of the plateau, the NE tip of the Altun fault moved in a NE direction, while the SW tip grew in a SW direction.

  15. Contemporary fault mechanics in southern Alaska (United States)

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

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

  16. Active faulting in apparently stable peninsular India: Rift inversion and a Holocene-age great earthquake on the Tapti Fault (United States)

    Copley, Alex; Mitra, Supriyo; Sloan, R. Alastair; Gaonkar, Sharad; Reynolds, Kirsty


    We present observations of active faulting within peninsular India, far from the surrounding plate boundaries. Offset alluvial fan surfaces indicate one or more magnitude 7.6-8.4 thrust-faulting earthquakes on the Tapti Fault (Maharashtra, western India) during the Holocene. The high ratio of fault displacement to length on the alluvial fan offsets implies high stress-drop faulting, as has been observed elsewhere in the peninsula. The along-strike extent of the fan offsets is similar to the thickness of the seismogenic layer, suggesting a roughly equidimensional fault rupture. The subsiding footwall of the fault is likely to have been responsible for altering the continental-scale drainage pattern in central India and creating the large west flowing catchment of the Tapti river. A preexisting sedimentary basin in the uplifting hanging wall implies that the Tapti Fault was active as a normal fault during the Mesozoic and has been reactivated as a thrust, highlighting the role of preexisting structures in determining the rheology and deformation of the lithosphere. The slip sense of faults and earthquakes in India suggests that deformation south of the Ganges foreland basin is driven by the compressive force transmitted between India and the Tibetan Plateau. The along-strike continuation of faulting to the east of the Holocene ruptures we have studied represents a significant seismic hazard in central India.

  17. Another Look at Rocket Thrust (United States)

    Hester, Brooke; Burris, Jennifer


    Rocket propulsion is often introduced as an example of Newton's third law. The rocket exerts a force on the exhaust gas being ejected; the gas exerts an equal and opposite force--the thrust--on the rocket. Equivalently, in the absence of a net external force, the total momentum of the system, rocket plus ejected gas, remains constant. The law of…

  18. Another Look at Rocket Thrust (United States)

    Hester, Brooke; Burris, Jennifer


    Rocket propulsion is often introduced as an example of Newton's third law. The rocket exerts a force on the exhaust gas being ejected; the gas exerts an equal and opposite force--the thrust--on the rocket. Equivalently, in the absence of a net external force, the total momentum of the system, rocket plus ejected gas, remains constant. The law of…

  19. Study on flow behavior and structure over chined fuselage at high angle of attack

    Institute of Scientific and Technical Information of China (English)


    A study of leeward vortex structure over chined fuselage and the effects of micro tip perturbation on its vortex flow have been carried out in wind tunnel experiments at Reynolds numbers from 1.26×105 to 5.04×105 with PIV and pressure measurement techniques.Firstly,the experiment results have proved that micro tip perturbation has no effects on the vortex flow and its aerodynamic characteristics over chined fuselage at high angle of attack,in which there are not any non-deterministic flow behaviors.Secondly,the evolution of leeward vortex structure over chined fuselage along the axis of model can be divided into four flow regimes:linear conical developed regime,decay regime of leeward vortex intensity,asymmetric leeward vortex break down regime and completely break down regime.And a correlation between leeward vortex structure and sectional aerodynamic force was also revealed in the present paper.Thirdly,the experiment results show the behavior of leeward vortex core trajectories and zonal characteristics of leeward vortex structure with angles of attack.Finally,the experiment results of Reynolds number effect on the leeward vortex flow have further confirmed research conclusions from previous studies:the flows over chined fuselage at high angles of attack are insensitive to variation of Reynolds number,and there is a little effect on the secondary boundary layer separation and the suction peak induced by leeward vortex.


    Institute of Scientific and Technical Information of China (English)

    YANG Li-zhi; GAO Zheng-hong


    A numerical investigation of the structure of the vortical flowfield over delta wings at high angles of attack in longitudinal and with small sideslip angle is presented.Three-dimensional Navier-Stokes numerical simulations were carried out to predict the complex leeward-side flowfield characteristics that are dominated by the effect of the breakdown of the leading-edge vortices. The methods that analyze the flowfield structure quantitatively were given by using flowfield data from the computational results. In the region before the vortex breakdown, the vortex axes are approximated as being straight line. As the angle of attack increases, the vortex axes are closer to the root chord, and farther away from the wing surface. Along the vortex axes, as the adverse pressure gradients occur, the axial velocity decreases, that is, λ is negative, so the vortex is unstable, and it is possible to breakdown. The occurrence of the breakdown results in the instability of lateral motion for a delta wing, and the lateral moment diverges after a small perturbation occurs at high angles of attack. However,after a critical angle of attack is reached, the vortices breakdown completely at the wing apex, and the instability resulting from the vortex breakdown disappears.

  1. High Thrust-Density Electrostaic Engines Project (United States)

    National Aeronautics and Space Administration — These issues are addressable by: increasing the thrust, power, and thrust-to-power ratio capability of EP systems; reducing the non-recurring engineering systems...

  2. Geometry and Kinematics of Tumuxiuke Fold and Thrust Belt in Bachu Uplift, Tarim Basin (United States)

    Song, Z.; Tang, L.


    Bachu uplift, mainly characterized by a series of out-of-sequence basement involved structures, is a large scale Cenozoic structural unit located in the west of Tarim basin. The NW-SE oriented, arc shaped Tumuxiuke fold and thrust belt (TFTB), which is roughly 200km in length, constrains the northern boundary of Bachu uplift. Based on multiple 2D seismic reflection profiles, we analysed the differences in structural styles along the strike of TFTB. It is mainly consist of several basement involved thrust faults and associated folds (or monoclines). The western segment of TFTB is characterized by a single basement involved structure; as to the middle segment, there is also backthrust branching from the main basement involved structure; in contrast, the eastern segment is consist of basement involved contractional wedge structures. According to the analysis of stratigraphy involved in deformation, fault slip and growth strata, we summarized that the TFTB mainly constructed by the compressional stress during late Miocene Himalayan orogency. Then, we analyzed the kinematics of TFTB with trishear fault propagation folding model. It is suggested that the initial fault tip that located below the basement-cover contact began to propagate during the late Miocene epoch and the propagation to slip ratio (P/S) also changes along strike. At the early stage of compression, the P/S was low and sedimentary cover mainly folded; then, the thrust faults of western segment and middle segment propagated rapidly with high P/S ratio and broke through early formed folds into Neogene strata; but in the eastern segment, the main thrust fault pinch out in the thick gypsum salt layer of middle Cambrian and the sedimentary cover decoupled from basement. About the genesis of basement-involved structures of TFTB in the intracontinent circumstance, we consider the effect of positive inversion of late Proterozoic-early Palaeozoic rift which requires further evidences.

  3. Geomorphic and paleoseismic evidence for late Quaternary deformation in the southwest Kashmir Valley, India: Out-of-sequence thrusting, or deformation above a structural ramp? (United States)

    Madden, C.; Ahmad, S.; Meigs, A.


    is sub-vertical, suggesting incision rate is a proxy for minimum slip rate for the BF. Paleoseismic trenches where the BF crosses the RR reveal evidence for at least one event between 1.5-18.7 ka, and another between 33.4-38.4 ka, with as many as four events in ~40 ka. Thus the BF did not rupture during any documented historical events. Furthermore, the high angle, sub-mm/yr slip rate, and long average earthquake recurrence all suggest that the BF is not a major out-of-sequence thrust that accommodates significant shortening related to the Indian-Eurasian collision. Long terrace profile surveys along the RR show that terraces diverge upstream of the BF, reflecting ramping of an underlying décollement toward the southwest side of the KV. We speculate that the BF is a minor accommodational structure produced by a change in dip of the décollement, and that strain accumulation at this inflection zone resulting from down-dip loading could be the source of frequent earthquakes documented in the KV.

  4. Summarization on variable liquid thrust rocket engines

    Institute of Scientific and Technical Information of China (English)


    The technology actuality and development trend of variable thrust rocket engines at home and abroad are summarized. Key technologies of developing variable thrust rocket engines are analyzed. Development advices on developing variable thrust rocket engines that are adapted to the situation of our country are brought forward.

  5. Nonlinear dynamics of a vectored thrust aircraft

    DEFF Research Database (Denmark)

    Sørensen, C.B; Mosekilde, Erik


    With realistic relations for the aerodynamic coefficients, numerical simulations are applied to study the longitudional dynamics of a thrust vectored aircraft. As function of the thrust magnitude and the thrust vectoring angle the equilibrium state exhibits two saddle-node bifurcations and three...

  6. Nonlinear dynamics of a vectored thrust aircraft

    DEFF Research Database (Denmark)

    Sørensen, C.B; Mosekilde, Erik


    With realistic relations for the aerodynamic coefficients, numerical simulations are applied to study the longitudional dynamics of a thrust vectored aircraft. As function of the thrust magnitude and the thrust vectoring angle the equilibrium state exhibits two saddle-node bifurcations and three ...

  7. Large seismic faults in the Hellenic arc

    Directory of Open Access Journals (Sweden)

    B. S. Papazachos


    Full Text Available Using information concerning reliable fault plane solutions, spatial distribution of strong earthquakes (Ms³ 6.0 as well as sea bottom and coastal topography, properties of the seismic faults (orientation, dimension, type of faulting were determined in seven shallow (h < 40 km seismogenic regions along the convex part of thc Hellenic arc (Hellenic trench and in four seismogenic regions of intermediate depth earthquakes (h = 40-100 km along the concave part of this arc. Except for the northwesternmost part of the Hellenic trench, where the strike-slip Cephalonia transform fault dominates, all other faults along this trench are low angle thrust faults. III thc western part of the trench (Zante-west Crete faults strike NW-SE and dip NE, while in its eastern part (east Crete-Rhodos faults strike WNW-ESE and dip NNE. Such system of faulting can be attributed to an overthrust of the Aegean lithosphere on the eastern Mediterranean lithosphere. The longest of these faults (L = 300 km is that which produced the largest known shallow earthquake in the Mediterranean area (21 July 365, Ms = 8.3 which is located near the southwestern coast of Crete. The second longest such fault (L = l 70 km is that which produced a large earthquake (December 1303, Ms = 8.0 in the easternmost part of the trench (east of Rhodos island. Both earthquakes were associated with gigantic tsunamis which caused extensive damage in the coast of many Eastern Mediterranean countries. Seismic faults of the intermediate depth earthquakes in the shallow part of the Benioff zone (h = 40- 100 km are of strike-slip type, with a thrust component. The orientations of these faults vary along the concave part of the arc in accordance with a subduction of remnants of all old lithospheric slab from the convex side (Mediterranean to the concave side (Aegean of thc Hellenic arc. The longest of these faults (L = 220 km is that which produced the largest known intermediate depth earthquake in the

  8. Control of structural inheritance on thrust initiation and material transfer in accretionary wedges (United States)

    Leever, Karen; Geersen, Jacob; Ritter, Malte; Lieser, Kathrin; Behrmann, Jan


    Faults in the incoming sediment layer are commonly observed in subduction zone settings and well developed in the incoming plate off Sumatra. To investigate how they affect the structural development of the accretionary wedge, we conducted a series of 2D analogue tectonic experiments in which a 2 cm thick quartz sand layer on top of a thin detachment layer of glass beads was pulled against a rigid backstop by a basal conveyor belt in a 20cm wide box with glass walls. A gap at the base of the back wall avoids entrainment of the glass beads. At regular spacing of either 2.3, 5.5 or 7.8 cm (fractions of the thrust sheet length in the reference model), conjugate pairs of weakness zones dipping 60deg were created by cutting the sand layer with a thin (1 mm) metal blade. Both the undisturbed sand and the pre-cuts have an angle of internal friction of ~29o, but their cohesion is different by 50 Pa (110 Pa for the undisturbed material, 60 Pa along the pre-cuts). Friction of the glass beads is ~24deg. The experiments are monitored with high resolution digital cameras; displacement fields derived from digital image correlation are used to constrain fault activity. In all experiments, a critically tapered wedge developed with a surface slope of 7.5deg. In the reference model (no weakness zones in the input section), the position of new thrust faults is controlled by the frontal slope break. The average length of the thrust sheets is 11 cm and the individual thrusts accommodate on average 8 cm displacement each. The presence of weakness zones causes thrust initiation at a position different from the reference case, and affects their dip. For a fault spacing of 7.8 cm (or 75% of the reference thrust sheet length), every single incoming weakness zone causes the formation of a new thrust, thus resulting in thrust sheets shorter than the equilibrium case. In addition, less displacement is accommodated on each thrust. As a consequence, the frontal taper is smaller than expected


    Institute of Scientific and Technical Information of China (English)

    DENG Xueying; WANG Yankui


    The studies of asymmetric vortices flow over slender body and its active control at high angles of attack have significant importance for both academic field and engineering area. This paper attempts to provide an update state of art to the investigations on the fields of forebody asymmetric vortices. This review emphasizes the correlation between micro-perturbation on the model nose and its response and evolution behaviors of the asymmetric vortices. The critical issues are discussed,which include the formation and evolution mechanism of asymmetric multi-vortices; main behaviors of asymmetric vortices flow including its deterministic feature and vortices flow structure; the evolution and development of asymmetric vortices under the perturbation on the model nose; forebody vortex active control especially discussed micro-perturbation active control concept and technique in more detail. However present understanding in this area is still very limited and this paper tries to identify the key unknown problems in the concluding remarks.

  10. Bifurcation analysis and stability design for aircraft longitudinal motion with high angle of attack

    Directory of Open Access Journals (Sweden)

    Xin Qi


    Full Text Available Bifurcation analysis and stability design for aircraft longitudinal motion are investigated when the nonlinearity in flight dynamics takes place severely at high angle of attack regime. To predict the special nonlinear flight phenomena, bifurcation theory and continuation method are employed to systematically analyze the nonlinear motions. With the refinement of the flight dynamics for F-8 Crusader longitudinal motion, a framework is derived to identify the stationary bifurcation and dynamic bifurcation for high-dimensional system. Case study shows that the F-8 longitudinal motion undergoes saddle node bifurcation, Hopf bifurcation, Zero-Hopf bifurcation and branch point bifurcation under certain conditions. Moreover, the Hopf bifurcation renders series of multiple frequency pitch oscillation phenomena, which deteriorate the flight control stability severely. To relieve the adverse effects of these phenomena, a stabilization control based on gain scheduling and polynomial fitting for F-8 longitudinal motion is presented to enlarge the flight envelope. Simulation results validate the effectiveness of the proposed scheme.

  11. Towards weighing individual atoms by high-angle scattering of electrons

    CERN Document Server

    Argentero, G; Kotakoski, J; Eder, F R; Meyer, J C


    We consider theoretically the energy loss of electrons scattered to high angles when assuming that the primary beam can be limited to a single atom. We discuss the possibility of identifying the isotopes of light elements and of extracting information about phonons in this signal. The energy loss is related to the mass of the much heavier nucleus, and is spread out due to atomic vibrations. Importantly, while the width of the broadening is much larger than the energy separation of isotopes, only the shift in the peak positions must be detected if the beam is limited to a single atom. We conclude that the experimental case will be challenging but is not excluded by the physical principles as far as considered here. Moreover, the initial experiments demonstrate the separation of gold and carbon based on a signal that is related to their mass, rather than their atomic number.

  12. Flight validation of ground-based assessment for control power requirements at high angles of attack (United States)

    Ogburn, Marilyn E.; Ross, Holly M.; Foster, John V.; Pahle, Joseph W.; Sternberg, Charles A.; Traven, Ricardo; Lackey, James B.; Abbott, Troy D.


    A review is presented in viewgraph format of an ongoing NASA/U.S. Navy study to determine control power requirements at high angles of attack for the next generation high-performance aircraft. This paper focuses on recent flight test activities using the NASA High Alpha Research Vehicle (HARV), which are intended to validate results of previous ground-based simulation studies. The purpose of this study is discussed, and the overall program structure, approach, and objectives are described. Results from two areas of investigation are presented: (1) nose-down control power requirements and (2) lateral-directional control power requirements. Selected results which illustrate issues and challenges that are being addressed in the study are discussed including test methodology, comparisons between simulation and flight, and general lessons learned.

  13. Quasi-periodic dynamics of a high angle of attack aircraft (United States)

    Rohith, G.; Sinha, Nandan K.


    High angle of attack maneuvers closer to stall is a commonly accessed flight regime especially in case of fighter aircrafts. Stall and post-stall dynamics are dominated by nonlinearities which make the analysis difficult. Presence of external factors such as wind makes the system even more complex. Rich nonlinearities point to the possibility of existence of chaotic solutions. Past studies in this area confirm the development of such solutions. These studies are mainly concentrated on very high angle of attack regimes, which may not be practically easily accessible. This paper examines the possibility of existence of chaotic solutions in the lower, more accessible areas in the post stall domain. The analysis is composed of the study of effect of external wind as an agent to drive the system towards the possibility of a chaotic solution. Investigations reveal presence of quasi-periodic solutions, which are characterized by two incommensurate frequencies. This solution appears in the time simulation by varying the control parameter viz., wind. The solutions correspond to the values in the lower region of the angle of attack versus elevator bifurcation curve in the post-stall region. A steady wind is considered for the analysis and explores the possibility of chaotic motion by increasing the wind in a step wise manner. It is found that wind adds extra energy to the system which in turn drives the system in to chaos. The analysis is done with the help of phase portrait, Poincare map and amplitude spectrum and a quasi-periodic route to chaos via torus doubling is also presented.

  14. Investigation on high angle of attack characteristics of hypersonic space vehicle

    Institute of Scientific and Technical Information of China (English)

    HUANG Wei; LI ShiBin; LIU Jun; WANG ZhenGuo


    The high angle of attack characteristics play an important role in the aerodynamic performances of the hypersonic space vehicle.The three-dimensional Reynolds Averaged Navier-Stokes (RANS) equations and the two-equation RNG k-ε turbulence model have been employed to investigate the influence of the high angle of attack on the lift-to-drag ratio and the flow field characteristics of the hypersonic space vehicle,and the contributions of each component to the aerodynamic forces of the vehicle have been discussed as well.At the same time,in order to validate the numerical method,the predicted results have been compared with the available experimental data of a hypersonic slender vehicle,and the grid independency has been analyzed.The obtained results show that the predicted lift-to-drag ratio and pitching moment coefficient show very good agreement with the experimental data in the open literature,and the grid system makes only a slight difference to the numerical results.There exists an optimal angle of attack for the aerodynamic performance of the hypersonic space vehicle,and its value is 20°.When the angle of attack is 20°,the high pressure does not leak from around the leading edge to the upper surface.With the further increasing of the angle of attack,the high pressure spreads from the wing tips to the central area of the vehicle,and overflows from the leading edge again.Further,the head plays an important role in the drag performance of the vehicle,and the lift percentage of the flaperon is larger than that of the rudderevator.This illustrates that the optimization of the flaperon configuration is a great work for the improvement of the aerodynamic performance of the hypersonic space vehicle,especially for a high lift-to-drag ratio.

  15. A kinematic model for the formation of duplex systems with a perfectly planar roof thrust (United States)

    Contreras, Juan; Suter, Max


    We present a cross-sectional kinematic forward model for the formation of duplexes with a perfectly planar roof thrust. The major assumptions are a constant dip and constant spacing of the ramps in the undeformed state and sequential deformation in the direction of tectonic transport, with equal displacement along each ramp. The model is based on a coordinate transformation that simulates flexural slip parallel to the active fault surface. This causes angular parallel folds and keeps the layer thickness constant, except in the forelimbs of the horses. Attempts by previous workers to simulate the formation of duplexes with a perfectly planar roof thrust, on the other hand, were based on the assumptions of constant bed thickness and bed length, or a different topology of the axial planes delimiting the forelimbs of the horses, and resulted in corrugated roof thrusts. We show that it is not possible to form a flat roof duplex type and preserve the forelimb thickness of the horses under flexural slip parallel to the active fault. We describe duplexes by three parameters which are the separation s between ramps, the ramp length l, and the displacement u along the ramps. In a {u}/{s} vs {l}/{s} diagram, duplexes with a perfectly planar roof thrust, resulting from numerical experiments with our kinematic algorithm, occupy specific families of straight lines. Our results are independent of the dip or internal geometry of the thrust ramps.

  16. Cenozoic faults and faulting phases in the western Tarim Basin (NW China): Effects of the collisions on the southern margin of the Eurasian Plate (United States)

    Li, Yue-Jun; Zhang, Qiang; Zhang, Guang-Ya; Tian, Zuo-Ji; Peng, Geng-Xin; Qiu, Bin; Huang, Zhi-Bin; Luo, Jun-Cheng; Wen, Lei; Zhao, Yan; Jia, Tie-Gan


    The Bachu Rise in the western Tarim Basin is the fore-bulge of the Kunlun late Cenozoic intra-continental foreland basin system formed under the far-field effect of India-Asia collision. Cenozoic faults and faulting are abnormally developed in the Bachu Rise and its adjacent area. Taking the Niaoshan-Gudongshan area on the southern boundary of the Bachu Rise as the key study area, 5 Cenozoic faulting phases were identified in the Bachu Rise and its adjacent area after careful seismic interpretation. They are end Cretaceous ∼ beginning Paleogene (ca. 65 Ma) décollement-thrusting, end Paleogene ∼ beginning Neogene (ca. 23 Ma) décollement-thrusting, end Miocene ∼ beginning Pliocene (ca. 5 Ma) basement-involved thrusting, late Pliocene ∼ early Pleistocene (ca. 3-2 Ma) normal faulting, middle Pleistocene ∼ Holocene (ca. <1.5 Ma) décollement-thrusting and strike-slip faulting. The Middle Cambrian and Paleogene gypsum-salt layers serve as the two main décollement layers in the study area. Thrusting of ca. 65 Ma was under the far-field effect of the collision between Lhasa (part of the Cimmerian Continent) and Asia; and the other 4 Cenozoic faulting phases were all under the far-field effect of the India-Asia collision. The late Cenozoic faulting is characterized by pulse thrust. There is one tectonic pause between each two successive thrust pulses. The compressive tectonic stress is weaker and even evolved into a slight tensional tectonic stress and forms normal fault in the tectonic pauses.

  17. Fault diagnosis (United States)

    Abbott, Kathy


    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. The relationship of near-surface active faulting to megathrust splay fault geometry in Prince William Sound, Alaska (United States)

    Finn, S.; Liberty, L. M.; Haeussler, P. J.; Northrup, C.; Pratt, T. L.


    We interpret regionally extensive, active faults beneath Prince William Sound (PWS), Alaska, to be structurally linked to deeper megathrust splay faults, such as the one that ruptured in the 1964 M9.2 earthquake. Western PWS in particular is unique; the locations of active faulting offer insights into the transition at the southern terminus of the previously subducted Yakutat slab to Pacific plate subduction. Newly acquired high-resolution, marine seismic data show three seismic facies related to Holocene and older Quaternary to Tertiary strata. These sediments are cut by numerous high angle normal faults in the hanging wall of megathrust splay. Crustal-scale seismic reflection profiles show splay faults emerging from 20 km depth between the Yakutat block and North American crust and surfacing as the Hanning Bay and Patton Bay faults. A distinct boundary coinciding beneath the Hinchinbrook Entrance causes a systematic fault trend change from N30E in southwestern PWS to N70E in northeastern PWS. The fault trend change underneath Hinchinbrook Entrance may occur gradually or abruptly and there is evidence for similar deformation near the Montague Strait Entrance. Landward of surface expressions of the splay fault, we observe subsidence, faulting, and landslides that record deformation associated with the 1964 and older megathrust earthquakes. Surface exposures of Tertiary rocks throughout PWS along with new apatite-helium dates suggest long-term and regional uplift with localized, fault-controlled subsidence.

  19. Microtectonic and geochemical characterization of thrusting in a foreland basin: Example of the South-Pyrenean orogenic wedge (Spain) (United States)

    Lacroix, B.; Buatier, M.; Labaume, P.; Travé, A.; Dubois, M.; Charpentier, D.; Ventalon, S.; Convert-Gaubier, D.


    In orogenic systems, thrust faults play a major role in stacking different tectonic units and may act as conduits for the expulsion of large amounts of fluid of different origins (metamorphic, diagenetic, meteoric). This study focuses on the Monte Perdido thrust unit emplaced in the Paleogene Jaca thrust-sheet-top basin, in the SW-central Pyrenees. We aim to decipher the mechanisms and P-T conditions of deformation in fault zones and characterize the related fluid involvement, through combined microstructural, geochemical and microthermometry analyses. Two thrust faults cutting platform limestones, marls and siliciclastic turbidites of the lower part of the basin-fill (Paleocene-lower Eocene) have been studied. The fault zones are characterized by metre-thick shear zones with highly deformed, foliated clay-rich sediments. Foliation is underlined by preferentially oriented phyllosilicates. Several generations of shear and extension calcite, quartz and chlorite-bearing veins attest to fluid-rock interactions during a multi-stage deformation. Microstructural observations and stable isotope analyses on calcite from veins and host sediments suggest that deformation was aseismic and dominated by diffusive mass transfer from pressure solution sites along cleavage and stylolites to the precipitation sites in veins, with mineralizing fluids in equilibrium with the host sediments. Our results suggest an essentially closed hydrologic system, and imply the absence of significant fluid flow along the studied fault zones. Microthermometric study on fluid inclusions present in calcite and quartz veins, and calcite-quartz oxygen isotopic fractionation determined for the first generation shear veins, allow a geothermal gradient of 34 °C/km to be estimated. Analytical results demonstrate an evolution of the fault zones in three stages. The first stage was related to the emplacement of the Monte Perdido thrust unit during the middle Eocene at a temperature of ˜208 °C and a burial

  20. Polyphase evolution of the Chaîne des Matheux frontal thrust (Haiti) (United States)

    Wessels, Richard; Ellouz-Zimmermann, Nadine; Rosenberg, Claudio; Bellahsen, Nicolas; Hamon, Youri; Deschamps, Remy; Battani, Anne; Leroy, Sylvie; Momplaisir, Roberte


    The NW - SE trending Haitian fold-and-thrust belt (HFTB) is located in the western part of the Caribbean island of Hispaniola. It covers the suture between the Cretaceous Caribbean island arc in the north and the Late Cretaceous thickened oceanic crust in the south. The HFTB is bounded to the north and south by the left-lateral Septentrional (SFZ) and Enriquillo-Plantain Garden (EPGFZ) fault zones, respectively. Compressional deformation on the HFTB commenced as early as Eocene times. It was followed by transpressional deformation from the early Miocene onwards, with in sequence progressive stacking of thrust sheets towards the SW. Seismicity at the junction between the HFTB and the EPGFZ is recorded by the 12 January 2010 Mw 7.0 earthquake. Surface mapping did not reveal a rupture, as the main activity occurred on the steep NNW dipping oblique transpressional Léogâne fault, while aftershocks documented motion on a shallow SW dipping thrust segment. The structural style of deformation of the HFTB, either the stacking of thrust sheets on basement heterogeneities or basement-involved thrusting, has not been studied in detail. Also lacking are conceptual models addressing the amount of convergence between the northern and southern domains, and describing how convergence was accommodated. To address these problems we conducted a detailed fieldwork on the southernmost thrust sheet, known as the Chaîne des Matheux front. Using stratigraphy, geological mapping, cross sections, kinematic fault slip data, analysis of mineralizations and fluid inclusions, and geochemical analysis of fluid seeps, we decipher the evolution of this anticlinal structure. Stratigraphic data reveal stable Eocene platform sedimentation over the whole region, which preceded deepening of the basin throughout Oligocene and early Miocene times. A diachronous evolution is evident from the middle Miocene onwards. The NE flank displays a shallowing upwards trend and clastic sedimentation, while the

  1. Kozu-Matsuda fault system in northern Izu collision zone, western part of Kanagawa Prefecture, central Japan (United States)

    Odawara, K.; Aketagawa, T.; Yoshida, A.


    Western area of Kanagawa Prefecture is techtonically highlighted by its geological setting that the Izu-Bonin volcanic arc collides with the Japan Island arc there. The Kozu-Matsuda fault system which consists of the Kozu-Matsuda fault, the Matsuda-kita fault, the Hinata fault and the Hirayama fault is a surface manifestation of the plate boundary. Research of the Kozu-Matsuda fault has advanced dramatically after the 1995 Kobe Earthquake. Having conducted a trench survey, Kanagawa Prefectural Government (2004) reported that the Kozu-Matsuda fault was activated at least four times in the past 4000 years and the latest activity occurred 650-950 years ago (AD. 1350-1050). However, details of the activity of the Hinata and Hirayama faults, the northern extension of the Kozu-Matsuda fault, are not well understood. The Special Project for Earthquake Disaster Mitigation in Urban areas (DaiDaiToku) made a 2040 m deep drilling in 2004 in Yamakita Town (Hayashi et al., 2006). DaiDaiToku also carried out the seismic reflection profiling along a route from Odawara to Yamanashi in 2005 (Sato et al., 2005). The study done by DaiDaiToku elucidated presence of two north-dipping thrusts. The northern thrust corresponds to the Hinata fault, and the southern one which is also considered to be a continuation of the Kozu-Matsuda fault probably represents a frontal thrust (Miyauchi et al., 2006). We have conducted paleoseismic investigations using data from boreholes across these thrusts.

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

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


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

  3. Mandibular advancement surgery in high-angle and low-angle class II patients: different long-term skeletal responses. (United States)

    Mobarak, K A; Espeland, L; Krogstad, O; Lyberg, T


    The objective of this cephalometric study was to compare skeletal stability and the time course of postoperative changes in high-angle and low-angle Class II patients after mandibular advancement surgery. The subjects were 61 consecutive mandibular retrognathism patients whose treatment included bilateral sagittal split osteotomy and rigid fixation. The patients were divided according to the preoperative mandibular plane angle; the 20 patients with the lowest mandibular plane angle (20.8 degrees +/- 4.9 degrees ) constituted the low-angle group, while the 20 cases with the highest mandibular plane angle (43.0 degrees +/- 4.0 degrees ) represented the high-angle group. Lateral cephalograms were taken on 6 occasions: immediately before surgery, immediately after surgery, 2 and 6 months after surgery, and 1 and 3 years after surgery. Results demonstrated that the high-angle and low-angle groups had different patterns of surgical and postoperative changes. High-angle patients were associated with both a higher frequency and a greater magnitude of horizontal relapse. While 95% of the total relapse took place during the first 2 months after surgery in the low-angle group, high-angle patients demonstrated a more continuous relapse pattern, with a significant proportion (38%) occurring late in the follow-up period. Possible reasons for the different postsurgical response are discussed.

  4. Transient thrust events recorded in the Aare Massif, Bernese Alps (Grimsel Test Site, Switzerland) (United States)

    Hartvich, F.; Stemberk, J.


    The Grimsel Test Site (GTS) is located at an altitude of 1730 m a.s.l. in the granitic formations of the Aare Massif 300 - 500 m under the surface. In November 2012, documented faults within the GTS were instrumented for 3-D monitoring of fault slips in the scope of the LArge Scale MOnitoring project (LASMO). In total 7 devices were installed across faults crossing a 350 m long section of the GTS. The instrumented faults have various strike: W-E, SW-NE, WNW-ESE and WSW-ENE. The faults are instrumented with optical-mechanical extensometers TM71 which allow to measure 3D micro-displacements as well as rotations on the basis of the moiré effect of optical interference. The devices installed in GTS reach the accuracy better than 0.007 mm and the angular deviation between two blocks separated by a discontinuity - i.e. their relative rotation - can be measured with a resolution better than 0.00016 rad. Regular monitoring has started on Dec. 5,2012 and the reading is performed regularly once per day. The first results of 3-D fault displacement monitoring show transient slips recorded during 2 short periods along all monitored faults, alternating with long periods of tectonic quiescence without any fault activity. The measured directions of fault slips enable us to estimate two approximately N - S oriented compression events, causing northwards thrust movements. First period lasted from Dec. 27, 2012 to Feb. 13, 2013. However, major phase of the displacement occurred between Jan. 26 and 29, 2013. Recorded fault slips represent northwards oriented thrusts and strike-slips. A value of individual slips ranges from 0.004 to 0.04 mm. Moreover, the strike-slip movements were recorded during days when two local micro-earthquakes were observed close to GTS: on Jan. 29, 2013 (M = 1.29) and on Feb. 13, 2013 (M = 1.15). The second period of activity lasted from Sept. 7, 2013 to Oct. 28, 2013, and occurred after more than 7 months of no recorded fault slips. The main phase of the

  5. Towards weighing individual atoms by high-angle scattering of electrons

    Energy Technology Data Exchange (ETDEWEB)

    Argentero, G.; Mangler, C.; Kotakoski, J.; Eder, F.R.; Meyer, J.C., E-mail:


    We consider theoretically the energy loss of electrons scattered to high angles when assuming that the primary beam can be limited to a single atom. We discuss the possibility of identifying the isotopes of light elements and of extracting information about phonons in this signal. The energy loss is related to the mass of the much heavier nucleus, and is spread out due to atomic vibrations. Importantly, while the width of the broadening is much larger than the energy separation of isotopes, only the shift in the peak positions must be detected if the beam is limited to a single atom. We conclude that the experimental case will be challenging but is not excluded by the physical principles as far as considered here. Moreover, the initial experiments demonstrate that the separation of gold and carbon based on a signal that is related to their mass, rather than their atomic number. - Highlights: • We explore how energy loss spectroscopy could be used to obtain information about the mass, rather than the charge, of atoms. • The dose and precision that would be needed to distinguish between the two isotopes of carbon, C12 and C13, is estimated. • Signal broadening due to phonons is included in the calculation. • Initial experiments show the separation between gold and carbon based on their mass rather than charge.

  6. Influence of spatial and temporal coherences on atomic resolution high angle annular dark field imaging. (United States)

    Beyer, Andreas; Belz, Jürgen; Knaub, Nikolai; Jandieri, Kakhaber; Volz, Kerstin


    Aberration-corrected (scanning) transmission electron microscopy ((S)TEM) has become a widely used technique when information on the chemical composition is sought on an atomic scale. To extract the desired information, complementary simulations of the scattering process are inevitable. Often the partial spatial and temporal coherences are neglected in the simulations, although they can have a huge influence on the high resolution images. With the example of binary gallium phosphide (GaP) we elucidate the influence of the source size and shape as well as the chromatic aberration on the high angle annular dark field (HAADF) intensity. We achieve a very good quantitative agreement between the frozen phonon simulation and experiment for different sample thicknesses when a Lorentzian source distribution is assumed and the effect of the chromatic aberration is considered. Additionally the influence of amorphous layers introduced by the preparation of the TEM samples is discussed. Taking into account these parameters, the intensity in the whole unit cell of GaP, i.e. at the positions of the different atomic columns and in the region between them, is described correctly. With the knowledge of the decisive parameters, the determination of the chemical composition of more complex, multinary materials becomes feasible.

  7. Dynamic surface measurements on a model helicopter rotor during blade slap at high angles of attack (United States)

    Hubbard, J. E., Jr.; Harris, W. L.


    The modern helicopter offers a unique operational capability to both the public and private sectors. However, the use of the helicopter may become severely limited due to the radiated noise generated by the rotor system. A description is presented of some of the experimental results obtained with a model helicopter rotor in an anechoic wind tunnel with regard to blade stall as a source mechanism of blade slap. Attention is given to dynamic rotor blade surface phenomena and the resulting far field impulsive noise from the model helicopter rotor at high angles of attack and low tip speed. The results of the investigation strongly implicates the boundary layer as playing an important role in blade slap due to blade/vortex interaction (BVI) in a highly loaded rotor. Intermittent stall cannot be ruled out as a possible source mechanism for blade slap. This implies that blade surface characteristics, airfoil shape and local Reynolds number may now be used as tools to reduce the resultant far-field sound pressure levels in helicopters.

  8. Bifurcation analysis and stability design for aircraft longitudinal motion with high angle of attack

    Institute of Scientific and Technical Information of China (English)

    Xin Qi; Shi Zhongke


    Bifurcation analysis and stability design for aircraft longitudinal motion are investigated when the nonlinearity in flight dynamics takes place severely at high angle of attack regime. To pre-dict the special nonlinear flight phenomena, bifurcation theory and continuation method are employed to systematically analyze the nonlinear motions. With the refinement of the flight dynam-ics for F-8 Crusader longitudinal motion, a framework is derived to identify the stationary bifurca-tion and dynamic bifurcation for high-dimensional system. Case study shows that the F-8 longitudinal motion undergoes saddle node bifurcation, Hopf bifurcation, Zero-Hopf bifurcation and branch point bifurcation under certain conditions. Moreover, the Hopf bifurcation renders ser-ies of multiple frequency pitch oscillation phenomena, which deteriorate the flight control stability severely. To relieve the adverse effects of these phenomena, a stabilization control based on gain scheduling and polynomial fitting for F-8 longitudinal motion is presented to enlarge the flight envelope. Simulation results validate the effectiveness of the proposed scheme.

  9. High angle of attack: Forebody flow physics and design emphasizing directional stability (United States)

    Ravi, R.

    A framework for understanding the fundamental physics of flowfields over forebody type shapes at low speed, high angle of attack conditions with special emphasis on sideslip has been established. Computational Fluid Dynamics (CFD) has been used to study flowfieids over experimentally investigated forebodies: the Lamont tangent-ogive forebody, the F-5A forebody and the Erickson chine forebody. A modified version of a current advanced code, CFL3D, was used to solve the Euler and thin-layer Navier-Stokes equations. The Navier-Stokes equations used a form of the Baldwin-Lomax turbulence model modified to account for massive crossflow separation. Using the insight provided by the solutions obtained using CFD, together with comparison with limited available data, the aerodynamics of forebodies with positive directional stability has been revealed. An unconventional way of presenting the results is used to illustrate how a positive contribution to directional stability arises. Based on this new understanding, a parametric study was then conducted to determine which shapes promote a positive contribution to directional stability. The effect of cross-sectional shape on directional stability was found to be very significant. Broad chine-shaped cross-sections were found to promote directional stability. Also, directional stability is improved if the chine is placed closer to the top of the cross-section. Planform shapes also played an important role in determining the forebody directional stability characteristics. This initial parametric study has been used to propose some guidelines for aerodynamic design to promote positive directional stability.

  10. Characterization of slow slip rate faults in humid areas: Cimandiri fault zone, Indonesia (United States)

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


    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.

  11. Seismicity and Tectonics of the West Kaibab Fault Zone, AZ (United States)

    Wilgus, J. T.; Brumbaugh, D. S.


    The West Kaibab Fault Zone (WKFZ) is the westernmost bounding structure of the Kaibab Plateau of northern Arizona. The WKFZ is a branching complex of high angle, normal faults downthrown to the west. There are three main faults within the WKFZ, the Big Springs fault with a maximum of 165 m offset, the Muav fault with 350 m of displacement, and the North Road fault having a maximum throw of approximately 90 m. Mapping of geologically recent surface deposits at or crossing the fault contacts indicates that the faults are likely Quaternary with the most recent offsets occurring one of the most seismically active areas in Arizona and lies within the Northern Arizona Seismic Belt (NASB), which stretches across northern Arizona trending NW-SE. The data set for this study includes 156 well documented events with the largest being a M5.75 in 1959 and including a swarm of seven earthquakes in 2012. The seismic data set (1934-2014) reveals that seismic activity clusters in two regions within the study area, the Fredonia cluster located in the NW corner of the study area and the Kaibab cluster located in the south central portion of the study area. The fault plane solutions to date indicate NE-SW to EW extension is occurring in the study area. Source relationships between earthquakes and faults within the WKFZ have not previously been studied in detail. The goal of this study is to use the seismic data set, the available data on faults, and the regional physiography to search for source relationships for the seismicity. Analysis includes source parameters of the earthquake data (location, depth, and fault plane solutions), and comparison of this output to the known faults and areal physiographic framework to indicate any active faults of the WKFZ, or suggested active unmapped faults. This research contributes to a better understanding of the present nature of the WKFZ and the NASB as well.

  12. Tectonic origin for polygonal normal faults in pelagic limestones of the Cingoli anticline hinge (Italy) (United States)

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


    Polygonal faults are a relatively-recent new class of normal faults which are thought to be formed during early burial and diagenesis as a consequence of heterogeneous lateral volume changes. Polygonal faults are non-systematically oriented and, in map view, they form rhombus-, pentagon-, or hexagon-like pattern, suggesting a non-tectonic origin. Furthermore, polygonal faults are layer bound and they are restricted to particular stratigraphic level. Predicting the pattern of polygonal normal fault results crucial for geofluid exploration and exploitation, but, despite the large number of studies, the origin of these faults remains still largely controversial. One of the main reason for this uncertainty is that they are poorly known in outcrops. Polygonal faults have been identified in few localities within Mesozoic chalk (United Kingdom, France, and Egypt), in Paleogene claystone (Belgium), and in the Cretaceous Khoman Formation (Egypt) where polygonal faults have been observed in an extensive exposure of chalk. In this study, we describe an outcrop in the Cingoli anticline hinge, which is located at external front of the northern Apennines fold-thrust belt (Italy), showing normal faults that we interpreted as syn-tectonically (syn-thrusting) polygonal faults. The outcrop shows three vertical exposures of sub-horizontal fine-grained marly limestones with chert interlayers of Albian-Turonian age. Intraformational short normal faults affect the carbonate and chert beds. These faults are poorly-systematic and they cut through the carbonate beds whereas usually stop against the chert layers. The fault surfaces are often characterized by slickolites, clayey residue, and micro-breccias including clasts of chert and carbonate. Fault displacement is partly or largely accommodated by pressure solution. At the fault tips, the displacement is generally transferred, via a lateral step, to an adjacent similar fault segment. The aim of our study is to understand the nucleation

  13. Significant Cenozoic faulting, east margin of the Española Basin, Rio Grande rift, New Mexico (United States)

    Vernon, James H.; Riecker, Robert E.


    Tectonic interpretation of the east margin of the Española Basin, Rio Grande rift, New Mexico, has been controversial. Previous authors have disagreed as to whether significant faulting defines the boundary between the basin and the Sangre de Cristo Mountains. A more recent geophysical basin transect that suggests no significant faulting and held observation of faceted spurs along the western Sangre de Cristo Mountain front indicating a faulted margin motivate our study. The east margin of the Española Basin for about 37 km north of Santa Fe, New Mexico, is marked by a complex array of significant, late Cenozoic high-angle faults. Locally, three parallel, north-trending, high-angle faults cut Precambrian basement and Tertiary basin-fill rocks along the basin margin. Elsewhere along the margin, tilted fault blocks and intersecting faults occur. Fault area, fault attitude with depth, magnitude of fault motion, and timing of fault motion remain uncertain. However, faults studied in detail are 1-2 km long, have minimum dip-slip motion of 33-100 m, and underwent movement during the late Cenozoic. Potentially significant tectonic and seismic hazard implications arise from the possibility of post-150 ka fault motion.

  14. Upper crustal mechanical stratigraphy and the evolution of thrust wedges: insights from sandbox analogue experiments (United States)

    Milazzo, Flavio; Storti, Fabrizio; Nestola, Yago; Cavozzi, Cristian; Magistroni, Corrado; Meda, Marco; Salvi, Francesca


    Crustal mechanical stratigraphy i.e. alternating mechanically weaker and stronger layers within the crust, plays a key role in determining how contractional deformations are accommodated at convergent plate boundaries. In the upper crust, evaporites typically provide preferential décollement layers for fault localization and foreland ward propagation, thus significantly influencing evolution of thrust-fold belts in terms of mechanical balance, geometries, and chronological sequences of faulting. Evaporites occur at the base of many passive margin successions that underwent positive inversion within orogenic systems. They typically produce salient geometries in deformation fronts, as in the Jura in the Northern Alps, the Salakh Arch in the Oman Mountains, or the Ainsa oblique thrust-fold belt in the Spanish Pyrenees. Evaporites frequently occur also in foredeep deposits, as in the Apennines, the Pyrenees, the Zagros etc. causing development of additional structural complexity. Low-friction décollement layers also occur within sedimentary successions involved in thrust-fold belts and they contribute to the development of staircase fault trajectories. The role of décollement layers in thrust wedge evolution has been investigated in many experimental works, particularly by sandbox analogue experiments that have demonstrated the impact of basal weak layers on many first order features of thrust wedges, including the dominant fold vergence, the timing of fault activity, and the critical taper. Some experiments also investigated on the effects of weak layers within accreting sedimentary successions, showing how this triggers kinematic decoupling of the stratigraphy above and below the décollements, thus enhancing disharmonic deformation. However, at present a systematic experimental study of the deformation modes of an upper crustal mechanical stratigraphy consisting of both low-friction and viscous décollement layers is still missing in the specific literature. In

  15. Gorringe Ridge gravity and magnetic anomalies are compatible with thrusting at a crustal scale (United States)

    Galindo-Zaldívar, J.; Maldonado, A.; Schreider, A. A.


    The main features of the deep structure of the Gorringe Ridge are analysed on the basis of gravity and magnetic measurements, as well as seismic profiles, drill holes, rock dredges, submersible observations and seismicity data. The gravity and magnetic models of the Gettysburg and Ormonde seamounts, which form the Gorringe Ridge, suggest that the Moho is approximately flat and the upper part of the ridge corresponds to a northwestwards vergent fold. This structure is the result of a northwestward vergent thrust that deformed the oceanic crust, with a minimum slip of approximately 20 km. The activity of the thrust probably started 20 Myr, and produced the recent stages of seamount uplift. The seamount is mainly composed of gabbros of the oceanic crust, serpentinized rocks and alkaline basalts. The large antiform, located in the hangingwall of the thrust, is probably deformed by minor faults. This oceanic ridge is a consequence of the oblique convergence between the African Plate and the overlapping Eurasian Plate.

  16. Core Description and Characteristics of Fault Zones from Hole-A of the Taiwan Chelungpu-Fault Drilling Project

    Directory of Open Access Journals (Sweden)

    En-Chao Yeh


    Full Text Available Taiwan Chelungpu-fault Drilling Project was conducted in drill site Dakeng, Taichung City of central western Taiwan during 2004 - 2005 principally to investigate the rupture mechanism in the northern segment of the Chi-Chi earthquake of 21 September 1999, and also to examine regional stratigraphy and tectonics. Core examination (500 - 1800 m of Hole-A gave profound results aiding in illustrating the lithologic column, deformation structure, and architectural pattern of fault zones along the borehole. Lithology column of Hole-A was identified downward as the Cholan Formation (500 - 1027 m, Chinshui Shale (1027 - 1268 m, Kueichulin Formation (1268 - 1712 m, and back to the Cholan Formation (1712 - 2003 m again. A dramatic change is observed regarding sedimentation age and deformation structure around 1712 m. Along the core, most bedding dips _ _ Around 1785 m, bedding dip jumps up to _ the bottom of borehole. Five structure groups of different orientations (dip direction/dip are observed throughout the core. Based on the orientation and sense of shear, they are categorized as thrust (105/30, left-lateral fault (015/30 - 80, right-lateral fault (195/30 - 80, normal fault (105/5 - 10, and backthrust (285/40 - 50. Ten fault zones have been recognized between 500 and 2003 m. We interpret the fault zone located at around 1111 m as being the most likely candidate for rupture deformation during Chi-Chi earthquake. The fault zone seated around 1712 m is recognized as the Sanyi fault zone which is 600 m beneath the Chelungpu fault zone. Ten fault zones including thrust faults, strike-slip faults and backthrust are classified as the Chelungpu Fault System (1500 m. According to the deformation textures within fault zones, the fault zones can be categorized as three types of deformation: distinct fracture deformation, clayey-gouge deformation, and soft-rock deformation. Fracture deformation is dominant within the Chelungpu Fault System and abother two

  17. Vestiges of an Ordovician west-vergent thin-skinned Ocloyic thrust belt in the Argentine Precordillera, southern Central Andes (United States)

    Thomas, William A.; Astini, Ricardo A.


    Collision of the down-going, Laurentia-derived Argentine Precordillera terrane with the Gondwanan margin drove the Ordovician Ocloyic orogeny, including subduction volcanism, metamorphism, and top-to-west shearing east of the Precordillera. In the Precordillera, above passive-margin carbonates (Lower Ordovician San Juan Limestone and older carbonates), a Middle to Upper Ordovician westward-prograding synorogenic clastic wedge of black shale (Gualcamayo Shale) and coarser clastic sediment (Las Vacas Conglomerate and Trapiche Formation) fills a peripheral foreland basin. New research has identified vestiges of a west-directed thin-skinned Ocloyic foreland thrust belt that has been fragmented by east-directed Andean thrusting. The El Corral thrust sheet, with hanging-wall detachment in the San Juan Limestone, extends over a west-directed footwall frontal ramp and extensive flat to low-angle footwall cutoff in the Gualcamayo and Las Vacas formations. Las Vacas conglomerates in the footwall include olistoliths (10-m scale) exclusively of San Juan Limestone and Gualcamayo Shale; the beds in some olistoliths are folded. The advancing El Corral thrust sheet successively supplied and overrode the stratigraphically restricted olistoliths. In the El Corral footwall, tight west-vergent folds and faults within an anticlinorium in the San Juan Limestone and Gualcamayo Shale suggest a deeper (unexposed) thrust fault, the Los Celestitos fault. West of the anticlinorium, easterly dip (restored to remove Andean deformation) beneath an angular unconformity between Las Vacas and Trapiche beds is consistent geometrically with the trailing limb of a west-vergent fault-propagation anticline in the hanging wall of the subsurface Los Celestitos fault. The same angular unconformity truncates the El Corral fault and hanging-wall strata. In the Trapiche Formation, contrasting sedimentary facies from sandy turbidites westward to limestone-clast megabeds and olistoliths suggest another frontal

  18. Dielectric Barrier Discharge (DBD) Plasma Actuators Thrust-Measurement Methodology Incorporating New Anti-Thrust Hypothesis (United States)

    Ashpis, David E.; Laun, Matthew C.


    We discuss thrust measurements of Dielectric Barrier Discharge (DBD) plasma actuators devices used for aerodynamic active flow control. After a review of our experience with conventional thrust measurement and significant non-repeatability of the results, we devised a suspended actuator test setup, and now present a methodology of thrust measurements with decreased uncertainty. The methodology consists of frequency scans at constant voltages. The procedure consists of increasing the frequency in a step-wise fashion from several Hz to the maximum frequency of several kHz, followed by frequency decrease back down to the start frequency of several Hz. This sequence is performed first at the highest voltage of interest, then repeated at lower voltages. The data in the descending frequency direction is more consistent and selected for reporting. Sample results show strong dependence of thrust on humidity which also affects the consistency and fluctuations of the measurements. We also observed negative values of thrust or "anti-thrust", at low frequencies between 4 Hz and up to 64 Hz. The anti-thrust is proportional to the mean-squared voltage and is frequency independent. Departures from the parabolic anti-thrust curve are correlated with appearance of visible plasma discharges. We propose the anti-thrust hypothesis. It states that the measured thrust is a sum of plasma thrust and anti-thrust, and assumes that the anti-thrust exists at all frequencies and voltages. The anti-thrust depends on actuator geometry and materials and on the test installation. It enables the separation of the plasma thrust from the measured total thrust. This approach enables more meaningful comparisons between actuators at different installations and laboratories. The dependence on test installation was validated by surrounding the actuator with a large diameter, grounded, metal sleeve.

  19. A Foil Thrust Bearing Test Rig for Evaluation of High Temperature Performance and Durability (United States)


    communication faults. Test Articles Thrust runners, shown in figures 4 and 5, are rotating disks usually constructed of Inconel 718 , a nickel-based superalloy...constructed of various corrosion-resistant steels, and bearing foils are most often constructed from Inconel X750. Commercial bearings are purchased with...coatings with increased temperature capability are required for some applications. Uncoated Inconel X750 top foils run against PS304-coatings in

  20. Geomorphic features of active faults around the Kathmandu Valley, Nepal, and no evidence of surface rupture associated with the 2015 Gorkha earthquake along the faults (United States)

    Kumahara, Yasuhiro; Chamlagain, Deepak; Upreti, Bishal Nath


    The M7.8 April 25, 2015, Gorkha earthquake in Nepal was produced by a slip on the low-angle Main Himalayan Thrust, a décollement below the Himalaya that emerges at the surface in the south as the Himalayan Frontal Thrust (HFT). The analysis of the SAR interferograms led to the interpretations that the event was a blind thrust and did not produce surface ruptures associated with the seismogenic fault. We conducted a quick field survey along four active faults near the epicentral area around the Kathmandu Valley (the Jhiku Khola fault, Chitlang fault, Kulekhani fault, Malagiri fault and Kolphu Khola fault) from July 18-22, 2015. Those faults are located in the Lesser Himalaya on the hanging side of the HFT. Based on our field survey carried out in the area where most typical tectonic landforms are developed, we confirmed with local inhabitants the lack of any new surface ruptures along these faults. Our observations along the Jhiku Khola fault showed that the fault had some definite activities during the Holocene times. Though in the past it was recognized as a low-activity thrust fault, our present survey has revealed that it has been active with a predominantly right-lateral strike-slip with thrust component. A stream dissecting a talus surface shows approximately 7-m right-lateral offset, and a charcoal sample collected from the upper part of the talus deposit yielded an age of 870 ± 30 y.B.P, implying that the talus surface formed close to 870 y.B.P. Accordingly, a single or multiple events of the fault must have occurred during the last 900 years, and the slip rate we estimate roughly is around 8 mm/year. The fault may play a role to recent right-lateral strike-slip tectonic zone across the Himalayan range. Since none of the above faults showed any relationship corresponding to the April 25 Gorkha earthquake, it is possibility that a potential risk of occurrence of large earthquakes does exist close to the Kathmandu Valley due to movements of these active

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

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


    surface that we interpret as a folded 1-3 km-thick, slab of Coast Range Ophiolite. Modeling shows that the northeast edge of this magnetic slab is defined by a northeast-dipping structure that we interpret as the Paicines fault. The base of this magnetic slab, which is folded up along the Calaveras-Paicines fault zone, could represent a roof thrust formed by an eastward-migrating wedge of Franciscan Complex (Jachens et al., 1995).

  2. Measuring Model Rocket Engine Thrust Curves (United States)

    Penn, Kim; Slaton, William V.


    This paper describes a method and setup to quickly and easily measure a model rocket engine's thrust curve using a computer data logger and force probe. Horst describes using Vernier's LabPro and force probe to measure the rocket engine's thrust curve; however, the method of attaching the rocket to the force probe is not discussed. We show how a…

  3. Mu rhythm desynchronization by tongue thrust observation. (United States)

    Sakihara, Kotoe; Inagaki, Masumi


    We aimed to investigate the mu rhythm in the sensorimotor area during tongue thrust observation and to obtain an answer to the question as to how subtle non-verbal orofacial movement observation activates the sensorimotor area. Ten healthy volunteers performed finger tap execution, tongue thrust execution, and tongue thrust observation. The electroencephalogram (EEG) was recorded from 128 electrodes placed on the scalp, and regions of interest were set at sensorimotor areas. The event-related desynchronization (ERD) and event-related synchronization (ERS) for the mu rhythm (8-13 Hz) and beta (13-25 Hz) bands were measured. Tongue thrust observation induced mu rhythm ERD, and the ERD was detected at the left hemisphere regardless whether the observed tongue thrust was toward the left or right. Mu rhythm ERD was also recorded during tongue thrust execution. However, temporal analysis revealed that the ERD associated with tongue thrust observation preceded that associated with execution by approximately 2 s. Tongue thrust observation induces mu rhythm ERD in sensorimotor cortex with left hemispheric dominance.

  4. Measuring Model Rocket Engine Thrust Curves (United States)

    Penn, Kim; Slaton, William V.


    This paper describes a method and setup to quickly and easily measure a model rocket engine's thrust curve using a computer data logger and force probe. Horst describes using Vernier's LabPro and force probe to measure the rocket engine's thrust curve; however, the method of attaching the rocket to the force probe is not discussed. We show how a…

  5. Application of remote sensing techniques to study the neotectonics in the northwestern Himalayan fold-and-thrust belt, Pakistan (United States)

    Chen, Lize

    The northwestern Himalayan foreland fold-and-thrust belt in Pakistan is characterized by a gentle slope, extraordinary width, and abrupt lateral structural variations at the front of this belt. To understand the structures and the formation mechanism of the structural reentrants, remote sensing and seismic interpretation techniques are used to study the surface and subsurface geology. Geomorphic features are extracted from the Shuttle Radar Topography Mission (SRTM) DEM data. Structures are interpreted from Landsat ETM+ images and published maps. These data suggest that the varying resistance under the fold-and-thrust belt is the main cause of the distinct topographic and structural features. ASTER data are used to map the detailed lithology and structures in the Kalabagh Fault Zone, which is the largest lateral structure connecting the Salt Range and the Surghar Range at leading edge of the fold-and-thrust belt. Combining surface geology with seismic interpretations, cross sections are constructed to understand the fault geometry. Salt is found to have played an important role in the development of the Kalabagh Fault. InSAR observations are used to estimate the slip rate, and slip direction along the Kalalabagh Fault Zone. The deformation style interpreted from the interferogram is in concordance with the analogue modeling results. Integration of the geomorphologic analysis, structures, current deformation, and previous studies suggests that the foreland fold-and-thrust belt can be divided into three thrust wedges propagating on decollements with different rheological properties. The viscous salt decollement allows the Salt Range to propagate further southwards than the Surghar Range. The Kalabagh Fault accommodates different shortening between these wedges.

  6. Co-seismic Faults and Geological Hazards and Incidence of Active Fault of Wenchuan Ms 8.0 Earthquake, Sichuan, China

    Institute of Scientific and Technical Information of China (English)

    MA Yinsheng; LONG Changxing; TAN Chengxuan; WANG Tao; GONG Mingquan; LIAO Chunting; WU Manlu; SHI Wei; DU Jianjun; PAN Feng


    There are two co-seismic faults which developed when the Wenchuan earthquake happened. One occurred along the active fault zone in the central Longmen Mts. and the other in the front of Longmen Mts. The length of which is more than 270 km and about 80 km respectively. The co-seismic fault shows a reverse flexure belt with strike of N45°-60°E in the ground, which caused uplift at its northwest side and subsidence at the southeast. The fault face dips to the northwest with a dip angle ranging from 50° to 60°. The vertical offset of the co-seismic fault ranges 2.5-3.0 m along the Yingxiu-Beichuan co-seismic fault, and 1.5-1.1 m along the Doujiangyan-Hanwang fault. Movement of the co-seismic fault presents obvious segmented features along the active fault zone in central Longmen Mts. For instance, in the section from Yingxiu to Leigu town, thrust without evident slip occurred; while from Beichuan to Qingchuan, thrust and dextral strike-slip take place. Main movement along the front Longmen Mts. shows thrust without slip and segmented features. The area of earthquake intensity more than IX degree and the distribution of secondary geological hazards occurred along the hanging wall of co-seismic faults, and were consistent with the area of aftershock, and its width is less than 40km from co-seismic faults in the hanging wail. The secondary geological hazards, collapses, landslides, debris flows et al., concentrated in the hanging wall of co-seismic fault within 0--20 km from co-seismic fault.

  7. How the structure of a continental margin affects the development of a fold and thrust belt. 2: Imaging basement structures with seismic velocities and seismicity in south-central Taiwan (United States)

    Biete, Cristina; Brown, Dennis; Alvarez-Marron, Joaquina; Camanni, Giovanni; Kuo-Chen, Hao; Ho, Chun-Wei


    We investigate the geophysical signature within the south-central Taiwan fold and thrust belt of the reactivation of pre-existing structures developed on the Eurasian margin. Seismic tomography (P-wave) and earthquake hypocenters are combined to trace structures mapped on the margin offshore western Taiwan into the fold and thrust belt. The extensional tectonic history of the margin began in the Early Eocene and culminated in the Late Eocene to Early Oligocene with sea-floor spreading and the opening of the South China Sea. Several NE trending basins developed during the rifting of a pre-Cenozoic basement and these were filled with Eocene sediments. Further extension on the outer margin took place during the Middle to Late Miocene, forming basins that are now involved in the Taiwan deformation. Finally, the margin's transition from the platform to the slope takes place across south-central Taiwan and is oriented at a high angle to the active deformation front. We define the basement as pre-Eocene rocks and use a P-wave velocity (Vp) of 5.2 km/s as a proxy for the interface between them and their younger cover. This Vp interface is characterized by highs and lows that can be interpreted to image basement topography whose possible causes we investigate here. In the Hsuehshan Range there is a pronounced shallowing of the 5.2 km/s surface across the Shuilikeng fault. It is accompanied by an east-dipping cluster of seismicity down to more than 25 km depth, and forming what appears to be a crustal ramp across which the Eocene-age Hsuehshan Basin is being inverted. Westward, the 5.2 km/s interface forms a high called Paikang basement high, the southern flank of which is the on land projection of the Mesozoic basement shelf break. Southward, there is an increase in seismicity and topography that is associated to a NE-SW oriented lateral structure in the fold and thrust belt. South of this lateral structure, beneath the Alishan Range, a shallowing of the 5.2 km/s interface

  8. Selective reverse-reactivation of normal faults, and deformation around reverse-reactivated faults in the Mesozoic of the Somerset coast (United States)

    Kelly, P. G.; Peacock, D. C. P.; Sanderson, D. J.; McGurk, A. C.


    Normal faults exposed in the Triassic-Jurassic limestones and shales of the Somerset coast were formed during the Mesozoic development of the Bristol Channel Basin. Reverse-reactivation of some of these normal faults occurred during Late Cretaceous to Early Tertiary north-south contraction. The contraction is also evident from thrusts and conjugate strike-slip faults. Preferential reactivation of the normal faults is attributed to: (1) decreased fault-plane friction, (2) domino block rotation, (3) displacement magnitude, and (4) fault connectivity. The geometries of overlapping and underlapping zones in reactivated fault zones are dependent on the existing structural geometry. Two distinctive styles of displacement accommodation occur between reverse-reactivated normal faults: (1) formation of a network of strike-slip faults, conjugate about NNE-SSW, and (2) oblique steeply-dipping reverse faults. Interaction between strike-slip and an existing fault is dependent on whether the normal fault was reactivated. The range of structures related to the north-south contraction has been incorporated into a single deformation model, controlled by the northwards movement of the hanging wall of the Quantock's Head Fault. Pure dip-slip movement occurred in the centre of its curved fault trace, with a sinistral component at the western tip, and a dextral component of displacement and strike-slip block rotations occurred at the eastern tip. Shortening of these blocks was achieved through development of a strike-slip fault network and NW-striking thrusts. In an underlap zone, loading of the footwall by the hanging wall block modified the local stress system to allow formation of oblique, steeply-dipping reverse faults.

  9. Thrust duplex deformation in the volcaniclastic sequence of the Fatima fold-and-thrust belt in the west-central Arabian Shield (United States)

    El-Shafei, Mohamed K.


    In this study, we present a field-based structural analysis of the unmetamorphosed Precambrian volcaniclastic sequences of the west-central Arabian Shield. The study area is known as the Fatima fold-and-thrust belt, which is an overturned synclinorium that developed during the Neoproterozoic era. This belt is composed primarily of green mudstone, green sandstone, an andesite flow, limestone, red mudstone and pyroclastic units. This stratigraphic succession, which presents different rheological multilayers, offers significant mesoscale folding and thrust-related structures. Mechanical anisotropy and thickness contrasts have played significant roles in controlling the style of the deformation. Deformed hinge zones, a simple duplex, a domino-style duplex, and imbricated and antiformal stacks are among the thrust-related structures presented and analyzed. The domino-style duplex observed on the backlimbs of the overturned anticlines formed a unique pattern that developed during thrust propagation. The results of this study indicate that the thrust duplex developed according to a thick-skinned model, and it represents a newly recognized tectonic regime in the Arabian Shield. Comprehensive field mapping and structural analyses revealed that the zone under study area was affected by four phases of deformation (D1-D4). The D1 and D2 phases present ductile deformation that developed during the final cratonization and assembly of the Arabian Shield, and they can be recognized at both the map and outcrop scales. The D1 phase represents a progressive regime and is indicated by a NW-SE stress orientation and the formation of a series of coaxial symmetrical NE-SW-plunging folds. NNW-directed thrust-related structures progressively developed during the D2 phase. An approximately fifty-three percent tectonic shortening can be calculated based on the restored structures. D3 and D4 have a brittle nature and are indicated by shearing and normal faulting, respectively.

  10. Apparent stress, fault maturity and seismic hazard for normal-fault earthquakes at subduction zones (United States)

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


    The behavior of apparent stress for normal-fault earthquakes at subduction zones is derived by examining the apparent stress (?? a = ??Es/Mo, where E s is radiated energy and Mo is seismic moment) of all globally distributed shallow (depth, ?? 1 MPa) are also generally intraslab, but occur where the lithosphere has just begun subduction beneath the overriding plate. They usually occur in cold slabs near trenches where the direction of plate motion across the trench is oblique to the trench axis, or where there are local contortions or geometrical complexities of the plate boundary. Lower ??a (tectonic regime suggests that the level of ?? a is related to fault maturity. Lower stress drops are needed to rupture mature faults such as those found at plate interfaces that have been smoothed by large cumulative displacements (from hundreds to thousands of kilometres). In contrast, immature faults, such as those on which intraslab-normal-fault earthquakes generally occur, are found in cold and intact lithosphere in which total fault displacement has been much less (from hundreds of metres to a few kilometres). Also, faults on which high ??a oceanic strike-slip earthquakes occur are predominantly intraplate or at evolving ends of transforms. At subduction zones, earthquakes occurring on immature faults are likely to be more hazardous as they tend to generate higher amounts of radiated energy per unit of moment than earthquakes occurring on mature faults. We have identified earthquake pairs in which an interplate-thrust and an intraslab-normal earthquake occurred remarkably close in space and time. The intraslab-normal member of each pair radiated anomalously high amounts of energy compared to its thrust-fault counterpart. These intraslab earthquakes probably ruptured intact slab mantle and are dramatic examples in which Mc (an energy magnitude) is shown to be a far better estimate of the potential for earthquake damage than Mw. This discovery may help explain why loss of

  11. Exploring for hydrocarbons under thrust belts - A challenging new frontier in the Carpathians and elsewhere

    Energy Technology Data Exchange (ETDEWEB)

    Picha, F.J. [Chevron Overseas Petroleum, Inc., San Ramon, CA (United States)


    New significant reserves of hydrocarbons may occur in subthrust autochthonous and parautochthonous series buried below the frontal zones of thin-skinned thrust belts. The subthrust plays have been tested in several orogenic belts of the world, the Carpathians being one of the best examples. The arcuate thin-skinned Carpathian orogenic belt, which evolved during the Mesozoic and Cenozoic, is thrust tens of kilometers over its Neogene foredeeps and the underlying. European plate. Various structural and stratigraphic settings and potential hydrocarbon plays have been recognized within the buried margins of the European plate, including a late Paleozoic Hercynian compressional system, Mesozoic rifted margins of the Tethys, and a Cenozoic synorogenic foreland-type fault system. Possibly, deeper parautochthonous structures, documented on examples from the southern Apennines, may also be present below the thin-skinned frontal zone of the Carpathian thrust belt. In addition to these structural settings, large Paleogene valleys/submarine canyons have been found within the margins of the European plate. These structural and morphologic features, if combined with source rocks, reservoirs, and proper burial history, represent potential hydrocarbon plays. Generation of hydrocarbons from sources within the subthrust plate was greatly enhanced by emplacement of the wedge-shaped thrust belt, which may also provide a regional seal; therefore, the combination of the long and complex geological history of the European plate with the impact of the Alpine thrusting and foreland deformation created unique conditions for generation, entrapment, and preservation of hydrocarbons in subthrust settings.

  12. Oblique transpression in the western thrust front of the Colombian Eastern Cordillera (United States)

    Acosta, J.; Lonergan, L.; Coward, M. P.


    New kinematic data reveal that the main faults of the western foothills of the Colombian Eastern Cordillera are a series of left-lateral to oblique thrusts that are offset by steeply dipping, northwest-trending, left-lateral, strike-slip faults. Kinematic data were collected from the main structures that dominate the 350-km length of the western foothills of the Eastern Cordillera, north of Bogota (La Salina-Bituima, Cambrás, Dos Hermanos-Alto del Trigo, and Bucaramanga faults). These data indicate that transpression is responsible for the Cenozoic formation of the folds and thrusts that deform the Mesozoic and Cenozoic sedimentary sequences of the Middle Magdalena Valley. Kinematic and structural data suggest that the La Salina-Bituima fault changed from a reverse fault to a fault with a left-lateral, strike-slip sense of displacement during middle to late Miocene times. As it propagated, a transpressive zone was generated in the western foothills of the Eastern Cordillera, with the development of arcuate, oblique-reverse secondary faults on the leading edge of the Magdalena basin (e.g. Cambrás, Dos Hermanos). This development implies that during the Neogene (?), the tectonics of the western foothills were dominated by nonplanar deformation with shortening accompanied by significant left-lateral, strike-slip displacements. These new data indicate that the oblique convergence vector imposed by convergence among the Nazca, Caribbean, and South American plates is not fully partitioned in space but instead must be distributed in a diffuse zone of transpressional deformation along the western margin of the Eastern Cordillera and its associated foreland basin.

  13. From tomographic images to fault heterogeneities

    Directory of Open Access Journals (Sweden)

    A. Amato


    Full Text Available Local Earthquake Tomography (LET is a useful tool for imaging lateral heterogeneities in the upper crust. The pattern of P- and S-wave velocity anomalies, in relation to the seismicity distribution along active fault zones. can shed light on the existence of discrete seismogenic patches. Recent tomographic studies in well monitored seismic areas have shown that the regions with large seismic moment release generally correspond to high velocity zones (HVZ's. In this paper, we discuss the relationship between the seismogenic behavior of faults and the velocity structure of fault zones as inferred from seismic tomography. First, we review some recent tomographic studies in active strike-slip faults. We show examples from different segments of the San Andreas fault system (Parkfield, Loma Prieta, where detailed studies have been carried out in recent years. We also show two applications of LET to thrust faults (Coalinga, Friuli. Then, we focus on the Irpinia normal fault zone (South-Central Italy, where a Ms = 6.9 earthquake occurred in 1980 and many thousands of attershock travel time data are available. We find that earthquake hypocenters concentrate in HVZ's, whereas low velocity zones (LVZ’ s appear to be relatively aseismic. The main HVZ's along which the mainshock rupture bas propagated may correspond to velocity weakening fault regions, whereas the LVZ's are probably related to weak materials undergoing stable slip (velocity strengthening. A correlation exists between this HVZ and the area with larger coseismic slip along the fault, according to both surface evidence (a fault scarp as high as 1 m and strong ground motion waveform modeling. Smaller wave-length, low-velocity anomalies detected along the fault may be the expression of velocity strengthening sections, where aseismic slip occurs. According to our results, the rupture at the nucleation depth (~ 10-12 km is continuous for the whole fault lenoth (~ 30 km, whereas at shallow depth

  14. Main Frontal thrust deformation and topographic growth of the Mohand Range, northwest Himalaya (United States)

    Srivastava, Vinee; Mukul, Malay; Barnes, Jason B.


    The Main Frontal thrust (MFT) uplifts the Himalayan topographic front. Deciphering MFT deformation kinematics is crucial for understanding how the orogen accommodates continuing continental collision and assessing associated hazards. Here, we (a) detail newly discovered fault-zone exposures along the MFT at the Mohand Range front in northwestern India and (b) apply contemporary fault zone theory to show that the MFT is an emergent fault with a well-developed fault zone overlain by uplifted Quaternary gravels over a horizontal length of ∼700 m. Northward from the front, the fault zone grades from a central, gouge-dominated core to a hanging-wall, rock-dominated damage zone. We observed incohesive, non-foliated breccia, fault gouge, and brittle deformation microstructures within the fractured country rocks (Middle Siwaliks) and outcrop scale, non-plunging folds in the proximal hanging wall. We interpret these observations to suggest that (1) elastico-frictional (brittle) deformation processes operated in the fault zone at near surface (∼1-5 km depth) conditions and (2) the folds formed first at the propagating MFT fault tip, then were subsequently dismembered by the fault itself. Thus, we interpret the Mohand Range as a fault-propagation fold driven by an emergent MFT in contrast to the consensus view that it is a fault-bend fold. A fault-propagation fold model is more consistent with these new observations, the modern range-scale topography, and existing erosion estimates. To further evaluate our proposed structural model, we used a Boundary Element Method-based dislocation model to simulate topographic growth from excess slip at a propagating fault tip. Results show that the frontal topography could have evolved by slip along a (a) near-surface fault plane consistent with the present-day MFT location, or (b) blind MFT at ∼3 km depth farther north near the drainage divide. Comparing modelled vs. measured high resolution (∼16 cm) topographic profiles for each

  15. Fault locking and slip rate deficit of the Haiyuan-Liupanshan fault zone in the northeastern margin of the Tibetan Plateau (United States)

    Li, Yanchuan; Shan, Xinjian; Qu, Chunyan; Wang, Zhenjie


    GPS-derived horizontal velocities, geologic fault slip rates and earthquake-derived fault slip vector azimuths are inverted simultaneously for fault coupling and slip rate deficit on the Haiyuan-Liupanshan fault in the northeastern margin of the Tibetan Plateau. Along the Haiyuan fault, the results show 3.2-6.2 mm/yr of left-lateral strike-slip, and the strike-slip transformed into thrusting deformation (2.8-3.5 mm/yr) along the Liupanshan fault. The results suggest full coupling down to ∼10 km along the Haiyuan fault. Significant portions from the Jinqianghe fault to the Maomaoshan fault, however, are locked to ∼23 km depth. The abrupt change in fault coupling coincides with the Tianzhu seismic gap. High slip rate deficit (3.0-4.5 mm/yr) and seismic moment accumulation rate are also interpreted along the seismic gap. The Liupanshan fault is locked to 15-20 km depth. A high seismic moment accumulation rate, low slip rate deficit (2.0-3.2 mm/yr) and scarcity of large seismic event over the last 1400 years may imply high strain accumulation on the fault. The results demonstrate that crustal deformation in the northeastern Tibetan Plateau is dominated by elastic block rotation. We also conclude that deformation due to fault coupling is limited along the near-field (less than 50 km with velocities less than 2 mm/yr) of the Haiyuan-Liupanshan fault.

  16. Subsurface deformation along major thrusts in the outer-arc high off northwest Sumatra (United States)

    Misawa, A.; Hirata, K.; Seeber, L.; Arai, K.; Ashi, J.; Rahardiawan, R.; Udrekh, U.; Baba, H.; Kinoshita, M.; Fujiwara, T.; Tokuyama, H.; Nakamura, Y.; Permana, H.; Djajadihardja, Y. S.


    A huge ocean-wide tsunami, with average heights of more than 20 meters along the west coast of the northern tip of Sumatra followed the 2004 Sumatra-Andaman earthquake (Mw9.2). Several working hypotheses have been proposed, but the generation mechanism for this tsunami remains unresolved. Several hypotheses suggest a possible coseismic slip on splay faults in the outer-arc-high off northwest Sumatra [e.g., Sibuet et al., 2007]. Among these splay faults, the Middle Thrust(MT) (or possibly the Lower Thrust(LT)), can best account for features of the Indian Ocean tsunamis observed at regional and ocean-wide distances [Hirata et al., 2008]. In 2009, we conducted KY09-09 bathymetry survey offshore northern Sumatra and recognized many geological structures, including candidate traces of these splay faults in the outer-arc-high. In 2010, we conducted the KH-10-5 high-resolution MCS survey with a total of 18 seismic lines to image the subsurface structure associated with LT, MT, and the Upper Thrust(UT) in the outer-arc high. Many of subsurface deformations that can be identified on MCS profiles are distributed along these major thrusts. For an example, more than ten of these MCS profiles show clear indication of subsurface deformation along MT. However, a fraction of subsurface deformations are distributed along other large faults existing between these major thrusts. 14 MCS lines cross basins adjoining MT. Several of these MCS profiles show that the uppermost sediment layers of the basins are deformed, either progressively tilted up to a horizontal sea floor, or sub-parallel tilted along with the sea floor. This suggests geologically "recent" deformation associated with slip along MT. However, other MCS lines did not image such a clear "recent" deformation structures near MT. This may imply lack of deformation, or lack of recent sediment along these profiles to record the deformation. Three MCS lines cross UT of Sibuet et al.[2007] or neighboring basins but we could not

  17. Benchmarking numerical models of brittle thrust wedges (United States)

    Buiter, Susanne J. H.; Schreurs, Guido; Albertz, Markus; Gerya, Taras V.; Kaus, Boris; Landry, Walter; le Pourhiet, Laetitia; Mishin, Yury; Egholm, David L.; Cooke, Michele; Maillot, Bertrand; Thieulot, Cedric; Crook, Tony; May, Dave; Souloumiac, Pauline; Beaumont, Christopher


    We report quantitative results from three brittle thrust wedge experiments, comparing numerical results directly with each other and with corresponding analogue results. We first test whether the participating codes reproduce predictions from analytical critical taper theory. Eleven codes pass the stable wedge test, showing negligible internal deformation and maintaining the initial surface slope upon horizontal translation over a frictional interface. Eight codes participated in the unstable wedge test that examines the evolution of a wedge by thrust formation from a subcritical state to the critical taper geometry. The critical taper is recovered, but the models show two deformation modes characterised by either mainly forward dipping thrusts or a series of thrust pop-ups. We speculate that the two modes are caused by differences in effective basal boundary friction related to different algorithms for modelling boundary friction. The third experiment examines stacking of forward thrusts that are translated upward along a backward thrust. The results of the seven codes that run this experiment show variability in deformation style, number of thrusts, thrust dip angles and surface slope. Overall, our experiments show that numerical models run with different numerical techniques can successfully simulate laboratory brittle thrust wedge models at the cm-scale. In more detail, however, we find that it is challenging to reproduce sandbox-type setups numerically, because of frictional boundary conditions and velocity discontinuities. We recommend that future numerical-analogue comparisons use simple boundary conditions and that the numerical Earth Science community defines a plasticity test to resolve the variability in model shear zones.

  18. Collar nut and thrust ring (United States)

    Lowery, Guy B.


    A collar nut comprises a hollow cylinder having fine interior threads at one end for threadably engaging a pump mechanical seal assembly and an inwardly depending flange at the other end. The flange has an enlarged portion with a groove for receiving an O-ring for sealing against the intrusion of pumpage from the exterior. The enlarged portion engages a thrust ring about the pump shaft for crushing a hard O-ring, such as a graphite O-ring. The hard O-ring seals the interior of the mechanical seal assembly and pump housing against the loss of lubricants or leakage of pumpage. The fine threads of the hollow cylinder provide the mechanical advantage for crushing the hard O-ring evenly and easily with a hand tool from the side of the collar nut rather than by tightening a plurality of bolts from the end and streamlines the exterior surface of the mechanical seal. The collar nut avoids the spatial requirements of bolt heads at the end of a seal and associated bolt head turbulence.

  19. Complex fold and thrust belt structural styles: Examples from the Greater Juha area of the Papuan Fold and Thrust Belt, Papua New Guinea (United States)

    Mahoney, Luke; Hill, Kevin; McLaren, Sandra; Hanani, Amanda


    The remote and inhospitable Papuan Fold Belt in Papua New Guinea is one of the youngest yet least well-documented fold and thrust belts on Earth. Within the frontal Greater Juha area we have carried out >100 km of geological traverses and associated analyses that have added significantly to the contemporary geological and geophysical dataset. Our structural analysis provides evidence of major inversion, detachment and triangle zone faults within the uplifted Eastern Muller Ranges. We have used the dataset to develop a quasi-3D model for the Greater Juha area, with associated cross-sections revealing that the exposed Cenozoic Darai Limestone is well-constrained with very low shortening of 12.6-21.4% yet structures are elevated up to 7 km above regional. We suggest the inversion of pre-existing rift architecture is the primary influence on the evolution of the area and that structures link to the surface via triangle zones and detachment faults within the incompetent Mesozoic passive-margin sedimentary sequence underlying competent Darai Limestone. Arc-normal oriented structures, dominantly oblique dextral, up-to-the-southeast, are pervasive across a range of scales and are here interpreted to relate at depth to weakened pre-existing basement cross-structures. It is proposed that Palaeozoic basement fabric controlled the structural framework of the basin during Early Mesozoic rifting forming regional-scale accommodation zones and related local-scale transfer structures that are now expressed as regional-scale arc-normal lineaments and local-scale arc-normal structures, respectively. Transfer structures, including complexly breached relay ramps, utilise northeast-southwest striking weaknesses associated with the basement fabric, as a mechanism for accommodating displacement along major northwest-southeast striking normal faults. These structures have subsequently been inverted to form arc-normal oriented zones of tear faulting that accommodate laterally variable

  20. Subsurface geometry and evolution of the Seattle fault zone and the Seattle Basin, Washington (United States)

    ten Brink, U.S.; Molzer, P.C.; Fisher, M.A.; Blakely, R.J.; Bucknam, R.C.; Parsons, T.; Crosson, R.S.; Creager, K.C.


    The Seattle fault, a large, seismically active, east-west-striking fault zone under Seattle, is the best-studied fault within the tectonically active Puget Lowland in western Washington, yet its subsurface geometry and evolution are not well constrained. We combine several analysis and modeling approaches to study the fault geometry and evolution, including depth-converted, deep-seismic-reflection images, P-wave-velocity field, gravity data, elastic modeling of shoreline uplift from a late Holocene earthquake, and kinematic fault restoration. We propose that the Seattle thrust or reverse fault is accompanied by a shallow, antithetic reverse fault that emerges south of the main fault. The wedge enclosed by the two faults is subject to an enhanced uplift, as indicated by the boxcar shape of the shoreline uplift from the last major earthquake on the fault zone. The Seattle Basin is interpreted as a flexural basin at the footwall of the Seattle fault zone. Basin stratigraphy and the regional tectonic history lead us to suggest that the Seattle fault zone initiated as a reverse fault during the middle Miocene, concurrently with changes in the regional stress field, to absorb some of the north-south shortening of the Cascadia forearc. Kingston Arch, 30 km north of the Seattle fault zone, is interpreted as a more recent disruption arising within the basin, probably due to the development of a blind reverse fault.

  1. Machine Fault Signature Analysis

    Directory of Open Access Journals (Sweden)

    Pratesh Jayaswal


    Full Text Available The objective of this paper is to present recent developments in the field of machine fault signature analysis with particular regard to vibration analysis. The different types of faults that can be identified from the vibration signature analysis are, for example, gear fault, rolling contact bearing fault, journal bearing fault, flexible coupling faults, and electrical machine fault. It is not the intention of the authors to attempt to provide a detailed coverage of all the faults while detailed consideration is given to the subject of the rolling element bearing fault signature analysis.

  2. Structure and regional significance of the Late Permian(?) Sierra Nevada - Death Valley thrust system, east-central California (United States)

    Stevens, C.H.; Stone, P.


    An imbricate system of north-trending, east-directed thrust faults of late Early Permian to middle Early Triassic (most likely Late Permian) age forms a belt in east-central California extending from the Mount Morrison roof pendant in the eastern Sierra Nevada to Death Valley. Six major thrust faults typically with a spacing of 15-20 km, original dips probably of 25-35??, and stratigraphic throws of 2-5 km compose this structural belt, which we call the Sierra Nevada-Death Valley thrust system. These thrusts presumably merge into a de??collement at depth, perhaps at the contact with crystalline basement, the position of which is unknown. We interpret the deformation that produced these thrusts to have been related to the initiation of convergent plate motion along a southeast-trending continental margin segment probably formed by Pennsylvanian transform truncation. This deformation apparently represents a period of tectonic transition to full-scale convergence and arc magmatism along the continental margin beginning in the Late Triassic in central California. ?? 2005 Elsevier B.V. All rights reserved.

  3. AEROX: Computer program for transonic aircraft aerodynamics to high angles of attack. Volume 1: Aerodynamic methods and program users' guide (United States)

    Axelson, J. A.


    The AEROX program estimates lift, induced-drag and pitching moments to high angles (typ. 60 deg) for wings and for wingbody combinations with or without an aft horizontal tail. Minimum drag coefficients are not estimated, but may be input for inclusion in the total aerodynamic parameters which are output in listed and plotted formats. The theory, users' guide, test cases, and program listing are presented.

  4. Fault-zone structure and weakening processes in basin-scale reverse faults: The Moonlight Fault Zone, South Island, New Zealand (United States)

    Alder, S.; Smith, S. A. F.; Scott, J. M.


    The >200 km long Moonlight Fault Zone (MFZ) in southern New Zealand was an Oligocene basin-bounding normal fault zone that reactivated in the Miocene as a high-angle reverse fault (present dip angle 65°-75°). Regional exhumation in the last c. 5 Ma has resulted in deep exposures of the MFZ that present an opportunity to study the structure and deformation processes that were active in a basin-scale reverse fault at basement depths. Syn-rift sediments are preserved only as thin fault-bound slivers. The hanging wall and footwall of the MFZ are mainly greenschist facies quartzofeldspathic schists that have a steeply-dipping (55°-75°) foliation subparallel to the main fault trace. In more fissile lithologies (e.g. greyschists), hanging-wall deformation occurred by the development of foliation-parallel breccia layers up to a few centimetres thick. Greyschists in the footwall deformed mainly by folding and formation of tabular, foliation-parallel breccias up to 1 m wide. Where the hanging-wall contains more competent lithologies (e.g. greenschist facies metabasite) it is laced with networks of pseudotachylyte that formed parallel to the host rock foliation in a damage zone extending up to 500 m from the main fault trace. The fault core contains an up to 20 m thick sequence of breccias, cataclasites and foliated cataclasites preserving evidence for the progressive development of interconnected networks of (partly authigenic) chlorite and muscovite. Deformation in the fault core occurred by cataclasis of quartz and albite, frictional sliding of chlorite and muscovite grains, and dissolution-precipitation. Combined with published friction and permeability data, our observations suggest that: 1) host rock lithology and anisotropy were the primary controls on the structure of the MFZ at basement depths and 2) high-angle reverse slip was facilitated by the low frictional strength of fault core materials. Restriction of pseudotachylyte networks to the hanging-wall of the

  5. High Performance Methane Thrust Chamber (HPMTC) Project (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop a High-Performance Methane Thrust Chamber (HPMRE) to meet the demands of advanced chemical propulsion systems for deep-space mission...

  6. Combination radial and thrust magnetic bearing (United States)

    Blumenstock, Kenneth A. (Inventor)


    A combination radial and thrust magnetic bearing is disclosed that allows for both radial and thrust axes control of an associated shaft. The combination radial and thrust magnetic bearing comprises a rotor and a stator. The rotor comprises a shaft, and first and second rotor pairs each having respective rotor elements. The stator comprises first and second stator elements and a magnet-sensor disk. In one embodiment, each stator element has a plurality of split-poles and a corresponding plurality of radial force coils and, in another embodiment, each stator element does not require thrust force coils, and radial force coils are replaced by double the plurality of coils serving as an outer member of each split-pole half.

  7. 14 CFR 33.97 - Thrust reversers. (United States)


    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.97 Thrust reversers. (a) If the engine incorporates a reverser, the endurance calibration, operation, and vibration tests prescribed...

  8. Benchmarking numerical models of brittle thrust wedges

    NARCIS (Netherlands)

    Buiter, Susanne J H; Schreurs, Guido; Albertz, Markus; Gerya, Taras V.; Kaus, Boris; Landry, Walter; le Pourhiet, Laetitia; Mishin, Yury; Egholm, David L.; Cooke, Michele; Maillot, Bertrand; Thieulot, Cedric|info:eu-repo/dai/nl/270177493; Crook, Tony; May, Dave; Souloumiac, Pauline; Beaumont, Christopher


    We report quantitative results from three brittle thrust wedge experiments, comparing numerical results directly with each other and with corresponding analogue results. We first test whether the participating codes reproduce predictions from analytical critical taper theory. Eleven codes pass the

  9. Internal structure of a thrust associated with subduction underplating from the Okitsu melange in the Shimanto accretionary complex, Japan (United States)

    Kanaya, T.; Chester, F.; Sakaguchi, A.


    The structure of large-displacement, plate-boundary faults in subduction zones is poorly defined relative to other tectonic settings. The thrust faults in the Okitsu melange constitute a duplex, which juxtapose oceanic pillow basalt (hanging walls) and trench-fill-sedimentary rocks (footwalls), and may represent a paleo-underplating zone of a plate-boundary subduction thrust at seismogenic depth. One well exposed duplex-fault, with displacement greater than several kilometers, is examined through structural mapping at scales of 1:100 to 1:1, mesoscale fabric analysis, and geochemical analysis. The duplex-fault zone displays a unique, asymmetric internal structure: brittle deformation dominates in the hanging wall and brittle and ductile deformation is evident in the footwall. The internal structure and surrounding host rocks reflect three accretionary processes: underthrusting, underplating, and uplifting along Out-of-Sequence-Thrusts (OOSTs). On the basis of style of deformation and displacement field, two distinct deformation episodes are identified, which likely correspond to underthrusting and underplating. The elongation of basalt pillows and the boudinage structure of sandstone blocks in shale indicate an elongation of 1.1 to 1.5 parallel to the oceanic crust layer throughout the host rocks of both the hanging wall and footwall, consistent with uniform extension of the crust during underthrusting. Pillow basalt and sedimentary rocks are juxtaposed by a single cataclasite layer composed of decimeter thick ultracataclasite derived from both rock types along the duplex-fault. Mesoscale implosion breccia and micro textures indicative of pressure solution are observed along the master duplex-fault and thought to be products of alternating fast- and slow-rate slip, respectively. Mesoscale fault fabric indicates a paleostress with the maximum principal compression at 15-20° to the master duplex-fault reflecting layer parallel contraction, which is consistent with

  10. Along-fault migration of the Mount McKinley restraining bend of the Denali fault defined by late Quaternary fault patterns and seismicity, Denali National Park & Preserve, Alaska (United States)

    Burkett, Corey A.; Bemis, Sean P.; Benowitz, Jeff A.


    The tallest mountain in North America, Denali (formerly Mount McKinley, 6,190 m), is situated inside an abrupt bend in the right-lateral strike-slip Denali fault. This anomalous topography is clearly associated with the complex geometry of the Denali fault, but how this restraining bend has evolved in conjunction with the regional topography is unknown. To constrain how this bend in the Denali fault is deforming, we document the Quaternary fault-related deformation north of the Denali fault through combined geologic mapping, active fault characterization, and analysis of background seismicity. Our mapping illustrates an east-west change in faulting style where normal faults occur east of the fault bend and thrust faults predominate to the west. The complex and elevated regional seismicity corroborates the style of faulting adjacent to the fault bend and provides additional insight into the change in local stress field in the crust adjacent to the bend. The style of active faulting and seismicity patterns define a deforming zone that accommodates the southwestward migration of this restraining bend. Fault slip rates for the active faults north of the Denali fault, derived from offset glacial outwash surfaces, indicate that the Mount McKinley restraining bend is migrating along the Denali fault at a late Pleistocene/Holocene rate of 2-6 mm/yr. Ongoing thermochronologic and structural studies of the Mount McKinley restraining bend will extend these constraints on the migration and evolution of the restraining bend deeper in time and to the south of the Denali fault.

  11. Multiphysics Nuclear Thermal Rocket Thrust Chamber Analysis (United States)

    Wang, Ten-See


    The objective of this effort is t o develop an efficient and accurate thermo-fluid computational methodology to predict environments for hypothetical thrust chamber design and analysis. The current task scope is to perform multidimensional, multiphysics analysis of thrust performance and heat transfer analysis for a hypothetical solid-core, nuclear thermal engine including thrust chamber and nozzle. The multiphysics aspects of the model include: real fluid dynamics, chemical reactivity, turbulent flow, and conjugate heat transfer. The model will be designed to identify thermal, fluid, and hydrogen environments in all flow paths and materials. This model would then be used to perform non- nuclear reproduction of the flow element failures demonstrated in the Rover/NERVA testing, investigate performance of specific configurations and assess potential issues and enhancements. A two-pronged approach will be employed in this effort: a detailed analysis of a multi-channel, flow-element, and global modeling of the entire thrust chamber assembly with a porosity modeling technique. It is expected that the detailed analysis of a single flow element would provide detailed fluid, thermal, and hydrogen environments for stress analysis, while the global thrust chamber assembly analysis would promote understanding of the effects of hydrogen dissociation and heat transfer on thrust performance. These modeling activities will be validated as much as possible by testing performed by other related efforts.

  12. Modes of thrust generation in flying animals (United States)

    Luo, Haoxiang; Song, Jialei; Tobalske, Bret; Luo Team; Tobalske Team


    For flying animals in forward flight, thrust is usually much smaller as compared with weight support and has not been given the same amount of attention. Several modes of thrust generation are discussed in this presentation. For insects performing slow flight that is characterized by low advance ratios (i.e., the ratio between flight speed and wing speed), thrust is usually generated by a "backward flick" mode, in which the wings moves upward and backward at a faster speed than the flight speed. Paddling mode is another mode used by some insects like fruit flies who row their wings backward during upstroke like paddles (Ristroph et al., PRL, 2011). Birds wings have high advance ratios and produce thrust during downstroke by directing aerodynamic lift forward. At intermediate advance ratios around one (e.g., hummingbirds and bats), the animal wings generate thrust during both downstroke and upstroke, and thrust generation during upstroke may come at cost of negative weight support. These conclusions are supported by previous experiment studies of insects, birds, and bats, as well as our recent computational modeling of hummingbirds. Supported by the NSF.

  13. The Wallula fault and tectonic framework of south-central Washington, as interpreted from magnetic and gravity anomalies

    Energy Technology Data Exchange (ETDEWEB)

    Blakely, Richard J. [U.S. Geological Survey, Menlo Park, CA (United States); Sherrod, Brian [U.S. Geological Survey, Seattle, WA (United States); Weaver, Craig [U.S. Geological Survey, Seattle, WA (United States); Wells, Ray E. [U.S. Geological Survey, Menlo Park, CA (United States); Rohay, Alan C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)


    Magnetic and gravity data, collected in south-central Washington near the Yakima Fold and Thrust Belt (YFTB) are used to model upper crustal structure, the extent of the late Columbia River Basalt flow named the Ice Harbor member, the vertical conduits (dikes) that the Ice Harbor erupted from, and whether the dikes are offset or affected by faulting on the Wallula Fault zone.

  14. Imaging fault zones using 3D seismic image processing techniques (United States)

    Iacopini, David; Butler, Rob; Purves, Steve


    Significant advances in structural analysis of deep water structure, salt tectonic and extensional rift basin come from the descriptions of fault system geometries imaged in 3D seismic data. However, even where seismic data are excellent, in most cases the trajectory of thrust faults is highly conjectural and still significant uncertainty exists as to the patterns of deformation that develop between the main faults segments, and even of the fault architectures themselves. Moreover structural interpretations that conventionally define faults by breaks and apparent offsets of seismic reflectors are commonly conditioned by a narrow range of theoretical models of fault behavior. For example, almost all interpretations of thrust geometries on seismic data rely on theoretical "end-member" behaviors where concepts as strain localization or multilayer mechanics are simply avoided. Yet analogue outcrop studies confirm that such descriptions are commonly unsatisfactory and incomplete. In order to fill these gaps and improve the 3D visualization of deformation in the subsurface, seismic attribute methods are developed here in conjunction with conventional mapping of reflector amplitudes (Marfurt & Chopra, 2007)). These signal processing techniques recently developed and applied especially by the oil industry use variations in the amplitude and phase of the seismic wavelet. These seismic attributes improve the signal interpretation and are calculated and applied to the entire 3D seismic dataset. In this contribution we will show 3D seismic examples of fault structures from gravity-driven deep-water thrust structures and extensional basin systems to indicate how 3D seismic image processing methods can not only build better the geometrical interpretations of the faults but also begin to map both strain and damage through amplitude/phase properties of the seismic signal. This is done by quantifying and delineating the short-range anomalies on the intensity of reflector amplitudes

  15. Kumano Seismogenic Zone Imaging and Splay Fault Property (United States)

    Kuramoto, S.; Okano, T.; Hashimoto, T.; Tanaka, H.; Taira, A.


    Splay faults or out-of-sequence thrusts (OOSTs) are prominent structure in the Nankai accretionary prism. The splay faults merging to the plate interface between the subducting Philippine Sea plate and the overriding Eurasian plate. The contact area of the splay faults and decollement plane may be a possible up-dip limit of the seismogenic zone from geological interpretation point of view. The splay faults are not continuously traced nearly parallel to the trough axis. The discontinuity of splay fault system coincides with the basement structure from magnetic anomaly map. The faults are recognized as the outer-arc-high in the Kumano accretionary wedge. The splay fault system has an important scientific target that will be clarified by drilling. A new bathymetric survey and dive observations by manned submersible are carried out in the Kumano accretionary wedge. Basic morphological interpretation and dive observations give a new insight of tectonic framework of the Kumano area. Prominent splay fault system shows transpressional fault system and associated by active folding and faulting structures. One of the splay faults shows dextral slip phenomena from en-echelon structural interpretation. Several seepage sites are discovered along the splay faults. Preliminary chemical analysis of sediment pore fluids on the splay fault shows up to 10 % depletion of chloride concentration compare with bottom seawater and extremely high methane concentration of more than 600 umol/kg (Toki et al., in prep.). A significant gamma-ray anomaly also discovered from the same site (Ashi et al.). These data suggest that the origin of fluid is significantly deep and the fluid may flow along the splay fault. A recent Tsunami inversion study suggests that the rupture area during the last large earthquake (Tonankai, 1944) spread over even the splay fault system area. The splay faults show significant differences of activities from structural interpretation of each fault. The lower fault is cut

  16. A workflow for 3D model building in fold-thrust belts (United States)

    Watkins, Hannah; Bond, Clare; Butler, Rob


    3D geological models can be used in fold-thrust belts for many purposes such as analysing geometric variation in folds, kinematic modelling to restore fold surfaces, generating strain distribution maps and predicting fracture network distribution. We present a workflow for 3D model building using outcrop bedding data, geological maps, Digital Terrain Models (DTM's), air photos and field photographs. We discuss the challenges of software limitations for 3D kinematic restoration and forward modelling in fold-thrust belt settings. We then discuss the sensitivity of model building approaches to the application of 3D geological models in fold-thrust belts for further analysis e.g. changes in along strike fold geometry, restoration using kinematic and geomechanical modelling, strain prediction and Discrete Fracture Network (DFN) modelling. To create 3D models geological maps and bedding data are digitised using Move software; digitised maps and data are then draped onto DTM's. A series of closely spaced cross section lines are selected; the orientation of these is calculated by determining the average orientation of bedding dip direction. Fault and horizon line intersections, along with bedding data from within a narrow margin of the section lines are projected onto each cross section. Field photographs and sketches are integrated into the cross sections to determine thrust angles at the surface. Horizon lines are then constructed using bedding data. Displacement profiles for thrusts are plotted to ensure thrust displacements are valid with respect to neighbouring cross section interpretations; any discrepancies are alleviated by making minor adjustments to horizon and thrust lines, while ensuring that resultant cross section geometries still adhere to bedding data and other field observations. Once the cross sections have been finalised, 3D surfaces are created using the horizon and thrust line interpretations on each cross section. The simple curvature of 3D surfaces

  17. 14 CFR 33.79 - Fuel burning thrust augmentor. (United States)


    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel burning thrust augmentor. 33.79... thrust augmentor. Each fuel burning thrust augmentor, including the nozzle, must— (a) Provide cutoff of the fuel burning thrust augmentor; (b) Permit on-off cycling; (c) Be controllable within the intended...

  18. Study on seal improvement and rotor thrust control of centrifugal compressor

    Institute of Scientific and Technical Information of China (English)


    Fluid pressure variations due to process fluctuations or balance drum seal degradation can result in rotor thrust increasing that may jeopardize thrust bearing and compressor's reliability. Also, the leakage flow through balance drum seal can seriously affect the efficiency of compressor. A method that can improve both the efficiency and reliability of centrifugal compressor is presented. The method focused on rotor thrust control and balance drum seal upgrading. The low leakage feature of Dry-Gas-Seal(DGS), high reliability of labyrinth, and the feasibility of upgrading existing structure are taken into account at the same time to design a combined labyrinth-dry gas seal system on the balancing drum. Based on the combined seal system, a Fault Self-Recovering(FSR) system for the fault of rotor shaft displacement is introduced to assure the safety and reliability of centrifugal compressor. The modern Computational Fluid Dynamics(CFD) is used to validate this envision. The numerical result and relevant information indicate that the combined sealing system could improve the efficiency of the centrifugal compressor by about 4%.

  19. Mechanical Analysis of Fault Interaction in the Puente Hills Region, Los Angeles Basin, California (United States)

    Griffith, W. A.; Cooke, M.


    A three-dimensional model of the Puente Hills thrust system (PHT) and the Whittier fault has been constructed using published cross sections, surface trace maps [Shaw (1999); Shaw and Suppe (1996); Wright (1991)] and products of the Southern California Earthquake Center. This study utilizes boundary element method models to validate the proposed fault geometry of the Puente Hills region via investigating fault interaction. The interaction between PHT and Whittier faults is evaluated within an elastic half-space under horizontal contraction and evidenced by slip rates on faults, strain energy density (SED), and Navier-Coulomb stress (NC) throughout the host rock. Modeled slip rates are compared to paleoseismic estimates to validate the proposed fault configuration while maps of SED and NC highlight regions of high strain in the host rock and likely faulting. Subsequently, the sensitivity of SED and NC distribution to changes in fault geometry illuminate the nature of fault interaction within this complex system of interacting faults. We explore interaction of faults within the PHT region using two sets of models. The first examines slip rates and SED and NC distribution within a local model of the PHT region while the second set incorporates the PHT faults within the context of the Los Angeles basin. Both sets explore the response of the fault system to systematic addition of faults. Adding faults within regions of high SED and NC does not influence slip on neighboring faults; however the addition of fault surfaces in regions of low/moderate SED and NC reduces slip along adjacent faults. The sensitivity of fault slip rates to direction of remote contraction in the Los Angeles Basin is examined with contraction directions of 036, 017, and 006.5 [Bawden (2001), Argus (1999), and Feigl (1993)]. Furthermore, variations on intersection geometry between the PHT and Whittier fault are explored. Portions of the PHT and Whittier faults show reasonable match to available

  20. Evolving seismogenic plate boundary megathrust and mega-splay faults in subduction zone (Invited) (United States)

    Kimura, G.; Hamahashi, M.; Fukuchi, R.; Yamaguchi, A.; Kameda, J.; Kitamura, Y.; Hashimoto, Y.; Hamada, Y.; Saito, S.; Kawasaki, R.


    Understanding the fault mechanism and its relationship to the sesimo-tsunamigenesis is a key of the scientific targets of subduction zone and therefore NantroSEIZE project of IODP and future new drilling project of International Ocean Discovery Program keeps focusing on that. Mega-splay fault branched from plate boundary megathrust in subduction zone is located around the border between outer and inner wedges and is considered to cause great earthquake and tsunami such as 1960 Alaska earthquake, 1944 and 1946 Nankai-Tonankai earthquakes, and 2004 Sumatra earthquakes. Seismic reflection studies for the mega-splay fault in 2D and 3D in the Nankai forearc present the reflector with negative or positive polarities with various amplitudes and suggest complicated petrophysical properties and condition of the fault and its surroundings. The Nankai mega-splay fault at a depth of ~5km is going to be drilled and cored by NantroSEIZE experiments and is expected for great progress of understanding of the fault mechanics. Before drilling the really targeted seismogenic fault, we are conducting many exercises of geophysical and geological observations. The core-log-seismic integrated exercise for the exhumed mega-splay fault by drilling was operated for the Nobeoka thrust in the Shimanto Belt, Kyushu, Japan. The Nobeoka thrust was once buried in the depth >~10km and suffered maximum temperature >~300 dgree C. As the core recovery is ~99%, perfect correlation between the core and logging data is possible. Thickness of the fault zone is >200 m with a ~50 cm thick central fault core dividing the phyllitic hanging wall and the footwall of broken-melange like cataclasite. A-few-meter-thick discrete damage zones with fault cores are recognized by difference in physical properties and visual deformation textures at several horizons in the fault zone. Host rocks for those damaged zones are completely lithified cataclasites with abundant mineral veins, which record the older and deeper

  1. Fault-controlled geomorphology and paleoseismology of Fethiye fault and gulf (United States)

    Chatzipetros, Alexandros; Pavlides, Spyros; Yaǧmurlu, Fuzuli; Özgür, Nevzat; Kamaci, Züheyr; Şentürk, Murat


    Fethiye gulf is located at the south-westernmost part of the large left-lateral Fethiye-Burdur fault zone. It is modified and controlled by sets of NE - SW trending normal and oblique left-lateral faults. The gulf forms coastlines that are often aligned nearly perpendicular to one another. Coastlines are mainly NE - SW trending and they are inundated by small bays, mainly in NNW-SSE direction. Those directions are comparable to the main mainland fault lines, as measured on outcrops in the area. The brittle features of the area overprint the pre-existing tectonic fabric of low-angle thrusts and pure strike-slip faults. Recent activity of the faults seems to be possible, since there is indication for hangingwall submergence at the "Cleopatra's bath" site, where an early-Byzantine building complex has been submerged by at least 2 m. The mainland active fault zone is located S-SE of Fethiye town and it forms an N-NW dipping fault scarp that is characterized by multiple en échelon segments. The quantitative tectonic geomorphology of this fault has been studied by using morphotectonic indices (scarp sinuosity, valley width/depth ratio, etc.), which show that the fault has a rather low level of activity. Nevertheless, the fault zone near Fethiye presents other morphotectonic features, such as riverbed catchment, slight left-lateral bend of streams at the foot of the scarp, etc. The fault zone seems to fan out towards the west and the deformation is less evident. Although the fault segments near Fethiye are classified as low-activity ones, they are associated with the large 1957 earthquake (Ms 7.1). This earthquake produced extensive damage and casualties. It was physically manifested by surface ruptures, rockfalls, etc. A palaeoseismological survey has been carried out in the area. Trenches in two different segments show that the 1957 surface rupture is traceable along the fault, while at least two previous events seem to have affected the area and produced surface

  2. Minerals Anomalies and Their Significances in Fault Rocks along the Front Longmenshan Fault (United States)

    Si, J.; Li, H.; Song, S.; Kuo, L.; Pei, J.; Chen, P.; Hsiao, H.; Wang, H.


    Anxian-Guanxian fault is the front fault of the Longmenshan fault system. In the Wenchuan earthquake (Ms8.0) of 12 May 2008, the surface rupture zone developed along the Anxian-Guanxian fault was also named as Hanwang rupture zone, which was approximately pure thrust, about 80km long accompanied with the vertical displacement of 0.5~4m averaged about 2m, and the maximum 4.2m occurred in the fifth villager group of Shaba village belonging to the Jiulong Town of Mianzhu City. We made several trenches cutting through the Anxian-Guanxian rupture zone. In the trenches near the Qingquan village of Jiulong town, three different colored strata including black, gray green and red layers developed from west to east. The black segment is carbonaceous mudstone and fault gouge, the gray green part is fault gouge, cataclasite and siltstone, and the purple red section is mainly mudstone with a few thin gouge layers at the top. Two continuous U-channel samples collected from the trench have been prepared for the synchrotron X-ray diffraction measurements. Viewing from the data, clay minerals including illite, mica, kaolinite and chlorite are more abundant in fine and black gouge than the coarse rocks and purple red mudstone. Moreover, there are significant graphite occur at and near the slip plane. Considering the low friction coefficient and the distinct different features different from the Yingxiu-Beichuan fault, the carbon matter might have acted as lubrication and played certain significant role in the faulting process of the slow angle Anxian-Guanxian fault.

  3. Lateral continuity of the Blarney Creek Thrust, Doonerak Windown, Central Brooks Range, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Seidensticker, C.M.; Julian, F.E.; Phelps, J.C.; Oldow, J.S.; Avellemant, H.G.


    The contact between Carboniferous and lower Paleozoic rocks, exposed along the northern margin of the Doonerak window in the central Brooks Range, is a major thrust fault called the Blarney Creek thrust (BCT). The BCT has been traced over a distance of 25 km, from Falsoola Mountain to Wien Mountain. The tectonic nature of this contact is demonstrated by: (1) omission of stratigraphic units above and below the BCT; (2) large angular discordance in orientation of first-generation cleavage at the BCT; (3) numerous thrust imbricates developed in the upper-plate Carboniferous section that sole into the BCT; and (4) truncation of an upper-plate graben structure at the BCT. Lack of evidence for pre-Carboniferous deformation in the lower plate casts doubt on the interpretation of the contact as an angular unconformity. However, the localized presence below the BCT of Mississippian Kekiktuk Conglomerate and Kayak Shale, in apparent depositional contact with lower Paleozoic rocks, suggests that the BCT follows an originally disconformable contact between the Carboniferous and lower Paleozoic rocks. The juxtaposition of younger over older rocks at the BCT is explained by calling upon the BCT to act as the upper detachment surface of a duplex structure. Duplex development involves initial imbrication of the Carboniferous section using the BCT as a basal decollement, followed by formation of deeper thrusts in the lower Paleozoic section, which ramp up and merge into the BCT.

  4. Miocene Tectonics at the Pannonian - Carpathian Transition: The Bogdan Voda - Dragos Voda fault system, northern Romania (United States)

    Tischler, M.; Gröger, H.; Marin, M.; Schmid, S. M.; Fügenschuh, B.


    Tertiary tectonics in the Pannonian-Carpathian transition zone was dominated by opposed rotations of Alcapa and Tisza-Dacia, separated by the Mid-Hungarian lineament (MHL). While in the Pannonian basin the MHL is well known from geophysical and borehole data, its northeastern continuation remains a matter of discussion. Our field based study, located in the Maramures mountains of northern Romania, provides new kinematic data from the Bogdan Voda fault, a first order candidate for the prolongation of the MHL to the northeast. In the Burdigalian, the Pienides (unmetamorphic flysch nappes) were emplaced onto the autochthonous Paleogene flysch units. Kinematic data consistently indicate top to the SE-directed thrusting of the Pienides and selected imbrications in the autochthonous units. Between Langhian and Tortonian these thrust contacts were offset by the E-W trending Bogdan Voda fault and its eastern continuation, the Dragos-Voda fault. These two faults share a common polyphase history, at least since the Burdigalian. Kinematic data derived from mesoscale faults indicate sinistral strike-slip displacement, in good agreement with kinematics inferred from map view. The NE-SW trending Greben fault, another fault of regional importance, was coevally active as a normal fault. From stratigraphic arguments major activity of this fault system is constrained to the time interval between 16.4-10 Ma. While deformation is strongly concentrated in the sedimentary units, the easterly located basement units are affected by abundant minor faults of similar kinematics covering a wide area. These SW-NE trending strike slip faults feature a normal component and resemble an imbricate fan geometry. Since Burdigalian thrusting is consistently SE-directed on either side of the Bogdan-Dragos Voda fault, major post-Burdigalian differential rotations can be excluded for the northern and southern block respectively. Hydrothermal veins within Pannonian volcanic units are aligned along the

  5. Paleoseismic study of the Cathedral Rapids fault in the northern Alaska Range near Tok, Alaska (United States)

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


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


    Institute of Scientific and Technical Information of China (English)

    PEI Hai-lin; QI Xue-yi; LI Hui; LI Jian-hui; PEI Ze-yu


    Owing to the high temperature of the thrust bearing pads, the No.1 unit wasn't performed in the upgrading test at Liujiaxia Hydropower Plant. Through the experimental and theoretical analysis, it has been confirmed that the fault unit was caused by the high water pressure in the head-cover chamber. This type of the fault is out-of-the-way. After the suitable measure wags against the fault were taken, the No.1 unit can stably operate. The conclusions and the methodology are of the certain reference value to the fault-diagnosis of the hydroelectric unit.

  7. Thrust distribution for attitude control in a variable thrust propulsion system with four ACS nozzles (United States)

    Lim, Yeerang; Lee, Wonsuk; Bang, Hyochoong; Lee, Hosung


    A thrust distribution approach is proposed in this paper for a variable thrust solid propulsion system with an attitude control system (ACS) that uses a reduced number of nozzles for a three-axis attitude maneuver. Although a conventional variable thrust solid propulsion system needs six ACS nozzles, this paper proposes a thrust system with four ACS nozzles to reduce the complexity and mass of the system. The performance of the new system was analyzed with numerical simulations, and the results show that the performance of the system with four ACS nozzles was similar to the original system while the mass of the whole system was simultaneously reduced. Moreover, a feasibility analysis was performed to determine whether a thrust system with three ACS nozzles is possible.

  8. Structural analysis of Nalagarh lobe, NW Himalaya: implication of thrusting across tectonic edge of NW limb of Nahan salient, Himachal Pradesh, India (United States)

    Bhakuni, S. S.; Philip, G.; Suresh, N.


    The Main Boundary Fault (MBF), convex towards southwest, forms the leading edge of the Nahan salient. Near the southern end of an oblique ramp, a lobe-shaped physiographic front, named in this work as Nalagarh lobe, has developed across NW limb of salient. The lobe has formed across the MBF that separates the hanging wall Lower Tertiary Dharmsala rocks from the footwall Upper Tertiary Siwalik rocks and overlying Quaternaries. In front of lobe, thrust fault splays (Splay-1 and Splay-2) and associated tectonic fabrics have developed within the Late Pleistocene fan deposit. Structural elements developed across the front of Nalagarh lobe are analysed with reference to evolution of lobe. An unweathered 15-m-high hanging wall or wedge top forms the uplifted and rejuvenated bedrock fault scarp of the MBF. Below the MBF, the fan deposit has underthrust along Splay-1. Later the Splay-2 formed within fan deposit near south of Splay-1. Geometry of the overturned limb of tight to isoclinal fault propagation fold, formed on Splay-2 plane, suggests that the fold formed by normal drag, produced by intermittent fault-slips along Splay-2. The displacement along Splay-2 offset the marker bed to 1 m by which some clasts rotated parallel to the traces of brittle axial planes of fold. The variable fold geometry and style of deformation are analysed along length of thrust splays for 5 km. It is revealed that the lobe is bounded by transverse thrust faults along its NW and SE margins. The geometry of salient and oblique ramp suggests that the transverse thrust faults and associated transverse folds formed by right-lateral displacement along the NW limb of the salient. Marking the northern margin of the intermontane piggyback basin of Pinjaur dun, the MBF is interpreted to be an out-of-sequence thrust that has brought up the Lower Tertiary Dharmsala rocks over the Late Pleistocene fan deposit. The geometry of lobe and its bounding transverse faults suggest that faults are intimately

  9. Multidisciplinary approach for fault detection: Integration of PS-InSAR, geomorphological, stratigraphic and structural data in the Venafro intermontane basin (Central-Southern Apennines, Italy) (United States)

    Amato, Vincenzo; Aucelli, Pietro P. C.; Bellucci Sessa, Eliana; Cesarano, Massimo; Incontri, Pietro; Pappone, Gerardo; Valente, Ettore; Vilardo, Giuseppe


    A multidisciplinary methodology, integrating stratigraphic, geomorphological and structural data, combined with GIS-aided analysis and PS-InSAR interferometric data, was applied to characterize the relationships between ground deformations and the stratigraphic and the morphostructural setting of the Venafro intermontane basin. This basin is a morphostructural depression related to NW-SE and NE-SW oriented high angle normal faults bordering and crossing it. In particular, a well-known active fault crossing the plain is the Aquae Juliae Fault, whose recent activity is evidenced by archeoseismological data. The approach applied here reveals new evidence of possible faulting, acting during the Lower to Upper Pleistocene, which has driven the morphotectonic and the environmental evolution of the basin. In particular, the tectonic setting emerging from this study highlights the influence of the NW-SE oriented extensional phase during the late Lower Pleistocene - early Middle Pleistocene, in the generation of NE-SW trending, SE dipping, high-angle faults and NW-SE trending, high-angle transtensive faults. This phase has been followed by a NE-SW extensional one, responsible for the formation of NW-SE trending, both NW and SE dipping, high-angle normal faults, and the reactivation of the oldest NE-SW oriented structures. These NW-SE trending normal faults include the Aquae Juliae Fault and a new one, unknown until now, crossing the plain between the Venafro village and the Colle Cupone Mt. (hereinafter named the Venafro-Colle Cupone Fault, VCCF). This fault has controlled deposition of the youngest sedimentary units (late Middle Pleistocene to late Upper Pleistocene) suggesting its recent activity and it is well constrained by PS-InSAR data, as testified by the increase of the subsidence rate in the hanging wall block.

  10. Effects of fault propagation on superficial soils/gravel aquifer properties: The Chihshang Fault in Eastern Taiwan (United States)

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


    A mature bedrock fault zone generally consists of a fault core, a damage zone, and a surrounding host rock with different permeabilities, which mainly depend on the fracture density. However, near the surface, when an active thrust fault propagates from bedrocks into an unconsolidated surface cover, it results in a diffused fault zone, which may influence the hydraulic and mechanical properties around the fault zone. It is thus of great concern to understand to which extent surface soil/gravel hydraulic properties modifications by continuously active faulting can impact geotechnical projects in countries under active tectonic context, such as Taiwan, where active faults often are blinded beneath thick soil/gravel covers. By contrast, it is also interesting to decipher those fault-induced permeability modifications to estimate potential activity precursors to large earthquakes. Here, we combined a variety of measurements and analyses on the Chihshang fault, located at the plate suture between the Philippine Sea and Eurasian plates, which converge at a rapid rate of 8 cm/yr in Taiwan. At the Chinyuan site, the Chihshang fault is propagating from depth to emerge through thick alluvial deposits. We characterized the fault geometry and slip behavior at the shallow level by measuring and analyzing horizontal, vertical displacements, and groundwater table across the surface fault zone. The yielded fault dip of 45o in the shallow alluvium is consistent with the observations from surface ruptures and subsurface core logging. The 7-year-long groundwater table record shows that the piezometric level in the hanging wall is about 8 meter higher than that in the footwall in the summer; and about 10 meter higher in the winter. Repeated slug tests have been monthly conducted since 2007 to provide the average permeability within the fault zone and the presumably low-deformed zone outside of the diffused fault zone. Based on in-situ measurements at four wells across the fault zone

  11. Pulsed thrust measurements using electromagnetic calibration techniques

    Energy Technology Data Exchange (ETDEWEB)

    Tang Haibin; Shi Chenbo; Zhang Xin' ai; Zhang Zun; Cheng Jiao [School of Astronautics, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)


    A thrust stand for accurately measuring impulse bits, which ranged from 10-1000 {mu}N s using a noncontact electromagnetic calibration technique is described. In particular, a permanent magnet structure was designed to produce a uniform magnetic field, and a multiturn coil was made to produce a calibration force less than 10 mN. The electromagnetic calibration force for pulsed thrust measurements was linear to the coil current and changed less than 2.5% when the distance between the coil and magnet changed 6 mm. A pulsed plasma thruster was first tested on the thrust stand, and afterward five single impulse bits were measured to give a 310 {mu}N s average impulse bit. Uncertainty of the measured impulse bit was analyzed to evaluate the quality of the measurement and was found to be 10 {mu}N s with 95% credibility.

  12. Status of Low Thrust Work at JSC (United States)

    Condon, Gerald L.


    High performance low thrust (solar electric, nuclear electric, variable specific impulse magnetoplasma rocket) propulsion offers a significant benefit to NASA missions beyond low Earth orbit. As NASA (e.g., Prometheus Project) endeavors to develop these propulsion systems and associated power supplies, it becomes necessary to develop a refined trajectory design capability that will allow engineers to develop future robotic and human mission designs that take advantage of this new technology. This ongoing work addresses development of a trajectory design and optimization tool for assessing low thrust (and other types) trajectories. This work targets to advance the state of the art, enable future NASA missions, enable science drivers, and enhance education. This presentation provides a summary of the low thrust-related JSC activities under the ISP program and specifically, provides a look at a new release of a multi-gravity, multispacecraft trajectory optimization tool (Copernicus) along with analysis performed using this tool over the past year.

  13. Role of wing morphing in thrust generation

    Directory of Open Access Journals (Sweden)

    Mehdi Ghommem


    Full Text Available In this paper, we investigate the role of morphing on flight dynamics of two birds by simulating the flow over rigid and morphing wings that have the characteristics of two different birds, namely the Giant Petrel and Dove Prion. The simulation of a flapping rigid wing shows that the root of the wing should be placed at a specific angle of attack in order to generate enough lift to balance the weight of the bird. However, in this case the generated thrust is either very small, or even negative, depending on the wing shape. Further, results show that morphing of the wing enables a significant increase in the thrust and propulsive efficiency. This indicates that the birds actually utilize some sort of active wing twisting and bending to produce enough thrust. This study should facilitate better guidance for the design of flapping air vehicles.

  14. Kinematic Analysis of Fold-Thrust-Belt Using Integrated Analogue Sandbox Modeling and 3D Palinspatic Reconstructions in Babar-Selaru Area, Banda Sea Region, Indonesia (United States)

    Sapiie, Benyamin; Hadiana, Meli; Kurniawan, Ade; Daniel, Dicky; Danio, Harya; Fujimoto, Masamichi; Ohara, Michio; Alam Perdana, Lisnanda; Saputra, Afif


    Kinematic analysis of Babar-Selaru fold-thrust-belt is challenging and often difficult particularly in conducting seismic interpretation due to complex structural geometries. Resolving such as issue, in this study we proposed to use integrated seismic interpretation, analogue sandbox modeling and 3D palinspatic reconstructions. This paper is presented results of detail kinematic analysis for understanding tectonic evolution as well as mechanism of fold-thrust-belt in relation to their hydrocarbon prospect. Babar-Selaru Area is located within the collisional boundary between Australian continental margin and Banda Arc region of Indonesia. The area is characterized by complex deformation zone of fold-thrust-belt, involving Mesozoic and Tertiary sedimentary sequences of Australian continental margin. The age of deformation is ranging from 8-5 Ma. Seismic interpretations show two styles of faults developed in the area, which are thrust and normal faults system. The last deformation observed in the Babar Selaru area is controlled by south verging imbricated thin-skinned thrust fault system, with the staircase style of fault detachment. Although, both structural styles occurred in separated locations, they are formed not only in the same time but also related in time and space. Total extension is ranging from 1-3 % where average shortening is in the order of 35-38%. Sandbox modeling is an effective way to study and understand the style, pattern and geometry of the deformed sedimentary sequences in the study area. Based on comparison of five settings experiments (mainly different geological boundary condition) with more than 50 different modeling; deformation is particularly controlled by types and thickness of lithology package and detachment geometry. These two parameters were quite sensitive in generating different deformation style and pattern in Babar-Selaru fold-thrust-belt. Therefore, choosing the right combination of stratigraphy model and material setting are

  15. Structural modelling of thrust zones utilizing photogrammetry: Western Champsaur basin, SE France (United States)

    Totake, Yukitsugu; Butler, Rob; Bond, Clare


    Recent advances in photogrammetric technologies allow geoscientists to easily obtain a high-resolution 3D geospatial data across multiple scales, from rock specimen to landscape. Although resolution and accuracy of photogrammetry models are dependent on various factors (a quality of photography, number of overlapping photo images, distance to targets, etc), modern photogrammetry techniques can even provide a comparable data resolution to laser scanning technologies (modelling of various geological objects. Another advantages of photogrammetry techniques, high portability and low costs for infrastructures, ease to incorporate these techniques with conventional geological surveys. Photogrammetry techniques have a great potential to enhance performances of geological surveys. We present a workflow for building basin-scale 3D structural models utilizing the ground-based photogrammetry along with field observations. The workflow is applied to model thrust zones in Eocene-Oligocene turbidite sequences called Champsaur Sandstone (Gres du Champsaur) filling an Alpine fore-deep basin, Western Champsaur basin, in southeastern France. The study area is located ca. 20km northeast from Gap, and approximately extends 10 km from east to west and 6 km from north to south. During a 2-week fieldwork, over 9400 photographs were taken at 133 locations by a handheld digital camera from ground, and were georeferenced with a handheld GPS. Photo images were processed within software PhotoScan to build a 3D photogrammetric model. The constructed photogrammetry model was then imported into software Move to map faults and geological layers along with georeferenced field data so that geological cross sections and 3D surfaces are produced. The workflow succeeded to produce a detailed topography and textures of landscape at ~1m resolution, and enabled to characterize thrust systems in the study area at bed-scale resolution. Three-dimensionally characterized architectures of thrust zones at high

  16. Kinematic Evolution of the Western Pyrenees Thrust Front From Paleomagnetic Analysis on its Foreland Basin. (United States)

    Almar, Y.; Beamud, E.; Muñoz, J. A.; Garcés, M.; Murelaga, X.


    The Pyrenees is a collisional orogen formed during the Alpine orogeny. Its southwestern frontal thrust was originated as a result of the Cenozoic inversion of preexisting extensional faults. The emplacement of the frontal thrust in the Western Pyrenees generated a foreland basin, which locally accumulated more than 4,500 meters of Tertiary sediments. The kinematic evolution of the Western Pyrenees thrust front is poorly constrained due to the scarcity of reliable age constraints within the Tertiary sediments. However, the good exposure conditions of syntectonic continental deposits in its foreland basin makes it an excellent scenario to carry out paleomagnetic and structural studies in order to unravel the kinematic history, geometry and evolution of the thrust front. A magnetostratigraphic composite section along the continental basin infill was sampled covering up to 3,000 m of succession. Correlation of the local magnetostratigraphy with the GPTS was helped by a new mammal fossil locality found in continental sediments and attributed to the Agenian local biozone Y (MN2D). The cronostratigraphy of the tectosedimentary units, ranging from lower Oligocene (Cr12r) to lower Miocene, provides further constraints on the timing of two main tectosedimentary events recorded as major unconformities within the basin infill. From this study, sedimentation rates have been also obtained. The analysis of several paleomagnetic sites revealed that no vertical axes rotations occurred in the Tertiary sediments regardless superimposed folding with oblique axes could be observed, and the proximity of adjacent structures as the Estella diapir and the Pamplona fault. Finally, the analysis of the anisotropy of magnetic susceptibility together with collected sedimentary data suggests that magnetic fabrics record both, a depositional and tectonic fabric.

  17. Paleomagnetic, structural, and stratigraphic constraints on transverse fault kinematics during basin inversion: The Pamplona Fault (Pyrenees, north Spain) (United States)

    LarrasoañA, Juan Cruz; ParéS, Josep MaríA.; MilláN, HéCtor; Del Valle, JoaquíN.; Pueyo, Emilio Luis


    The Pamplona Fault in the Pyrenees is a major transverse structure that has been classically interpreted as a strike-slip fault. However, lack of consensus concerning the sense of movement casts doubt on its actual kinematics and, as a consequence, its role in the Cenozoic evolution of the Pyrenees remains controversial. In order to assess its kinematics, we have conducted a paleomagnetic, structural, and stratigraphic study focused on the Mesozoic and Tertiary sedimentary rocks that outcrop around the southern segment of the fault. Restoration of balanced cross sections allows us to examine the present-day spatial relationship of the sedimentary sequences on both sides of the fault and to reconstruct the geometry of the extensional basins formed during Mesozoic rifting episodes in the Bay of Biscay and Pyrenean domains. Paleomagnetic results indicate that no significant tectonic rotations occurred around the fault during Tertiary inversion of the Pyrenees. The lack of tectonic rotations and revaluation of previous hypotheses argues against a strike-slip movement of the fault. We propose a new model in which the Pamplona Fault is treated as a large-scale "hanging wall drop" fault whose kinematics was determined by variations in the geometry and thickness of Mesozoic sequences on both sides of the fault. These variations influenced the geometry of the thrust sheet developed during Tertiary compression. We are unaware of any other transverse fault that has been interpreted in this fashion; thus the Pamplona Fault serves as a case study for the evolution of transverse faults involved in basin inversion processes.

  18. On the lag time between internal strain and basement involved thrust induced exhumation: The case of the Colombian Eastern Cordillera (United States)

    Mora, Andrès; Blanco, Vladimir; Naranjo, Julian; Sanchez, Nelson; Ketcham, Richard A.; Rubiano, Jorge; Stockli, Daniel F.; Quintero, Isaid; Nemčok, Michal; Horton, Brian K.; Davila, Hamblet


    Thrust sheets accumulate internal strain before they start moving along discrete fault planes. However, there are no previous studies evaluating the time difference between initiation of strain and fault displacement. In this paper we use observations from the Eastern Cordillera of Colombia to evaluate this interval. We utilize multiple thermochronometers and paleothermometers to refine the timing of deformation. Based on these new data we build time-temperature path estimates that together with geometric outcrop-based structural analysis and fluid inclusions allow us to assign relative timing to features associated with strain, such as cleavage, veins and certain types of fractures, and compare that with the timing of thrusting. We find that cleavage was only formed close to maximum paleotemperatures, almost coeval with the onset of thrust-induced denudation by the Late Oligocene. The corresponding structural level of fold-related veins suggest that they were formed later but still when the country rocks were at temperatures higher than 160 °C, mostly during the Early Miocene and still coexisted with the latest stages of cleavage formation. Our data show that the main period of strain hardening was short (probably a few million years) and occurred before first-order basement thrusting was dominant, but was associated with second-order folding.

  19. The Kuqa late Cenozoic fold-thrust belt on the southern flank of the Tian Shan Mountains (United States)

    Li, Yue-Jun; Wen, Lei; Zhang, Hong-An; Huang, Tai-Zhu; Li, Hui-Li; Shi, Yuan-Yuan; Meng, Qing-Long; Peng, Geng-Xin; Huang, Shao-Ying; Zhang, Qiang


    The Kuqa fold-thrust belt (KFTB), a late Cenozoic fold-thrust belt on the southern flank of the Tian Shan Mountains, consists of several deformation zones trending nearly W-E. The main décollement fault of the KFTB gradually rises southwards. There are three regional main décollement faults in the Triassic dark mudstone, Paleogene gypsum salt (Kumugeliemu Formation), and Neogene gypsum salt (Jidike Formation), respectively, and possibly a fourth in the Jurassic coalbed. Laterally, thin-skinned structures are developed in the main segments of the KFTB, whereas thick-skinned structures are in the root zone. Vertically, the structural deformation above the Cenozoic gypsum-salt layers (Paleogene gypsum salt in the middle segment of the KFTB and Neogene gypsum salt in the eastern segment) is characterized by décollement folding, whereas that below is characterized by thrusting. The KFTB was resulted from the late Cenozoic intra-continental orogeny in the Tian Shan area under the far-field effect of the India-Asia collision. The deformation of KFTB began (folding and thrusting) ca. 23 Ma, when the far-field effect of the India-Asia collision reached the Tian Shan area. The deformation of KFTB accelerated ca. 10, 5-2, and 1-0 Ma. In general, the evolution of the KFTB is forward propagating, and the hinter parts of the KFTB continue to deform, while its front propagates southwards.

  20. A microNewton thrust stand for average thrust measurement of pulsed microthruster. (United States)

    Zhou, Wei-Jing; Hong, Yan-Ji; Chang, Hao


    A torsional thrust stand has been developed for the study of the average thrust for microNewton pulsed thrusters. The main body of the thrust stand mainly consists of a torsional balance, a pair of flexural pivots, a capacitive displacement sensor, a calibration assembly, and an eddy current damper. The behavior of the stand was thoroughly studied. The principle of thrust measurement was analyzed. The average thrust is determined as a function of the average equilibrium angle displacement of the balance and the spring stiffness. The thrust stand has a load capacity up to 10 kg, and it can theoretically measure the force up to 609.6 μN with a resolution of 24.4 nN. The static calibrations were performed based on the calibration assembly composed of the multiturn coil and the permanent magnet. The calibration results demonstrated good repeatability (less than 0.68% FSO) and good linearity (less than 0.88% FSO). The assembly of the multiturn coil and the permanent magnet was also used as an exciter to simulate the microthruster to further research the performance of the thrust stand. Three sets of force pulses at 17, 33.5, and 55 Hz with the same amplitude and pulse width were tested. The repeatability error at each frequency was 7.04%, 1.78%, and 5.08%, respectively.

  1. A microNewton thrust stand for average thrust measurement of pulsed microthruster (United States)

    Zhou, Wei-Jing; Hong, Yan-Ji; Chang, Hao


    A torsional thrust stand has been developed for the study of the average thrust for microNewton pulsed thrusters. The main body of the thrust stand mainly consists of a torsional balance, a pair of flexural pivots, a capacitive displacement sensor, a calibration assembly, and an eddy current damper. The behavior of the stand was thoroughly studied. The principle of thrust measurement was analyzed. The average thrust is determined as a function of the average equilibrium angle displacement of the balance and the spring stiffness. The thrust stand has a load capacity up to 10 kg, and it can theoretically measure the force up to 609.6 μN with a resolution of 24.4 nN. The static calibrations were performed based on the calibration assembly composed of the multiturn coil and the permanent magnet. The calibration results demonstrated good repeatability (less than 0.68% FSO) and good linearity (less than 0.88% FSO). The assembly of the multiturn coil and the permanent magnet was also used as an exciter to simulate the microthruster to further research the performance of the thrust stand. Three sets of force pulses at 17, 33.5, and 55 Hz with the same amplitude and pulse width were tested. The repeatability error at each frequency was 7.04%, 1.78%, and 5.08%, respectively.

  2. Structural Load Analysis of a Wind Turbine under Pitch Actuator and Controller Faults (United States)

    Etemaddar, Mahmoud; Gao, Zhen; Moan, Torgeir


    In this paper, we investigate the characteristics of a wind turbine under blade pitch angle and shaft speed sensor faults as well as pitch actuator faults. A land-based NREL 5MW variable speed pitch reg- ulated wind turbine is considered as a reference. The conventional collective blade pitch angle controller strategy with independent pitch actuators control is used for load reduction. The wind turbine class is IEC-BII. The main purpose is to investigate the severity of end effects on structural loads and responses and consequently identify the high-risk components according to the type and amplitude of fault using a servo-aero-elastic simulation code, HAWC2. Both transient and steady state effects of faults are studied. Such information is useful for wind turbine fault detection and identification as well as system reliability analysis. Results show the effects of faults on wind turbine power output and responses. Pitch sensor faults mainly affects the vibration of shaft main bearing, while generator power and aerodynamic thrust are not changed significantly, due to independent pitch actuator control of three blades. Shaft speed sensor faults can seriously affect the generator power and aerodynamic thrust. Pitch actuator faults can result in fully pitching of the blade, and consequently rotor stops due to negative aerodynamic torque.

  3. Along-strike thickness variations of décollement levels controlling lateral changes in fold-and-thrust belts: the Barbastro-Balaguer Anticline (Southern Pyrenees) (United States)

    Santolaria, Pablo; Calvín, Pablo; Pueyo, Emilio L.; Soto, Ruth; Ayala, Concepción; Casas, Antonio; Oliván, Carlota; Luzón, Aránzazu


    The subsurface vertical and lateral distribution of two evaporitic levels (Middle-Upper Triassic and Eocene) is here studied to better understand their role as a controlling factor on the geometry and kinematics of the central part of the South Pyrenean deformation front. Field work with hundreds of bedding attitudes, 5 exploration boreholes (up to 5000 m deep), the residual Bouguer anomaly and the interpretation of 27 seismic reflection profiles (approximately 440 km of sections) crossing the different allochthonous units and the adjacent Ebro foreland basin have been analysed in this work. Subsoil information is crucial because part of the studied area is extensively covered by the Oligocene-Miocene molasse that prevents any direct observation of the structure underneath to be done. Interpreted key horizons and faults have been identified from the lithological description of partially reinterpreted lithological well data and surface geology. Lithological well data has been anchored to seismic profiles by means of sonic log data. Kingdom software has been used to perform the 2D interpretation of seismic reflection profiles, supported by 2.5D gravity modelling, in a georeferenced workspace and then, surfaces of key horizons and faults were built and assembled together in a 3D model. The studied area is characterized from north to south by several minor thrust sheets, detached on the Middle-Upper Triassic décollement, which represents the basal décollement of the Pyrenees. Some of them can be linked with the South Pyrenean Frontal Thrust (SPFT) and others have structural continuation towards the NW. The SPFT displays a N160E trend and its hanging wall progressively deepens towards the west. To the east, this structure locally crops out. On the other hand, the footwall geometry of the SPBT shows very distinct features; the western part (External Sierras sector) displays a single ramp with moderate-high angle (20-30°) while the eastern part (linking zone to the

  4. Favorable areas for prospecting adjacent to the Roberts Mountains thrust in southern Lander County, Nevada (United States)

    Stewart, John Harris; McKee, Edwin H.


    Recent geologic mapping by the U.S. Geological Survey of more than 2,500 square miles of a relatively little-studied part of central Nevada has outlined four areas favorable for the discovery of metallic mineral deposits. In these areas, lower Paleozoic carbonate rocks crop out below the Roberts Mountains thrust, a widespread fault in central and north-central Nevada. These areas have a stratigraphic and structural setting similar to that of the areas where large, open-pit gold deposits have been discovered recently at Carlin and Cortez in north-central Nevada.

  5. Paleogeodesy of the Southern Santa Cruz Mountains Frontal Thrusts, Silicon Valley, CA (United States)

    Aron, F.; Johnstone, S. A.; Mavrommatis, A. P.; Sare, R.; Hilley, G. E.


    We present a method to infer long-term fault slip rate distributions using topography by coupling a three-dimensional elastic boundary element model with a geomorphic incision rule. In particular, we used a 10-m-resolution digital elevation model (DEM) to calculate channel steepness (ksn) throughout the actively deforming southern Santa Cruz Mountains in Central California. We then used these values with a power-law incision rule and the Poly3D code to estimate slip rates over seismogenic, kilometer-scale thrust faults accommodating differential uplift of the relief throughout geologic time. Implicit in such an analysis is the assumption that the topographic surface remains unchanged over time as rock is uplifted by slip on the underlying structures. The fault geometries within the area are defined based on surface mapping, as well as active and passive geophysical imaging. Fault elements are assumed to be traction-free in shear (i.e., frictionless), while opening along them is prohibited. The free parameters in the inversion include the components of the remote strain-rate tensor (ɛij) and the bedrock resistance to channel incision (K), which is allowed to vary according to the mapped distribution of geologic units exposed at the surface. The nonlinear components of the geomorphic model required the use of a Markov chain Monte Carlo method, which simulated the posterior density of the components of the remote strain-rate tensor and values of K for the different mapped geologic units. Interestingly, posterior probability distributions of ɛij and K fall well within the broad range of reported values, suggesting that the joint use of elastic boundary element and geomorphic models may have utility in estimating long-term fault slip-rate distributions. Given an adequate DEM, geologic mapping, and fault models, the proposed paleogeodetic method could be applied to other crustal faults with geological and morphological expressions of long-term uplift.

  6. Polyphase tertiary fold-and-thrust tectonics in the Belluno Dolomites: new mapping, kinematic analysis, and 3D modelling (United States)

    Chistolini, Filippo; Bistacchi, Andrea; Massironi, Matteo; Consonni, Davide; Cortinovis, Silvia


    The Belluno Dolomites are comprised in the eastern sector of the Southern Alps, which corresponds to the fold-and-thrust belt at the retro-wedge of the Alpine collisional orogen. They are characterized by a complex and polyphase fold-and-thrust tectonics, highlighted by multiple thrust sheets and thrust-related folding. We have studied this tectonics in the Vajont area where a sequence of Jurassic, Cretaceous and Tertiary units have been involved in multiple deformations. The onset of contractional tectonics in this part of the Alps is constrained to be Tertiary (likely Post-Eocene) by structural relationships with the Erto Flysch, whilst in the Mesozoic tectonics was extensional. We have recognized two contractional deformation phases (D1 and D2 in the following), of which only the second was mentioned in previous studies of the area and attributed to the Miocene Neoalpine event. D1 and D2 are characterized by roughly top-to-WSW (possibly Dinaric) and top-to-S (Alpine) transport directions respectively, implying a 90° rotation of the regional-scale shortening axis, and resulting in complex thrust and fold interference and reactivation patterns. Geological mapping and detailed outcrop-scale kinematic analysis allowed us to characterize the kinematics and chronology of deformations. Particularly, relative chronology was unravelled thanks to (1) diagnostic fold interference patterns and (2) crosscutting relationships between thrust faults and thrust-related folds. A km-scale D1 syncline, filled with the Eocene Erto Flysch and "decapitated" by a D2 thrust fault, provides the best map-scale example of crosscutting relationships allowing to reconstruct the faulting history. Due to the strong competence contrast between Jurassic carbonates and Tertiary flysch, in this syncline spectacular duplexes were also developed during D2. In order to quantitatively characterize the complex interference pattern resulting from two orthogonal thrusting and folding events, we

  7. Seaward- Versus Landward-Verging Thrusts in Accretionary Wedges: A Numerical Modeling Study of the Effects of Heterogeneity in Pore Fluid Pressure and Frictional Strength (United States)

    Ito, G.; Moore, G. F.; Olive, J. A. L.; Weiss, J. R.


    Whereas seaward-verging thrust faults are, by far, the most common large faults associated with accretionary wedges, the importance of the globally rare, landward verging thrusts has recently been highlighted given the prominence of landward vergence along the Cascadia margin as well as along the Andaman-Sumatra subduction zone, especially in the rupture area of the great 2004 earthquake. The mechanical processes that lead to seaward- versus landward-verging thrusts in accretionary wedges has long been a topic of debate. A weak frictional décollement is one explanation that indeed promotes landward vergence, but not only so, because the typical pattern is of dual verging conjugate faults. A non-brittle, ductile décollement is a second explanation that has been shown in the laboratory to produce a wide sequence of only landward-verging thrusts, but the mechanical causes are not well understood and numerical modeling studies have yet to reproduce this behavior. A seaward-dipping backstop is a third explanation; it promotes landward vergence locally, but more distally the backstop effects diminish and the sense of vergence transitions back to seaward. Mohr-Coulomb and minimum work theory predict that landward vergence should predominate when the direction of maximum principal compression dips landward. We hypothesize that such a condition can arise due to the migration of pore fluids and the associated spatial heterogeneity in frictional strength within the wedge. We test this hypothesis using 2-D numerical models that use a finite-difference, particle-in-cell method for simulating the deformation of an accretionary wedge with a viscoelastic-plastic rheology. With a uniform internal frictional strength, the calculations reproduce many of the faulting behaviors seen in prior laboratory and numerical modeling studies. We are exploring the impacts of heterogeneity in pore fluid pressure and frictional strength on the pattern and vergence of thrust faults.

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

    Lavier, L. L.; Bennett, R.


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

  9. Benchmarking numerical models of brittle thrust wedges

    NARCIS (Netherlands)

    Buiter, Susanne J H; Schreurs, Guido; Albertz, Markus; Gerya, Taras V.; Kaus, Boris; Landry, Walter; le Pourhiet, Laetitia; Mishin, Yury; Egholm, David L.; Cooke, Michele; Maillot, Bertrand; Thieulot, Cedric; Crook, Tony; May, Dave; Souloumiac, Pauline; Beaumont, Christopher


    We report quantitative results from three brittle thrust wedge experiments, comparing numerical results directly with each other and with corresponding analogue results. We first test whether the participating codes reproduce predictions from analytical critical taper theory. Eleven codes pass the s

  10. Reverse Core Engine with Thrust Reverser (United States)

    Suciu, Gabriel L. (Inventor); Chandler, Jesse M. (Inventor)


    An engine system has a gas generator, a bi-fi wall surrounding at least a portion of the gas generator, a casing surrounding a fan, and the casing having first and second thrust reverser doors which in a deployed position abut each other and the bi-fi wall.

  11. Comparing slip behavior and hydromechanical properties of fault systems in the Nankai subduction zone (United States)

    Ikari, M.; Saffer, D. M.; Marone, C.; Knuth, M. W.


    At subduction zones, the plate boundary system includes several active faults, including the master décollement and splay faults that branch from it and cut the overriding margin wedge. The partitioning of strain accumulation and slip on these structures may provide important information about the mechanical behavior of the plate boundary, and for earthquake rupture and tsunamigenesis. We conducted laboratory experiments to measure the frictional and hydrologic properties of fault and wall rock from three distinct fault zone systems sampled during IODP Expedition 316 and ODP Leg 190 to the Nankai Trough offshore Japan. These fault zones are: (1) a major out-of-sequence thrust fault that terminates ~25 km landward of the trench and extends for >120 km along-strike, termed the “megasplay”; (2) the frontal thrust, comprising a region of diffuse thrust faulting near the trench; and (3) the décollement zone sampled 2 km from the trench. We observe predominantly low friction (µ ≤ 0.46), and low permeability (k ≤ 7.00x10-19 m2) consistent with the clay-rich composition of the samples. Samples from the décollement zone are both consistently weaker (µ ≤ 0.30) and less permeable than those from the megasplay area and the frontal thrust system. Fault zone material from the megasplay is both significantly weaker and less permeable than the surrounding wall rocks, a pattern not observed in the frontal thrust and décollement. All samples exhibit velocity-strengthening frictional behavior over most of the experimental conditions we explored, consistent with aseismic slip at shallow depths. Slip stability does not vary between fault zone and wall rock in any of the three settings. A previously observed minimum in the friction rate parameter a-b at sliding velocities of ~1-3 µm/s (~0.1-0.3 m/d) for samples from the megasplay fault zone is also observed for both the frontal thrust and décollement, and our data suggests that this phenomenon may be controlled

  12. Development of microprocessor-based laser velocimeter and its application to measurement of jet exhausts and flows over missiles at high angles of attack (United States)

    Harwell, K. E.; Farmer, W. M.; Hornkohl, J. O.; Stallings, E.


    During the past three years, personnel have developed a unique three-component laser velocimeter for the in situ measurement of particle and/or gas velocities in flow fields produced behind bodies at high angles of attack and in jet exhaust plumes. This report describes the development of the laser velocimeter and its subsequent application of the measurement of the velocity distribution and vortex structure in free jets and in flows over missiles at high angles of attack.

  13. Neotectonics and structure of the Himalayan deformation front in the Kashmir Himalaya, India: Implication in defining what controls a blind thrust front in an active fold-thrust belt (United States)

    Gavillot, Y. G.; Meigs, A.; Yule, J. D.; Rittenour, T. M.; Malik, M. O. A.


    Active tectonics of a deformation front constrains the kinematic evolution and structural interaction between the fold-thrust belt and most-recently accreted foreland basin. In Kashmir, the Himalayan Frontal thrust (HFT) is blind, characterized by a broad fold, the Suruin-Mastargh anticline (SMA), and displays no emergent faults cutting either limb. A lack of knowledge of the rate of shortening and structural framework of the SMA hampers quantifying the earthquake potential for the deformation front. Our study utilized the geomorphic expression of dated deformed terraces on the Ujh River in Kashmir. Six terraces are recognized, and three yield OSL ages of 53 ka, 33 ka, and 0.4 ka. Vector fold restoration of long terrace profiles indicates a deformation pattern characterized by regional uplift across the anticlinal axis and back-limb, and by fold limb rotation on the forelimb. Differential uplift across the fold trace suggests localized deformation. Dip data and stratigraphic thicknesses suggest that a duplex structure is emplaced at depth along the basal décollement, folding the overlying roof thrust and Siwalik-Muree strata into a detachment-like fold. Localized faulting at the fold axis explains the asymmetrical fold geometry. Folding of the oldest dated terrace, suggest that rock uplift rates across the SMA range between 2.0-1.8 mm/yr. Assuming a 25° dipping ramp for the blind structure on the basis of dip data constraints, the shortening rate across the SMA ranges between 4.4-3.8 mm/yr since ~53 ka. Of that rate, ~1 mm/yr is likely absorbed by minor faulting in the near field of the fold axis. Given that Himalaya-India convergence is ~18.8-11 mm/yr, internal faults north of the deformation front, such as the Riasi thrust absorbs more of the Himalayan shortening than does the HFT in Kashmir. We attribute a non-emergent thrust at the deformation front to reflect deformation controlled by pre-existing basin architecture in Kashmir, in which the thick succession

  14. Fault Tolerant Feedback Control

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, H.


    An architecture for fault tolerant feedback controllers based on the Youla parameterization is suggested. It is shown that the Youla parameterization will give a residual vector directly in connection with the fault diagnosis part of the fault tolerant feedback controller. It turns out...... that there is a separation be-tween the feedback controller and the fault tolerant part. The closed loop feedback properties are handled by the nominal feedback controller and the fault tolerant part is handled by the design of the Youla parameter. The design of the fault tolerant part will not affect the design...... of the nominal feedback con-troller....

  15. Evidence of paleoearthquakes from trench investigations along Pinjore Garden fault in Pinjore Dun, NW Himalaya

    Indian Academy of Sciences (India)

    Javed N Malik; George Mathew


    The Pinjore Garden Fault (PGF) striking NNW–SSE is now considered one of the active faults displacing the younger Quaternary surfaces in the piggyback basin of Pinjore Dun. This has displaced the older Kalka and Pinjore surfaces, along with the other younger surfaces giving rise to WSW and SW-facing fault scarps with heights ranging from 2 to 16m. The PGF represents a younger branch of the Main Boundary Thrust (MBT) system. An ∼4m wide trench excavated across the PGF has revealed displacement of younger Quaternary deposits along a low angle thrust fault. Either side of the trench-walls reveals contrasting slip-related deformation of lithounits. The northern wall shows displacement of lithounits along a low-angle thrust fault, while the southern wall shows well-developed fault-related folding of thick sand unit. The sudden change in the deformational features on the southern wall is an evidence of the changing fault geometry within a short distance. Out of five prominent lithounits identified in the trench, the lower four units show displacement along a single fault. The basal unit ‘A’ shows maximum displacement of about To = 2.85 m, unit B = 1.8m and unit C = 1.45 m. The displacement measured between the sedimentary units and retro-deformation of trench log suggests that at least two earthquake events have occurred along the PGF. The units A and D mark the event horizons. Considering the average amount of displacement during one single event (2m) and the minimum length of the fault trace (∼45 km), the behaviour of PGF seems similar to that of the Himalayan Frontal Fault (HFF) and appears capable of producing large magnitude earthquakes.

  16. High-angle triple-axis specimen holder for three-dimensional diffraction contrast imaging in transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hata, S., E-mail: [Department of Electrical and Materials Science, Kyushu University, Kasuga, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Miyazaki, H. [Mel-Build, Nishi-ku, Fukuoka 819-0052 (Japan); Miyazaki, S. [FEI Company Japan Ltd., Minato-ku, Tokyo 108-0075 (Japan); Mitsuhara, M. [Department of Electrical and Materials Science, Kyushu University, Kasuga, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Tanaka, M.; Kaneko, K.; Higashida, K. [Department of Materials Science and Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395 (Japan); Ikeda, K.; Nakashima, H. [Department of Electrical and Materials Science, Kyushu University, Kasuga, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Matsumura, S. [Department of Applied Physics and Nuclear Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395 (Japan); Barnard, J.S. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Sharp, J.H. [Department of Materials Science and Engineering, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD (United Kingdom); Midgley, P.A. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)


    Electron tomography requires a wide angular range of specimen-tilt for a reliable three-dimensional (3D) reconstruction. Although specimen holders are commercially available for tomography, they have several limitations, including tilting capability in only one or two axes at most, e.g. tilt-rotate. For amorphous specimens, the image contrast depends on mass and thickness only and the single-tilt holder is adequate for most tomographic image acquisitions. On the other hand, for crystalline materials where image contrast is strongly dependent on diffraction conditions, current commercially available tomography holders are inadequate, because they lack tilt capability in all three orthogonal axes needed to maintain a constant diffraction condition over the whole tilt range. We have developed a high-angle triple-axis (HATA) tomography specimen holder capable of high-angle tilting for the primary horizontal axis with tilting capability in the other (orthogonal) horizontal and vertical axes. This allows the user to trim the specimen tilt to obtain the desired diffraction condition over the whole tilt range of the tomography series. To demonstrate its capabilities, we have used this triple-axis tomography holder with a dual-axis tilt series (the specimen was rotated by 90{sup o} ex-situ between series) to obtain tomographic reconstructions of dislocation arrangements in plastically deformed austenitic steel foils. -- Highlights: {yields} A double tilt-rotate specimen holder for diffraction contrast imaging in electron tomography. {yields} Precise alignment of a diffraction condition for tilt-series acquisition of TEM/STEM images. {yields} Complete visualization of 3D dislocation arrangements by dual-axis STEM tomography.

  17. Persistent basement wrenching as controlling mechanism of Variscan thin-skinned thrusting and sedimentation, Cantabrian Mountains Spain (United States)

    Nijman, W.; Savage, J. F.


    In this classical area of thin-skinned tectonics current models of the complex fold and thrust belt seem to be approaching a successful synthesis without the necessity for extreme regional bending to account for the characteristic horse-shoe form of the orogen. Fundamental wrench fault zones (e.g., the León and Sabero-Gordón lineaments) whose influence is recorded throughout the Palaeozoic stratigraphic history have also played an important role in the sedimentary and structural events of the Variscan cycle. Strike-slip motion not only interfered with thrusting far into Stephanian times, but also effectively controlled molasse fanglomerate sedimentation, rendered traceable by multiple clast sources, depocentre migration, fan skewing and progressive unconformities. From the surficial pattern of sedimentation and structure a left-stepping pull-apart basement structure is deduced. It is held responsible for block tilting opposite to the thrusting, modifying the backfolding of the thrust sheets and generating the concurrent surficial collapse of its fanglomerate cover. It is considered that the persistence of strike-slip motion throughout the Palaeozoic justifies the conclusion that deeper crustal events of this type may form the source of the thrusting and induce the variable stress orientations in the upper crust to implement the complex near-surface deformation. The proposed basement configuration fits well into the plate tectonic concept of a Palaeo-Africo-Iberian promontory to account for the initiation of the Ibero-Armorican arc.

  18. Co-seismic ruptures of the 12 May 2008, Ms 8.0 Wenchuan earthquake, Sichuan: East-west crustal shortening on oblique, parallel thrusts along the eastern edge of Tibet (United States)

    Liu-Zeng, J.; Zhang, Z.; Wen, L.; Tapponnier, P.; Sun, Jielun; Xing, X.; Hu, G.; Xu, Q.; Zeng, L.; Ding, L.; Ji, C.; Hudnut, K.W.; van der Woerd, J.


    The Ms 8.0, Wenchuan earthquake, which devastated the mountainous western rim of the Sichuan basin in central China, produced a surface rupture over 200??km-long with oblique thrust/dextral slip and maximum scarp heights of ~ 10??m. It thus ranks as one of the world's largest continental mega-thrust events in the last 150??yrs. Field investigation shows clear surface breaks along two of the main branches of the NE-trending Longmen Shan thrust fault system. The principal rupture, on the NW-dipping Beichuan fault, displays nearly equal amounts of thrust and right-lateral slip. Basin-ward of this rupture, another continuous surface break is observed for over 70??km on the parallel, more shallowly NW-dipping Pengguan fault. Slip on this latter fault was pure thrusting, with a maximum scarp height of ~ 3.5??m. This is one of the very few reported instances of crustal-scale co-seismic slip partitioning on parallel thrusts. This out-of-sequence event, with distributed surface breaks on crustal mega-thrusts, highlights regional, ~ EW-directed, present day crustal shortening oblique to the Longmen Shan margin of Tibet. The long rupture and large offsets with strong horizontal shortening that characterize the Wenchuan earthquake herald a re-evaluation of tectonic models anticipating little or no active shortening of the upper crust along this edge of the plateau, and require a re-assessment of seismic hazard along potentially under-rated active faults across the densely populated western Sichuan basin and mountains. ?? 2009 Elsevier B.V.

  19. Precise Thrust Actuation by a Micro RF Ion Engine Project (United States)

    National Aeronautics and Space Administration — Busek proposes to develop a radio-frequency discharge, gridded micro ion engine that produces 5N level of thrust precisely adjustable over a wide dynamic thrust...

  20. Structural Geology and Exhumation of the Paleogene Southern Sivas Fold and Thrust Belt, Central Anatolia, Turkey (United States)

    Darin, M. H.; Umhoefer, P. J.; Lefebvre, C.; Thomson, S. N.


    The Anatolian plate (Turkey) was formed during the late Miocene-Pliocene transition from contractional strain in central and eastern Anatolia (collision) to localized strike-slip faulting along inherited collisional structures (escape tectonics). Structural inheritance undoubtedly played a role in this major plate boundary reorganization, although its significance is not well understood. Considerable uncertainty also exists regarding the timing and kinematics of Tauride-Eurasia collision, initial Arabia-Eurasia collision, and the terminal closure of the Neotethys Ocean. The Sivas Basin is a ~E-W-elongate collisional forearc basin located between the Tauride micro-continent in the south and the Pontide Arc along the southern Eurasian margin in the north. Well-exposed contractional structures in Paleocene-Eocene marine strata of the Southern Sivas fold and thrust belt (SSFTB) provide an excellent opportunity to investigate the timing and kinematics of both Tauride and Arabian collisions and their potential roles in localizing strain and facilitating tectonic escape. We use detailed geologic mapping, structural analysis and detrital geo/thermochronology to investigate the magnitude, style, and timing of collision-related crustal shortening across the SSFTB. The structural geology of the SSFTB is characterized by ENE- to ESE-trending, gently plunging fault propagation folds with slight asymmetry towards the north. Vergence on thrust faults is mainly towards the north, although a few previously unmapped faults are south-vergent. Detrital apatite fission track data from Paleocene-Eocene strata reveal a single phase of rapid exhumation ca. ~36-31 Ma, which may be related to either Tauride or initial Arabian collision. We propose that structural growth of the SSFTB at this time played a major role in marine basin isolation and early Oligocene evaporite deposition. In the central and northern Sivas Basin where salt was likely thickest, salt tectonics was initiated by

  1. Recent Mega-Thrust Tsunamigenic Earthquakes and PTHA (United States)

    Lorito, S.


    The occurrence of several mega-thrust tsunamigenic earthquakes in the last decade, including but not limited to the 2004 Sumatra-Andaman, the 2010 Maule, and 2011 Tohoku earthquakes, has been a dramatic reminder of the limitations in our capability of assessing earthquake and tsunami hazard and risk. However, the increasingly high-quality geophysical observational networks allowed the retrieval of most accurate than ever models of the rupture process of mega-thrust earthquakes, thus paving the way for future improved hazard assessments. Probabilistic Tsunami Hazard Analysis (PTHA) methodology, in particular, is less mature than its seismic counterpart, PSHA. Worldwide recent research efforts of the tsunami science community allowed to start filling this gap, and to define some best practices that are being progressively employed in PTHA for different regions and coasts at threat. In the first part of my talk, I will briefly review some rupture models of recent mega-thrust earthquakes, and highlight some of their surprising features that likely result in bigger error bars associated to PTHA results. More specifically, recent events of unexpected size at a given location, and with unexpected rupture process features, posed first-order open questions which prevent the definition of an heterogeneous rupture probability along a subduction zone, despite of several recent promising results on the subduction zone seismic cycle. In the second part of the talk, I will dig a bit more into a specific ongoing effort for improving PTHA methods, in particular as regards epistemic and aleatory uncertainties determination, and the computational PTHA feasibility when considering the full assumed source variability. Only logic trees are usually explicated in PTHA studies, accounting for different possible assumptions on the source zone properties and behavior. The selection of the earthquakes to be actually modelled is then in general made on a qualitative basis or remains implicit

  2. Lateral propagation of active normal faults throughout pre-existing fault zones: an example from the Southern Apennines, Italy (United States)

    Agosta, Fabrizio; Prosser, Giacomo; Ivo Giano, Salvatore


    The main active structures in the Southern Apennines are represented by a set of NW-trending normal faults, which are mainly located in the axial sector of the chain. Evidences arising from neotectonics and seismology show activity of a composite seismic source, the Irpinia - Agri Valley, located across the Campania-Basilicata border. This seismic source is made up of two right-stepping, individual seismic sources forming a relay ramp. Each individual seismic source consists of a series of nearly parallel normal fault segments. The relay ramp area, located around the Vietri di Potenza town, is bounded by two seismic segments, the San Gregorio Magno Fault, to the NW, and the Pergola-Melandro Fault, to the SE. The possible interaction between the two right-stepping fault segments has not been proven yet, since the fault system of the area has never been analyzed in detail. This work is aimed at assessing the geometry of such fault system, inferring the relative age of the different fault sets by studying the crosscutting relationships, characterizing the micromechanics of fault rocks associated to the various fault sets, and understanding the modalities of lateral propagation of the two bounding fault segments. Crosscutting relationships are recognized by combining classical geological mapping with morphotectonic methods. This latter approach, which include the analysis of aerial photographs and field inspection of quaternary slope deposits, is used to identify the most recent structures among those cropping out in the field area. In the relay ramp area, normal faults crosscut different tectonic units of the Apennine chain piled up, essentially, during the Middle to Late Miocene. The topmost unit (only few tens of meter-thick) consists of a mélange containing blocks of different lithologies in a clayish matrix. The intermediate thrust sheet consists of 1-1.5 km-thick platform carbonates of late Triassic-Jurassic age, with dolomites at the base and limestones at the

  3. Slip partitioning on the Enriquillo and Lamentin faults during the 2010 Haiti earthquake (United States)

    Saint Fleur, Newdeskarl; Feuillet, Nathalie; Grandin, Raphaël; Jacques, Éric; Weil-Accardo, Jennifer; Klinger, Yann


    A general consensus has emerged from the study of the 12 January 2010, Mw 7.0 Haiti earthquake: the coseismic rupture was complex, portraying both reverse and strike-slip motion, but lacking unambiguous surface break. Based on seismological, geodetic and geologic data, numerous slip models have been proposed for that event. However, using an incomplete fault map, the latter models were preliminary, proposing a rupture on unmapped buried faults. Here, using bathymetric data offshore Port-au-Prince along with a digital elevation model derived from LiDAR on-land, we identified the south-dipping Lamentin thrust in the Bay of Port-au-Prince. The fault prolongs on-land where it deforms active alluvial fans in the city of Carrefour. The geometry and distribution of the aftershocks of the 2010 earthquake and the analysis of the regional geology allow us to place constraints on the connection at depth between the Lamentin thrust and the sinistral strike-slip Enriquillo -Plantain Garden Fault (EPGF). Inversion of geodetic data suggests that both faults may have broken in 2010, consistently with the regional geodynamical setting. The rupture initiated along the Lamentin thrust and further propagated along the EPGF due to instantaneous unclamping at depth. The corals uplifted around the Léogâne Delta Fan, contributing to the build-up of long-term topography between the Lamentin thrust and the EPGF. The 2010 earthquake increased the stress toward failure on unruptured EPGF segments as well as on the thrust fault sitting in the middle of the city of Carrefour, in the direct vicinity of Port-au-Prince, thereby increasing the seismic hazard in these areas.

  4. The Calama-Olacapato-El Toro fault system in the Puna Plateau, Central Andes: Geodynamic implications and stratovolcanoes emplacement (United States)

    Norini, Gianluca; Baez, Walter; Becchio, Raul; Viramonte, Jose; Giordano, Guido; Arnosio, Marcelo; Pinton, Annamaria; Groppelli, Gianluca


    The structural evolution of the Puna Plateau is characterized by the activity of both orogen-parallel and orogen-oblique faults. Understanding the possible relationship between these two structural styles, their geodynamic implications and the influence on the migration of magmas is important to get insights into the tectonic and magmatic evolution of the Central Andes. In this study, we present a structural analysis of the orogen-oblique Calama-Olacapato-El Toro fault system and the surrounding orogen-parallel thrust faults in the central-eastern Puna Plateau. Morphostructural analysis and field mapping reveal the geometry, kinematics and dynamics of the tectonic features in the studied area. We propose a three-dimensional geometrical reconstruction of the main fault planes showing their attitude and intersections at depth. The study indicates that the crust underwent simultaneous deformation along both the vertical transcurrent Calama-Olacapato-El Toro fault system and the low-angle thrust faults, and that the back-arc portion of the Calama-Olacapato-El Toro fault system developed as a transfer zone among the main N-striking thrusts. Our model considers that both orogen-parallel and orogen-oblique fault systems should be regarded as parts of the same tectonic system, accommodating crustal shortening of a thickened crust. The study suggests that the tectonic control on the magma and fluid circulation in the crust is mainly related to the geometry of the fault planes and the orientation of the stress field, with a previously unrecognized important role played by the orogen-parallel thrust faults on the emplacement of the stratovolcanoes.

  5. Geophysical characterization of transtensional fault systems in the Eastern California Shear Zone-Walker Lane Belt (United States)

    McGuire, M.; Keranen, K. M.; Stockli, D. F.; Feldman, J. D.; Keller, G. R.


    The Eastern California Shear Zone (ECSZ) and Walker Lane belt (WL) accommodate ~25% of plate motion between the North American and Pacific plates. Faults within the Mina deflection link the ECSZ and the WL, transferring strain from the Owens Valley and Death Valley-Fish Lake Valley fault systems to the transcurrent faults of the central Walker Lane. During the mid to late Miocene the majority of strain between these systems was transferred through the Silver Peak-Lone Mountain (SPLM) extensional complex via a shallowly dipping detachment. Strain transfer has since primarily migrated north to the Mina Deflection; however, high-angle faults bounding sedimentary basins and discrepancies between geodetic and geologic models indicate that the SPLM complex may still actively transfer a portion of the strain from the ECSZ to the WL on a younger set of faults. Establishing the pattern and amount of active strain transfer within the SPLM region is required for a full accounting of strain accommodation, and provides insight into strain partitioning at the basin scale within a broader transtensional zone. To map the active structures in and near Clayton Valley, within the SPLM region, we collected seismic reflection and refraction profiles and a dense grid of gravity readings that were merged with existing gravity data. The primary goals were to determine the geometry of the high-angle fault system, the amount and sense of offset along each fault set, connectivity of the faults, and the relationship of these faults to the Miocene detachment. Seismic reflection profiles imaged the high-angle basin-bounding normal faults and the detachment in both the footwall and hanging wall. The extensional basin is ~1 km deep, with a steep southeastern boundary, a gentle slope to the northwest, and a sharp boundary on the northwest side, suggestive of another fault system. Two subparallel dip-slip faults bound the southeast (deeper) basin margin with a large lateral velocity change (from ~2

  6. Alpine fold-and-thrust structures revealed: A 3D model from the Helvetic Zone (Säntis area, Switzerland) (United States)

    Sala, Paola; Pfiffner, Adrian; Frehner, Marcel


    To investigate the geometrical relationships between folding and thrust faulting, a 3D model of the Helvetic fold-and-thrust belt in Eastern Switzerland is built from several cross-sections in the Säntis area, between Hoher Kasten and Wildhaus. Existing cross-sections from Schlatter (1941), Kempf (1966), and Pfiffner (2000; 2011) were partly redrawn and cross-checked for line length balancing. Additional cross-sections based on surface geology were newly constructed to fill areas with a low cross-section density and to solve geological problems. The interpolation of the formation interfaces and the thrusts between the cross-sections allowed generating six main surfaces corresponding to the base of the Öhrli and Betlis Limestones, the Helvetic Kieselkalk, the Schrattenkalk and Garschella Formations, and the Seewen Limestone. The main structural elements in the Säntis area, such as the Säntis Thrust or the Sax-Schwende Fault, are also implemented in the model. The 3D model highlights the shape of the main anticline-syncline pairs (e.g., Altmann-Wildseeli, Schafberg-Moor, Roslenfirst-Mutschen, etc...) and how these fold trains vary in amplitude and wavelength along strike. The model also clearly shows the lateral extension, the trend, and the variation in displacement of the principal faults. The reconstruction of 3D horizons allows the geologists investigating cross-sections along any given direction. The 3D model is useful to understand how the changes of the internal nappe structures, namely folds and thrust faults, change along strike. Such changes occur either across transverse faults or in a more gradual manner. The model can and will also be used as a base to perform retrodeformation and strain estimation. Shortening will be calculated using the base Schrattenkalk as the reference horizon. REFERENCES Pfiffner, O.A., 2000: Cross-sections in Funk, H., Habich, J.K., Hantke, R. & Pfiffner, O.A., 2000: Blatt 1115 Säntis - Geologischer Atlas der Schweiz 1

  7. Thrust and Propulsive Efficiency from an Instructive Viewpoint (United States)

    Kaufman, Richard D.


    In a typical engineering or physics curriculum, the momentum equation is used for the determination of jet engine thrust. Even a simple thrust analysis requires a heavy emphasis on mathematics that can cause students and engineers to lose a physical perspective on thrust. This article provides for this physical understanding using only static…

  8. Relationship between Biomechanical Characteristics of Spinal Manipulation and Neural Responses in an Animal Model: Effect of Linear Control of Thrust Displacement versus Force, Thrust Amplitude, Thrust Duration, and Thrust Rate

    Directory of Open Access Journals (Sweden)

    William R. Reed


    Full Text Available High velocity low amplitude spinal manipulation (HVLA-SM is used frequently to treat musculoskeletal complaints. Little is known about the intervention’s biomechanical characteristics that determine its clinical benefit. Using an animal preparation, we determined how neural activity from lumbar muscle spindles during a lumbar HVLA-SM is affected by the type of thrust control and by the thrust's amplitude, duration, and rate. A mechanical device was used to apply a linear increase in thrust displacement or force and to control thrust duration. Under displacement control, neural responses during the HVLA-SM increased in a fashion graded with thrust amplitude. Under force control neural responses were similar regardless of the thrust amplitude. Decreasing thrust durations at all thrust amplitudes except the smallest thrust displacement had an overall significant effect on increasing muscle spindle activity during the HVLA-SMs. Under force control, spindle responses specifically and significantly increased between thrust durations of 75 and 150 ms suggesting the presence of a threshold value. Thrust velocities greater than 20–30 mm/s and thrust rates greater than 300 N/s tended to maximize the spindle responses. This study provides a basis for considering biomechanical characteristics of an HVLA-SM that should be measured and reported in clinical efficacy studies to help define effective clinical dosages.

  9. Relationship between Biomechanical Characteristics of Spinal Manipulation and Neural Responses in an Animal Model: Effect of Linear Control of Thrust Displacement versus Force, Thrust Amplitude, Thrust Duration, and Thrust Rate. (United States)

    Reed, William R; Cao, Dong-Yuan; Long, Cynthia R; Kawchuk, Gregory N; Pickar, Joel G


    High velocity low amplitude spinal manipulation (HVLA-SM) is used frequently to treat musculoskeletal complaints. Little is known about the intervention's biomechanical characteristics that determine its clinical benefit. Using an animal preparation, we determined how neural activity from lumbar muscle spindles during a lumbar HVLA-SM is affected by the type of thrust control and by the thrust's amplitude, duration, and rate. A mechanical device was used to apply a linear increase in thrust displacement or force and to control thrust duration. Under displacement control, neural responses during the HVLA-SM increased in a fashion graded with thrust amplitude. Under force control neural responses were similar regardless of the thrust amplitude. Decreasing thrust durations at all thrust amplitudes except the smallest thrust displacement had an overall significant effect on increasing muscle spindle activity during the HVLA-SMs. Under force control, spindle responses specifically and significantly increased between thrust durations of 75 and 150 ms suggesting the presence of a threshold value. Thrust velocities greater than 20-30 mm/s and thrust rates greater than 300 N/s tended to maximize the spindle responses. This study provides a basis for considering biomechanical characteristics of an HVLA-SM that should be measured and reported in clinical efficacy studies to help define effective clinical dosages.

  10. Thrust and Propulsive Efficiency from an Instructive Viewpoint (United States)

    Kaufman, Richard D.


    In a typical engineering or physics curriculum, the momentum equation is used for the determination of jet engine thrust. Even a simple thrust analysis requires a heavy emphasis on mathematics that can cause students and engineers to lose a physical perspective on thrust. This article provides for this physical understanding using only static…

  11. Fault detection and isolation in systems with parametric faults

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, Hans Henrik


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

  12. Iowa Bedrock Faults (United States)

    Iowa State University GIS Support and Research Facility — This fault coverage locates and identifies all currently known/interpreted fault zones in Iowa, that demonstrate offset of geologic units in exposure or subsurface...

  13. null Faults, null Images (United States)

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

  14. The fluid budget of a continental plate boundary fault: Quantification from the Alpine Fault, New Zealand (United States)

    Menzies, Catriona D.; Teagle, Damon A. H.; Niedermann, Samuel; Cox, Simon C.; Craw, Dave; Zimmer, Martin; Cooper, Matthew J.; Erzinger, Jörg


    Fluids play a key role in modifying the chemical and physical properties of fault zones, which may prime them for repeated rupture by the generation of high pore fluid pressures and precipitation of commonly weak, secondary minerals. Fluid flow paths, sources and fluxes, and the permeability evolution of fault zones throughout their seismic cycles remain poorly constrained, despite their importance to understanding fault zone behaviour. Here we use geochemical tracers of fluid-rock exchange to determine budgets for meteoric, metamorphic and mantle fluids on a major compressional tectonic plate boundary. The Alpine Fault marks the transpressional Pacific-Australian plate boundary through South Island, New Zealand and appears to fail in regular (329 ± 68 yrs) large earthquakes (Mw ∼ 8) with the most recent event in 1717 AD. Significant convergent motion has formed the Southern Alps and elevated geothermal gradients in the hangingwall, which drive crustal fluid flow. Along the Alpine Fault the Alpine Schist of the Pacific Plate is thrust over radiogenic metasedimentary rocks on the Australian plate. The absence of highly radiogenic (87Sr/86Sr > 0.7200) strontium isotope ratios of hangingwall hot springs and hydrothermal minerals formed at a range of depths in the Alpine Fault damage zone indicates that the fluid flow is restricted to the hangingwall by a cross-fault fluid flow barrier throughout the seismogenic crust. Helium isotope ratios measured in hot springs near to the Alpine Fault (0.15-0.81 RA) indicate the fault is a crustal-scale feature that acts as a conduit for fluids from the mantle. Rock-exchanged oxygen, but meteoric water-like hydrogen isotope signatures of hydrothermal veins indicate that partially rock-exchanged meteoric fluids dominate down to the top of the brittle to ductile transition zone at ∼6 km. Geochemical tracer transport modelling suggests only ∼0.02 to 0.05% of total rainfall west of the Main Divide penetrates to depth, yet this

  15. Fault geometry and mechanics of marly carbonate multilayers: An integrated field and laboratory study from the Northern Apennines, Italy (United States)

    Giorgetti, C.; Collettini, C.; Scuderi, M. M.; Barchi, M. R.; Tesei, T.


    Sealing layers are often represented by sedimentary sequences characterized by alternating strong and weak lithologies. When involved in faulting processes, these mechanically heterogeneous multilayers develop complex fault geometries. Here we investigate fault initiation and evolution within a mechanical multilayer by integrating field observations and rock deformation experiments. Faults initiate with a staircase trajectory that partially reflects the mechanical properties of the involved lithologies, as suggested by our deformation experiments. However, some faults initiating at low angles in calcite-rich layers (θi = 5°-20°) and at high angles in clay-rich layers (θi = 45°-86°) indicate the important role of structural inheritance at the onset of faulting. With increasing displacement, faults develop well-organized fault cores characterized by a marly, foliated matrix embedding fragments of limestone. The angles of fault reactivation, which concentrate between 30° and 60°, are consistent with the low friction coefficient measured during our experiments on marls (μs = 0.39), indicating that clay minerals exert a main control on fault mechanics. Moreover, our integrated analysis suggests that fracturing and faulting are the main mechanisms allowing fluid circulation within the low-permeability multilayer, and that its sealing integrity can be compromised only by the activity of larger faults cutting across its entire thickness.

  16. Earthquake stress drops and inferred fault strength on the Hayward Fault, east San Francisco Bay, California (United States)

    Hardebeck, J.L.; Aron, A.


    We study variations in earthquake stress drop with respect to depth, faulting regime, creeping versus locked fault behavior, and wall-rock geology. We use the P-wave displacement spectra from borehole seismic recordings of M 1.0-4.2 earthquakes in the east San Francisco Bay to estimate stress drop using a stack-and-invert empirical Green's function method. The median stress drop is 8.7 MPa, and most stress drops are in the range between 0.4 and 130 MPa. An apparent correlation between stress drop and magnitude is entirely an artifact of the limited frequency band of 4-55 Hz. There is a trend of increasing stress drop with depth, with a median stress drop of ~5 MPa for 1-7 km depth, ~10 MPa for 7-13 km depth, and ~50 MPa deeper than 13 km. We use S=P amplitude ratios measured from the borehole records to better constrain the first-motion focal mechanisms. High stress drops are observed for a deep cluster of thrust-faulting earthquakes. The correlation of stress drops with depth and faulting regime implies that stress drop is related to the applied shear stress. We compare the spatial distribution of stress drops on the Hayward fault to a model of creeping versus locked behavior of the fault and find that high stress drops are concentrated around the major locked patch near Oakland. This also suggests a connection between stress drop and applied shear stress, as the locked patch may experience higher applied shear stress as a result of the difference in cumulative slip or the presence of higher-strength material. The stress drops do not directly correlate with the strength of the proposed wall-rock geology at depth, suggesting that the relationship between fault strength and the strength of the wall rock is complex.

  17. Performance based fault diagnosis

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik


    Different aspects of fault detection and fault isolation in closed-loop systems are considered. It is shown that using the standard setup known from feedback control, it is possible to formulate fault diagnosis problems based on a performance index in this general standard setup. It is also shown...

  18. Fault tolerant computing systems

    CERN Document Server

    Randell, B


    Fault tolerance involves the provision of strategies for error detection, damage assessment, fault treatment and error recovery. A survey is given of the different sorts of strategies used in highly reliable computing systems, together with an outline of recent research on the problems of providing fault tolerance in parallel and distributed computing systems. (15 refs).

  19. Fault Tolerant Control Systems

    DEFF Research Database (Denmark)

    Bøgh, S. A.

    was to avoid a total close-down in case of the most likely faults. The second was a fault tolerant attitude control system for a micro satellite where the operation of the system is mission critical. The purpose was to avoid hazardous effects from faults and maintain operation if possible. A method...

  20. Coulomb static stress interactions between simulated M>7 earthquakes and major faults in Southern California (United States)

    Rollins, J. C.; Ely, G. P.; Jordan, T. H.


    We calculate the Coulomb stress changes imparted to major Southern California faults by thirteen simulated worst-case-scenario earthquakes for the region, including the “Big Ten” scenarios (Ely et al, in progress). The source models for the earthquakes are variable-slip simulations from the SCEC CyberShake project (Graves et al, 2010). We find strong stress interactions between the San Andreas and subparallel right-lateral faults, thrust faults under the Los Angeles basin, and the left-lateral Garlock Fault. M>7 earthquakes rupturing sections of the southern San Andreas generally decrease Coulomb stress on the San Jacinto and Elsinore faults and impart localized stress increases and decreases to the Garlock, San Cayetano, Puente Hills and Sierra Madre faults. A M=7.55 quake rupturing the San Andreas between Lake Hughes and San Gorgonio Pass increases Coulomb stress on the eastern San Cayetano fault, consistent with Deng and Sykes (1996). M>7 earthquakes rupturing the San Jacinto, Elsinore, Newport-Inglewood and Palos Verdes faults decrease stress on parallel right-lateral faults. A M=7.35 quake on the San Cayetano Fault decreases stress on the Garlock and imparts localized stress increases and decreases to the San Andreas. A M=7.15 quake on the Puente Hills Fault increases stress on the San Andreas and San Jacinto faults, decreases stress on the Sierra Madre Fault and imparts localized stress increases and decreases to the Newport-Inglewood and Palos Verdes faults. A M=7.25 shock on the Sierra Madre Fault increases stress on the San Andreas and decreases stress on the Puente Hills Fault. These findings may be useful for hazard assessment, paleoseismology, and comparison with dynamic stress interactions featuring the same set of earthquakes.


    Energy Technology Data Exchange (ETDEWEB)



    This booklet contains project descriptions of work performed by the Department of Energy (DOE), Office of Civilian Radioactive Waste Management (OCRWM), Office of Science and Technology and International's (OST&I) Natural Barriers Targeted Thrust during Fiscal Year (FY) 2004. The Natural Barriers Targeted Thrust is part of OST&I's Science and Technology Program which supports the OCRWM mission to manage and dispose of high-level radioactive waste and spent nuclear fuel in a manner that protects health, safety, and the environment; enhances national and energy security; and merits public confidence. In general, the projects described will continue beyond FY 2004 assuming that the technical work remains relevant to the proposed Yucca Mountain Repository and sufficient funding is made available to the Science and Technology Program.


    Energy Technology Data Exchange (ETDEWEB)



    The Yucca Mountain site was recommended by the President to be a geological repository for commercial spent nuclear fuel and high-level radioactive waste. The multi-barrier approach was adopted for assessing and predicting system behavior, including both natural barriers and engineered barriers. A major component of the long-term strategy for safe disposal of nuclear waste is first to completely isolate the radionuclides in waste packages for long times and then to greatly retard the egress and transport of radionuclides from penetrated packages. The goal of the Materials Performance Targeted Thrust program is to further enhance the understanding of the role of engineered barriers in waste isolation. In addition, the Thrust will explore technical enhancements and seek to offer improvements in materials costs and reliability.

  3. Benchmarking analogue models of brittle thrust wedges (United States)

    Schreurs, Guido; Buiter, Susanne J. H.; Boutelier, Jennifer; Burberry, Caroline; Callot, Jean-Paul; Cavozzi, Cristian; Cerca, Mariano; Chen, Jian-Hong; Cristallini, Ernesto; Cruden, Alexander R.; Cruz, Leonardo; Daniel, Jean-Marc; Da Poian, Gabriela; Garcia, Victor H.; Gomes, Caroline J. S.; Grall, Céline; Guillot, Yannick; Guzmán, Cecilia; Hidayah, Triyani Nur; Hilley, George; Klinkmüller, Matthias; Koyi, Hemin A.; Lu, Chia-Yu; Maillot, Bertrand; Meriaux, Catherine; Nilfouroushan, Faramarz; Pan, Chang-Chih; Pillot, Daniel; Portillo, Rodrigo; Rosenau, Matthias; Schellart, Wouter P.; Schlische, Roy W.; Take, Andy; Vendeville, Bruno; Vergnaud, Marine; Vettori, Matteo; Wang, Shih-Hsien; Withjack, Martha O.; Yagupsky, Daniel; Yamada, Yasuhiro


    We performed a quantitative comparison of brittle thrust wedge experiments to evaluate the variability among analogue models and to appraise the reproducibility and limits of model interpretation. Fifteen analogue modeling laboratories participated in this benchmark initiative. Each laboratory received a shipment of the same type of quartz and corundum sand and all laboratories adhered to a stringent model building protocol and used the same type of foil to cover base and sidewalls of the sandbox. Sieve structure, sifting height, filling rate, and details on off-scraping of excess sand followed prescribed procedures. Our analogue benchmark shows that even for simple plane-strain experiments with prescribed stringent model construction techniques, quantitative model results show variability, most notably for surface slope, thrust spacing and number of forward and backthrusts. One of the sources of the variability in model results is related to slight variations in how sand is deposited in the sandbox. Small changes in sifting height, sifting rate, and scraping will result in slightly heterogeneous material bulk densities, which will affect the mechanical properties of the sand, and will result in lateral and vertical differences in peak and boundary friction angles, as well as cohesion values once the model is constructed. Initial variations in basal friction are inferred to play the most important role in causing model variability. Our comparison shows that the human factor plays a decisive role, and even when one modeler repeats the same experiment, quantitative model results still show variability. Our observations highlight the limits of up-scaling quantitative analogue model results to nature or for making comparisons with numerical models. The frictional behavior of sand is highly sensitive to small variations in material state or experimental set-up, and hence, it will remain difficult to scale quantitative results such as number of thrusts, thrust spacing

  4. Low Carbon Propulsion Strategic Thrust Overview (United States)

    Dryer, Jay


    NASA is taking a leadership role with regard to developing new options for low-carbon propulsion. Work related to the characterization of alternative fuels is coordinated with our partners in government and industry, and NASA is close to concluding a TC in this area. Research on alternate propulsion concepts continues to grow and is an important aspect of the ARMD portfolio. Strong partnerships have been a key enabling factor for research on this strategic thrust.

  5. Identification of Baribis fault - West Java using second vertical derivative method of gravity (United States)

    Sari, Endah Puspita; Subakti, Hendri


    Baribis fault is one of West Java fault zones which is an active fault. In modern era, the existence of fault zone can be observed by gravity anomaly. Baribis fault zone has not yet been measured by gravity directly. Based on this reason, satellite data supported this research. Data used on this research are GPS satellite data downloaded from TOPEX. The purpose of this research is to determine the type and strike of Baribis fault. The scope of this research is Baribis fault zone which lies on 6.50o - 7.50o S and 107.50o - 108.80o E. It consists of 5146 points which one point to another is separated by 1 minute meridian. The method used in this research is the Second Vertical Derivative (SVD) of gravity anomaly. The Second Vertical Derivative of gravity anomaly show as the amplitude of gravity anomaly caused by fault structure which appears as residual anomaly. The zero value of residual gravity anomaly indicates that the contact boundary of fault plane. Second Vertical Derivative method of gravity was applied for identifying Baribis fault. The result of this research shows that Baribis fault has a thrust mechanism. It has a lineament strike varies from 107o to 127o. This result agrees with focal mechanism data of earthquakes occurring on this region based on Global CMT catalogue.


    Institute of Scientific and Technical Information of China (English)

    许冲; 徐锡伟


    landslides spatial distribution is carried out with four indices. They are a) landslide centroid number density (LCND) ,defined as the number of landslide centroid per square kilometer, b) landslide top number density(LTND) , defined as the number of landslide top point per square kilometer, c ) landslide area percentage ( LAP) , defined as the percentage of the area affected by the landslides, and d) landslide erosion thickness (LET) , defined as the landslide material thickness per square kilometer. It is to determine how the occurrence of landslides and their erosion thickness correlates with seismic parameters, topographic conditions and distance from roads. It is observed that values of four indices ( LCND, LTND, LAP and LET) have generally positive correlations with slope angle and peak ground acceleration ( PGA) , and have generally negative correlations with distance from the Enriquillo-Plan-tain Garden fault, and distance from drainages. Statistical results of landslide and their erosion thickness with distance along the Enriquillo-Plantain Garden fault show that areas from 22 to 26 km and 8 to 12km, western of the epicenter, and from 6 to 18km, eastern of the epicenter are landslide high susceptibility areas. It also represents more slope curvature close to zero, more difficult to earthquake triggered landslide occurrerice. The highest values appear at range from 200m to 1200m in elevation. The landslides have preferred orientation dominated by the eastern. No apparent correlations were found in the LCND, LTND, LAP and LET values with distance from epicenter and distance from roads.

  7. Early Cenozoic Shortening and Foreland Basin Sedimentation in the Marañon Fold-thrust Belt, Central Peruvian Andes (United States)

    Jackson, L. J.; Carlotto, V.; Horton, B. K.; Rosell, L. N.


    The Marañon fold-thrust belt in the westernmost Andes of Peru has long been considered a robust signature of early Cenozoic shortening in the Andean orogenic belt. However, the structural details and potential records of coeval synorogenic sedimentation remain elusive. We report results from new geologic mapping (1:50,000), cross-section construction, and U-Pb geochronology for the Matucana-Ticlio region at 11-12°S along the Lima-La Oroya highway. Zircon U-Pb age data from volcanic rocks and clastic basin fill provide a maximum depositional age of ~43 Ma for a middle Eocene syndeformational unit that we identify as the Anta Formation, which overlies the Paleocene Casapalca Formation. Sedimentary lithofacies and unconformable relationships within the volcaniclastic Anta Formation reveal mixed fluvial, alluvial-fan, and volcanic depositional conditions during shortening accommodated by a NE-verging thrust/reverse fault and corresponding backthrust (here named the Chonta fault system). Our cross-section reconstruction and geochronological data indicate that the region is a critical, possibly unique, zone of the broader NE-directed Marañon fold-thrust belt where pre-Neogene synorogenic sediments and their associated structures are preserved. We interpret this combined structural and basin system as an Eocene-age (Incaic) frontal thrust belt and corresponding foredeep to wedge-top depozone in central Peru. As one of the better-constrained segments of the Marañon fold-thrust belt, this zone provides insight into potential linkages with elusive early Cenozoic (Incaic) structures and foreland basin fill of the Western Cordillera and Altiplano farther south in the central Andean plateau.

  8. Thrust and power measurements of Olympic swimmers (United States)

    Wei, Timothy; Wu, Vicki; Hutchison, Sean; Mark, Russell


    Elite level swimming is an extremely precise and even choreographed activity. Swimmers not only know the exact number of strokes necessary to take them across the pool, they also plan to be a precise distance from the wall at the end of their last stroke. Too far away and they lose time by drifting into the wall. Too close and their competitor may slide in before their hand comes forward to touch the wall. In this context, it is important to know, in detail, where and how a swimmer propels her/himself through the water. Over the past decade, state-of-the-art flow and thrust measurement diagnostics have been brought to competitive swimming. But the ability to correlate stroke mechanics to thrust production without somehow constraining the swimmer has here-to-fore not been possible. Using high speed video, a simple approach to mapping the swimmer's speed, thrust and net power output in a time resolved manner has been developed. This methodology has been applied to Megan Jendrick, gold medalist in the 100 individual breast stroke and 4 × 100 medley relay events in 2000 and Ariana Kukors, 2009 world champion and continuing world record holder in the 200 individual medley. Implications for training future elite swimmers will be discussed.

  9. The thrust belts of Western North America

    Energy Technology Data Exchange (ETDEWEB)

    Moulton, F.C.


    Most of the Basin and Range physiographic province of western North America is now believed to be part of the overthrust. The more obvious overthrust belt along the eastern edge of the Basin and Range Province is named the Sevier orogenic belt, where older rocks are observed thrust onto younger rocks. More detailed surface geological mapping, plus deep multiple-fold geophysical work and many oil and gas wildcat wells, have confirmed an east-vergent shortened and stacked sequence is present in many places in the Basin and Range. This western compressive deformed area in east central Nevada is now named the Elko orogenic belt by the U.S. Geological Survey. This older compressed Elko orogenic belt started forming approximately 250 m.y. ago when the North American plate started to move west as the Pangaea supercontinent started to fragment. The North American plate moved west under the sediments of the Miogeocline that were also moving west. Surface-formed highlands and oceanic island arcs on the west edge of the North American plate restricted the westward movement of the sediments in the Miogeocline, causing east-vergent ramp thrusts to form above the westward-moving North American plate. The flat, eastward-up-cutting thrust assemblages moved on the detachment surfaces.

  10. Thrust Vector Control for Nuclear Thermal Rockets (United States)

    Ensworth, Clinton B. F.


    Future space missions may use Nuclear Thermal Rocket (NTR) stages for human and cargo missions to Mars and other destinations. The vehicles are likely to require engine thrust vector control (TVC) to maintain desired flight trajectories. This paper explores requirements and concepts for TVC systems for representative NTR missions. Requirements for TVC systems were derived using 6 degree-of-freedom models of NTR vehicles. Various flight scenarios were evaluated to determine vehicle attitude control needs and to determine the applicability of TVC. Outputs from the models yielded key characteristics including engine gimbal angles, gimbal rates and gimbal actuator power. Additional factors such as engine thrust variability and engine thrust alignment errors were examined for impacts to gimbal requirements. Various technologies are surveyed for TVC systems for the NTR applications. A key factor in technology selection is the unique radiation environment present in NTR stages. Other considerations including mission duration and thermal environments influence the selection of optimal TVC technologies. Candidate technologies are compared to see which technologies, or combinations of technologies best fit the requirements for selected NTR missions. Representative TVC systems are proposed and key properties such as mass and power requirements are defined. The outputs from this effort can be used to refine NTR system sizing models, providing higher fidelity definition for TVC systems for future studies.

  11. MHD thrust vectoring of a rocket engine (United States)

    Labaune, Julien; Packan, Denis; Tholin, Fabien; Chemartin, Laurent; Stillace, Thierry; Masson, Frederic


    In this work, the possibility to use MagnetoHydroDynamics (MHD) to vectorize the thrust of a solid propellant rocket engine exhaust is investigated. Using a magnetic field for vectoring offers a mass gain and a reusability advantage compared to standard gimbaled, elastomer-joint systems. Analytical and numerical models were used to evaluate the flow deviation with a 1 Tesla magnetic field inside the nozzle. The fluid flow in the resistive MHD approximation is calculated using the KRONOS code from ONERA, coupling the hypersonic CFD platform CEDRE and the electrical code SATURNE from EDF. A critical parameter of these simulations is the electrical conductivity, which was evaluated using a set of equilibrium calculations with 25 species. Two models were used: local thermodynamic equilibrium and frozen flow. In both cases, chlorine captures a large fraction of free electrons, limiting the electrical conductivity to a value inadequate for thrust vectoring applications. However, when using chlorine-free propergols with 1% in mass of alkali, an MHD thrust vectoring of several degrees was obtained.

  12. Aircraft Engine Thrust Estimator Design Based on GSA-LSSVM (United States)

    Sheng, Hanlin; Zhang, Tianhong


    In view of the necessity of highly precise and reliable thrust estimator to achieve direct thrust control of aircraft engine, based on support vector regression (SVR), as well as least square support vector machine (LSSVM) and a new optimization algorithm - gravitational search algorithm (GSA), by performing integrated modelling and parameter optimization, a GSA-LSSVM-based thrust estimator design solution is proposed. The results show that compared to particle swarm optimization (PSO) algorithm, GSA can find unknown optimization parameter better and enables the model developed with better prediction and generalization ability. The model can better predict aircraft engine thrust and thus fulfills the need of direct thrust control of aircraft engine.

  13. Active inversion tectonics, simple shear folding and back-thrusting at Rioni Basin, Georgia (United States)

    Tibaldi, A.; Alania, V.; Bonali, F. L.; Enukidze, O.; Tsereteli, N.; Kvavadze, N.; Varazanashvili, O.


    The Rioni Basin, located between the Greater and Lesser Caucasus in Georgia, is an outstanding example of ongoing inversion tectonics. Marine and continental deposits of Cretaceous-Neogene age have been locally uplifted since the end of Miocene. The uplifted area totals 1300 km2, and Plio-Quaternary river deposits have been raised up to 200 m above the surrounding plains. Inversion tectonics has been accompanied by the development of south-vergent asymmetrical folds and strike-slip faults along the border of the uplifted area. The folds have locally an en-échelon geometry and microtectonic data indicate rotation of the paleostress direction over time, suggesting simple shear deformation. In the interiors of the uplifted area, there are gentle symmetrical folds and one main active south-dipping reverse fault, corresponding to a backthrust. Morphostructural evidence, as well as the tilting of Quaternary strata, the offset of Quaternary alluvial deposits and the presence of crustal seismic activity, indicate that compressional tectonics is still active. The combination of field data with seismic reflection sections shows that inversion tectonics took place through a series of north-dipping blind thrusts and a wedge with passive back-thrusting. Uplift and contraction are more developed along the eastern part of the study area, suggesting the westward propagation of the closure of the Transcaucasian depression.

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

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


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

  15. Crustal wedging triggering recent deformation in the Andean thrust front between 31°S and 33°S: Sierras Pampeanas-Precordillera interaction (United States)

    VergéS, J.; Ramos, V. A.; Meigs, A.; Cristallini, E.; Bettini, F. H.; CortéS, J. M.


    We document a new model of crustal structure of the Andean front in Argentina where numerous historic earthquakes destroyed the cities of Mendoza in 1861 (Ms = ˜7) and San Juan in 1944 (Mw = 7.0). The Cerro Salinas anticline is formed above the west directed Cerro Salinas thrust. An east facing monocline with an amplitude of about 2 km folds the Cerro Salinas thrust and overlying Neogene succession. This monocline is formed above a blind crustal thrust in the basement. Its dip of 14° west is inferred from fold geometry. This thick-skinned east directed blind thrust and the thin-skinned west directed Cerro Salinas thrust define a tectonic wedge; the wedge tip occurs at a depth of 5.4 km. Growth of the monocline after ˜8.5 Ma is revealed on multichannel seismic (MSC) profile 31017 (Repsol-YPF). Rates of Cerro Salinas thrust displacement are of the order of 1 mm/yr, whereas vertical uplift of ˜0.45 mm/yr results from the combined displacement on the Cerro Salinas thrust and growth of east facing monocline. The lateral extent of the east directed crustal blind ramp corresponds with the along-strike extent of the Eastern Precordillera. When combined with the low displacement rate, a long earthquake recurrence interval is implied. Smaller magnitude earthquakes, however, indicate that segments of the blind thrust ramps ruptured in historic events. If all the segments of the blind thrust ruptured together the fault area is ˜7000 km2 and could produce a Mw ˜ 7.7 earthquake. The crustal wedge model provides new constraints on the origin and potential size of earthquakes that threaten the densely populated region.

  16. Information Based Fault Diagnosis

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad


    Fault detection and isolation, (FDI) of parametric faults in dynamic systems will be considered in this paper. An active fault diagnosis (AFD) approach is applied. The fault diagnosis will be investigated with respect to different information levels from the external inputs to the systems....... These inputs are disturbance inputs, reference inputs and auxilary inputs. The diagnosis of the system is derived by an evaluation of the signature from the inputs in the residual outputs. The changes of the signatures form the external inputs are used for detection and isolation of the parametric faults....

  17. Fault-Tree Compiler (United States)

    Butler, Ricky W.; Boerschlein, David P.


    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.

  18. Relationships between thrusting and joint systems in the Jaca thrust-top basin, Spanish Pyrenees (United States)

    Turner, J. P.; Hancock, P. L.

    The Oligo-Miocene rocks of the West Jaca thrust-top basin and adjacent parts of the Ebro basin are cut by up to eight sets of joints and allied mesofractures. The fractures belong to three groups that can be distinguished on the basis of their relative ages and geometry. An older group of joints strikes normal or subnormal to the Pyrenean mountain front and is restricted to subareas (here called front-normal joint domains) coincident with the immediate footwalls of thrusts. Joints striking parallel to a buried lateral ramp characterize a lateral ramp joint domain. Younger joints striking parallel or subparallel to the mountain front occur throughout most of the West Jaca and Ebro basins, and define front-parallel joint domains. The joint domains appear to reflect the geometry and evolution of thrust sheets. Joints in front-normal domains were formed during stretching of footwalls as a result of their loading by overriding thrust sheets. Stretching above a lateral ramp is thought to be responsible for the development of joints in the lateral ramp domain. Joints in the front-parallel domains of the West Jaca basin are related to stretching in growth folds that were amplifying during salt doming. Front-parallel joints in the Ebro basin are attributed to stretching of a foreland basin sequence above a basement flexure related to thrust loading.

  19. Thrust Performance Evaluation of a Turbofan Engine Based on Exergetic Approach and Thrust Management in Aircraft (United States)

    Yalcin, Enver


    The environmental parameters such as temperature and air pressure which are changing depending on altitudes are effective on thrust and fuel consumption of aircraft engines. In flights with long routes, thrust management function in airplane information system has a structure that ensures altitude and performance management. This study focused on thrust changes throughout all flight were examined by taking into consideration their energy and exergy performances for fuel consumption of an aircraft engine used in flight with long route were taken as reference. The energetic and exergetic performance evaluations were made under the various altitude conditions. The thrust changes for different altitude conditions were obtained to be at 86.53 % in descending direction and at 142.58 % in ascending direction while the energy and exergy efficiency changes for the referenced engine were found to be at 80.77 % and 84.45 %, respectively. The results revealed here can be helpful to manage thrust and reduce fuel consumption, but engine performance will be in accordance with operation requirements.

  20. Large-scale thrusting at the northern Junggar Basin since Cretaceous and its implications for the rejuvenation of the Central Asian Orogenic Belt

    Directory of Open Access Journals (Sweden)

    Jieyun Tang


    Full Text Available The Wulungu Depression is the northernmost first-order tectonic unit in the Junggar Basin. It can be divided into three sub-units: the Hongyan step-fault zone, the Suosuoquan sag and the Wulungu south slope. The Cenozoic strata in the basin are intact and Mesozoic–Cenozoic deformation can be observed in the Wulungu step-fault zone, so this is an ideal place to study the Mesozoic–Cenozoic deformation. By integration of fault-related folding theories, regional geology and drilling data, the strata of the Cretaceous–Paleogene systems are divided into small layers which are selected as the subjects of this research. The combination of the developing unconformity with existing growth strata makes it conceivable that faults on the step-fault zone have experienced different degrees of reactivation of movement since the Cretaceous. Evolutionary analyses of the small layers using 2D-Move software showed certain differences in the reactivation of different segments of the Wulungu Depression such as the timing of reactivation of thrusting, for which the reactivity time of the eastern segment was late compared with those of the western and middle segments. In addition the resurrection strength was similarly slightly different, with the shortening rate being higher in the western segment than in the other segments. Moreover, the thrust fault mechanism is basement-involved combined with triangle shear fold, for which a forward evolution model was proposed.

  1. Faulting at Thebes Gap, Mo. -Ill. : Implications for New Madrid tectonism

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, R.W.; Schultz, A.P. (Geological Survey, Reston, VA (United States))


    Recent geologic mapping in the Thebes Gap area has identified numerous NNE- and NE-striking faults having a long-lived and complex structural history. The faults are located in an area of moderate recent seismicity at the northern margin of the Mississippi embayment, approximately 45 km north of the New Madrid seismic zone. Earliest deformation occurred along dextral strike-slip faults constrained as post-Devonian and pre-Cretaceous. Uplift and erosion of all Carboniferous strata suggest that this faulting is related to development of the Pascola arch (Ouachita orogeny). This early deformation is characterized by strongly faulted and folded Ordovician through Devonian rocks overlain in places with angular unconformity by undeformed Cretaceous strata. Elsewhere, younger deformation involves Paleozoic, Cretaceous, Paleocene, and Eocene formations. These units have experienced both minor high-angle normal faulting and major, dextral strike-slip faulting. Quaternary-Tertiary Mounds Gravel is also involved in the latest episode of strike-slip deformation. Enechelon north-south folds, antithetic R[prime] shears, and drag folds indicate right-lateral motion. Characteristic positive and negative flower structures are commonly revealed in cross section. Right-stepping fault strands have produced pull-apart basins where Ordovician, Silurian, Devonian, Cretaceous, and Tertiary units are downdropped several hundreds of meters and occur in chaotic orientations. Similar fault orientations and kinematics, as well as recent seismicity and close proximity, clearly suggest a structural relationship between deformation at Thebes Gap and tectonism associated with the New Madrid area.

  2. Earthquake fault superhighways (United States)

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


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

  3. Modelling of AlAs/GaAs interfacial structures using high-angle annular dark field (HAADF) image simulations. (United States)

    Robb, Paul D; Finnie, Michael; Craven, Alan J


    High angle annular dark field (HAADF) image simulations were performed on a series of AlAs/GaAs interfacial models using the frozen-phonon multislice method. Three general types of models were considered-perfect, vicinal/sawtooth and diffusion. These were chosen to demonstrate how HAADF image measurements are influenced by different interfacial structures in the technologically important III-V semiconductor system. For each model, interfacial sharpness was calculated as a function of depth and compared to aberration-corrected HAADF experiments of two types of AlAs/GaAs interfaces. The results show that the sharpness measured from HAADF imaging changes in a complicated manner with thickness for complex interfacial structures. For vicinal structures, it was revealed that the type of material that the probe projects through first of all has a significant effect on the measured sharpness. An increase in the vicinal angle was also shown to generate a wider interface in the random step model. The Moison diffusion model produced an increase in the interface width with depth which closely matched the experimental results of the AlAs-on-GaAs interface. In contrast, the interface width decreased as a function of depth in the linear diffusion model. Only in the case of the perfect model was it possible to ascertain the underlying structure directly from HAADF image analysis.

  4. Extraction of structural and chemical information from high angle annular dark-field image by an improved peaks finding method. (United States)

    Yin, Wenhao; Huang, Rong; Qi, Ruijuan; Duan, Chungang


    With the development of spherical aberration (Cs) corrected scanning transmission electron microscopy (STEM), high angle annular dark filed (HAADF) imaging technique has been widely applied in the microstructure characterization of various advanced materials with atomic resolution. However, current qualitative interpretation of the HAADF image is not enough to extract all the useful information. Here a modified peaks finding method was proposed to quantify the HAADF-STEM image to extract structural and chemical information. Firstly, an automatic segmentation technique including numerical filters and watershed algorithm was used to define the sub-areas for each atomic column. Then a 2D Gaussian fitting was carried out to determine the atomic column positions precisely, which provides the geometric information at the unit-cell scale. Furthermore, a self-adaptive integration based on the column position and the covariance of statistical Gaussian distribution were performed. The integrated intensities show very high sensitivity on the mean atomic number with improved signal-to-noise (S/N) ratio. Consequently, the polarization map and strain distributions were rebuilt from a HAADF-STEM image of the rhombohedral and tetragonal BiFeO3 interface and a MnO2 monolayer in LaAlO3 /SrMnO3 /SrTiO3 heterostructure was discerned from its neighbor TiO2 layers. Microsc. Res. Tech. 79:820-826, 2016. © 2016 Wiley Periodicals, Inc.

  5. The potential link between high angle grain boundary morphology and grain boundary deformation in a nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Carter, Jennifer L.W., E-mail: [Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 44321 (United States); Sosa, John M. [Center for Accelerated Maturation of Materials, The Ohio State University, Columbus, OH 44321 (United States); Shade, Paul A. [Air Force Research Laboratory, Materials & Manufacturing Directorate, AFRL/RXCM, Wright-Patterson AFB, Dayton, OH 45433 (United States); Fraser, Hamish L. [Center for Accelerated Maturation of Materials, The Ohio State University, Columbus, OH 44321 (United States); Uchic, Michael D. [Air Force Research Laboratory, Materials & Manufacturing Directorate, AFRL/RXCM, Wright-Patterson AFB, Dayton, OH 45433 (United States); Mills, Michael J. [Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 44321 (United States)


    Focused ion beam (FIB) based serial sectioning was utilized to characterize the morphology of two high angle grain boundaries (HAGB) in a nickel based superalloy, one that experienced grain boundary sliding (GBS) and the other experienced strain accumulation, during elevated temperature constant stress loading conditions. A custom script was utilized to serial section and collect ion-induced secondary electron images from the FIB-SEM system. The MATLAB based MIPAR{sup TM} software was utilized to align, segment and reconstruct 3D volumes from the sectioned images. Analysis of the 3D data indicates that the HAGB that exhibited GBS had microscale curvature that was planar in nature, and local serrations on the order of ±150 nm. In contrast, the HAGB that exhibited strain accumulation was not planar and had local serrations an order of magnitude greater than the other grain boundary. It is hypothesized that the serrations and the local grain boundary network are key factors in determining which grain boundaries experience GBS during creep deformation.

  6. Paleo-earthquake signatures from the South Wagad Fault (SWF), Wagad Island, Kachchh, Gujarat, western India: A potential seismic hazard (United States)

    Malik, Javed N.; Gadhavi, Mahendrasinh S.; Kothyari, Girish Ch; Satuluri, Sravanthi


    In last 500 years, Kachchh experienced several large magnitude earthquakes (6.0 ≥ M ≤ 7.8), however, not all accompanied surface rupture. The 1819 Allah Bund earthquake (Mw7.8) accompanied surface rupture, whereas, the 2001 Bhuj event (Mw7.6) occurred at a depth of 23 km on E-W striking south dipping thrust fault remained blind. Discontinuities between the denser-brittle basement (?) and overlying ductile-softer Mesozoic-Tertiary-Quaternary succession resulted in a different geometry of faulting. Normal faults associated with rift were reactivated as reverse faults during inversion tectonics, propagated in sedimentary succession and arrested. Thrust-ramps developed along the discontinuities accompanied surface ruptures. Folded structures along the South Wagad Fault (SWF) - an active thrust, exhibits lateral-propagation of fold segments and linkage, suggestive of fault-related-fold growth. Paleoseismic investigations revealed evidence of at least three paleo-earthquakes. Event I occurred before BCE 5080; Event II between BCE 4820 and 2320, and was probably responsible for a massive damage at Dholavira - Harappan site. Event III was between BCE 1230 and 04, most likely caused severe damage to Dholavira. Archaeo-seismological Quality Factor (AQF) of 0.5 suggests that the Dholavira is vulnerable to earthquakes from nearby active faults. With 1500-2000 yr of recurrence interval, occurrence of a large magnitude earthquake on SWF cannot be ruled out.

  7. A Late Quaternary shortening rate for the frontal thrust of the Andean Precordillera north of Mendoza (United States)

    Schmidt, S.; Kuhlmann, J.; Hetzel, R.; Mingorance, F.; Ramos, V. A.


    Although large historical earthquakes occurred in the Andean back-arc region between 28° and 34°S - for instance Mendoza was destroyed by an earthquake of magnitude MS = 7.0 in 1861 - the slip rates of active faults remain unknown. We report a slip rate for the 50-km-long Las Penas thrust, which constitutes the frontal thrust of the Precordillera. In its southern part, a well preserved fluvial terrace along La Escondida Creek (Costa et al., 2000) is displaced vertically by 10.6 ± 0.7 m as documented by several fault scarp profiles. Apart from radiocarbon dating of plant remnants, three different approaches for 10Be exposure dating have been applied to constrain the age of the terrace. Amalgamated sandstone pebbles (corrected for an inherited 10Be component using similar pebbles from the active creek) and a depth profile obtained from four sand samples yield 10Be exposure ages of 12.2 ± 1.5 and 11.3 ± 2.0 kyr, respectively. Both ages are in excellent agreement with the 14C age of 12.61 ± 0.20 cal kyr BP. In contrast, 10Be ages of five sandstone boulders vary significantly and exceed the age of the terrace by 10 to 70 kyr, which demonstrates that the widely used assumption of a negligible inherited component is not valid here. The age of the river terrace combined with the vertical fault offset yields an uplift rate of ~0.8 mm/yr for the Las Penas thrust. Combined with the fault dip of 25°, we determine a Late Quaternary horizontal shortening rate of ~1.8 mm/yr, which is about 40% of the GPS derived shortening rate of 4.5 ± 1.7 mm/yr in the back-arc region of the Andes (Brooks et al., 2003). References Brooks, B.A., Bevis, M., Smalley, R., Kendrick, E., Manceda, R., Lauria, E., Maturana, R. & Araujo, M. (2003): Crustal motion in the Southern Andes (26° - 36°S): Do the Andes behave like a microplate? Geochem. Geophys. Geosyst., 4 (10), pp. 14, 1085, doi 10.1029/2003GC000505. Costa, C.H., Gardini, C.E., Diederix, H., Cortés, J.M. (2000): The Andean orogenic

  8. Origin and role of fluids involved in the seismic cycle of extensional faults in carbonate rocks (United States)

    Smeraglia, Luca; Berra, Fabrizio; Billi, Andrea; Boschi, Chiara; Carminati, Eugenio; Doglioni, Carlo


    We examine the potentially-seismic right-lateral transtensional-extensional Tre Monti Fault (central Apennines, Italy) with structural and geochemical methods and develop a conceptual evolutionary model of extensional faulting with fluid involvement in shallow (≤3 km depth) faults in carbonate rocks. In the analysed fault zone, multiscale fault rock structures include injection veins, fluidized ultracataclasite layers, and crackle breccias, suggesting that the fault slipped seismically. We reconstructed the relative chronology of these structures through cross-cutting relationship and cathodoluminescence analyses. We then used C- and O-isotope data from different generations of fault-related mineralizations to show a shift from connate (marine-derived) to meteoric fluid circulation during exhumation from 3 to ≤1 km depths and concurrent fluid cooling from ∼68 to hydrological system, where prevalently connate fluids circulated within the fault zone at temperatures between 60° and 75 °C. During fault zone exhumation, at depths ≤1 km and temperatures hydrological circulation became open and meteoric-derived fluids progressively infiltrated and circulated within the fault zone. The role of these fluids during syn-exhumation seismic cycles of the Tre Monti Fault has been substantially passive along the whole fault zone, the fluids being passively redistributed at hydrostatic pressure following co-seismic dilatancy. Only the principal fault has been characterized, locally and transiently, by fluid overpressures. The presence of low-permeability clayey layers in the sedimentary sequence contributed to control the type of fluids infiltrating into the fault zone and possibly their transient overpressures. These results can foster the comprehension of seismic faulting at shallow depths in carbonate rocks of other fold-thrust belts involved in post-collisional seismogenic extensional tectonics.

  9. The 2009MW 6.1 L'Aquila fault system imaged by 64k earthquake locations (United States)

    Valoroso, Luisa


    On April 6 2009, a MW 6.1 normal-faulting earthquake struck the axial area of the Abruzzo region in central Italy. We investigate the complex architecture and mechanics of the activated fault system by using 64k high-resolution foreshock and aftershock locations. The fault system is composed by two major SW dipping segments forming an en-echelon NW trending system about 50km long: the high-angle L'Aquila fault and the listric Campotosto fault, located in the first 10km depth. From the beginning of 2009, foreshocks activated the deepest portion of the mainshock fault. A week before the MW 6.1 event, the largest (MW 4.0) foreshock triggered seismicity migration along a minor off-fault segment. Seismicity jumped back to the main plane a few hours before the mainshock. High-precision locations allowed us to peer into the fault zone showing complex geological structures from the metre to the kilometre scale, analogous to those observed by field studies and seismic profiles. Also, we were able to investigate important aspects of earthquakes nucleation and propagation through the upper crust in carbonate-bearing rocks such as: the role of fluids in normal-faulting earthquakes; how crustal faults terminate at depths; the key role of fault zone structure in the earthquake rupture evolution processes.

  10. Active fold-thrust belts in the foreland of eastern Tibet, the Longquan and Xiongpu anticlines in Sichuan, China (United States)

    Lee, Jian-Cheng; Chan, Yu-Chang; Lu, Chia-Yu; Chen, Chih-Tung; Chu, Hao-Tsu; Liu, Yuiping; Li, Jianzhong


    The 2008 M7.9 Wenchuan earthquake ruptured from the Longmenshan fault system, which is the frontal thrust system in eastern Tibet. Further east toward the foreland area in the Sichuan basin, it sits two anticlinal structures, the Longquan and Xiongpu anticlines, which trends sub-parallel to the Longmenshan range with a distance of about 70-100 km to the mountain front. It is widely considered that these two anticlinal features are attributed to propagation of the eastward extrusion of the eastern Tibetan plateau, similar to the stress system the Wenchuan earthquake. In this study, we carried out field investigations on these two active anticlinal structures in order to characterize the bulk deformation of the anticlines. We also conducted fracture analysis and fault-slip data analysis, in an attempt to characterize the fracture developments of the rock and the paleostress states related to the faulting events associated growth of the anticlines. We thus constructed a series of geological cross sections along these two anticlines. Our results show that the Longquan anticline is characterized by pop up structure with a dominant west-vergent thrust (i.e., backthrust) on the western limb. On the other hand to the eastern limb, an east-vergent thrust only well developed in the middle part of the anticline and die out toward the north and the south. For the Xiongpu anticline, it is characterized by a pre-dominant west-vergent backthrust system without developing an east-vergent thrust. A strike-slip fault and a series of N-S-trending pop-up thrusts cut across the Xiongpu anticline indicate a rather complex stress system with two dominant compression directions, NW-SE and E-W, subsequently or alternatively affected the area. Finally, the fracture analysis revealed that 2-3 pre-dominant bedding-perpendicular fracture sets are commonly developed in the massive sandstone layers. Most of them seemingly are of the characteristics of the mode I open joint, without clear

  11. The Suckling Hills Fault, Kayak Island Zone, and accretion of the Yakutat microplate, Alaska (United States)

    Chapman, James B.; Worthington, Lindsay L.; Pavlis, Terry L.; Bruhn, Ronald L.; Gulick, Sean P.


    The Suckling Hills and Kayak Island are isolated mountain blocks located along strike from each other within the foreland of the St. Elias orogen in southern Alaska. These blocks preserve an erosional surface that was deformed by slip on northwest-dipping reverse faults in the Pleistocene. We suggest that the Suckling Hills Fault and Kayak Island Zone form a segmented fault network that links with the Bering Glacier structure to the north. This fault network separates the central Yakataga fold and thrust belt from complex, multiply deformed structures in the western syntaxis. Ongoing accretion of the Yakutat microplate to North America results in translation of structures of the fold and thrust belt into the western syntaxis. The composite Suckling Hills Fault, Kayak Island Zone, and Bering Glacier structure may have formed because the older structures of the fold and thrust belt were unfavorably oriented within the western syntaxis region. This pattern of deformation provides a template for understanding the complex deformation within the core of the western syntaxis and predicts refolding and straightening of the western syntaxis margin with continued accretion. This study provides an analog for structural overprinting and changing deformation patterns through time in orogenic corners.

  12. The seismogenic fault of the 2010 Efpalion moderate-size seismic sequence (western Corinth gulf, Central Greece) (United States)

    Tranos, M. D.


    The 2010 Efpalion seismic sequence with two main moderate earthquake events occurred in the northwestern part of the Corinth Gulf (Central Greece)—a region that has been intensely stretched due to an on-going N-S extensional stress regime. Previous studies assign these two events to activations of (a) two faults dipping to the north with low angles; (b) two faults dipping at high angles, the first dipping to the south, and the second to the north; and (c) two faults dipping at high angles, but the first dips to the north, and the second to the south. The recently proposed TR method for focal mechanisms that identifies the seismogenic fault of an earthquake sequence is applied on the available focal mechanisms of the sequence, and its results are interrelated with the geology of the region, and previous contradictory interpretations. The focal mechanisms constructed with MT inversion define a steep north-dipping normal fault, whereas those constructed with first motions of P-waves define the activation of two adjoining faults that dip with high angles to the SSE and south, respectively, and which are characterized by strain (slip) compatibility. The latter option fits well with the geology of the region that is dominated by a SE to S-dipping horse-tail splay fault zone which exists at the eastern tip of the Nafpaktos Mountain Front. The application of the TR method reveals that the usage itself of different methods for the construction of the focal mechanisms complicates the problem of correctly identifying the seismogenic fault.

  13. Fluid-rock interactions related to metamorphic reducing fluid flow in meta-sediments: example of the Pic-de-Port-Vieux thrust (Pyrenees, Spain) (United States)

    Trincal, Vincent; Buatier, Martine; Charpentier, Delphine; Lacroix, Brice; Lanari, Pierre; Labaume, Pierre; Lahfid, Abdeltif; Vennemann, Torsten


    In orogens, shortening is mainly accommodated by thrusts, which constitute preferential zones for fluid-rock interactions. Fluid flow, mass transfer, and mineralogical reactions taking place along thrusts have been intensely investigated, especially in sedimentary basins for petroleum and uranium research. This study combines petrological investigations, mineralogical quantifications, and geochemical characterizations with a wide range of analytical tools with the aim of defining the fluid properties (nature, origin, temperature, and redox) and fluid-host rock interactions (mass transfers, recrystallization mechanisms, and newly formed synkinematic mineralization) in the Pic-de-Port-Vieux thrust fault zone (Pyrenees, Spain). We demonstrate that two geochemically contrasted rocks have been transformed by fluid flow under low-grade metamorphism conditions during thrusting. The hanging-wall Triassic red pelite was locally bleached, while the footwall Cretaceous dolomitic limestone was mylonitized. The results suggest that thrusting was accompanied by a dynamic calcite recrystallization in the dolomitic limestone as well as by leaching of iron via destabilization of iron oxides and phyllosilicate crystallization in the pelite. Geochemical and physical changes highlighted in this study have strong implications on the understanding of the thrust behavior (tectonic and hydraulic), and improve our knowledge of fluid-rock interactions in open fluid systems in the crust.

  14. High-power, null-type, inverted pendulum thrust stand. (United States)

    Xu, Kunning G; Walker, Mitchell L R


    This article presents the theory and operation of a null-type, inverted pendulum thrust stand. The thrust stand design supports thrusters having a total mass up to 250 kg and measures thrust over a range of 1 mN to 5 N. The design uses a conventional inverted pendulum to increase sensitivity, coupled with a null-type feature to eliminate thrust alignment error due to deflection of thrust. The thrust stand position serves as the input to the null-circuit feedback control system and the output is the current to an electromagnetic actuator. Mechanical oscillations are actively damped with an electromagnetic damper. A closed-loop inclination system levels the stand while an active cooling system minimizes thermal effects. The thrust stand incorporates an in situ calibration rig. The thrust of a 3.4 kW Hall thruster is measured for thrust levels up to 230 mN. The uncertainty of the thrust measurements in this experiment is +/-0.6%, determined by examination of the hysteresis, drift of the zero offset and calibration slope variation.

  15. Continental deformation accommodated by non-rigid passive bookshelf faulting: An example from the Cenozoic tectonic development of northern Tibet (United States)

    Zuza, Andrew V.; Yin, An


    Collision-induced continental deformation commonly involves complex interactions between strike-slip faulting and off-fault deformation, yet this relationship has rarely been quantified. In northern Tibet, Cenozoic deformation is expressed by the development of the > 1000-km-long east-striking left-slip Kunlun, Qinling, and Haiyuan faults. Each have a maximum slip in the central fault segment exceeding 10s to ~ 100 km but a much smaller slip magnitude (~rigid-body motion and flow-like distributed deformation end-member models for continental tectonics. Here we propose a non-rigid bookshelf-fault model for the Cenozoic tectonic development of northern Tibet. Our model, quantitatively relating discrete left-slip faulting to distributed off-fault deformation during regional clockwise rotation, explains several puzzling features, including the: (1) clockwise rotation of east-striking left-slip faults against the northeast-striking left-slip Altyn Tagh fault along the northwestern margin of the Tibetan Plateau, (2) alternating fault-parallel extension and shortening in the off-fault regions, and (3) eastward-tapering map-view geometries of the Qimen Tagh, Qaidam, and Qilian Shan thrust belts that link with the three major left-slip faults in northern Tibet. We refer to this specific non-rigid bookshelf-fault system as a passive bookshelf-fault system because the rotating bookshelf panels are detached from the rigid bounding domains. As a consequence, the wallrock of the strike-slip faults deforms to accommodate both the clockwise rotation of the left-slip faults and off-fault strain that arises at the fault ends. An important implication of our model is that the style and magnitude of Cenozoic deformation in northern Tibet vary considerably in the east-west direction. Thus, any single north-south cross section and its kinematic reconstruction through the region do not properly quantify the complex deformational processes of plateau formation.

  16. Segmentation and step-overs along strike-slip fault systems in the inner California borderlands: Implications for fault architecture and basin formation (United States)

    Maloney, J. M.; Driscoll, N. W.; Kent, G.; Brothers, D. S.


    Reprocessed, industry multichannel seismic reflection data and high resolution Chirp data were examined to characterize the geometry and recency of faulting in the inner California borderlands (ICB). Two end-member models have been proposed to explain the deformation observed in the ICB. One model invokes reactivation of detachment faults by the Oceanside Blind Thrust (OBT) to explain the deformation and margin architecture (e.g., San Mateo/Carlsbad Trend). In contrast, the other model explains the deformation by step-overs along the strike-slip fault systems. Several observations in both the southern and central portions of the ICB are more consistent with the step-over model than the regional blind thrust model. For example, regions in the ICB exhibit both tensional and compressional structures across the margin, which are more readily explained by the strike-slip model. Localized compression and extension occurs as predicted at fault bends and step-overs. Furthermore, strike slip fault systems that bound extensional regions (i.e., San Diego Bay) exhibit localized normal deformation as they approach the releasing step-overs. In addition, onlapping turbidites reveal that the deformation becomes younger toward the east, an observation not consistent with a westward verging blind thrust fault system. Finally, rotational deformation previously attributed to a splay off the OBT instead appears to be a southward transported gravitational slide deposit. In summary, the nested high-resolution Chirp and MCS data have provided new constraints on ICB tectonic deformation and margin architecture, which are best explained by step-overs on strike slip fault systems.

  17. Which Fault Segments Ruptured in the 2008 Wenchuan Earthquake and Which Did Not? New Evidence from Near‐Fault 3D Surface Displacements Derived from SAR Image Offsets

    KAUST Repository

    Feng, Guangcai


    The 2008 Mw 7.9 Wenchuan earthquake ruptured a complex thrust‐faulting system at the eastern edge of the Tibetan plateau and west of Sichuan basin. Though the earthquake has been extensively studied, several details about the earthquake, such as which fault segments were activated in the earthquake, are still not clear. This is in part due to difficult field access to the fault zone and in part due to limited near‐fault observations in Interferometric Synthetic Aperture Radar (InSAR) observations because of decorrelation. In this study, we address this problem by estimating SAR image offsets that provide near‐fault ground displacement information and exhibit clear displacement discontinuities across activated fault segments. We begin by reanalyzing the coseismic InSAR observations of the earthquake and then mostly eliminate the strong ionospheric signals that were plaguing previous studies by using additional postevent images. We also estimate the SAR image offsets and use their results to retrieve the full 3D coseismic surface displacement field. The coseismic deformation from the InSAR and image‐offset measurements are compared with both Global Positioning System and field observations. The results indicate that our observations provide significantly better information than previous InSAR studies that were affected by ionospheric disturbances. We use the results to present details of the surface‐faulting offsets along the Beichuan fault from the southwest to the northeast and find that there is an obvious right‐lateral strike‐slip component (as well as thrust faulting) along the southern Beichuan fault (in Yingxiu County), which was strongly underestimated in earlier studies. Based on the results, we provide new evidence to show that the Qingchuan fault was not ruptured in the 2008 Wenchuan earthquake, a topic debated in field observation studies, but show instead that surface faulting occurred on a northward extension of the Beichuan fault during

  18. An experimental study of an airfoil with a bio-inspired leading edge device at high angles of attack (United States)

    Mandadzhiev, Boris A.; Lynch, Michael K.; Chamorro, Leonardo P.; Wissa, Aimy A.


    Robust and predictable aerodynamic performance of unmanned aerial vehicles at the limits of their design envelope is critical for safety and mission adaptability. Deployable aerodynamic surfaces from the wing leading or trailing edges are often used to extend the aerodynamic envelope (e.g. slats and flaps). Birds have also evolved feathers at the leading edge (LE) of their wings, known as the alula, which enables them to perform high angles of attack maneuvers. In this study, a series of wind tunnel experiments are performed to quantify the effect of various deployment parameters of an alula-like LE device on the aerodynamic performance of a cambered airfoil (S1223) at stall and post stall conditions. The alula relative angle of attack, measured from the mean chord of the airfoil, is varied to modulate tip-vortex strength, while the alula deflection angle is varied to modulate the distance between the tip vortex and the wing surface. Integrated lift force measurements were collected at various alula-inspired device configurations. The effect of the alula-inspired device on the boundary layer velocity profile and turbulence intensity were investigated through hot-wire anemometer measurements. Results show that as alula deflection angle increases, the lift coefficient also increase especially at lower alula relative angles of attack. Moreover, at post stall wing angles of attack, the wake velocity deficit is reduced in the presence of alula device, confirming the mitigation of the wing adverse pressure gradient. The results are in strong agreement with measurements taken on bird wings showing delayed flow reversal and extended range of operational angles of attack. An engineered alula-inspired device has the potential to improve mission adaptability in small unmanned air vehicles during low Reynolds number flight.

  19. Jaw thrust can deteriorate upper airway patency. (United States)

    von Ungern-Sternberg, B S; Erb, T O; Frei, F J


    Upper airway obstruction is a frequent problem in spontaneously breathing children undergoing anesthesia or sedation procedures. Failure to maintain a patent airway can rapidly result in severe hypoxemia, bradycardia, or asystole, as the oxygen demand of children is high and oxygen reserve is low. We present two children with cervical masses in whom upper airway obstruction exaggerated while the jaw thrust maneuver was applied during induction of anesthesia. This deterioration in airway patency was probably caused by medial displacement of the lateral tumorous tissues which narrowed the pharyngeal airway.

  20. Optimum Staging with Varying Thrust Attitude Angle

    Directory of Open Access Journals (Sweden)

    T. N. Srivastava


    Full Text Available Optimum staging programme for step rockets of arbitrary number of stages having different specific impulses and mass fractions with stages is derived, the optimization criterion being minimum take-off weight for a desired burntout velocity at an assigned altitude. Variation of thrust attitude angle from stage to stage and effects of gravity factor are taken into account. Analysis is performed for a degenerate problem obtained by relaxing the altitude constraint and it has been shown that problems of Weisbord, Subotowicz, Hall & Zambelli and Malina & Summerfield are the particular cases of the degenerate problem.

  1. Structure and kinematics of the Sumatran Fault System in North Sumatra (Indonesia) (United States)

    Fernández-Blanco, David; Philippon, Melody; von Hagke, Christoph


    Lithospheric-scale faults related to oblique subduction are responsible for some of the most hazardous earthquakes reported worldwide. The mega-thrust in the Sunda sector of the Sumatran oblique subduction has been intensively studied, especially after the infamous 2004 Mw 9.1 earthquake, but its onshore kinematic complement within the Sumatran subduction, the transform Sumatran Fault System, has received considerably less attention. In this paper, we apply a combination of analysis of Digital Elevation Models (ASTER GDEM) and field evidence to resolve the kinematics of the leading edge of deformation of the northern sector of the Sumatran Fault System. To this end, we mapped the northernmost tip of Sumatra, including the islands to the northwest, between 4.5°N and 6°N. Here, major topographic highs are related to different faults. Using field evidence and our GDEM structural mapping, we can show that in the area where the fault bifurcates into two fault strands, two independent kinematic regimes evolve, both consistent with the large-scale framework of the Sumatran Fault System. Whereas the eastern branch is a classic Riedel system, the western branch features a fold-and-thrust belt. The latter contractional feature accommodated significant amounts (c. 20%) of shortening of the system in the study area. Our field observations of the tip of the NSFS match a strain pattern with a western contractional domain (Pulau Weh thrust splay) and an eastern extensional domain (Pulau Aceh Riedel system), which are together characteristic of the tip of a propagating strike-slip fault, from a mechanical viewpoint. For the first time, we describe the strain partitioning resulting from the propagation of the NSFS in Sumatra mainland. Our study helps understanding complex kinematics of an evolving strike-slip system, and stresses the importance of field studies in addition to remote sensing and geophysical studies.

  2. Active tectonics and rheology of slow-moving thrusts in the Tibetan foreland of peninsular India (United States)

    Copley, Alex; Mitra, Supriyo; Sloan, Alastair; Gaonkar, Sharad; Avouac, Jean-Philippe; Hollingsworth, James


    Peninsular India is cut by active thrust faults that break in earthquakes in response to the compressive force exerted between India and the Tibetan Plateau. The rate of deformation is low, with 2 +/- 1 mm/yr of shortening being accommodated over the entire N-S extent of the Indian sub-continent. However, the large seismogenic thickness in the region (40-50 km), and the long faults, mean that the rare earthquakes that do occur can have magnitudes up to at least 8. This contribution describes studies of two large Indian earthquakes, and their rheological and hazard implications, using a range of techniques. First, the Mw 7.6 Bhuj (Gujarat) earthquake of 2001 is examined using a combination of seismology, InSAR, and levelling data. A slip model for the earthquake will be presented, which allows the material properties of the fault plane to be examined. Second, a Holocene-age earthquake rupture from central India will be discussed. Geomorphic analysis of the scarps produced by the event suggest a magnitude of 7.6 - 8.4. Both of these earthquakes had unusually large stress-drops, amongst the largest recorded for shallow earthquakes. The information provided by these two events will be combined with calculations for the total compressive force being transmitted through the Indian peninsular in order to suggest that the faults are characterised by a low coefficient of friction (approximately 0.1), and that the stress-drops in the earthquakes are close to complete. In turn, these results imply that the majority of the force being transmitted through the Indian plate is supported by the brittle crust. Finally, the along-strike continuation of the faults will be described, with implications for hazard assessment and material properties throughout India.

  3. Effect of Cohesion Uncertainty of Granular Materials on the Kinematics of Scaled Models of Fold-and-Thrust Belts (United States)

    Nilfouroushan, F.; Pysklywec, R.; Cruden, S.


    Cohesionless or very low cohesion granular materials are widely used in analogue/physical models to simulate brittle rocks in the upper crust. Selection of materials with appropriate cohesion values in such models is important for the simulation of the dynamics of brittle rock deformation in nature. Uncertainties in the magnitude of cohesion (due to measurement errors, extrapolations at low normal stresses, or model setup) in laboratory experiments can possibly result in misinterpretation of the styles and mechanisms of deformation in natural fold-and thrust belts. We ran a series of 2-D numerical models to investigate systematically the effect of cohesion uncertainties on the evolution of models of fold-and-thrust belts. The analyses employ SOPALE, a geodynamic code based on the arbitrary Lagrangian-Eulerian (ALE) finite element method. Similar to analogue models, the material properties of sand and transparent silicone (PDMS) are used to simulate brittle and viscous behaviors of upper crustal rocks. The suite of scaled brittle and brittle-viscous numerical experiments have the same initial geometry but the cohesion value of the brittle layers is increased systematically from 0 to 100 Pa. The stress and strain distribution in different sets of models with different cohesion values are compared and analyzed. The kinematics and geometry of thrust wedges including the location and number of foreland- and hinterland- verging thrust faults, pop-up structures, tapers and topography are also explored and their sensitivity to cohesion value is discussed.

  4. The January 2010 Haiti mainshock-aftershock sequence: Positive feedback between faults in strain-partitioned transpression (United States)

    Seeber, L.; Waldhauser, F.; Diehl, T.; Hjorleifsdottir, V.; Nettles, M.


    The Caribbean and North American plates converge ENE across the broad plate boundary in western Hispaniola. This motion is partitioned between a pair of parallel sinistral ~E-W striking transform faults and a set of NW-SE striking thrust-folds. The January 2010 M7.0 earthquake sequence in Haiti activated both these structural elements, shifting from mostly sinistral during the mainshock to pure thrusting in the aftershocks. Teleseismic waveforms of the mainshock point to a rupture on a WSW-striking segment of the Enriquillo-Plaintain Garden Fault (EPGF), dipping steeply north and mostly sinistral with a reverse component. Structural and coseismic surface deformation and lack of surface rupture, have lead to different interpretations. Which faults were activated in the sequence remains controversial. We greatly improved hypocenter resolution for the mainshock and 56 aftershocks (Mw 4.2-5.9) that occurred within two months by applying a teleseismic double-difference algorithm to the NEIC phase arrival times. Relative location uncertainties at the 90% confidence level are, on average, 1.9 km laterally and 1.3 km vertically. Aftershocks form two clusters, the smaller one near and east of the mainshock epicenter and the larger one about 30 km to the west and beyond. The gap between them is approximately the inferred main-rupture length. Focal mechanisms in both clusters exhibit nearly pure thrusting with planes striking from W to NW, except for one similar to and near the mainshock. Absolute location uncertainties, however, remain large so that the correlation between hypocenters and faults is interpretative. We place the relocated epicentres so that the two clusters correlate with restraining portions of the EPGF and the mainshock epicenter is on the fault trace, near the NEIC epicenter and well within the range of possible absolute locations. In agreement with more recent earthquake locations from local seismic stations and with the expected placement of thrust

  5. Seismic image of the Ivanhoe Lake Fault Zone in the Kapuskasing Uplift of the Canadian Shield (United States)

    Wu, Jianjun; Mereu, Robert F.; Percival, John A.


    The Kapuskasing uplift, located in the central Canadian shield, represents an oblique exposure of the Archean middle to lower crust. The Ivanhoe Lake fault zone, believed to be the basal thrust carrying the high-grade rocks of the Kapuskasing zone over the low-grade Abitibi greenstone belt, holds the key to understanding the nature and evolution of the Kapuskasing uplift. Despite numerous geological and geophysical studies, including LITHOPROBE deep seismic reflection profiles, and because of very limited bedrock exposure in the area, the shallow structure of the Ivanhoe Lake fault zone remains obscure. Here we present results obtained by reprocessing data from a LITHOPROBE seismic reflection profile across the fault zone. For the first time, the Ivanhoe Lake fault zone is clearly imaged on the seismic section as a series of west-dipping reflectors with an average dip of 20°, which can be traced to the surface. The results support the conclusion that fault zones form good reflectors.

  6. Landforms along transverse faults parallel to axial zone of folded mountain front, north-eastern Kumaun Sub-Himalaya, India (United States)

    Luirei, Khayingshing; Bhakuni, S. S.; Negi, Sanjay S.


    The shape of the frontal part of the Himalaya around the north-eastern corner of the Kumaun Sub-Himalaya, along the Kali River valley, is defined by folded hanging wall rocks of the Himalayan Frontal Thrust (HFT). Two parallel faults (Kalaunia and Tanakpur faults) trace along the axial zone of the folded HFT. Between these faults, the hinge zone of this transverse fold is relatively straight and along these faults, the beds abruptly change their attitudes and their widths are tectonically attenuated across two hinge lines of fold. The area is constituted of various surfaces of coalescing fans and terraces. Fans comprise predominantly of sandstone clasts laid down by the steep-gradient streams originating from the Siwalik range. The alluvial fans are characterised by compound and superimposed fans with high relief, which are generated by the tectonic activities associated with the thrusting along the HFT. The truncated fan along the HFT has formed a 100 m high-escarpment running E-W for ˜5 km. Quaternary terrace deposits suggest two phases of tectonic uplift in the basal part of the hanging wall block of the HFT dipping towards the north. The first phase is represented by tilting of the terrace sediments by ˜30 ∘ towards the NW; while the second phase is evident from deformed structures in the terrace deposit comprising mainly of reverse faults, fault propagation folds, convolute laminations, flower structures and back thrust faults. The second phase produced ˜1.0 m offset of stratification of the terrace along a thrust fault. Tectonic escarpments are recognised across the splay thrust near south of the HFT trace. The south facing hill slopes exhibit numerous landslides along active channels incising the hanging wall rocks of the HFT. The study area shows weak seismicity. The major Moradabad Fault crosses near the study area. This transverse fault may have suppressed the seismicity in the Tanakpur area, and the movement along the Moradabad and Kasganj

  7. Landforms along transverse faults parallel to axial zone of folded mountain front, north-eastern Kumaun Sub-Himalaya, India

    Indian Academy of Sciences (India)

    Khayingshing Luirei; S S Bhakuni; Sanjay S Negi


    The shape of the frontal part of the Himalaya around the north-eastern corner of the Kumaun Sub-Himalaya, along the Kali River valley, is defined by folded hanging wall rocks of the Himalayan Frontal Thrust (HFT). Two parallel faults (Kalaunia and Tanakpur faults) trace along the axial zone of the folded HFT. Between these faults, the hinge zone of this transverse fold is relatively straight and along these faults, the beds abruptly change their attitudes and their widths are tectonically attenuated across two hinge lines of fold. The area is constituted of various surfaces of coalescing fans and terraces. Fans comprise predominantly of sandstone clasts laid down by the steep-gradient streams originating from the Siwalik range. The alluvial fans are characterised by compound and superimposed fans with high relief, which are generated by the tectonic activities associated with the thrusting along the HFT. The truncated fan along the HFT has formed a 100 m high-escarpment running E–W for ~5 km. Quaternary terrace deposits suggest two phases of tectonic uplift in the basal part of the hanging wall block of the HFT dipping towards the north. The first phase is represented by tilting of the terrace sediments by ~30° towards the NW; while the second phase is evident from deformed structures in the terrace deposit comprising mainly of reverse faults, fault propagation folds, convolute laminations, flower structures and back thrust faults. The second phase produced ~1.0 m offset of stratification of the terrace along a thrust fault. Tectonic escarpments are recognised across the splay thrust near south of the HFT trace. The south facing hill slopes exhibit numerous landslides along active channels incising the hanging wall rocks of the HFT. The study area shows weak seismicity. The major Moradabad Fault crosses near the study area. This transverse fault may have suppressed the seismicity in the Tanakpur area, and the movement along the Moradabad and Kasganj

  8. Stress Transfer Processes during Great Plate Boundary Thrusting Events: A Study from the Andaman and Nicobar Segments (United States)

    Andrade, V.; Rajendran, K.


    The response of subduction zones to large earthquakes varies along their strike, both during the interseismic and post-seismic periods. The December 26, 2004 earthquake nucleated at 3° N latitude and its rupture propagated northward, along the Andaman-Sumatra subduction zone, terminating at 15°N. Rupture speed was estimated at about 2.0 km per second in the northern part under the Andaman region and 2.5 - 2.7 km per second under southern Nicobar and North Sumatra. We have examined the pre and post-2004 seismicity to understand the stress transfer processes within the subducting plate, in the Andaman (10° - 15° N ) and Nicobar (5° - 10° N) segments. The seismicity pattern in these segments shows distinctive characteristics associated with the outer rise, accretionary prism and the spreading ridge, all of which are relatively better developed in the Andaman segment. The Ninety East ridge and the Sumatra Fault System are significant tectonic features in the Nicobar segment. The pre-2004 seismicity in both these segments conform to the steady-state conditions wherein large earthquakes are fewer and compressive stresses dominate along the plate interface. Among the pre-2004 great earthquakes are the 1881 Nicobar and 1941 Andaman events. The former is considered to be a shallow thrust event that generated a small tsunami. Studies in other subduction zones suggest that large outer-rise tensional events follow great plate boundary breaking earthquakes due to the the up-dip transfer of stresses within the subducting plate. The seismicity of the Andaman segment (1977-2004) concurs with the steady-state stress conditions where earthquakes occur dominantly by thrust faulting. The post-2004 seismicity shows up-dip migration along the plate interface, with dominance of shallow normal faulting, including a few outer rise events and some deeper (> 100 km) strike-slip faulting events within the subducting plate. The September 13, 2002, Mw 6.5 thrust faulting earthquake at

  9. Reply to comments by Ahmad et al. on: Shah, A. A., 2013. Earthquake geology of Kashmir Basin and its implications for future large earthquakes International Journal of Earth Sciences DOI:10.1007/s00531-013-0874-8 and on Shah, A. A., 2015. Kashmir Basin Fault and its tectonic significance in NW Himalaya, Jammu and Kashmir, India, International Journal of Earth Sciences DOI:10.1007/s00531-015-1183-1 (United States)

    Shah, A. A.


    Shah (Int J Earth Sci 102:1957-1966, 2013) mapped major unknown faults and fault segments in Kashmir basin using geomorphological techniques. The major trace of out-of-sequence thrust fault was named as Kashmir basin fault (KBF) because it runs through the middle of Kashmir basin, and the active movement on it has backtilted and uplifted most of the basin. Ahmad et al. (Int J Earth Sci, 2015) have disputed the existence of KBF and maintained that faults identified by Shah (Int J Earth Sci 102:1957-1966, 2013) were already mapped as inferred faults by earlier workers. The early works, however, show a major normal fault, or a minor out-of-sequence reverse fault, and none have shown a major thrust fault.

  10. Active Faults of the Northwest Himalaya: Pattern, Rate, and Timing of Surface Rupturing Earthquakes (United States)

    Yule, J.; Madden, C.; Gavillot, Y.; Hebeler, A.; Meigs, A.; Hussein, A.; Malik, M.; Bhat, M.; Kausar, A.; Ramzan, S.; Sayab, M.; Yeats, R. S.


    The 2005 Kashmir earthquake (Mw 7.6) is the only Himalayan earthquake to rupture the surface since the 15th to 16th century A.D. when >Mw 8.5 earthquakes ruptured the Himalayan Frontal thrust (HFT) in the central Himalaya. Megathrust-type earthquakes like these seem to relieve a majority of the accumulated interseismic strain and concentrate permanent strain across a narrow width at the deformation front (faults within the orogen appear to accommodate little strain). The 2005 within-plate rupture in Kashmir may be a clue that a different seismotectonic model applies to the northwest Himalaya where active deformation occurs on faults distributed more than 120 km across the orogen. An asymmetric anticline marks the deformation front in Kashmir where the HFT is inferred to be blind, though ~20 m-high escarpments suggest that unrecognized thrust fault(s) may reach the surface locally. Folded river terraces and dip data also suggest that this frontal fold contains a SW-dipping back thrust. In Pakistan the Salt Range thrust system (SRT) defines the thrust front. New mapping and preliminary OSL dates from deformed Holocene sediments exposed along the westernmost SRT reveal that the fault slips at 1-7 mm/yr and last ruptured within the last several thousand years. Within the orogenic wedge to the north of the deformation front, active shortening occurs along a system of surface-rupturing reverse faults, extending from the Balakot-Bagh fault (source of the 2005 Kashmir earthquake) to the Reasi fault (RF) in Indian Kashmir to the southeast. One strand of the RF displaces a 350 m-high, 80 ± 6 ka (preliminary OSL age) fluvial terrace, yielding a minimum shortening rate of 3-5 mm/yr. Trenches excavated across the RF nearby reveal a distinct angular unconformity that likely formed during a surface rupture ~4500 yrs BP. Farther north, three northeast-dipping reverse faults cut Quaternary terraces on the southwest side of the Kashmir Valley. Trenches expose evidence for at least

  11. Emergency Control Aircraft System Using Thrust Modulation (United States)

    Burken, John J. (Inventor); Burcham, Frank W., Jr. (Inventor)


    A digital longitudinal Aircraft Propulsion Control (APC system of a multiengine aircraft is provided by engine thrust modulation in response to comparing an input flightpath angle signal (gamma)c from a pilot thumbwheel. or an ILS system with a sensed flightpath angle y to produce an error signal (gamma)e that is then integrated (with reasonable limits) to generate a drift correction signal to be added to the error signal (gamma)e after first subtracting a lowpass filtered velocity signal Vel(sub f) for phugoid damping. The output error signal is multiplied by a constant to produce an aircraft thrust control signal ATC of suitable amplitude to drive a throttle servo for all engines. each of which includes its own full-authority digital engine control (FADEC) computer. An alternative APC system omits sensed flightpath angle feedback and instead controls the flightpath angle by feedback of the lowpass filtered velocity signal Vel(sub f) which also inherently provides phugoid damping. The feature of drift compensation is retained.

  12. OMV/VTE variable thrust engine analysis (United States)

    Larosillere, L.; Litchford, R.; Jeng, S. M.


    The objective of the present work is to develop a predictive CFD based analytical tool for the Variable Thrust Engine (VTE) in the Orbital Maneuvering Vehicle (OMV). This objective is being accomplished within the framework of the Los Alamos KIVA computer code for chemically reactive flows with sprays. For the OMV application, the main structure of KIVA is to be retained while reformulating many of the phenomenological submodels, enhancing some of the numerics, and adding more features. The analytical model consists of the general conservation equations for two-phase reactive flows and of submodels for turbulence, chemical reactions, and bipropellant sprays. Tailoring this model to the OMV engine brings about the added complexities of combustion and flow processes that occur in a liquid hypergolic propellant rocket chamber. This report exposes the foundation upon which the analytical tool is being constructed and developed. Results from a cursory computational exercise involving the simulation of the flow and combustion processes in a hypothetical N2H4/N204 rocket engine thrust chamber is presented and discussed.

  13. Experimental Results of Schlicher's Thrusting Antenna (United States)

    Fralick, Gustave C.; Niedra, Janis M.


    Experiments were conducted to test the claims by Rex L. Schlicher, et al., (Patent 5,142,86 1) that a certain antenna geometry produces thrust greatly exceeding radiation reaction, when driven by repetitive, fast rise, and relatively slower decay current pulses. In order to test this hypothesis, the antenna was suspended by strings as a 3 in pendulum. Current pulses were fed to the antenna along the suspension path by a very flexible coaxial line constructed from loudspeaker cable and copper braid sheath. When driving the antenna via this cabling, our pulser was capable of sustaining 1200 A pulses at a rate of 30 per second up to a minute. In this way, bursts of pulses could be delivered in synch with the pendulum period in order to build up any motion. However, when using a laser beam passing through a lens attached to the antenna to amplify linear displacement by a factor of at least 25, no correlated motion of the beam spot could be detected on a distant wall. We conclude, in agreement with the momentum theorem of classical electromagnetic theory, that any thrust produced is far below practically useful levels. Hence, within classical electrodynamics, there is little hope of detecting any low level motion that cannot be explained by interactions with surrounding structural steel and the Earth's magnetic field.

  14. Structural character of the northern segment of the Paintbrush Canyon fault, Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Dickerson, R.P. [Science Applications International Corp., Golden, CO (United States); Spengler, R.W. [Geological Survey, Denver, CO (United States)


    Detailed mapping of exposed features along the northern part of the Paintbrush Canyon fault was initiated to aid in construction of the computer-assisted three-dimensional lithostratigraphic model of Yucca Mountain, to contribute to kinematic reconstruction of the tectonic history of the Paintbrush Canyon fault, and to assist in the interpretation of geophysical data from Midway Valley. Yucca Mountain is segmented into relatively intact blocks of east-dipping Miocene volcanic strata, bounded by north-striking, west-dipping high-angle normal faults. The Paintbrush Canyon fault, representing the easternmost block-bounding normal fault, separates Fran Ridge from Midway Valley and continues northward across Yucca Wash to at least the southern margin of the Timber Mountain Caldera complex. South of Yucca Wash, the Paintbrush Canyon Fault is largely concealed beneath thick Quaternary deposits. Bedrock exposures to the north reveal a complex fault, zone, displaying local north- and west-trending grabens, and rhombic pull-apart features. The fault scarp, discontinuously exposed along a mapped length of 8 km north of Yucca Wash, dips westward by 41{degrees} to 74{degrees}. Maximum vertical offset of the Rhyolite of Comb Peak along the fault measures about 210 m in Paintbrush Canyon and, on the basis of drill hole information, vertical offset of the Topopoah Spring Tuff is about 360 m near the northern part of Fran Ridge. Observed displacement along the fault in Paintbrush Canyon is down to the west with a component of left-lateral oblique slip. Unlike previously proposed tectonic models, strata adjacent to the fault dip to the east. Quaternary deposits do not appear displaced along the fault scarp north of Yucca Wash, but are displaced in trenches south of Yucca Wash.

  15. New mapping and structural constraints on the Queen Charlotte-Fairweather Fault system, southeast Alaska (United States)

    Levoir, M. A.; Roland, E. C.; Gulick, S. P.; Haeussler, P. J.; Christeson, G. L.; Van Avendonk, H. J.


    The dextral Queen Charlotte-Fairweather Fault lies along the western margin of Canada and southeastern Alaska, a transform plate boundary accommodating motion between the North American and Pacific Plates. The Fairweather Fault is the northern extension of the Queen Charlotte Fault and has numerous and complex splays, including the Chichagof-Baranof Fault, the Peril Strait Fault, the Chatham Strait Fault, and the Icy Point-Lituya Bay Fault. Except for a few small areas, these fault systems have not been mapped in detail. We present updated geometries and fault maps of the entirety of the strike-slip system using seismic reflection and bathymetric data, including a 2004 seismic reflection survey (EW0408), 2005 United Nations Commission on Law of the Sea multibeam bathymetry, and legacy data from the U.S. Geological Survey (USGS) and the National Geophysical Data Center. This work is highly relevant for earthquake hazard research and mitigation in southeast Alaska. Several large (> Mw 7.0) earthquakes have occurred along this margin in the last century, impacting communities of southeastern Alaska and western Canada. Two large, recent events include 1) a Mw 7.7 earthquake that took place on 28 October 2012 near the Haida Gwaii Islands offshore of western Canada, and 2) a Mw 7.5 event which occurred on 05 January 2013, 330 km to the northwest and offshore of Craig, Alaska. Interestingly, the Haida Gwaii earthquake ruptured as a thrust event and the Craig earthquake ruptured with a near-vertical dextral strike-slip mechanism. Since a change in Pacific Plate motion around 4 million years ago, the southern Queen Charlotte Fault system has been obliquely converging at a rate of 20 mm/year, with the boundary accommodating about 80 km of perpendicular motion over that time. This convergence explains the Haida Gwaii thrust earthquake, but leaves questions about the along-strike fault structure. Two opposing end-member theories suggest convergence is accommodated by either: 1

  16. Dynamic Model for Thrust Generation of Marine Propellers

    DEFF Research Database (Denmark)


    Mathematical models of propeller thrust and torque are traditionally based on steady state thrust and torque characteristics obtained in model basin or cavitation tunnel tests. Experimental results showed that these quasi steady state models do not accurately describe the transient phenomena...... the eects of transients in the ow over a wide range of operation. The results are essential for accurate thrust control in dynamic positioning and in underwater robotics....

  17. Explicit Low-Thrust Guidance for Reference Orbit Targeting (United States)

    Lam, Try; Udwadia, Firdaus E.


    The problem of a low-thrust spacecraft controlled to a reference orbit is addressed in this paper. A simple and explicit low-thrust guidance scheme with constrained thrust magnitude is developed by combining the fundamental equations of motion for constrained systems from analytical dynamics with a Lyapunov-based method. Examples are given for a spacecraft controlled to a reference trajectory in the circular restricted three body problem.

  18. Loss estimates for a Puente Hills blind-thrust earthquake in Los Angeles, California (United States)

    Field, E.H.; Seligson, H.A.; Gupta, N.; Gupta, V.; Jordan, T.H.; Campbell, K.W.


    Based on OpenSHA and HAZUS-MH, we present loss estimates for an earthquake rupture on the recently identified Puente Hills blind-thrust fault beneath Los Angeles. Given a range of possible magnitudes and ground motion models, and presuming a full fault rupture, we estimate the total economic loss to be between $82 and $252 billion. This range is not only considerably higher than a previous estimate of $69 billion, but also implies the event would be the costliest disaster in U.S. history. The analysis has also provided the following predictions: 3,000-18,000 fatalities, 142,000-735,000 displaced households, 42,000-211,000 in need of short-term public shelter, and 30,000-99,000 tons of debris generated. Finally, we show that the choice of ground motion model can be more influential than the earthquake magnitude, and that reducing this epistemic uncertainty (e.g., via model improvement and/or rejection) could reduce the uncertainty of the loss estimates by up to a factor of two. We note that a full Puente Hills fault rupture is a rare event (once every ???3,000 years), and that other seismic sources pose significant risk as well. ?? 2005, Earthquake Engineering Research Institute.

  19. Dynamically triggered slip on a splay fault in the Mw 7.8, 2016 Kaikoura (New Zealand) earthquake (United States)

    Hollingsworth, James; Ye, Lingling; Avouac, Jean-Philippe


    We investigate the Mw 7.8, 2016 Kaikoura (New Zealand) earthquake by using optical satellite imagery and seismology to reveal the main features of the rupture process. Correlation of Landsat8 images reveals a 30-40 km surface rupture on the Kekerengu Fault and Jordan Thrust, with up to 12 m of right-lateral slip. A previously unrecognized conjugate strike-slip fault, the Papatea Fault, also slipped coseismically (3-4 m). The global centroid moment tensor (gCMT) centroid indicates both thrust and right-lateral slip and is located 100 km NE of the main shock epicenter. The significant non-double-couple component of the gCMT (25%) suggests that the main shock is not well represented by a single planar fault. Back projection of teleseismic P waves reveals two main bursts of seismic radiation: (1) at 10-20 s, near the main shock epicenter, and (2) at 70 s, close to the observed surface ruptures. We determine a finite source kinematic model of the rupture from the inversion of seismic waveforms. We use two faults in our model, defined to match the observed slip on the Kekerengu Fault, and a deeper offshore fault with a lower dip angle to satisfy the long period seismological observations. We compute the equivalent moment tensor from our finite source model and find it to be remarkably consistent with the gCMT solution. Although little is known about the geometry of these faults at depth, if the Kekerengu Fault splays from the deeper thrust, then it provides a rare example where the contribution of slip on a splay fault can be clearly isolated in the seismological waveforms.

  20. Depth of Faulting in Mercury's Northern Hemisphere from Lobate Scarp Morphology (United States)

    Peterson, G.; Johnson, C.; Byrne, P. K.; Phillips, R. J.; Neumann, G. A.


    Lobate scarps on the surface of Mercury are interpreted to be a fault-induced anticlines atop blind or surface-breaking thrust faults, attributed to shortening of the lithosphere as the planet's interior cooled and contracted. In cross section, lobate scarps are characterized by a steeply rising scarp face and a gently sloping back limb. COULOMB dislocation modelling of an elastic half space can be used to investigate the relationship between fault-related topography and the properties of the underlying thrust fault. Using mapped shortening features and topography derived from the Mercury Laser Altimeter (MLA) instrument on the MESSENGER spacecraft, six lobate scarps across Mercury's northern smooth plains and cratered terrain were examined. For each scarp, topographic profiles were taken perpendicular to strike, and the average profile and its standard deviation generated for each scarp. COULOMB modelling incorporated a rectangular homoclinal fault. By varying the fault displacement and dip angle, as well as the minimum (Zu) and maximum (Zm) depths of faulting, best-fit parameters and their uncertainties were determined for each averaged profile. Assuming that lobate scarps deform the entire lithosphere to the brittle-ductile transition depth, estimations of faulting depth provide constraints on Mercury's elastic thickness at the time of faulting. This, in turn, provides constraints on the planet's thermal history. Our results suggest that across the northern hemisphere, the smooth terrain surrounding the northern rise has Zm = 19(+9,-7)km to 28(+10,-8)km, compared to the Carnegie-Victoria region for which Zm = 33(+15,-10) km to 53(+5,-5) km. Best-fit values for Zu are 3-9 km. Comparison of Zm with crustal thickness (Tc) values derived from Mercury's gravity field indicates that faulting typically extends at least 50% of the way through the crust, and in some case through the entire crust.

  1. Versatile and Extensible, Continuous-Thrust Trajectory Optimization Tool Project (United States)

    National Aeronautics and Space Administration — We propose to develop an innovative, versatile and extensible, continuous-thrust trajectory optimization tool for planetary mission design and optimization of...

  2. Improved Propulsion Modeling for Low-Thrust Trajectory Optimization (United States)

    Knittel, Jeremy M.; Englander, Jacob A.; Ozimek, Martin T.; Atchison, Justin A.; Gould, Julian J.


    Low-thrust trajectory design is tightly coupled with spacecraft systems design. In particular, the propulsion and power characteristics of a low-thrust spacecraft are major drivers in the design of the optimal trajectory. Accurate modeling of the power and propulsion behavior is essential for meaningful low-thrust trajectory optimization. In this work, we discuss new techniques to improve the accuracy of propulsion modeling in low-thrust trajectory optimization while maintaining the smooth derivatives that are necessary for a gradient-based optimizer. The resulting model is significantly more realistic than the industry standard and performs well inside an optimizer. A variety of deep-space trajectory examples are presented.

  3. Faulting evidence of isostatic uplift in the Rincon Mountains metamorphic core complex: An image processing analysis (United States)

    Rodriguez-Guerra, Edna Patricia

    This study focuses on the applications of remote sensing techniques and digital analysis to characterizing of tectonic features of the Rincon Mountains metamorphic core complex. Data included Landsat Thematic Mapper (TM) images, digital elevation models (DEM), and digital orthophoto quadrangle quads (DOQQ). The main findings in this study are two nearly orthogonal systems of structures that have never been reported in the Rincon Mountains. The first system, a penetrative faulting system of the footwall rocks, trends N10--30°W. Similar structures identified in other metamorphic core complexes. The second system trends N60--70°E, and has only been alluded indirectly in the literature of metamorphic core complexes. The structures pervade mylonites in Tanque Verde Mountain, Mica Mountain, and the Rincon Peak area. As measured on the imagery, spacing between the N10--30°W lineaments ranges from ˜0.5 to 2 km, and from 0.25 to 1 km for the N60--70°E system. Field inspection reveals that the N10--30°W trending system, are high-angle normal faults dipping mainly to the west. One of the main faults, named here the Cabeza de Vaca fault, has a polished, planar, striated and grooved surface with slickenlines indicating pure normal dip-slip movement (N10°W, 83°SW; slickensides rake 85°SW). The Cabeza de Vaca fault is the eastern boundary of a 2 km-wide graben, with displacement as great as 400 meters. The N10--30°W faults are syn- to post-mylonitic, high-angle normal faults that formed during isostatic uplift of the Rincon core complex during mid-Tertiary time. This interpretation is based on previous works, which report similar fault patterns in other metamorphic core complexes. Faults trending N20--30°W, shape the east flank of Mica Mountain. These faults, on the back dipping mylonitic zone, dip east and may represent late-stage antithetic shear zones. The Cabeza de Vaca fault and the back dipping antithetic faults accommodate as much as 65% of the extension due to

  4. Distribution, migration and derivation of Mesozoic-Cenozoic regional fault systems in the central continental margin of eastern China

    Institute of Scientific and Technical Information of China (English)

    SUN Xiaomeng; HAO Fujiang; BIAN Weihua; GAO Yi; BAO Yafan


    Deep-large faults in the central continental margin of eastern China are well developed. Based on the regularity of spatial and temporal distribution of the faults,four fault systems were divided: the Yanshan orogenic belt fault system, the Qinling-Dabie-Sulu orogenic belt fault system, the Tanlu fault system and the East China Sea shelfbasin-Okinawa trough fault system. The four fault systems exhibit different migration behaviors. The Yanshan orogenic belt fault system deflected from an EW to a NE direction,then to a NNE direction during the Indo-Chinese epoch-Yanshanian epoch. The thrust-nappe strength of the Qinling-Dabie orogenic belt fault system showed the tendency that the strength was greater in the south and east, but weaker in the north and west. This fault system faulted in the east and folded in the west from the Indo-Chinese epoch to the early Yanshanian epoch. At the same time, the faults also had a diachronous migration from east to west from the Indo-Chinese epoch to the early Yanshanian epoch. On the con-trary, the thrust-nappe strength was greater in the north and west, weaker in the south and east during the late Yanshanian epoch-early Himalayan epoch. The Tanlu fault system caused the basin to migrate from west to east and south to north. The migration regularity of the East China Sea shelf basin-Okinawa trough fault system shows that the for mation age became younger in the west. The four fault systems and their migration regularities were respectively the results of four different geodynamic backgrounds. The Yanshan orogenicbelt fault system derived from the intracontinental orogeny.The Qinling-Dabie-Sulu orogenic belt fault system derived from the collision of plates and intracontinental subduction.The Tanlu fault system derived from the strike-slip movement and the East China Sea shelf basin-Okinawa trough fault system derived from plate subduction and retreat of the subduction belt.

  5. Kashmir Basin Fault and its tectonic significance in NW Himalaya, Jammu and Kashmir, India (United States)

    Shah, A. A.


    The Kashmir Basin Fault is located in the Jammu and Kashmir region of Kashmir Basin in NW Himalaya, India. It is a classic example of an out-of-sequence thrust faulting and is tectonically active as observed from multiple geological evidences. Its geomorphology, structure and lateral extent indicate significant accommodation of stress since long, which is further supported by the absence of a large earthquake in this region. It seems this fault is actively accommodating some portion of the total India-Eurasia convergence, apart from two well-recognised active structures the Medlicott-Wadia Thrust and the Main Frontal Thrust, which are referred in Vassallo et al. (Earth Planet Sci Lett 411:241-252, 2015). This requires its quantification and inclusion into slip distribution scheme of NW Himalaya. Therefore, it should be explored extensively because this internal out-of-sequence thrust could serve major seismic hazard in KB, repeating a situation similar to Muzaffarabad earthquake of Northern Pakistan in 2005.

  6. Late Quaternary sinistral slip rate along the Altyn Tagh fault and its structural transformation model

    Institute of Scientific and Technical Information of China (English)

    XU; Xiwei; P.; Tapponnier; J.; Van; Der; Woerd; F.; J.; Ryer


    Based on technical processing of high-resolution SPOT images and aerophotos,detailed mapping of offset landforms in combination with field examination and displacement measurement, and dating of offset geomorphic surfaces by using carbon fourteen (14C), cosmogenic nuclides (10Be+26Al) and thermoluminescence (TL) methods, the Holocene sinistral slip rates on different segments of the Altyn Tagh Fault (ATF) are obtained. The slip rates reach 17.5±2 mm/a on the central and western segments west of Aksay Town, 11±3.5 mm/a on the Subei-Shibaocheng segment, 4.8± 1.0 mm/a on the Sulehe segment and only 2.2± 0.2 mm/a on the Kuantanshan segment, an easternmost segment of the ATF. The sudden change points for loss of sinistral slip rates are located at the Subei, Shibaocheng and Shulehe triple junctions where NW-trending active thrust faults splay from the ATF and propagate southeastward. Slip vector analyses indicate that the loss of the sinistral slip rates from west to east across a triple junction has structurally transformed into local crustal shortening perpendicular to the active thrust faults and strong uplifting of the thrust sheets to form the NW-trending Danghe Nanshan,Daxueshan and Qilianshan Ranges. Therefore, the eastward extrusion of the northern Qinghai-Tibetan Plateau is limited and this is in accord with "the imbricated thrusting transformation-limited extrusion model".

  7. Kinematic evolution of Andean fold-thrust structures along the boundary between the Eastern Cordillera and Middle Magdalena Valley basin, Colombia (United States)

    SáNchez, Javier; Horton, Brian K.; Tesón, Eliseo; Mora, AndréS.; Ketcham, Richard A.; Stockli, Daniel F.


    Surface and subsurface data support a kinematic reconstruction of Cenozoic fold-thrust deformation along the Eastern Cordillera-Magdalena Valley transition in Colombia. The La Salina fault (LSF) marks the boundary between west-vergent Eastern Cordillera structures and hinterland deposits of the Middle Magdalena Valley basin. Apatite fission track and (U-Th)/He thermochronological results for the west-directed LSF reveal initial hanging wall exhumation during middle Eocene-early Oligocene (45-30 Ma) shortening, renewed exhumation in the early middle Miocene (18-12 Ma), and accelerated late Miocene-Pliocene (12-3 Ma) exhumation. Vitrinite reflectance data suggest maximum burial of 4-6 km, helping constrain Cenozoic basin architecture. Mapping of the LSF reveals hanging wall Cretaceous-Eocene rocks in a broad anticline-syncline pair with limited faulting and footwall Eocene-Quaternary basin fill in a complex series of tight thrust-related folds. Limited displacement along the westernmost (frontal) thrust suggests that shortening is largely accommodated by east-directed thrusting within a broader triangle zone of a passive-roof duplex (and probable minor strike-slip deformation). In the preferred kinematic restoration, the most recent phase of shortening to transpressional deformation represents out-of-sequence reactivation of the LSF consistent with irregular crosscutting relationships among footwall structures. Earliest exhumation by 45-30 Ma in the Eastern Cordillera fold-thrust belt is correlated with increased sedimentary lithic fragments and high compositional maturity in sandstones of the adjacent Magdalena Valley basin. Exhumation since ˜15 Ma coincided with decreased compositional maturity and elevated accumulation rates for the Real Group. The compositional provenance shifts are attributed to westward advance of fold-thrust deformation into the proximal (eastern) segments of the Magdalena Valley basin.

  8. The Cenozoic fold-and-thrust belt of Eastern Sardinia: Evidences from the integration of field data with numerically balanced geological cross section (United States)

    Arragoni, S.; Maggi, M.; Cianfarra, P.; Salvini, F.


    Newly collected structural data in Eastern Sardinia (Italy) integrated with numerical techniques led to the reconstruction of a 2-D admissible and balanced model revealing the presence of a widespread Cenozoic fold-and-thrust belt. The model was achieved with the FORC software, obtaining a 3-D (2-D + time) numerical reconstruction of the continuous evolution of the structure through time. The Mesozoic carbonate units of Eastern Sardinia and their basement present a fold-and-thrust tectonic setting, with a westward direction of tectonic transport (referred to the present-day coordinates). The tectonic style of the upper levels is thin skinned, with flat sectors prevailing over ramps and younger-on-older thrusts. Three regional tectonic units are present, bounded by two regional thrusts. Strike-slip faults overprint the fold-and-thrust belt and developed during the Sardinia-Corsica Block rotation along the strike of the preexisting fault ramps, not affecting the numerical section balancing. This fold-and-thrust belt represents the southward prosecution of the Alpine Corsica collisional chain and the missing link between the Alpine Chain and the Calabria-Peloritani Block. Relative ages relate its evolution to the meso-Alpine event (Eocene-Oligocene times), prior to the opening of the Tyrrhenian Sea (Tortonian). Results fill a gap of information about the geodynamic evolution of the European margin in Central Mediterranean, between Corsica and the Calabria-Peloritani Block, and imply the presence of remnants of this double-verging belt, missing in the Southern Tyrrhenian basin, within the Southern Apennine chain. The used methodology proved effective for constraining balanced cross sections also for areas lacking exposures of the large-scale structures, as the case of Eastern Sardinia.

  9. A Large-scale Tertiary Salt Nappe Complex in the Leading Edge of the Kuqa Foreland Fold-Thrust Belt, the Tarim Basin, Northwest China

    Institute of Scientific and Technical Information of China (English)

    TANG Liangjie; JIN Zhijun; JIA Chengzao; PI Xuejun; CHEN Shuping; XIE Huiwen; WANG Ziyu


    The tectono-stratigraphic sequences of the Kuqa foreland fold-thrust belt in the northern Tarim basin,northwest China, can be divided into the Mesozoic sub-salt sequence, the Paleocene-Eocene salt sequence and the Oligocene-Quaternary supra-salt sequence. The salt sequence is composed mainly of light grey halite, gypsum, marl and brown clastics. A variety of salt-related structures have developed in the Kuqa foreland fold belt, in which the most fascinating structures are salt nappe complex. Based on field observation, seismic interpretation and drilling data, a large-scale salt nappe complex has been identified. It trends approximately east-west for over 200 km and occurs along the west Qiulitag Mountains. Its thrusting displacement is over 30 km. The salt nappe complex appears as an arcuate zone projecting southwestwards along the leading edge of the Kuqa foreland fold belt. The major thrust fault is developed along the Paleocene-Eocene salt beds. The allochthonous nappes comprise large north-dipping faulting monoclines which are made up of Paleocene-Pliocene sediments. Geological analysis and cross-section restoration revealed that the salt nappes were mainly formed at the late Himalayan stage (c.a. 1.64 Ma BP) and have been active until the present day. Because of inhomogeneous thrusting, a great difference may exist in thrust displacement, thrust occurrence, superimposition of allochthonous and autochthonous sequences and the development of the salt-related structures, which indicates the segmentation along the salt nappes. Regional compression, gravitational gliding and spreading controlled the formation and evolution of the salt nappe complex in the Kuqa foreland fold belt.

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

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


    The Rodgers Creek–Maacama fault system in the northern California Coast Ranges (United States) takes up substantial right-lateral motion within the wide transform boundary between the Pacific and North American plates, over a slab window that has opened northward beneath the Coast Ranges. The fault system evolved in several right steps and splays preceded and accompanied by extension, volcanism, and strike-slip basin development. Fault and basin geometries have changed with time, in places with younger basins and faults overprinting older structures. Along-strike and successional changes in fault and basin geometry at the southern end of the fault system probably are adjustments to frequent fault zone reorganizations in response to Mendocino Triple Junction migration and northward transit of a major releasing bend in the northern San Andreas fault. The earliest Rodgers Creek fault zone displacement is interpreted to have occurred ca. 7 Ma along extensional basin-forming faults that splayed northwest from a west-northwest proto-Hayward fault zone, opening a transtensional basin west of Santa Rosa. After ca. 5 Ma, the early transtensional basin was compressed and extensional faults were reactivated as thrusts that uplifted the northeast side of the basin. After ca. 2.78 Ma, the Rodgers Creek fault zone again splayed from the earlier extensional and thrust faults to steeper dipping faults with more north-northwest orientations. In conjunction with the changes in orientation and slip mode, the Rodgers Creek fault zone dextral slip rate increased from ∼2–4 mm/yr 7–3 Ma, to 5–8 mm/yr after 3 Ma. The Maacama fault zone is shown from several data sets to have initiated ca. 3.2 Ma and has slipped right-laterally at ∼5–8 mm/yr since its initiation. The initial Maacama fault zone splayed northeastward from the south end of the Rodgers Creek fault zone, accompanied by the opening of several strike-slip basins, some of which were later uplifted and compressed

  11. Brittle tectonics in the Lufilian fold-and-thrust belt and its foreland. An insight into the stress field record in relation to moving plates (Katanga, DRC)



    The Lufilian fold-and-thrust belt – also known as the Lufilian Arc – and the Kundulungu foreland in the Katanga region (Democratic Republic of Congo) have attracted the attention of several generations of geologists thanks to the discovery of world class Cu-Co ore deposits. Its geological context, tectonic evolution and metallogenesis are relatively well known, in particular for the Neoproterozoic to early Paleozoic, Katangan sedimentary sequences that have been folded and faulted during the ...

  12. Comparison of {gamma}-ray profile across active normal and reverse faults; Seidansogata to gyakudansogata katsudanso ni okeru hoshano tansa kekka no hikaku

    Energy Technology Data Exchange (ETDEWEB)

    Iwata, A.; Wada, N.; Sumi, H. [Shimada Technical Consultants, Ltd., Shimane (Japan); Yamauchi, S.; Iga, T. [Shimane Univ., Shimane (Japan)


    Active faults confirmed at trench and outcrop were surveyed by the {gamma}-ray spectrometry. The active fault found at trench is a normal fault, and that found at outcrop is a reverse fault. The {gamma}-ray spectral characteristics of these two types of faults were compared to each other. The normal fault is named as Asagane fault located in Aimi-machi, Saihaku-gun, Tottori prefecture. The reverse fault is named as Yokota reverse fault located in Yokota-cho, Nita-gun, Shimane prefecture. Rises of radon gas indicating the existence of opening cracks were confirmed above the fault for the normal fault, and at the side of thrust block for the reverse fault. It was considered that such characteristics were caused by the difference of fault formation in the tensile stress field and in the compressive stress field. It was also reconfirmed that much more information as to faults can be obtained by the combined exploration method using the total counting method and the spectral method. 14 refs., 7 figs.


    Institute of Scientific and Technical Information of China (English)

    ZHU Junjiang; ZHAN Wenhuan; QIU Xuelin; XU Huilong; TANG Cheng


    The Red River Fault Zone is a gigantic slide-slip fault zone extending up to 1000km from Tibet to SouthChina Sea. It has been divided into the north, central and south segments according to the difference of thegeometry, kinetics, and seismicity on the land, but according to the contacted relationship between the old pre-Cenozoic block in Indochina Peninsula and the South China block, the Red River Fault Zone was divided into two parts extending from land to ocean, the north and south segments. Since the Tertiary, the Red River Fault Zone suffered first the sinistral movement and then the dextral movement. The activities of the north and the south segments were different. Based on the analysis of earthquakes and focal mechanism solutions,earthquakes with the focus depths of 0-33km are distributed over the whole region and more deep earthquakes are distributed on the northeastern sides of the Red River fault. Types of faulting activities are the thrust in the northwest, the normal in the north and the strike-slip in the south, with the odd type, viz. the transition type, in the other region. These show the Red River Fault Zone and its adjacent region suffered the extruding force in NNW direction and the normal stress in NEE direction and it makes the fault in the region extrude-thrust,horizontal strike-slip and extensional normal movement.

  14. New paleomagnetic constraints on middle Miocene strike-slip faulting along the middle Altyn Tagh Fault (United States)

    Li, Bingshuai; Yan, Maodu; Zhang, Weilin; Fang, Xiaomin; Meng, Qingquan; Zan, Jinbo; Chen, Yi; Zhang, Dawen; Yang, Yongpeng; Guan, Chong


    Knowledge of the evolution of the Altyn Tagh Fault (ATF) has significant implications for our understanding of the tectonic deformation of the Tibetan Plateau. Controversy exists regarding the formation of the orocline-like arcuate structures or curved thrust faults south of the ATF. In this paper, we conducted a paleomagnetic rotation study of the Akatengnengshan (AK) and Youshashan (YSS) anticlines to determine whether the changes in the anticlines' axes were caused by frictional drag associated with sinistral strike-slip faulting along the ATF. No significant paleomagnetic rotations during the last 20 Ma were observed at the Xichagou and Laomangai localities, which are situated along the YSS anticline, whereas significant counterclockwise (CCW) rotations of 50° that occurred between 16.2 and 11.1 Ma were noted at the Yitunbulake locality, which lies along the western edge of the AK anticline. This amount of CCW rotation is consistent with the difference in axes between the AK and YSS anticlines. Combined with other geological evidence, we believe that the middle ATF was active between 16 and 11 Ma. Frictional drag associated with sinistral strike-slip motion likely resulted in the 50° CCW rotation of the AK anticline, which was originally straight or parallel to the YSS anticline. There was concentrated or insignificant strike-slip faulting along the middle ATF before 16 Ma, but rapid and distributed (< 40 km) strike-slip faulting occurred between 16 and 11 Ma at a rate of ≥10 mm/yr, and the minimum displacement was 50 km.

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

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


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

  16. Secondary production of massive quarks in thrust

    Energy Technology Data Exchange (ETDEWEB)

    Hoang, André H. [University of Vienna, Faculty of Physics, Boltzmanngasse 5, A-1090 Wien (Austria); Erwin Schrödinger International Institute for Mathematical Physics, University of Vienna, Boltzmanngasse 9, A-1090 Vienna (Austria); Mateu, Vicent [University of Vienna, Faculty of Physics, Boltzmanngasse 5, A-1090 Wien (Austria); Pietrulewicz, Piotr [Theory Group, Deutsches Elektronen-Synchrotron (DESY), D-22607 Hamburg (Germany)


    We present a factorization framework that takes into account the production of heavy quarks through gluon splitting in the thrust distribution for e{sup +}e{sup −} → hadrons. The explicit factorization theorems and some numerical results are displayed in the dijet region where the kinematic scales are widely separated, which can be extended systematically to the whole spectrum. We account for the necessary two-loop matrix elements, threshold corrections, and include resummation up to N{sup 3}LL order. We include nonperturbative power corrections through a field theoretical shape function, and remove the O(Λ{sub QCD}) renormalon in the partonic soft function by appropriate mass-dependent subtractions. Our results hold for any value of the quark mass, from an infinitesimally small (merging to the known massless result) to an infinitely large one (achieving the decoupling limit). This is the first example of an application of a variable flavor number scheme to final state jets.

  17. Secondary production of massive quarks in thrust

    Energy Technology Data Exchange (ETDEWEB)

    Hoang, Andre H. [Wien Univ. (Austria). Fakultaet fuer Physik; Vienna Univ. (Austria). Erwin Schroedinger International Institute for Mathematical Physics; Mateu, Vicent [Wien Univ. (Austria). Fakultaet fuer Physik; Pietrulewicz, Piotr [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie


    We present a factorization framework that takes into account the production of heavy quarks through gluon splitting in the thrust distribution for e{sup +}e{sup -}→hadrons. The explicit factorization theorems and some numerical results are displayed in the dijet region where the kinematic scales are widely separated, which can be extended systematically to the whole spectrum. We account for the necessary two-loop matrix elements, threshold corrections, and include resummation up to N{sup 3}LL order. We include nonperturbative power corrections through a field theoretical shape function, and remove the O(Λ{sub QCD}) renormalon in the partonic soft function by appropriate mass-dependent subtractions. Our results hold for any value of the quark mass, from an infinitesimally small (merging to the known massless result) to an infinitely large one (achieving the decoupling limit). This is the first example of an application of a variable flavor number scheme to final state jets.

  18. Neotectonics of interior Alaska and the late Quaternary slip rate along the Denali fault system (United States)

    Haeussler, Peter J.; Matmon, Ari; Schwartz, David P.; Seitz, Gordon G.


    The neotectonics of southern Alaska (USA) are characterized by a several hundred kilometers–wide zone of dextral transpressional that spans the Alaska Range. The Denali fault system is the largest active strike-slip fault system in interior Alaska, and it produced a Mw 7.9 earthquake in 2002. To evaluate the late Quaternary slip rate on the Denali fault system, we collected samples for cosmogenic surface exposure dating from surfaces offset by the fault system. This study includes data from 107 samples at 19 sites, including 7 sites we previously reported, as well as an estimated slip rate at another site. We utilize the interpreted surface ages to provide estimated slip rates. These new slip rate data confirm that the highest late Quaternary slip rate is ∼13 mm/yr on the central Denali fault near its intersection with the eastern Denali and the Totschunda faults, with decreasing slip rate both to the east and west. The slip rate decreases westward along the central and western parts of the Denali fault system to 5 mm/yr over a length of ∼575 km. An additional site on the eastern Denali fault near Kluane Lake, Yukon, implies a slip rate of ∼2 mm/yr, based on geological considerations. The Totschunda fault has a maximum slip rate of ∼9 mm/yr. The Denali fault system is transpressional and there are active thrust faults on both the north and south sides of it. We explore four geometric models for southern Alaska tectonics to explain the slip rates along the Denali fault system and the active fault geometries: rotation, indentation, extrusion, and a combination of the three. We conclude that all three end-member models have strengths and shortcomings, and a combination of rotation, indentation, and extrusion best explains the slip rate observations.

  19. Seismic data, geometry, evolution, and shortening in the active Sulaiman fold-and-thrust belt of Pakistan, southwest of the Himalayas

    Energy Technology Data Exchange (ETDEWEB)

    Jadoon, I.A.K. (Quaid-i-Azam Univ., Islamabad (Panama)); Lawrence, R.D.; Lillie, R.J. (Oregon State Univ., Corvallis, OR (United States))


    Despite its long history of exploration, the Sulaiman fold and thrust belt is a poorly known structure and detailed structural and geochemical investigations are vital for the successful exploration, evaluation and exploitation of any hydrocarbons. Recent nappe and duplex structural models provide a framework for exploration. Surface and subsurface data from the Sulaiman fold-and-thrust belt are integrated to analyze the deep structure, tectonic, shortening, and kinematics of the Sulaiman fold-and-thrust belt at the western margin of the Indian subcontinent. Seismic reflection data show that nearly all the 10-km-thick sequence of dominantly platform (>7 km) and molasse strata is detached at the deformation front. The strata thicken tectonically to about 20 km in the hinterland without significant thrust faults in the foreland. A balanced structural cross-section suggests that structural uplift in the Sulaiman fold-and-thrust belt is a result of a thin-skinned, passive-roof duplex style of deformation. Sequential restoration of the balanced section reveals a series of structural and geometrical features including: (1) development of low-amplitude, broad concentric folds at the tip of the decollement; (2) increase in amplitude of a detachment fold to a critical level for development of ramp and duplex structures; and (3) out-of-sequence thrusting to create required critical taper for an outward translation of the foreland fold-and-thrust belt. A balanced structural cross-section 349 km long from the Sulaiman fold-and-thrust belt restores to an original length of 727 km, suggesting a maximum of 378 km of shortening since 21 Ma in the cover strata of the Indian subcontinent. Calculation of displacement rates over the Sulaiman fold-and-thrust belt (18 mm/yr) added to the resolved rate of the Chaman fault vector for the component parallel to the plate convergence direction (15 mm/yr) are close to the current India-Asia plate convergence rate (37 mm/yr). 68 refs., 13 figs.

  20. Discovery of the Longriba Fault Zone in Eastern Bayan Har Block, China and its tectonic implication

    Institute of Scientific and Technical Information of China (English)


    Re-measured GPS data have recently revealed that a broad NE trending dextral shear zone exists in the eastern Bayan Har block about 200 km northwest of the Longmenshan thrust on the eastern margin of the Qinghai-Tibet Plateau. The strain rate along this shear zone may reach up to 4-6 mm/a. Our interpretation of satellite images and field observations indicate that this dextral shear zone corresponds to a newly generated NE trending Longriba fault zone that has been ignored before. The northeast segment of the Longriba fault zone consists of two subparallel N54°±5°E trending branch faults about 30 km apart, and late Quaternary offset landforms are well developed along the strands of these two branch faults. The northern branch fault, the Longriqu fault, has relatively large reverse component, while the southern branch fault, the Maoergai fault, is a pure right-lateral strike slip fault. According to vector synthesizing principle, the average right-lateral strike slip rate along the Longriba fault zone in the late Quaternary is calculated to be 5.4±2.0 mm/a, the vertical slip rate to be 0.7 mm/a, and the rate of crustal shortening to be 0.55 mm/a. The discovery of the Longriba fault zone may provide a new insight into the tectonics and dynamics of the eastern margin of the Qinghai-Tibet Plateau. Taken the Longriba fault zone as a boundary, the Bayan Har block is divided into two sub-blocks: the Ahba sub-block in the west and the Longmenshan sub-block in the east. The shortening and uplifting of the Longmenshan sub-block as a whole reflects that both the Longmenshan thrust and Longriba fault zone are subordinated to a back propagated nappe tectonic system that was formed during the southeastward motion of the Bayan Har block owing to intense resistance of the South China block. This nappe tectonic system has become a boundary tectonic type of an active block supporting crustal deformation along the eastern margin of the Qinghai-Tibet Plateau from late Cenozoic

  1. Discovery of the Longriba Fault Zone in Eastern Bayan Har Block, China and its tectonic implication

    Institute of Scientific and Technical Information of China (English)

    XU XiWei; WEN XueZe; CHEN GuiHua; YU GuiHua


    Re-measured GPS data have recently revealed that a broad NE trending dextral shear zone exists in the eastern Bayan Har block about 200 km northwest of the Longmenshan thrust on the eastern margin of the Qinghai-Tibet Plateau.The strain rate along this shear zone may reach up to 4-6 mm/a.Our interpretation of satellite images and field observations indicate that this dextral shear zone corresponds to a newly generated NE trending Longriba fault zone that has been ignored before.The northeast segment of the Longriba fault zone consists of two subparallel N54°±5°E trending branch faults about 30 km apart, and late Quaternary offset landforms are well developed along the strands of these two branch faults.The northern branch fault, the Longriqu fault, has relatively large reverse component, while the southern branch fault, the Maoergai fault, is a pure right-lateral strike slip fault.According to vector synthesizing principle, the average right-lateral strike slip rate along the Longriba fault zone in the late Quaternary is calculated to be 5.4±2.0 mm/a, the vertical slip rate to be 0.7 mm/a, and the rate of crustal shortening to be 0.55 mm/a.The discovery of the Longriba fault zone may provide a new insight into the tectonics and dynamics of the eastern margin of the Qinghai-Tibet Plateau.Taken the Longriba fault zone as a boundary, the Bayan Har block is divided into two sub-blocks: the Ahba sub-block in the west and the Longmenshan sub-block in the east.The shortening and uplifting of the Longmenshan sub-block as a whole reflects that both the Longmenshan thrust and Longriba fault zone are subordinated to a back propagated nappe tectonic system that was formed during the southeastward motion of the Bayan Har block owing to intense resistance of the South China block.This nappe tectonic system has become a boundary tectonic type of an active block supporting crustal deformation along the eastern margin of the Qinghai-Tibet Plateau from late Cenozoic till now

  2. Short-lived tectonic switch mechanism for long-term pulses of volcanic activity after mega-thrust earthquakes

    Directory of Open Access Journals (Sweden)

    M. Lupi


    Full Text Available Eruptive rates in volcanic arcs increase significantly after mega-thrust earthquakes in subduction zones. Over short to intermediate time periods the link between mega-thrust earthquakes and arc response can be attributed to dynamic triggering processes or static stress changes, but a fundamental mechanism that controls long-term pulses of volcanic activity after mega-thrust earthquakes has not been proposed yet. Using geomechanical, geological, and geophysical arguments, we propose that increased eruption rates over longer timescales are due to the relaxation of the compressional regime that accompanies mega-thrust subduction zone earthquakes. More specifically, the reduction of the horizontal stress σh promotes the occurrence of short-lived strike-slip kinematics rather than reverse faulting in the volcanic arc. The relaxation of the pre-earthquake compressional regime facilitates magma mobilization by providing a short-circuit pathway to shallow depths by significantly increasing the hydraulic properties of the system. The timescale for the onset of strike-slip faulting depends on the degree of shear stress accumulated in the arc during inter-seismic periods, which in turn is connected to the degree of strain-partitioning at convergent margins. We performed Coulomb stress transfer analysis to determine the order of magnitude of the stress perturbations in present-day volcanic arcs in response to five actual mega-thrust earthquakes; the 2005 M8.6, 2007 M8.5, and 2007 M7.9 Sumatra earthquakes; the 2010 M8.8 Maule, Chile earthquake; and the 2011 M9.0 Tohoku, Japan earthquake. We find that all, but one, the shallow earthquakes that occurred in the arcs of Sumatra, Chile and Japan show a marked lateral component. Our hypothesis suggests that the long-term response of volcanic arcs to subduction zone mega-thrust earthquakes will be manifested as predominantly strike-slip seismic events, and that these future earthquakes will be followed closely by

  3. Evolving Stress State and Deformation Mechanism in the Himalayan Foreland Fold-and-Thrust Belt, Northern Pakistan (United States)

    Ahmad, I.; Dasti, N.


    Crustal deformation along with shortening due to northward under-thrusting of the Indian plate beneath the Eurasian plate continues to create active tectonic features on the northern fringes of the Indian craton since major collision began in the Eocene. Here the study provides insights on the evolving stress state and deformation mechanism of the Salt Range and Potwar area of Northern Pakistan. This part of Himalayan foreland fold-and-thrust-belt has severe history of deformation during 5.1 Ma and 2 Ma. This foreland area lies between Main Boundary Thrust (MBT) in the north, Himalayan Frontal Thrust (HFT) in the south and Jhelum fault of sinistral nature in the east & Kalabagh fault of dextral nature in the west. An integrated data from seismic reflection profiles and drilling logs reveal that the subsurface deformation encompasses pop-ups, imbricates, duplexes with in-sequence and out-of-sequence thrusting. It also depicts that intensity of deformation increases from the northern margin of Soan geosyncline towards north due to lacking of evaporites while in the south it decreases due to gradual increase in salt thickness. Surface geologic mapping glimpses a series of thrust sheets and anticlines trending ENE-SWS in the eastern and central part of the study area; whereas in the western part, the trend is almost E-W. This variation in the trend of structures is the result of counter clock rotational behaviour (~10°deviation from north to the west) of north-western part of the Indian lithospheric plate. Current outcrop-scale natural fracture data collected from selected anticlinal structures of the study area is presented to manifest the stress evolution and deformation styles under the established tectonic framework. Collected data is analysed for the evaluation of tectonic stress direction and deformation mechanism. The genetic arrangement and types of fractures observed in the study area indicate that the whole area is under compression. The data also testify

  4. Strike-slip faulting at Thebes Gap, Missouri and Illinois: Implications for New Madrid tectonism (United States)

    Harrison, Richard W.; Schultz, Art


    Numerous NNE and NE striking strike-slip faults and associated normal faults, folds, and transtensional grabens occur in the Thebes Gap area of Missouri and Illinois. These structures developed along the northwestern margin of the buried Reelfoot rift of Precambrian-Cambrian age at the northern edge of the Mississippi embayment. They have had a long-lived and complex structural history. This is an area of recent moderate seismicity, approximately 45 km north of the New Madrid seismic zone. Stratigraphic evidence suggests that these faults were active during the Middle Ordovician. They were subsequently reactivated between the Early Devonian and Late Cretaceous, probably in response to both the Acadian and Ouachita orogenies. Deformation during this period was characterized by strongly faulted and folded Ordovician through Devonian rocks. In places, these deformed rocks are overlain with angular unconformity by undeformed Cretaceous strata. Fault motion is interpreted as dominantly strike slip. A still younger period of reactivation involved Late Cretaceous and Cenozoic formations as young as the Miocene or Pliocene Mounds Gravel. These formations have experienced both minor high-angle normal faulting and subsequent major, right-lateral strike-slip faulting. En echelon north-south folds, ENE striking normal faults, regional fracture patterns, and drag folds indicate the right-lateral motion for this major episode of faulting which predates deposition of Quaternary loess. Several nondefinitive lines of evidence suggest Quaternary faulting. Similar fault orientations and kinematics, as well as recent seismicity and proximity, clearly suggest a structural relationship between deformation at Thebes Gap and tectonism associated with the New Madrid area.

  5. Fluid chemistry in the fault propataion zone in the mid-crust -fluid inclusion chemistry from the Lishan fault, Taiwan- (United States)

    Okamoto, K.; Iijima, C.; Kurosawa, M.; Chan, Y.; Terabayashi, M.


    Liberation of CO2-rich gas from fluid preserved in the fault propagation zone would be important phenomena in the earthquake and aftershock process. We have detected that injected fluid in link thrust would cause fault propagation and fault lubrication due to vapor-separation [1]. Recently, one of the authors, Yu-Chang Chan found unusual quartz vein on the great link-thrust, Lishan fault, in Taiwan orogenic belt [1]. The quartz vein is spherical shape and is composed of large crystals. The transparent quartz grains contain large primary fluid inclusions over 100 microns in diameters. The fluid inclusion is classified as three kinds of group. That is, two phase, vapor phase and three phase inclusion. Homogenization temperature is 260 oC and NaCl weight pecent is estimated to be 7.41. In order to measure the fluid chemistry, PIXE analysis was done at Tsukuba University. Analytical procedure is shown in [2]. The result is summarized as follows. 1. Br/Cr ratio is lower than that in seawater. 2. Ti, Cr, and Ni contents are high, suggesting that fluid is related to magma activity. 3. Vapor-phase inclusion contains considerable amount of metal elements (Ti, Zn, Ge, Mn, Ca, Fe, Pb, Rb, and Cu) as well as K, and Br. Fractionation between the vapor and the fluid would be useful tool to detect vapor separation due to fault propagation. References [1] Chan, Y. et al., Terra Nova 17, 439-499 (2005) [2] Kurosawa M. et al.,Island Arc, 19, 17-29 (2010)

  6. Morphological Considerations of Fish Fin Shape on Thrust Generation

    Directory of Open Access Journals (Sweden)

    Kenji Kikuchi


    Full Text Available In this study, we aimed to determine the relationship between thrust generation and fish fin shape. To compare the effect fin shape had on thrust generation, we categorized the morphological shapes of fish fins into equilateral polygonal shapes. Polygonal fins were used to generate thrust that depended only on shape. These fins were constructed of a hard elastic material to eliminate any influence of shape deformation. A servomotor with a reciprocal rotation moved a fin cyclically, and thrust was experimentally measured using a strain gage system. Thrust tended to be proportional to the inertia moment of a fin, which indicated difficulty with rotation. Moreover, this trend for thrust generation was directly related to the number of apexes of a polygonal fin. The force translated ratio, which was thrust divided by the force required for fin rotation, was evaluated to determine the hydrodynamic characteristics of fins. This finding showed that the force translated ratio of a fin increased with increased movable perimeter length. The greatest thrust was generated by a triangular fin rotated at its apex, which is often seen in general fish tail fins, whereas the hydrodynamic characteristics were the worst in polygonal fins.

  7. Electronics Engineering Department Thrust Area report FY'84

    Energy Technology Data Exchange (ETDEWEB)

    Minichino, C.; Phelps, P.L. (eds.)


    This report describes the work of the Electronics Engineering Department Thrust Areas for FY'84: diagnostics and microelectronic engineering; signal and control engineering; microwave and pulsed power engineering; computer-aided engineering; engineering modeling and simulation; and systems engineering. For each Thrust Area, an overview and a description of the goals and achievements of each project is provided.

  8. A magnetic coupling thrust stand for microthrust measurements (United States)

    Wright, W. P.; Ferrer, P.


    A direct thrust measurement system that is based on a horizontal lever and utilizes a novel magnetic coupling mechanism to measure thrust has been developed. The system is capable of measuring thrusts as low as 10’s of μN. While zero drift is observed in the balance, tests have shown that they do not have an appreciable effect on thrust measurements. The thrust stand’s sensitivity can be adjusted by shifting the position of the coupling magnet inside the stand’s thrust support member, which allows flexibility for testing both higher and lower powered thrusters. The thrust stand has been modeled theoretically and the predicted results from the model are compared with experimentally measured data. The system was tested using a simple cold gas thruster and provided credible results that can be compared with other systems studied in the literature. Advantages include that the thrust stand is very cheap and easy to construct and further, the calibration process takes no longer than half an hour, facilitating rapid turnaround times while still retaining accuracy. Repeatability tests have shown that the balance gives consistent results.

  9. Impact of plasma noise on a direct thrust measurement system (United States)

    Pottinger, S. J.; Lamprou, D.; Knoll, A. K.; Lappas, V. J.


    In order to evaluate the accuracy and sensitivity of a pendulum-type thrust measurement system, a linear variable differential transformer (LVDT) and a laser optical displacement sensor have been used simultaneously to determine the displacement resulting from an applied thrust. The LVDT sensor uses an analog interface, whereas the laser sensor uses a digital interface to communicate the displacement readings to the data acquisition equipment. The data collected by both sensors show good agreement for static mass calibrations and validation with a cold gas thruster. However, the data obtained using the LVDT deviate significantly from that of the laser sensor when operating two varieties of plasma thrusters: a radio frequency (RF) driven plasma thruster, and a DC powered plasma thruster. Results establish that even with appropriate shielding and signal filtering the LVDT sensor is subject to plasma noise and radio frequency interactions which result in anomalous thrust readings. Experimental data show that the thrust determined using the LVDT system in a direct current plasma environment and a RF discharge is approximately a factor of three higher than the thrust values obtained using a laser sensor system for the operating conditions investigated. These findings are of significance to the electric propulsion community as LVDT sensors are often utilized in thrust measurement systems and accurate thrust measurement and the reproducibility of thrust data is key to analyzing thruster performance. Methods are proposed to evaluate system susceptibility to plasma noise and an effective filtering scheme presented for DC discharges.

  10. 14 CFR 25.945 - Thrust or power augmentation system. (United States)


    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Thrust or power augmentation system. 25.945 Section 25.945 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant General § 25.945 Thrust or power...

  11. Simulations of directed energy thrust on rotating asteroids (United States)

    Griswold, Janelle; Madajian, Jonathan; Johansson, Isabella; Pfau, Krysten; Lubin, Philip; Hughes, Gary B.; Gilkes, Aidan; Meinhold, Peter; Motta, Caio; Brashears, Travis; Zhang, Qicheng


    Asteroids that threaten Earth could be deflected from their orbits using directed energy to vaporize the surface, because the ejected plume creates a reaction thrust that alters the asteroid's trajectory. One concern regarding directed energy deflection is the rotation of the asteroid, as this will reduce the average thrust magnitude and modify the thrust direction. Flux levels required to evaporate surface material depend on surface material composition and albedo, thermal, and bulk mechanical properties of the asteroid, and rotation rate. The observed distribution of asteroid rotation rates is used, along with an estimated range of material and mechanical properties, as input to a 3D thermal-physical model to calculate the resultant thrust vector. The model uses a directed energy beam, striking the surface of a rotating sphere with specified material properties, beam profile, and rotation rate. The model calculates thermal changes in the sphere, including vaporization and mass ejection of the target material. The amount of vaporization is used to determine a thrust magnitude that is normal to the surface at each point on the sphere. As the object rotates beneath the beam, vaporization decreases, as the temperature drops and causes both a phase shift and magnitude decrease in the average thrust vector. A surface integral is calculated to determine the thrust vector, at each point in time, producing a 4D analytical model of the expected thrust profile for rotating objects.

  12. Seismotectonics of southern Haiti: A new faulting model for the 12 January 2010 M7.0 earthquake (United States)

    Saint Fleur, Newdeskarl; Feuillet, Nathalie; Grandin, Raphaël.; Jacques, Eric; Weil-Accardo, Jennifer; Klinger, Yann


    The prevailing consensus is that the 2010 Mw7.0 Haiti earthquake left the Enriquillo-Plantain Garden strike-slip fault (EPGF) unruptured but broke unmapped blind north dipping thrusts. Using high-resolution topography, aerial images, bathymetry, and geology, we identified previously unrecognized south dipping NW-SE striking active thrusts in southern Haiti. One of them, Lamentin thrust, cuts across the crowded city of Carrefour, extends offshore into Port-au-Prince Bay, and connects at depth with the EPGF. We propose that both faults broke in 2010. The rupture likely initiated on the thrust and propagated further along the EPGF due to unclamping. This scenario is consistent with geodetic, seismological, and field data. The 2010 earthquake increased the stress toward failure on the unruptured segments of the EPGF and on neighboring thrusts, significantly increasing the seismic hazard in the Port-au-Prince urban area. The numerous active thrusts recognized in that area must be considered for future evaluation of the seismic hazard.

  13. Application of Anisotropy of Magnetic Susceptibility to large-scale fault kinematics: an evaluation (United States)

    Casas, Antonio M.; Roman-Berdiel, Teresa; Marcén, Marcos; Oliva-Urcia, Belen; Soto, Ruth; Garcia-Lasanta, Cristina; Calvin, Pablo; Pocovi, Andres; Gil-Imaz, Andres; Pueyo-Anchuela, Oscar; Izquierdo-Llavall, Esther; Vernet, Eva; Santolaria, Pablo; Osacar, Cinta; Santanach, Pere; Corrado, Sveva; Invernizzi, Chiara; Aldega, Luca; Caricchi, Chiara; Villalain, Juan Jose


    be observed within the same fault zone, depending on the proximity to the core zone. The transition between them is usually defined by oblate fabrics, with the long and intermediate axes contained within the main foliation plane in SC-like structures. The faults studied in this work are located in Northeast Iberia; most of them were formed during the Late-Variscan fracturing stage and constitute first-order structures controlling the Mesozoic and Cenozoic evolution of the Iberian plate. They include (i) large-scale (Cameros-Demanda) and plurikilometric (Monroyo, Rastraculos), thrusts resulting from basement thrusting and Mesozoic basin inversion, and (ii) strike-slip to transpressional structures in the Iberian Chain (Río Grío and Daroca faults, Aragonian Branch) and the Catalonian Range (Vallès fault). Application of AMS in combination with structural analysis has allowed us a deeper approach into the kinematics of these fault zones and namely to (i) accurately define the transport direction of Cenozoic thrusts (NNW to NE-SW for the studied E-W segments) and the flow directions of décollements and to evaluate the representativity of small-scale structures linked to thrusting; (ii) to assess the transpressional character of deformation for the main NW-SE and NE-SW Late-Variscan faults in NE Iberia during the Cenozoic (horizontal to intermediate-plunging transport directions) and (iii) to define the strain partitioning between different thrust sheets and strike-slip faults to finally establish the pattern of displacements in this intra-plate setting.

  14. Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum (United States)

    Brady, David A.; White, Harold G.; March, Paul; Lawrence, James T.; Davies, Frank J.


    This paper describes the test campaigns designed to investigate and demonstrate viability of using classical magnetoplasmadynamics to obtain a propulsive momentum transfer via the quantum vacuum virtual plasma. This paper will not address the physics of the quantum vacuum plasma thruster (QVPT), but instead will describe the recent test campaign. In addition, it contains a brief description of the supporting radio frequency (RF) field analysis, lessons learned, and potential applications of the technology to space exploration missions. During the first (Cannae) portion of the campaign, approximately 40 micronewtons of thrust were observed in an RF resonant cavity test article excited at approximately 935 megahertz and 28 watts. During the subsequent (tapered cavity) portion of the campaign, approximately 91 micronewtons of thrust were observed in an RF resonant cavity test article excited at approximately 1933 megahertz and 17 watts. Testing was performed on a low-thrust torsion pendulum that is capable of detecting force at a single-digit micronewton level. Test campaign results indicate that the RF resonant cavity thruster design, which is unique as an electric propulsion device, is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma.

  15. Thrust transport directions and thrust sheet restoration in the caledonides of finnmark, North Norway (United States)

    Townsend, C.

    Thrust sheets of the Late Cambrian to Early Ordovician Finnmarkian phase of the Caledonian Orogeny of Finnmark, northern Norway, have been displaced, firstly to the SE, under ductile conditions and later, under more brittle conditions, towards the ESE/E. These thrust sheets have been sequentially restored with the aid of branch-lines and balanced cross-sections. The minimum displacement for each thrust sheet is: Gaissa Nappe, 165 km; Laksefjord Nappe Complex, 105 km; Komagfjord Antiformal Stack, 30 km; and Kalak Nappe Complex, 75 km. This restoration has three significant implications: (1) the total displacement across the Finnmark Caledonides is over 375 km; (2) the Raipas Supergroup exposed within the Komagfjord Window, the allochthonous origin of which has previously been contentious, has been displaced as a basement horse, firstly to the SE and later to the ESE/E by at least 375 km; and (3) in a palinspastic reconstruction the Raipas Supergroup basement did not form the Finnmark Ridge, the source area for the sediments of the Laksefjord Nappe Complex. This restoration does not include the deformation within the Kalak Nappe Complex or the imbricates of the Gaissa Nappe in East Finnmark.

  16. Reaction thrust of water jet for conical nozzles

    Institute of Scientific and Technical Information of China (English)

    HUANG Guo-qin; YANG You-sheng; LI Xiao-hui; ZHU Yu-quan


    Clear knowledge on the reaction thrust of water jet is valuable for better design of water jet propulsion system.In this paper,theoretical,numerical and experimental studies were carried out to investigate the effects of the nozzle geometry as well as the inlet conditions on the reaction thrust of water jet.Comparison analyses reveal that the reaction thrust has a direct proportional relationship with the product of the inlet pressure,the square of flow rate and two-thirds power exponent of the input power.The results also indicate that the diameter of the cylinder column for the conical nozzle has great influence on the reaction thrust characteristics.In addition,the best values of the half cone angle and the cylinder column length exist to make the reaction thrust reach its maximum under the same inlet conditions.

  17. New Highly Dynamic Approach for Thrust Vector Control (United States)

    Hecht, M.; Ettl, J.; Grothe, D.; Hrbud, I.


    For a new launcher system a thrust vector control system is needed. This launch vehicle system consists of two rockets which are namely the VS-50 (two-stage suborbital vehicle) and the VLM-1 (three-stage microsatellite launch vehicle). VLM-1 and VS-50 are developed in a cooperation between the German Aerospace Center (DLR) and the Brazilian Aeronautics and Space Institute (IAE). To keep these two rockets on its trajectory during flight a highly dynamic thrust vector control system is required. For the purpose of developing such a highly dynamic thrust vector control system a master thesis was written by the author. The development includes all mechanical constructions as well as control algorithms and electronics design. Moreover an optimization of control algorithms was made to increase the dynamic capabilities of the thrust vector control system. The composition of the right components plus the sophisticated control algorithm make the thrust vector control system highly dynamic.

  18. Analysis of properties of thrust bearing in ship propulsion system (United States)

    Wu, Zhu-Xin; Liu, Zheng-Lin


    Thrust bearing is a key component of the propulsion system of a ship. It transfers the propulsive forces from the propeller to the ship’s hull, allowing the propeller to push the ship ahead. The performance of a thrust bearing pad is critical. When the thrust bearing becomes damaged, it can cause the ship to lose power and can also affect its operational safety. For this paper, the distribution of the pressure field of a thrust pad was calculated with numerical method, applying Reynolds equation. Thrust bearing properties for loads were analyzed, given variations in outlet thickness of the pad and variations between the load and the slope of the pad. It was noticed that the distribution of pressure was uneven. As a result, increases of both the outlet thickness and the slope coefficient of the pad were able to improve load bearing capability.

  19. Rapid hydrocarbon accumulation mechanism in later period in Kelasu thrust belt in Kuqa depression

    Institute of Scientific and Technical Information of China (English)


    Based on the analyses of generation, migration and accumulation of oil and gas in the structures of Kela 1, Kela 2 and Kela 3 in Kasangtuokai anticlinal belt using a series of geological and geochemical evidence, this paper proposes that the rapid rate of hydrocarbon generation, main drain path for over-pressured fluid flow and converging conduit system are indispensable conditions for the rapid, late-stage gas accumulation in the Kelasu thrust belt in the Kuqa depression. Due to structural over-lapping and the resultant rapid burial, the maturity of the source rocks had been increased rapidly from 1.3 to 2.5% Ro within 2.3 Ma, with an average rate of Ro increase up to 0.539% Ro/Ma. The rapid matura-tion of the source rocks had provided sufficient gases for late-stage gas accumulation. The kelasu structural belt has a variety of faults, but only the fault that related with fault propagation fold and cut through the gypsiferous mudstone cap could act as the main path for overpressured fluid release and then for fast gas accumulation in low fluid potential area. All the evidence from surface structure map, seismic profile explanation, authigenic kaolinite and reservoir property demonstrates that the main drain path related with faults for overpressured fluid and the converging conduit system are the key point for the formation of the giant Kela 2 gas field. By contrast, the Kela 1 and Kela 3 structures lo-cated on both sides of Kela 2 structure, are not favourable for gas accumulation due to lacking con-verging conduit system.

  20. Rapid hydrocarbon accumulation mechanism in later period in Kelasu thrust belt in Kuqa depression

    Institute of Scientific and Technical Information of China (English)

    ZOU HuaYao; WANG HongJun; HAO Fang; LIU GuangDi; ZHANG BaiQiao


    Based on the analyses of generation, migration and accumulation of oil and gas in the structures of Kela 1, Kela 2 and Kela 3 in Kasangtuokai anticlinal belt using a series of geological and geochemical evidence, this paper proposes that the rapid rate of hydrocarbon generation, main drain path for overpressured fluid flow and converging conduit system are indispensable conditions for the rapid,late-stage gas accumulation in the Kelasu thrust belt in the Kuqa depression. Due to structural overlapping and the resultant rapid burial, the maturity of the source rocks had been increased rapidly from 1.3 to 2.5% Ro within 2.3 Ma, with an average rate of Ro increase up to 0.539% Ro/Ma. The rapid maturation of the source rocks had provided sufficient gases for late-stage gas accumulation. The kelasu structural belt has a variety of faults, but only the fault that related with fault propagation fold and cut through the gypsiferous mudstone cap could act as the main path for overpressured fluid release and then for fast gas accumulation in low fluid potential area. All the evidence from surface structure map,seismic profile explanation, authigenic kaolinite and reservoir property demonstrates that the main drain path related with faults for overpressured fluid and the converging conduit system are the key point for the formation of the giant Kela 2 gas field. By contrast, the Kela 1 and Kela 3 structures located on both sides of Kela 2 structure, are not favourable for gas accumulation due to lacking converging conduit system.

  1. Fault-tolerant design

    CERN Document Server

    Dubrova, Elena


    This textbook serves as an introduction to fault-tolerance, intended for upper-division undergraduate students, graduate-level students and practicing engineers in need of an overview of the field.  Readers will develop skills in modeling and evaluating fault-tolerant architectures in terms of reliability, availability and safety.  They will gain a thorough understanding of fault tolerant computers, including both the theory of how to design and evaluate them and the practical knowledge of achieving fault-tolerance in electronic, communication and software systems.  Coverage includes fault-tolerance techniques through hardware, software, information and time redundancy.  The content is designed to be highly accessible, including numerous examples and exercises.  Solutions and powerpoint slides are available for instructors.   ·         Provides textbook coverage of the fundamental concepts of fault-tolerance; ·         Describes a variety of basic techniques for achieving fault-toleran...

  2. Late Quaternary activity along the Ferrara thrust inferred from stratigraphic architecture and geophysical surveys (United States)

    Stefani, Marco; Bignardi, Samuel; Caputo, Riccardo; Minarelli, Luca; Abu-Zeid, Nasser; Santarato, Giovanni


    Since Late Miocene, the Emilia-Romagna portion of the Po Plain-Adriatic foredeep basin was progressively affected by compressional deformation, due to the northward propagation of the Apennines fold-and-thrust belt. The major tectonic structures within the basin have been recognised and are relatively well known, thanks to the widespread, even if outdated, seismic survey, performed after WW II, for hydrocarbon exploration. More recently, a large amount of surface and shallow-subsurface information has been provided by the CARG geological mapping project. The region therefore provides a valuable opportunity to discuss the genetic relationship between tectonic deformation, eustatic-paleoclimatic fluctuations, and depositional architecture. The activity of blind thrusts and fault-propagation folds induced repeated angular unconformities and impressive lateral variations in the Pliocene-Quaternary stratigraphy, causing thickness changes, from a few metres, close to the Apennines piedmont line, to more than 9 km, in fast subsiding depocenters (e.g. Lido di Savio). In the Ferrara region, the post-Miocene succession ranges from about 4 km, west of Sant'Agostino, to less than 200 m, on the Casaglia anticline, where Late Quaternary fluvial strata rest on Miocene marine marls, with an angular unconformity relationship. In this sector of the Po Plain, the tip-line of the northernmost thrust has been reconstructed north of the Po River (Occhiobello) and is associated with the growth of a large fold (Ferrara-Casaglia anticline), cross-cut by a complex splay of minor backthrusts and reverse faults. The thrust-anticline structure hosts an energy producing geothermal field, whose hydrogeological behaviour is largely influenced by the fracture pattern. The Apennines frontal thrust probably provided the seismic source for the earthquakes that severely damaged Ferrara, during the 1570 a.D. fall season, as documented by the structural damage still visible in many historic buildings (e

  3. Fault Monitoring and Fault Recovery Control for Position Moored Tanker

    DEFF Research Database (Denmark)

    Fang, Shaoji; Blanke, Mogens


    This paper addresses fault tolerant control for position mooring of a shuttle tanker operating in the North Sea. A complete framework for fault diagnosis is presented but the loss of a sub-sea mooring line buoyancy element is given particular attention, since this fault could lead to mooring line....... Properties of detection and fault-tolerant control are demonstrated by high fidelity simulations....

  4. Fault tolerant control for uncertain systems with parametric faults

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad


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

  5. Fault isolability conditions for linear systems with additive faults

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Stoustrup, Jakob


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

  6. Fault Analysis in Cryptography

    CERN Document Server

    Joye, Marc


    In the 1970s researchers noticed that radioactive particles produced by elements naturally present in packaging material could cause bits to flip in sensitive areas of electronic chips. Research into the effect of cosmic rays on semiconductors, an area of particular interest in the aerospace industry, led to methods of hardening electronic devices designed for harsh environments. Ultimately various mechanisms for fault creation and propagation were discovered, and in particular it was noted that many cryptographic algorithms succumb to so-called fault attacks. Preventing fault attacks without

  7. Analysis of the pressure response of high angle multiple (HAM) fractures intersecting a welbore; Kokeisha multi fracture (HAM) kosei ni okeru atsuryoku oto kaiseki ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Ujo, S.; Osato, K. [Geothermal Energy Research and Development Co. Ltd., Tokyo (Japan); Arihara, N. [Waseda University, Tokyo (Japan); Schroeder, R.


    This paper reports pressure response analysis on wells piercing a high angle multi (HAM) fracture model. In this model which is defined on a three-dimensional space, a plurality of slanted fractures intersect with wells at high angles (however, intersection of fractures with each other is not considered). With respect to the pressure response analysis method using this model, the paper presents a basic differential equation on pressure drawdown and boundary conditions in the wells taking flows in the fractures pseudo-linear, as well as external boundary conditions in calculation regions (a reservoir spreads to an infinite distance, and its top and bottom are closed by non-water permeating beds). The paper also indicates that results of calculating a single vertical fracture model and a slanted fracture model by using a numerical computation program (MULFRAC) based on the above equations agree well respectively with the existing calculation results (calculations performed by Erlougher and Cinco et al). 5 refs., 6 figs.

  8. Structural styles of the intracratonic reactivation of the Perimbó fault zone, Paraná basin, Brazil (United States)

    Rostirolla, Sidnei Pires; Mancini, Fernando; Rigoti, Augustinho; Kraft, Ronaldo Paulo


    The style and origin of intracratonic deformation along the Perimbó fault zone (PFZ) in the Paraná basin, Santa Catarina State, southern Brazil, is defined by the integration of outcrop, borehole, aerial photography, and digital terrain modeling data. Typical structures are high-angle strike-slip and oblique-slip normal faults in the Permian sedimentary cover that propagate upward from medium-angle reverse faults in the underlying Precambrian basement. Regional and minor structures suggest blind transtensional faulting and tilting of the overlying strata controlled by the basement heritage. A hypothesis linking deformation between the cover and the basement is proposed on the basis of a structural analysis of a branched fault pattern striking N40-50E and N70-80E. Semi-detailed scale mapping shows that the PFZ has a complex history of polyphase reactivation and is characterized as a plate margin fault in the Proterozoic, evolving to an intracratonic fault in the Phanerozoic, with a main period of reactivation in Permian or Permian-Triassic transition times. The reported data imply that fault reactivation is characterized by normal to left-lateral strike-slip faulting produced by strain propagation from the La Ventana orogenic belt toward the continental interior.

  9. Possible reactivation of the Vincent-Chocolate Mountains thrust in the Gavilan Hills area, southeasternmost California

    Energy Technology Data Exchange (ETDEWEB)

    Oyarzabal, F.R.; Jacobson, C.E. (Iowa State Univ., Ames, IA (United States)); Haxel, G.B. (Geological Survey, Flagstaff, AZ (United States))


    The Late Cretaceous-early Tertiary Orocopia Schist (OS) of southeasternmost California consists of metamorphosed continental margin sedimentary and basaltic rocks, overlain by an upper plate of continental crust along the Vincent-Chocolate Mountains fault (VCMF). Previous analysis of late folds and shear band in OS and upper plate in the Gavilan Hills and adjacent ares indicated that the direction of transport of the upper plate was northeastward. This has been considered evidence of a SW dipping subduction zone, along which an outboard continental fragment was sutured to North America. Another view is that the VCMF was formed by underplating of the OS in an Andean continental margin, and that the NE-vergent late structures formed during uplift of the OS. The authors' continuing work in the Gavilan Hills confirm the NE sense of vergence but suggests a more complex structural history. The schist is characterized by refolded folds, shear bands, and two penetrative lineations. An older lineation that ranges from N10[degree]E to N30[degree]E is widespread in the area, but is more evident at low structural levels. A second lineation ranges from N40[degree]E to N70[degree]E and is strongly developed in rocks near the VCMF. The complex folding pattern, presence of mylonitic schist, relative thinness of upper-plate mylonite, and possible retrogressive character of the shear bands suggest that the VCMF in the Gavilan Hills area may have been reactivated after original thrusting. The VCMF in the Gavilan Hills is intermediate in character between the probable subduction thrust in the San Gabriel Mountains and the reactivated faults in the Orocopia Mountains and areas surrounding the Gavilan Hills.

  10. Apatite fission track dating evidence for tectonic move-ment of Yarlung Zangbo Thrust Zone

    Institute of Scientific and Technical Information of China (English)


    Fission track geological chronology is an effective method of study on tectonic movement of fault zone.Apatite fission track (AFT) dating analyses of 9-apatite and 4-zircon samples collected from Lhasa to Langkazi,-70-kin-long in SN provide an understanding of the age and the uplifting of both sides of the Yarlung Zangbo Thrust Zone (YZTZ) in this work. The AFT ages range from -37 to 14 Ma, indicating the time of major tectono-thermal events,i.e. the continent-continent collision along the YZTZ. Based on the relationship between the AFT ages and the sample elevations, there were two tectonic active periods: -37-20Ma and 20}-14 Ma. In the first period the tectonic event did not bring on differential uplifting. Rapid differential uplifting with rapid cooling, resulting from thrusting, took place in the second period. The vertical displacement was -1020 m and total -2.9 km of overburden has been removed from the present-day surface since cooling below -ll0℃ began. The maximum cooling and denudation occurred at a rate of -7℃/Ma and -207 m/Ma respectively since -14 Ma. The zircon fission track analysis demonstrates that the temperature of tectono-thermal events did not exceed 310℃.``

  11. Reaction weakening and emplacement of crystalline thrusts: Diffusion control on reaction rate and strain rate (United States)

    O'Hara, Kieran


    In the southern Appalachians, the Blue Ridge-Piedmont crystalline thrust sheet was emplaced onto low-grade Late Precambrian and Paleozoic sedimentary rocks in the footwall along a basal detachment consisting of phyllosilicate-rich mylonites (phyllonites). The phyllonites developed first by mechanical breakdown of feldspar followed by chemical breakdown to white mica in the presence of a pore fluid. Diffusion of solute in the pore fluid is the rate limiting step in controlling reaction rate and also the strain rate. Assuming solute diffusion follows the Stokes-Einstein equation, the shear st