Fault recovery characteristics of the fault tolerant multi-processor

NASA Technical Reports Server (NTRS)

Padilla, Peter A.

1990-01-01

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

Progressive failure during the 1596 Keicho earthquakes on the Median Tectonic Line active fault zone, southwest Japan

NASA Astrophysics Data System (ADS)

Ikeda, M.; Toda, S.; Nishizaka, N.; Onishi, K.; Suzuki, S.

2015-12-01

Rupture patterns of a long fault system are controlled by spatial heterogeneity of fault strength and stress associated with geometrical characteristics and stress perturbation history. Mechanical process for sequential ruptures and multiple simultaneous ruptures, one of the characteristics of a long fault such as the North Anatolian fault, governs the size and frequency of large earthquakes. Here we introduce one of the cases in southwest Japan and explore what controls rupture initiation, sequential ruptures and fault branching on a long fault system. The Median Tectonic Line active fault zone　(hereinafter MTL) is the longest and most active fault in Japan. Based on historical accounts, a series of M ≥ 7 earthquakes occurred on at least a 300-km-long portion of the MTL in 1596. On September 1, the first event occurred on the Kawakami fault segment, in Central Shikoku, and the subsequent events occurred further west. Then on September 5, another rupture initiated from the Central to East Shikoku and then propagated toward the Rokko-Awaji fault zone to Kobe, a northern branch of the MTL, instead of the eastern main extent of the MTL. Another rupture eventually extended to near Kyoto. To reproduce this progressive failure, we applied two numerical models: one is a coulomb stress transfer; the other is a slip-tendency analysis under the tectonic stress. We found that Coulomb stress imparted from historical ruptures have triggered the subsequent ruptures nearby. However, stress transfer does not explain beginning of the sequence and rupture directivities. Instead, calculated slip-tendency values show highly variable along the MTL: high and low seismic potential in West and East Shikoku. The initiation point of the 1596 progressive failure locates near the boundary in the slip-tendency values. Furthermore, the slip-tendency on the Rokko-Awaji fault zone is far higher than that of the MTL in Wakayama, which may explain the rupture directivity toward Kobe-Kyoto.

Examining Relay Ramp Evolution Through Paleo-shoreline Deformation Analysis, Warner Valley Fault, Oregon

NASA Astrophysics Data System (ADS)

Young, C. S.; Dawers, N. H.

2017-12-01

Fault growth is often accomplished by linking a series of en echelon faults through relay ramps. A relay ramp is the area between two overlapping fault segments that tilts and deforms as the faults accrue displacement. The structural evolution of breached normal fault relay ramps remains poorly understood because of the difficulty in defining how slip is partitioned between the most basinward fault (known as the outboard fault), the overlapping fault (inboard fault), and any ramp-breaching linking faults. Along the Warner Valley fault in south-central Oregon, two relay ramps displaying different fault linkage geometries are lined with a series of paleo-lacustrine shorelines that record a Pleistocene paleolake regression. The inner edges of these shorelines act as paleo-horizontal datums that have been deformed by fault activity, and are used to measure relative slip variations across the relay ramp bounding faults. By measuring the elevation changes using a 10m digital elevation model (DEM) of shoreline inner edges, we estimate the amount of slip partitioned between the inboard, outboard and ramp-breaching linking faults. In order to attribute shoreline deformation to fault activity we identify shoreline elevation anomalies, where deformation exceeds a ± 3.34 m window, which encompass our conservative estimates of natural variability in the shoreline geomorphology and the error associated with the data collection. Fault activity along the main length of the fault for each ramp-breaching style is concentrated near the intersection of the linking fault and the outboard portion of the main fault segment. However, fault activity along the outboard fault tip varies according to breaching style. At a footwall breach the entire outboard fault tip appears relatively inactive. At a mid-ramp breach the outboard fault tip remains relatively active because of the proximity of the linking fault to this fault tip.

Magnetometric and gravimetric surveys in fault detection over Acambay System

NASA Astrophysics Data System (ADS)

García-Serrano, A.; Sanchez-Gonzalez, J.; Cifuentes-Nava, G.

2013-05-01

In commemoration of the centennial of the Acambay intraplate earthquake of November 19th 1912, we carry out gravimetric and magnetometric surveys to define the structure of faults caused by this event. The study area is located approximately 11 km south of Acambay, in the Acambay-Tixmadeje fault system, where we performed two magnetometric surveys, the first consisting of 17 lines with a spacing of 35m between lines and 5m between stations, and the second with a total of 12 lines with the same spacing, both NW. In addition to these two lines we performed gravimetric profiles located in the central part of each magnetometric survey, with a spacing of 25m between stations, in order to correlate the results of both techniques, the lengths of such profiles were of 600m and 550m respectively. This work describes the data processing including directional derivatives, analytical signal and inversion, by means of which we obtain results of magnetic variations and anomaly traits highly correlated with those faults. It is of great importance to characterize these faults given the large population growth in the area and settlement houses on them, which involves a high risk in the security of the population, considering that these are active faults and cannot be discard earthquakes associated with them, so it is necessary for the authorities and people have relevant information to these problem.

The Northern end of the Dead Sea Basin: Geometry from reflection seismic evidence

USGS Publications Warehouse

Al-Zoubi, A. S.; Heinrichs, T.; Qabbani, I.; ten Brink, Uri S.

2007-01-01

Recently released reflection seismic lines from the Eastern side of the Jordan River north of the Dead Sea were interpreted by using borehole data and incorporated with the previously published seismic lines of the eastern side of the Jordan River. For the first time, the lines from the eastern side of the Jordan River were combined with the published reflection seismic lines from the western side of the Jordan River. In the complete cross sections, the inner deep basin is strongly asymmetric toward the Jericho Fault supporting the interpretation of this segment of the fault as the long-lived and presently active part of the Dead Sea Transform. There is no indication for a shift of the depocenter toward a hypothetical eastern major fault with time, as recently suggested. Rather, the north-eastern margin of the deep basin takes the form of a large flexure, modestly faulted. In the N-S-section along its depocenter, the floor of the basin at its northern end appears to deepen continuously by roughly 0.5??km over 10??km distance, without evidence of a transverse fault. The asymmetric and gently-dipping shape of the basin can be explained by models in which the basin is located outside the area of overlap between en-echelon strike-slip faults. ?? 2007 Elsevier B.V. All rights reserved.

Using Near Surface P and S Wave Velocities and Seismic Reflection Images to Detect the Westerly Extension of the Active Meishan Fault in Southwestern Taiwan

NASA Astrophysics Data System (ADS)

Putriani, E.; Huang, W. H.; Shih, R. C.

2017-12-01

The Southwestern Taiwan has higher potential seismic risks among the island. In 1906 the Meishan earthquake of magnitude 7.1 caused very severe damages. The associated Meishan fault was believed extended from Meishan westerly to Hsingang area for 23 km long; however, only the eastern part of the fault could be traces on the surface. The western part of the Meishan fault was simply proposed from the observed lineation of sand blow from the middle of the fault, the Minhsiung area westerly to the Hsingang area. The purpose of this paper is hope to prove the extension of this fault by using near surface P wave and S wave velocities and the seismic reflection images acquired across the suspicious fault location. Totally, we have conducted 20 seismic velocity survey lines, which were deployed in six areas with and without liquefaction observed, and 2 seismic reflection lines. The P and S wave velocities variations were used to analyze depth of the water table, the elastic modulus, soil porosity and the safety factor for soil liquefaction assessment. Preliminary result of the seismic velocity distribution was effective within 17 m deep from surface and showed no particular difference at the sites of liquefaction observed or no liquefaction. The results could indicate that the sand blow observed in 1906 were not site dependent, but more likely related to activity of the Meishan fault. In order to detect the detailed fault trace, the seismic reflection images will be combined for interpreting the buried Meishan fault in the final result.

Fault Location Based on Synchronized Measurements: A Comprehensive Survey

PubMed Central

Al-Mohammed, A. H.; Abido, M. A.

2014-01-01

This paper presents a comprehensive survey on transmission and distribution fault location algorithms that utilize synchronized measurements. Algorithms based on two-end synchronized measurements and fault location algorithms on three-terminal and multiterminal lines are reviewed. Series capacitors equipped with metal oxide varistors (MOVs), when set on a transmission line, create certain problems for line fault locators and, therefore, fault location on series-compensated lines is discussed. The paper reports the work carried out on adaptive fault location algorithms aiming at achieving better fault location accuracy. Work associated with fault location on power system networks, although limited, is also summarized. Additionally, the nonstandard high-frequency-related fault location techniques based on wavelet transform are discussed. Finally, the paper highlights the area for future research. PMID:24701191

Characterizing the Iron Wash fault: A fault line scarp in Utah

NASA Astrophysics Data System (ADS)

Kozaci, O.; Ostenaa, D.; Goodman, J.; Zellman, M.; Hoeft, J.; Sowers, J. M.; Retson, T.

2015-12-01

The Iron Wash fault (IWF) is an approximately 30 mile-long, NW-SE trending structure, oriented perpendicular to the San Rafael Monocline near Green River in Utah. IWF exhibits well-expressed geomorphic features such as a linear escarpment with consistently north side down displacement. The fault coincides with an abrupt change in San Rafael Monocline dip angle along its eastern margin. The IWF is exposed in incised drainages where Jurassic Navajo sandstone (oldest) and Lower Carmel Formation (old), are juxtaposed against Jurassic Entrada sandstone (younger) and Quaternary alluvium (youngest). To assess the recency of activity of the IWF we performed detailed geomorphic mapping and a paleoseismic trenching investigation. A benched trench was excavated across a Quaternary fluvial terrace remnant across the mapped trace of the IWF. The uppermost gravel units and overlying colluvium are exposed in the trench across the projection of the fault. In addition, we mapped the basal contact of the Quaternary gravel deposit in relation to the adjacent fault exposures in detail to show the geometry of the basal contact near and across the fault. We find no evidence of vertical displacement of these Quaternary gravels. A preliminary U-series date of calcite cementing unfaulted fluvial gravels and OSL dating of a sand lens within the unfaulted fluvial gravels yielded approximately 304,000 years and 78,000 years, respectively. These preliminary results of independent dating methods constrains the timing of last activity of the IWF to greater than 78,000 years before present suggesting that IWF not an active structure. Its distinct geomorphic expression is most likely the result of differential erosion, forming a fault-line scarp.

Arc burst pattern analysis fault detection system

NASA Technical Reports Server (NTRS)

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

1997-01-01

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

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

NASA Technical Reports Server (NTRS)

Padilla, Peter A.

1991-01-01

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

Interpretations on the Geologic Setting of Yogyakarta Earthquakes 2006 (Central Java, Indonesia) Based on Integration of Aftershock Monitoring and Existing Geologic, Geophysical and Remote Sensing Data

NASA Astrophysics Data System (ADS)

Setijadji, L. D.; Watanabe, K.; Fukuoka, K.; Ehara, S.; Setiadji, Y.; Rahardjo, W.; Susilo, A.; Barianto, D. H.; Harijoko, A.; Sudarno, I.; Pramumijoyo, S.; Hendrayana, H.; Akmalludin, A.; Nishijima, J.; Itaya, T.

2007-05-01

The unprecedented 26 May 2006 Yogyakarta earthquake (central Java, Indonesia) that took victims of 5,700 lives was generally accepted to have a depth of about 10 km and moment magnitude of 6.4. However, the definition of location of active fault is still under debate as the epicenter of mainshock was reported quite differently by several institutions. Many researchers believe that the Opak fault which is located at the eastern boundary of Yogyakarta low-land area (or Yogyakarta Basin) and the high-land region of Southern Mountains was the source of year 2006 earthquakes. However, our result of aftershocks observation suggests that the ruptured zone was not located along the Opak fault but from an unknown fault located about 10 km to the east from it and within the Southern Mountains domain. Unfortunately, surface geologic manifestations are scarce as this area is now largely covered by limestone. Therefore the suspected active fault system must be studied through interpretations of the subsurface geology and evaluation of the Cenozoic geo-history of the region utilizing existing geologic, geophysical and remote sensing data. This work suggests that the Yogyakarta Basin is a volcano-tectonic depression formed gradually since the early Tertiary period (Oligo-Miocene or older). Geological and geophysical evidence suggest that structural trends changed from the Oligocene NE-SW towards the Oligo-Miocene NNE-SSW and the Plio-Pleistocene NW-SE and E-W directions. The ruptured "X" fault during the Yogyakarta earthquakes 2006 is likely to be a NNE-SSW trending fault which is parallel to the Opak fault and both were firstly active in the Oligo-Miocene as sinistral strike-slip faults. However, while the Opak fault had changed into a normal faulting after the Pliocene, the evidence from Kali Ngalang and Kali Widoro suggests that the "X" fault system was still reactivated as a strike-slip one during the Plio-Pleistocene orogeny. As this new interpretation of active fault causes spatial discrepancy between locations of earthquakes epicenters and highly damaged regions, other geo-engineering factors must be considerably important in determining the final scale of seismic hazards. The most vulnerable areas for seismic hazards are those located nearest to the ruptured fault and are underlain by thick Quaternary unconsolidated deposits. In case of regions along the fault line, seismic hazards seem to reach more distance region, such as the case of Gantiwarno region, as the seismic waves can travel more easily along the fault line.

Recently Active Traces of the Berryessa Fault, California: A Digital Database

USGS Publications Warehouse

Lienkaemper, James J.

2012-01-01

The purpose of this map is to show the location of and evidence for recent movement on active fault traces within the Berryessa section and parts of adjacent sections of the Green Valley Fault Zone, California. The location and recency of the mapped traces is primarily based on geomorphic expression of the fault as interpreted from large-scale 2010 aerial photography and from 2007 and 2011 0.5 and 1.0 meter bare-earth LiDAR imagery (that is, high-resolution topographic data). In a few places, evidence of fault creep and offset Holocene strata in trenches and natural exposures have confirmed the activity of some of these traces. This publication is formatted both as a digital database for use within a geographic information system (GIS) and for broader public access as map images that may be browsed on-line or download a summary map. The report text describes the types of scientific observations used to make the map, gives references pertaining to the fault and the evidence of faulting, and provides guidance for use of and limitations of the map.

Structure of the active rift zone and margins of the northern Imperial Valley from Salton Seismic Imaging Project (SSIP) data

NASA Astrophysics Data System (ADS)

Livers, A.; Han, L.; Delph, J. R.; White-Gaynor, A. L.; Petit, R.; Hole, J. A.; Stock, J. M.; Fuis, G. S.

2012-12-01

First-arrival refraction data were used to create a seismic velocity model of the upper crust across the actively rifting northern Imperial Valley and its margins. The densely sampled seismic refraction data were acquired by the Salton Seismic Imaging Project (SSIP) , which is investigating rift processes in the northern-most rift segment of the Gulf of California extensional province and earthquake hazards at the southern end of the San Andreas Fault system. A 95-km long seismic line was acquired across the northern Imperial Valley, through the Salton Sea geothermal field, parallel to the five Salton Butte volcanoes and perpendicular to the Brawley Seismic Zone and major strike-slip faults. Nineteen explosive shots were recorded with 100 m seismometer spacing across the valley and with 300-500 m spacing into the adjacent ranges. First-arrival travel times were picked from shot gathers along this line and a seismic velocity model was produced using tomographic inversion. Sedimentary basement and seismic basement in the valley are interpreted to be sediment metamorphosed by the very high heat flow. The velocity model shows that this basement to the west of the Brawley Seismic Zone is at ~4-km depth. The basement shallows to ~2-km depth in the active geothermal field and Salton Buttes volcanic field which locally coincide with the Brawley Seismic Zone. At the eastern edge of the geothermal field, the basement drops off again to ~3.5-km depth. The eastern edge of the valley appears to be fault bounded by the along-strike extension of the Sand Hills Fault, an inactive strike-slip fault. The seismic velocities to the east of the fault correspond to metamorphic rock of the Chocolate Mountains, different from the metamorphosed basement in the valley. The western edge of the valley appears to be fault bounded by the active Superstition Hills Fault. To the west of the valley, >4-km deep valley basement extends to the active Superstition Hills Fault. Basement then shallows westward towards exposures of granitic basement in the Superstition Mountains. The basin between the Superstition Mountains and Coyote Mountains is ~2 km deep.

Development of an accurate transmission line fault locator using the global positioning system satellites

NASA Technical Reports Server (NTRS)

Lee, Harry

1994-01-01

A highly accurate transmission line fault locator based on the traveling-wave principle was developed and successfully operated within B.C. Hydro. A transmission line fault produces a fast-risetime traveling wave at the fault point which propagates along the transmission line. This fault locator system consists of traveling wave detectors located at key substations which detect and time tag the leading edge of the fault-generated traveling wave as if passes through. A master station gathers the time-tagged information from the remote detectors and determines the location of the fault. Precise time is a key element to the success of this system. This fault locator system derives its timing from the Global Positioning System (GPS) satellites. System tests confirmed the accuracy of locating faults to within the design objective of +/-300 meters.

Tectonoestratigraphic and Thermal Models of the Tiburon and Wagner Basins, northern Gulf of California Rift System

NASA Astrophysics Data System (ADS)

Contreras, J.; Ramirez Zerpa, N. A.; Negrete-Aranda, R.

2014-12-01

The northern Gulf of California Rift System consist sofa series faults that accommodate both normal and strike-slip motion. The faults formed a series of half-greens filled with more than 7 km of siliciclastic suc­cessions. Here, we present tectonostratigraphic and heat flow models for the Tiburón basin, in the southern part of the system, and the Wag­ner basin in the north. The models are constrained by two-dimensional seis­mic lines and by two deep boreholes drilled by PEMEX­-PEP. Analysis of the seismic lines and models' results show that: (i) subsidence of the basins is controlled by high-angle normal faults and by flow of the lower crust, (ii) basins share a common history, and (iii) there are significant differences in the way brittle strain was partitioned in the basins, a feature frequently observed in rift basins. On one hand, the bounding faults of the Tiburón basin have a nested geometry and became active following a west-to-east sequence of activation. The Tiburon half-graben was formed by two pulses of fault activity. One took place during the protogulf extensional phase in the Miocene and the other during the opening of Gulf of California in the Pleistocene. On the other hand, the Wagner basin is the result of two fault generations. During the late-to middle Miocene, the west-dipping Cerro Prieto and San Felipe faults formed a domino array. Then, during the Pleistocene the Consag and Wagner faults dissected the hanging-wall of the Cerro Prieto fault forming the modern Wagner basin. Thermal modeling of the deep borehole temperatures suggests that the heat flow in these basins in the order of 110 mW/m2 which is in agreement with superficial heat flow measurements in the northern Gulf of California Rift System.

Development of a Converter-Based Transmission Line Emulator with Three-Phase Short-Circuit Fault Emulation Capability

DOE PAGES

Zhang, Shuoting; Liu, Bo; Zheng, Sheng; ...

2018-01-01

A transmission line emulator has been developed to flexibly represent interconnected ac lines under normal operating conditions in a voltage source converter (VSC)-based power system emulation platform. As the most serious short-circuit fault condition, the three-phase short-circuit fault emulation is essential for power system studies. Here, this paper proposes a model to realize a three-phase short-circuit fault emulation at different locations along a single transmission line or one of several parallel-connected transmission lines. At the same time, a combination method is proposed to eliminate the undesired transients caused by the current reference step changes while switching between the fault statemore » and the normal state. Experiment results verify the developed transmission line three-phase short-circuit fault emulation capability.« less

Development of a Converter-Based Transmission Line Emulator with Three-Phase Short-Circuit Fault Emulation Capability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Shuoting; Liu, Bo; Zheng, Sheng

A transmission line emulator has been developed to flexibly represent interconnected ac lines under normal operating conditions in a voltage source converter (VSC)-based power system emulation platform. As the most serious short-circuit fault condition, the three-phase short-circuit fault emulation is essential for power system studies. Here, this paper proposes a model to realize a three-phase short-circuit fault emulation at different locations along a single transmission line or one of several parallel-connected transmission lines. At the same time, a combination method is proposed to eliminate the undesired transients caused by the current reference step changes while switching between the fault statemore » and the normal state. Experiment results verify the developed transmission line three-phase short-circuit fault emulation capability.« less

Power plant fault detection using artificial neural network

NASA Astrophysics Data System (ADS)

Thanakodi, Suresh; Nazar, Nazatul Shiema Moh; Joini, Nur Fazriana; Hidzir, Hidzrin Dayana Mohd; Awira, Mohammad Zulfikar Khairul

2018-02-01

The fault that commonly occurs in power plants is due to various factors that affect the system outage. There are many types of faults in power plants such as single line to ground fault, double line to ground fault, and line to line fault. The primary aim of this paper is to diagnose the fault in 14 buses power plants by using an Artificial Neural Network (ANN). The Multilayered Perceptron Network (MLP) that detection trained utilized the offline training methods such as Gradient Descent Backpropagation (GDBP), Levenberg-Marquardt (LM), and Bayesian Regularization (BR). The best method is used to build the Graphical User Interface (GUI). The modelling of 14 buses power plant, network training, and GUI used the MATLAB software.

Automatic fault tracing of active faults in the Sutlej valley (NW-Himalayas, India)

NASA Astrophysics Data System (ADS)

Janda, C.; Faber, R.; Hager, C.; Grasemann, B.

2003-04-01

In the Sutlej Valley the Lesser Himalayan Crystalline Sequence (LHCS) is actively extruding between the Munsiari Thrust (MT) at the base, and the Karcham Normal Fault (KNF) at the top. The clear evidences for ongoing deformation are brittle faults in Holocene lake deposits, hot springs activity near the faults and dramatically younger cooling ages within the LHCS (Vannay and Grasemann, 2001). Because these brittle fault zones obviously influence the morphology in the field we developed a new method for automatically tracing the intersections of planar fault geometries with digital elevation models (Faber, 2002). Traditional mapping techniques use structure contours (i.e. lines or curves connecting points of equal elevation on a geological structure) in order to construct intersections of geological structures with topographic maps. However, even if the geological structure is approximated by a plane and therefore structure contours are equally spaced lines, this technique is rather time consuming and inaccurate, because errors are cumulative. Drawing structure contours by hand makes it also impossible to slightly change the azimuth and dip direction of the favoured plane without redrawing everything from the beginning on. However, small variations of the fault position which are easily possible by either inaccuracies of measurement in the field or small local variations in the trend and/or dip of the fault planes can have big effects on the intersection with topography. The developed method allows to interactively view intersections in a 2D and 3D mode. Unlimited numbers of planes can be moved separately in 3 dimensions (translation and rotation) and intersections with the topography probably following morphological features can be mapped. Besides the increase of efficiency this method underlines the shortcoming of classical lineament extraction ignoring the dip of planar structures. Using this method, areas of active faulting influencing the morphology, can be mapped near the MT and the KNF suggesting that the most active zones are restricted to the Sutlej Valley. Faber R., 2002: WinGeol - Software for Analyzing and Visualization of Geological data, Department of Geological Sciences, University of Vienna. Vannay, J.-C., Grasemann, B., 2001. Himalayan inverted metamorphism and syn-convergence extension as a consequence of a general shear extrusion. Geol. Mag. 138 (3), 253-276.

Paleoseismic study of the Kamishiro Fault on the northern segment of the Itoigawa-Shizuoka Tectonic Line, Japan

NASA Astrophysics Data System (ADS)

Lin, Aiming; Sano, Mikako; Wang, Maomao; Yan, Bing; Bian, Di; Fueta, Ryoji; Hosoya, Takashi

2017-07-01

The Mw 6.2 (Mj 6.8) Nagano (Japan) earthquake of 22 November 2014 produced a 9.3-km long surface rupture zone with a thrust-dominated displacement of up to 1.5 m, which duplicated the pre-existing Kamishiro Fault along the Itoigawa-Shizuoka Tectonic Line (ISTL), the plate-boundary between the Eurasian and North American plates, northern Nagano Prefecture, central Japan. To characterize the activity of the seismogenic fault zone, we conducted a paleoseismic study of the Kamishiro Fault. Field investigations and trench excavations revealed that seven morphogenic paleohistorical earthquakes (E2-E8) prior to the 2014 Mw 6.2 Nagano earthquake (E1) have occurred on the Kamishiro Fault during the last ca. 6000 years. Three of these events (E2-E4) are well constrained and correspond to historical earthquakes occurring in the last ca. 1200 years. This suggests an average recurrence interval of ca. 300-400 years on the seismogenic fault of the 2014 Kamishiro earthquake in the past 1200 years. The most recent event prior to the 2014 earthquakes (E1) is E2 and the penultimate and antepenultimate faulting events are E3 and E4, respectively. The penultimate faulting event (E3) occurred during the period of AD 1800-1400 and is associated with the 1791 Mw 6.8 earthquake. The antepenultimate faulting event (E4) is inferred to have occurred during the period of ca. AD 1000-700, likely corresponding to the AD 841 Mw 6.5 earthquake. The oldest faulting event (E8) in the study area is thought to have occurred during the period of ca. 5600-6000 years. The throw rate during the early Holocene is estimated to be 1.2-3.3 mm/a (average, 2.2 mm/a) with an average amount of characteristic offset of 0.7-1.1 m produced by individual event. When compared with active intraplate faults on Honshu Island, Japan, these slip rates and recurrence interval estimated for morphogenic earthquakes on the Kamishiro Fault along the ISTL appear high and short, respectively. This indicates that present activity on this fault is closely related to seismic faulting along the plate boundary between the Eurasian and North American plates.

Paleoseismic study of the Kamishiro Fault on the northern segment of the Itoigawa-Shizuoka Tectonic Line, Japan.

PubMed

Lin, Aiming; Sano, Mikako; Wang, Maomao; Yan, Bing; Bian, Di; Fueta, Ryoji; Hosoya, Takashi

2017-01-01

The M w 6.2 (Mj 6.8) Nagano (Japan) earthquake of 22 November 2014 produced a 9.3-km long surface rupture zone with a thrust-dominated displacement of up to 1.5 m, which duplicated the pre-existing Kamishiro Fault along the Itoigawa-Shizuoka Tectonic Line (ISTL), the plate-boundary between the Eurasian and North American plates, northern Nagano Prefecture, central Japan. To characterize the activity of the seismogenic fault zone, we conducted a paleoseismic study of the Kamishiro Fault. Field investigations and trench excavations revealed that seven morphogenic paleohistorical earthquakes (E2-E8) prior to the 2014 M w 6.2 Nagano earthquake (E1) have occurred on the Kamishiro Fault during the last ca. 6000 years. Three of these events (E2-E4) are well constrained and correspond to historical earthquakes occurring in the last ca. 1200 years. This suggests an average recurrence interval of ca. 300-400 years on the seismogenic fault of the 2014 Kamishiro earthquake in the past 1200 years. The most recent event prior to the 2014 earthquakes (E1) is E2 and the penultimate and antepenultimate faulting events are E3 and E4, respectively. The penultimate faulting event (E3) occurred during the period of AD 1800-1400 and is associated with the 1791 M w 6.8 earthquake. The antepenultimate faulting event (E4) is inferred to have occurred during the period of ca. AD 1000-700, likely corresponding to the AD 841 M w 6.5 earthquake. The oldest faulting event (E8) in the study area is thought to have occurred during the period of ca. 5600-6000 years. The throw rate during the early Holocene is estimated to be 1.2-3.3 mm/a (average, 2.2 mm/a) with an average amount of characteristic offset of 0.7-1.1 m produced by individual event. When compared with active intraplate faults on Honshu Island, Japan, these slip rates and recurrence interval estimated for morphogenic earthquakes on the Kamishiro Fault along the ISTL appear high and short, respectively. This indicates that present activity on this fault is closely related to seismic faulting along the plate boundary between the Eurasian and North American plates.

Artificial Neural Network Based Fault Diagnostics of Rotating Machinery Using Wavelet Transforms as a Preprocessor

NASA Astrophysics Data System (ADS)

Paya, B. A.; Esat, I. I.; Badi, M. N. M.

1997-09-01

The purpose of condition monitoring and fault diagnostics are to detect and distinguish faults occurring in machinery, in order to provide a significant improvement in plant economy, reduce operational and maintenance costs and improve the level of safety. The condition of a model drive-line, consisting of various interconnected rotating parts, including an actual vehicle gearbox, two bearing housings, and an electric motor, all connected via flexible couplings and loaded by a disc brake, was investigated. This model drive-line was run in its normal condition, and then single and multiple faults were introduced intentionally to the gearbox, and to the one of the bearing housings. These single and multiple faults studied on the drive-line were typical bearing and gear faults which may develop during normal and continuous operation of this kind of rotating machinery. This paper presents the investigation carried out in order to study both bearing and gear faults introduced first separately as a single fault and then together as multiple faults to the drive-line. The real time domain vibration signals obtained for the drive-line were preprocessed by wavelet transforms for the neural network to perform fault detection and identify the exact kinds of fault occurring in the model drive-line. It is shown that by using multilayer artificial neural networks on the sets of preprocessed data by wavelet transforms, single and multiple faults were successfully detected and classified into distinct groups.

The characteristics of seismic activity during the 2016 Kumamoto Earthquake sequence

NASA Astrophysics Data System (ADS)

Yano, T. E.; Matsubara, M.

2016-12-01

We have relocated hypocenters (total number of hypocenters to be relocated within five independent regions; N= 37,136) during the 2016 Kumamoto Earthquake sequence applying the NIED Hi-net phase pick data and waveform cross-correlations to hypoDD (Waldhauser and Ellsworth, 2000), the double-difference method. The relocated seismicity clearly trace linearly to the background seismicity, such as the Hinagu, Futagawa, and Beppu-Haneyama fault zone, and Mt. Aso area, but also form a linear seismic activity at the previously quiet area including northern edge of the caldera of Mt. Aso (Aso caldera) and some areas within the Beppu-Haneyama fault zone. Two mainshocks of M6.5 on April 14th and M7.3 on April 16th occurred at the region where the Hinagu and Futagawa faults meet each other. Our results show that the seismicity forming a shape enough to identify a line along the Hinagu fault for about 20 km immediately after the M6.3 and continues after the M7.5 event. It also make enable to trace a line of seismicity along the Futagawa fault to the east (total of about 28 km), northern part of the Aso caldera, and Ohita region along the Beppu-Haneyama fault zone becomes active only after the M7.5 event. Not only seismicity following the known faults but also seismicity unconfirmed from background seismicity in previous relocation study between 2000 and 2012 (Yano, et al., 2016) appears during the Kumamoto Earthquake sequence. By comparing our high resolution relocated catalog in the Kumamoto region from previous study and this study enable us to identified interesting characteristics; (1) the quiet area making as a gap of seismicity between the northeast extension of the Futagawa fault zone and Mt. Aso region appears only after the M7.5 event, (2) the seismicity forming a vertical or high angle dip in Aso and Ohita regions are selectively activated, (3) the linear seismicity at previously unconfirmed regions where at the northern part of the Aso caldera and along the Beppu-Haneyama fault zone. We present these characteristics of seismicity during the Kumamoto Earthquake sequence in detail.

Scissoring Fault Rupture Properties along the Median Tectonic Line Fault Zone, Southwest Japan

NASA Astrophysics Data System (ADS)

Ikeda, M.; Nishizaka, N.; Onishi, K.; Sakamoto, J.; Takahashi, K.

2017-12-01

The Median Tectonic Line fault zone (hereinafter MTLFZ) is the longest and most active fault zone in Japan. The MTLFZ is a 400-km-long trench parallel right-lateral strike-slip fault accommodating lateral slip components of the Philippine Sea plate oblique subduction beneath the Eurasian plate [Fitch, 1972; Yeats, 1996]. Complex fault geometry evolves along the MTLFZ. The geomorphic and geological characteristics show a remarkable change through the MTLFZ. Extensional step-overs and pull-apart basins and a pop-up structure develop in western and eastern parts of the MTLFZ, respectively. It is like a "scissoring fault properties". We can point out two main factors to form scissoring fault properties along the MTLFZ. One is a regional stress condition, and another is a preexisting fault. The direction of σ1 anticlockwise rotate from N170°E [Famin et al., 2014] in the eastern Shikoku to Kinki areas and N100°E [Research Group for Crustral Stress in Western Japan, 1980] in central Shikoku to N85°E [Onishi et al., 2016] in western Shikoku. According to the rotation of principal stress directions, the western and eastern parts of the MTLFZ are to be a transtension and compression regime, respectively. The MTLFZ formed as a terrain boundary at Cretaceous, and has evolved with a long active history. The fault style has changed variously, such as left-lateral, thrust, normal and right-lateral. Under the structural condition of a preexisting fault being, the rupture does not completely conform to Anderson's theory for a newly formed fault, as the theory would require either purely dip-slip motion on the 45° dipping fault or strike-slip motion on a vertical fault. The fault rupture of the 2013 Barochistan earthquake in Pakistan is a rare example of large strike-slip reactivation on a relatively low angle dipping fault (thrust fault), though many strike-slip faults have vertical plane generally [Avouac et al., 2014]. In this presentation, we, firstly, show deep subsurface structures of the MTLFZ based on newly obtained data and previous research results. And then, we discuss how the relationship between the surface fault geometry and the deep subsurface structures changes through the MTLFZ which is under the heterogeneous regional stress condition.

Current limiting behavior in three-phase transformer-type SFCLs using an iron core according to variety of fault

NASA Astrophysics Data System (ADS)

Cho, Yong-Sun; Jung, Byung-Ik; Ha, Kyoung-Hun; Choi, Soo-Geun; Park, Hyoung-Min; Choi, Hyo-Sang

To apply the superconducting fault current limiter (SFCL) to the power system, the reliability of the fault-current-limiting operation must be ensured in diverse fault conditions. The SFCL must also be linked to the operation of the high-speed recloser in the power system. In this study, a three-phase transformer-type SFCL, which has a neutral line to improve the simultaneous quench characteristics of superconducting elements, was manufactured to analyze the fault-current-limiting characteristic according to the single, double, and triple line-to-ground faults. The transformer-type SFCL, wherein three-phase windings are connected to one iron core, reduced the burden on the superconducting element as the superconducting element on the sound phase was also quenched in the case of the single line-to-ground fault. In the case of double or triple line-to-ground faults, the flux from the faulted phase winding was interlinked with other faulted or sound phase windings, and the fault-current-limiting rate decreased because the windings of three phases were inductively connected by one iron core.

Faults in parts of north-central and western Houston metropolitan area, Texas

USGS Publications Warehouse

Verbeek, Earl R.; Ratzlaff, Karl W.; Clanton, Uel S.

1979-01-01

Hundreds of residential, commercial, and industrial structures in the Houston metropolitan area have sustained moderate to severe damage owing to their locations on or near active faults. Paved roads have been offset by faults at hundreds of locations, butted pipelines have been distorted by fault movements, and fault-induced gradient changes in drainage lines have raised concern among flood control engineers. Over 150 faults, many of them moving at rates of 0.5 to 2 cm/yr, have been mapped in the Houston area; the number of faults probably far exceeds this figure.This report includes a map of eight faults, in north-central and western Houston, at a scale useful for land-use planning. Seven of the faults, are known, to be active and have caused considerable damage to structures built on or near them. If the eighth fault is active, it may be of concern to new developments on the west side of Houston. A ninth feature shown on the map is regarded only as a possible fault, as an origin by faulting has not been firmly established.Seismic and drill-hold data for some 40 faults, studied in detail by various investigators have verified connections between scarps at the land surface and growth faults in the shallow subsurface. Some scarps, then, are known to be the surface manifestations of faults that have geologically long histories of movement. The degree to which natural geologic processes contribute to current fault movement, however, is unclear, for some of man’s activities may play a role in faulting as well.Evidence that current rates of fault movement far exceed average prehistoric rates and that most offset of the land surface in the Houston area has occurred only within the last 50 years indirectly suggest that fluid withdrawal may be accelerating or reinitiating movement on pre-existing faults. This conclusion, however, is based only on a coincidence in time between increased fault activity and increased rates of withdrawal of water, oil, and gas from subsurface sediments; no cause-and-effect relationship has been demonstrated. An alternative hypothesis is that natural fault movements are characterized by short—term episodicity and that Houston is experiencing the effects of a brief period of accelerated natural fault movement. Available data from monitored faults are insufficient to weigh the relative importance of natural vs. induced fault movements.

Study of a phase-to-ground fault on a 400 kV overhead transmission line

NASA Astrophysics Data System (ADS)

Iagăr, A.; Popa, G. N.; Diniş, C. M.

2018-01-01

Power utilities need to supply their consumers at high power quality level. Because the faults that occur on High-Voltage and Extra-High-Voltage transmission lines can cause serious damages in underlying transmission and distribution systems, it is important to examine each fault in detail. In this work we studied a phase-to-ground fault (on phase 1) of 400 kV overhead transmission line Mintia-Arad. Indactic® 650 fault analyzing system was used to record the history of the fault. Signals (analog and digital) recorded by Indactic® 650 were visualized and analyzed by Focus program. Summary of fault report allowed evaluation of behavior of control and protection equipment and determination of cause and location of the fault.

New Geologic Data on the Seismic Risks of the Most Dangerous Fault on Shore in Central Japan, the Itoigawa-Shizuoka Tectonic Line Active Fault System

NASA Astrophysics Data System (ADS)

Okumura, K.; Kondo, H.; Toda, S.; Takada, K.; Kinoshita, H.

2006-12-01

Ten years have past since the first official assessment of the long-term seismic risks of the Itoigawa-Shizuoka tectonic line active fault system (ISTL) in 1996. The disaster caused by the1995 Kobe (Hyogo-ken-Nanbu) earthquake urged the Japanese government to initiated a national project to assess the long-term seismic risks of on-shore active faults using geologic information. ISTL was the first target of the 98 significant faults and the probability of a M7 to M8 event turned out to be the highest among them. After the 10 years of continued efforts to understand the ISTL, now it is getting ready to revise the assessment. Fault mapping and segmentation: The most active segment of the Gofukuji fault (~1 cm/yr left-lateral strike slip, R=500~800 yrs.) had been maped only for less than 10 km. Adjacent segments were much less active. This large slip on such a short segment was contradictory. However, detailed topographic study including Lidar survey revealed the length of the Gofukuji fault to be 25 km or more. High slip rate with frequent earthquakes may be restricted to the Gofukuji fault while the 1996 assessment modeled frequent >100 km rupture scenario. The geometry of the fault is controversial especially on the left-lateral strike-slip section of the ISTL. There are two models of high-angle Middel ISTL and low-angle Middle ISTL with slip partitioning. However, all geomorphic and shallow geologic data supports high-angle almost pure strike slip on the faults in the Middle ISTL. CRIEPI's 3- dimensional trenching in several sites as well as the previous results clearly demonstrated repeated pure strike-slip offset during past a few events. In Middle ISTL, there is no evidence of recent activity of pre-existing low-angle thrust faults that are inferred to be active from shallow seismic survey. Separation of high (~3000 m) mountain ranges and low (<1000 m) basin floor requires significant dip-slip component, but basin-fill sediments and geology of the range do not need vertical separation along the Gofukuji fault. The key issue for the time-dependent assessment of the Northern ISTL (east dipping reverse faults) was the lack of reliable time constraints on past earthquakes. In order to solve this problem, we have carried out intensive geoslicer and boring survey of buried faults at Kisaki. Along a 35 m long transect, we collected total 150 m complete cores in 9 geoslicer and 5 all-core boring holes. This is one of the most intensive surveys of a buried fault scarp under the water table. About 20 m vertical offset of 6000-year-old buried A-horizon is now underlain by a series of flood deposits, point bars and over-bank sediments, that intercalates 2 or 3 faulting events. The precise timing and offset of each event recorded in the section will be the critical evidence to tell the synchroneity of earthquakes in the Northern ISTL and the Middle ISTL. The magnitude of the coming event on ISTL is the most important but uncertain parameter of the 1996 assessment. The structural and paleoseimological information will present better constraints on the earthquake.

Fuzzy Inference System Approach for Locating Series, Shunt, and Simultaneous Series-Shunt Faults in Double Circuit Transmission Lines

PubMed Central

Swetapadma, Aleena; Yadav, Anamika

2015-01-01

Many schemes are reported for shunt fault location estimation, but fault location estimation of series or open conductor faults has not been dealt with so far. The existing numerical relays only detect the open conductor (series) fault and give the indication of the faulty phase(s), but they are unable to locate the series fault. The repair crew needs to patrol the complete line to find the location of series fault. In this paper fuzzy based fault detection/classification and location schemes in time domain are proposed for both series faults, shunt faults, and simultaneous series and shunt faults. The fault simulation studies and fault location algorithm have been developed using Matlab/Simulink. Synchronized phasors of voltage and current signals of both the ends of the line have been used as input to the proposed fuzzy based fault location scheme. Percentage of error in location of series fault is within 1% and shunt fault is 5% for all the tested fault cases. Validation of percentage of error in location estimation is done using Chi square test with both 1% and 5% level of significance. PMID:26413088

Pattern Recognition Application of Support Vector Machine for Fault Classification of Thyristor Controlled Series Compensated Transmission Lines

NASA Astrophysics Data System (ADS)

Yashvantrai Vyas, Bhargav; Maheshwari, Rudra Prakash; Das, Biswarup

2016-06-01

Application of series compensation in extra high voltage (EHV) transmission line makes the protection job difficult for engineers, due to alteration in system parameters and measurements. The problem amplifies with inclusion of electronically controlled compensation like thyristor controlled series compensation (TCSC) as it produce harmonics and rapid change in system parameters during fault associated with TCSC control. This paper presents a pattern recognition based fault type identification approach with support vector machine. The scheme uses only half cycle post fault data of three phase currents to accomplish the task. The change in current signal features during fault has been considered as discriminatory measure. The developed scheme in this paper is tested over a large set of fault data with variation in system and fault parameters. These fault cases have been generated with PSCAD/EMTDC on a 400 kV, 300 km transmission line model. The developed algorithm has proved better for implementation on TCSC compensated line with its improved accuracy and speed.

Ground-penetrating radar investigation of active faults along the Dead Sea Transform and implications for seismic hazards within the city of Aqaba, Jordan

NASA Astrophysics Data System (ADS)

Slater, Lee; Niemi, Tina M.

2003-06-01

Ground-penetrating radar (GPR) was used in an effort to locate a major active fault that traverses Aqaba City, Jordan. Measurements over an exposed (trenched) cross fault outside of the city identify a radar signature consisting of linear events and horizontal offset/flexured reflectors both showing a geometric correlation with two known faults at a control site. The asymmetric linear events are consistent with dipping planar reflectors matching the known direction of dip of the faults. However, other observations regarding this radar signature render the mechanism generating these events more complex and uncertain. GPR measurements in Aqaba City were limited to vacant lots. Seven GPR profiles were conducted approximately perpendicular to the assumed strike of the fault zone, based on regional geological evidence. A radar response very similar to that obtained over the cross fault was observed on five of the profiles in Aqaba City, although the response is weaker than that obtained at the control site. The positions of the identified responses form a near straight line with a strike of 45°. Although subsurface verification of the fault by trenching within the city is needed, the geophysical evidence for fault zone location is strong. The location of the interpreted fault zone relative to emergency services, military bases, commercial properties, and residential areas is defined to within a few meters. This study has significant implications for seismic hazard analysis in this tectonically active and heavily populated region.

Adaptive sensor-fault tolerant control for a class of multivariable uncertain nonlinear systems.

PubMed

Khebbache, Hicham; Tadjine, Mohamed; Labiod, Salim; Boulkroune, Abdesselem

2015-03-01

This paper deals with the active fault tolerant control (AFTC) problem for a class of multiple-input multiple-output (MIMO) uncertain nonlinear systems subject to sensor faults and external disturbances. The proposed AFTC method can tolerate three additive (bias, drift and loss of accuracy) and one multiplicative (loss of effectiveness) sensor faults. By employing backstepping technique, a novel adaptive backstepping-based AFTC scheme is developed using the fact that sensor faults and system uncertainties (including external disturbances and unexpected nonlinear functions caused by sensor faults) can be on-line estimated and compensated via robust adaptive schemes. The stability analysis of the closed-loop system is rigorously proven using a Lyapunov approach. The effectiveness of the proposed controller is illustrated by two simulation examples. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Development of a low cost method to estimate the seismic signature of a geothermal field from ambient seismic noise analysis, Authors: Tibuleac, I. M., J. Iovenitti, S. Pullammanapallil, D. von Seggern, F.H. Ibser, D. Shaw and H. McLahlan

NASA Astrophysics Data System (ADS)

Tibuleac, I. M.; Iovenitti, J. L.; Pullammanappallil, S. K.; von Seggern, D. H.; Ibser, H.; Shaw, D.; McLachlan, H.

2015-12-01

A new, cost effective and non-invasive exploration method using ambient seismic noise has been tested at Soda Lake, NV, with promising results. Seismic interferometry was used to extract Green's Functions (P and surface waves) from 21 days of continuous ambient seismic noise. With the advantage of S-velocity models estimated from surface waves, an ambient noise seismic reflection survey along a line (named Line 2), although with lower resolution, reproduced the results of the active survey, when the ambient seismic noise was not contaminated by strong cultural noise. Ambient noise resolution was less at depth (below 1000m) compared to the active survey. Useful information could be recovered from ambient seismic noise, including dipping features and fault locations. Processing method tests were developed, with potential to improve the virtual reflection survey results. Through innovative signal processing techniques, periods not typically analyzed with high frequency sensors were used in this study to obtain seismic velocity model information to a depth of 1.4km. New seismic parameters such as Green's Function reflection component lateral variations, waveform entropy, stochastic parameters (Correlation Length and Hurst number) and spectral frequency content extracted from active and passive surveys showed potential to indicate geothermal favorability through their correlation with high temperature anomalies, and showed potential as fault indicators, thus reducing the uncertainty in fault identification. Geothermal favorability maps along ambient seismic Line 2 were generated considering temperature, lithology and the seismic parameters investigated in this study and compared to the active Line 2 results. Pseudo-favorability maps were also generated using only the seismic parameters analyzed in this study.

Characterizing the structural maturity of fault zones using high-resolution earthquake locations.

NASA Astrophysics Data System (ADS)

Perrin, C.; Waldhauser, F.; Scholz, C. H.

2017-12-01

We use high-resolution earthquake locations to characterize the three-dimensional structure of active faults in California and how it evolves with fault structural maturity. We investigate the distribution of aftershocks of several recent large earthquakes that occurred on immature faults (i.e., slow moving and small cumulative displacement), such as the 1992 (Mw7.3) Landers and 1999 (Mw7.1) Hector Mine events, and earthquakes that occurred on mature faults, such as the 1984 (Mw6.2) Morgan Hill and 2004 (Mw6.0) Parkfield events. Unlike previous studies which typically estimated the width of fault zones from the distribution of earthquakes perpendicular to the surface fault trace, we resolve fault zone widths with respect to the 3D fault surface estimated from principal component analysis of local seismicity. We find that the zone of brittle deformation around the fault core is narrower along mature faults compared to immature faults. We observe a rapid fall off of the number of events at a distance range of 70 - 100 m from the main fault surface of mature faults (140-200 m fault zone width), and 200-300 m from the fault surface of immature faults (400-600 m fault zone width). These observations are in good agreement with fault zone widths estimated from guided waves trapped in low velocity damage zones. The total width of the active zone of deformation surrounding the main fault plane reach 1.2 km and 2-4 km for mature and immature faults, respectively. The wider zone of deformation presumably reflects the increased heterogeneity in the stress field along complex and discontinuous faults strands that make up immature faults. In contrast, narrower deformation zones tend to align with well-defined fault planes of mature faults where most of the deformation is concentrated. Our results are in line with previous studies suggesting that surface fault traces become smoother, and thus fault zones simpler, as cumulative fault slip increases.

A Fault Location Algorithm for Two-End Series-Compensated Double-Circuit Transmission Lines Using the Distributed Parameter Line Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, Ning; Gombos, Gergely; Mousavi, Mirrasoul J.

A new fault location algorithm for two-end series-compensated double-circuit transmission lines utilizing unsynchronized two-terminal current phasors and local voltage phasors is presented in this paper. The distributed parameter line model is adopted to take into account the shunt capacitance of the lines. The mutual coupling between the parallel lines in the zero-sequence network is also considered. The boundary conditions under different fault types are used to derive the fault location formulation. The developed algorithm directly uses the local voltage phasors on the line side of series compensation (SC) and metal oxide varistor (MOV). However, when potential transformers are not installedmore » on the line side of SC and MOVs for the local terminal, these measurements can be calculated from the local terminal bus voltage and currents by estimating the voltages across the SC and MOVs. MATLAB SimPowerSystems is used to generate cases under diverse fault conditions to evaluating accuracy. The simulation results show that the proposed algorithm is qualified for practical implementation.« less

Fuzzy logic based on-line fault detection and classification in transmission line.

PubMed

Adhikari, Shuma; Sinha, Nidul; Dorendrajit, Thingam

2016-01-01

This study presents fuzzy logic based online fault detection and classification of transmission line using Programmable Automation and Control technology based National Instrument Compact Reconfigurable i/o (CRIO) devices. The LabVIEW software combined with CRIO can perform real time data acquisition of transmission line. When fault occurs in the system current waveforms are distorted due to transients and their pattern changes according to the type of fault in the system. The three phase alternating current, zero sequence and positive sequence current data generated by LabVIEW through CRIO-9067 are processed directly for relaying. The result shows that proposed technique is capable of right tripping action and classification of type of fault at high speed therefore can be employed in practical application.

A Novel Wide-Area Backup Protection Based on Fault Component Current Distribution and Improved Evidence Theory

PubMed Central

Zhang, Zhe; Kong, Xiangping; Yin, Xianggen; Yang, Zengli; Wang, Lijun

2014-01-01

In order to solve the problems of the existing wide-area backup protection (WABP) algorithms, the paper proposes a novel WABP algorithm based on the distribution characteristics of fault component current and improved Dempster/Shafer (D-S) evidence theory. When a fault occurs, slave substations transmit to master station the amplitudes of fault component currents of transmission lines which are the closest to fault element. Then master substation identifies suspicious faulty lines according to the distribution characteristics of fault component current. After that, the master substation will identify the actual faulty line with improved D-S evidence theory based on the action states of traditional protections and direction components of these suspicious faulty lines. The simulation examples based on IEEE 10-generator-39-bus system show that the proposed WABP algorithm has an excellent performance. The algorithm has low requirement of sampling synchronization, small wide-area communication flow, and high fault tolerance. PMID:25050399

Strain distribution across magmatic margins during the breakup stage: Seismicity patterns in the Afar rift zone

NASA Astrophysics Data System (ADS)

Brown, C.; Ebinger, C. J.; Belachew, M.; Gregg, T.; Keir, D.; Ayele, A.; Aronovitz, A.; Campbell, E.

2008-12-01

Fault patterns record the strain history along passive continental margins, but geochronological constraints are, in general, too sparse to evaluate these patterns in 3D. The Afar depression in Ethiopia provides a unique setting to evaluate the time and space relations between faulting and magmatism across an incipient passive margin that formed above a mantle plume. The margin comprises a high elevation flood basalt province with thick, underplated continental crust, a narrow fault-line escarpment underlain by stretched and intruded crust, and a broad zone of highly intruded, mafic crust lying near sealevel. We analyze fault and seismicity patterns across and along the length of the Afar rift zone to determine the spatial distribution of strain during the final stages of continental breakup, and its relation to active magmatism and dike intrusions. Seismicity data include historic data and 2005-2007 data from the collaborative US-UK-Ethiopia Afar Geodynamics Project that includes the 2005-present Dabbahu rift episode. Earthquake epicenters cluster within discrete, 50 km-long magmatic segments that lack any fault linkage. Swarms also cluster along the fault-line scarp between the unstretched and highly stretched Afar rift zone; these earthquakes may signal release of stresses generated by large lateral density contrasts. We compare Coulomb static stress models with focal mechanisms and fault kinematics to discriminate between segmented magma intrusion and crank- arm models for the central Afar rift zone.

Fault finder

DOEpatents

Bunch, Richard H.

1986-01-01

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

Connecting the Yakima fold and thrust belt to active faults in the Puget Lowland, Washington

USGS Publications Warehouse

Blakely, R.J.; Sherrod, B.L.; Weaver, C.S.; Wells, R.E.; Rohay, A.C.; Barnett, E.A.; Knepprath, N.E.

2011-01-01

High-resolution aeromagnetic surveys of the Cascade Range and Yakima fold and thrust belt (YFTB), Washington, provide insights on tectonic connections between forearc and back-arc regions of the Cascadia convergent margin. Magnetic surveys were measured at a nominal altitude of 250 m above terrain and along flight lines spaced 400 m apart. Upper crustal rocks in this region have diverse magnetic properties, ranging from highly magnetic rocks of the Miocene Columbia River Basalt Group to weakly magnetic sedimentary rocks of various ages. These distinctive magnetic properties permit mapping of important faults and folds from exposures to covered areas. Magnetic lineaments correspond with mapped Quaternary faults and with scarps identified in lidar (light detection and ranging) topographic data and aerial photography. A two-dimensional model of the northwest striking Umtanum Ridge fault zone, based on magnetic and gravity data and constrained by geologic mapping and three deep wells, suggests that thrust faults extend through the Tertiary section and into underlying pre-Tertiary basement. Excavation of two trenches across a prominent scarp at the base of Umtanum Ridge uncovered evidence for bending moment faulting possibly caused by a blind thrust. Using aeromagnetic, gravity, and paleoseismic evidence, we postulate possible tectonic connections between the YFTB in eastern Washington and active faults of the Puget Lowland. We suggest that faults and folds of Umtanum Ridge extend northwestward through the Cascade Range and merge with the Southern Whidbey Island and Seattle faults near Snoqualmie Pass 35 km east of Seattle. Recent earthquakes (MW ≤ 5.3) suggest that this confluence of faults may be seismically active today.

Anatomy of an Active Seismic Source: the Interplay between Present-Day Seismic Activity and Inherited Fault Zone Architecture (Central Apennines, Italy)

NASA Astrophysics Data System (ADS)

Fondriest, M.; Demurtas, M.; Bistacchi, A.; Fabrizio, B.; Storti, F.; Valoroso, L.; Di Toro, G.

2017-12-01

The mechanics and seismogenic behaviour of fault zones are strongly influenced by their internal structure, in terms of both fault geometry and fault rock constitutive properties. In recent years high-resolution seismological techniques yielded new constraints on the geometry and velocity structure of seismogenic faults down to 10s meters length scales. This reduced the gap between geophysical imaging of active seismic sources and field observations of exhumed fault zones. Nevertheless fundamental questions such as the origin of geometrical and kinematic complexities associated to seismic faulting remain open. We addressed these topics by characterizing the internal structure of the Vado di Corno Fault Zone, an active seismogenic normal fault cutting carbonates in the Central Apennines of Italy and comparing it with the present-day seismicity of the area. The fault footwall block, which was exhumed from < 2 km depth, was mapped with high detail (< 1 m spatial resolution) for 2 km of exposure along strike, combining field structural data and photogrammetric surveys in a three dimensional structural model. Three main structural units separated by principal fault strands were recognized: (i) cataclastic unit (20-100 m thick), (ii) damage zone (≤ 300 m thick), (iii) breccia unit ( 20 thick). The cataclastic unit lines the master fault and represents the core of the normal fault zone. In-situ shattering together with evidence of extreme (possibly coseismic) shear strain localization (e.g., mirror-like faults with truncated clasts, ultrafine-grained sheared veins) was recognized. The breccia unit is an inherited thrust zone affected by pervasive veining and secondary dolomitization. It strikes subparallel to the active normal fault and is characterized by a non-cylindrical geometry with 10-100 m long frontal and lateral ramps. The cataclastic unit cuts through thrust flats within the breccia unit, whereas normal to oblique inversion occur on frontal and lateral ramps. A comparable structural setting was imaged South-West of the study area, during the 2009 L'Aquila seismic sequence. Here at 2 km depth, the master normal fault cross-cuts a 10 km long flat structure and clear lateral ramps are illuminated, suggesting the superposition of normal seismic faulting on inherited compressional structures.

Imaging the polarity switch between large seismogenic normal faults in the southern Apennines (Italy)

NASA Astrophysics Data System (ADS)

Fracassi, U.; Milano, G.; di Giovambattista, R.; Ventura, G.

2009-04-01

The backbone of Italy's Apennines hosts the majority of the seismic moment release in the Italian peninsula. In particular, the area among the southern Abruzzo, southeastern Lazio and Molise regions in central-southern Italy includes the polarity switch, from north to south, between the large SW-verging seismogenic normal faults (the southernmost one being the Aremogna-Cinque Miglia, responsible for a Mw 6.4 event dated 800 B.C-1030 A.D.) and those NE-verging ones (the northernmost one being the Boiano Basin, responsible for the 26 July 1805, Mw 6.6 Molise earthquake), including the Carpino-Le Piane fault system. In addition, the area between these two faults is the locus of extension parallel to the chain axis, as shown by a low-magnitude (M < 3.3) seismic sequence occurred in 2001. As GPS data illustrate, NE-SW striking extension predominates in the western and the inner sectors of the Apennines. All active normal faults along the crest of the Apennines are essentially parallel to the mountain range (NW-SE) and are governed by the current extensional regime that has been in place since the Middle-Upper Pleistocene. However, the occurrence of such polarity switch between antithetic, conjugate seismogenic normal faults in Italy is very uncommon. In addition, the area of research marks the abrupt end of the two (three?) sub-parallel seismogenic belts in Abruzzo (to the north) and the inception of the single, aligned one in Molise (to the south), including the western termination of E-W striking, large oblique-slip faulting in the foreland. In other words, this is a critical area concerning seismogenesis in central Italy and, therefore, the tectonic mechanism that either causes or influences such polarity switch could represent a key ingredient in the above scenario. Between January and May 2005, the RSN (Italy's National Seismometric Network) recorded a rise in the background seismicity, that has been recently relocated. This sequence is essentially a low magnitude (Md < 3), swarm activity that clustered within the Ortona-Roccamonfina line, a regional structure striking NNE-SSW and separating the central from the southern Apennines, hypothesized and discussed by numerous authors; in particular its field evidence is still debated, as much as its present-day activity. Our data show that, at least in the area where the 2005 sequence has occurred, the spatial trend of seismic activity essentially coincides with a sector of the Ortona-Roccamonfina line. Concerning fault polarity switches, there are numerous case studies in the literature where such examples have been recognized and associated with accommodation zones. Various authors have shown that either a hard (transfer fault) or soft linkage (relay ramp) is kinematically needed to accommodate strain between the two. This would be particularly true in the case we present, i.e. with two large (~20-25 km long) convergent, approaching faults, at a distance (20-25 km) comparable in size to the length of the faults in question. According to these literature models for transfer zones, such transfer would occur at ~45° to the strike of the concerned faults, that is ~N-S in the studied area. The location of the clustered seismicity that occurred in 2005 between the Abruzzo and Molise regions shows a ~NNE-SSW alignment and falls within the area where a major polarity switch between large seismogenic faults occur. On the basis of (i) the spatial-temporal characteristics of this data and (ii) the geometry and kinematics of active faulting in the region, we hypothesize (a) the existence of a transfer zone between the Aremogna-Cinque Miglia and Boiano Basin faults, and (b) the activity of such linkage along the Ortona-Roccamonfina line in this sector of the chain where a major transition, both structural and seismogenic, occurs. Alternatively, this polarity switch could result mainly from the rheologic and tectonic control exerted by the abrupt passage between the two diverse paleogeographic domains that make up the boundary between the central and southern Apennines. The role of such possible control onto the nature and geometry of the transfer zone and their interaction with one another, including seismic activity, is part of a larger study currently underway.

The interpretation of crustal dynamics data in terms of plate interactions and active tectonics of the Anatolian Plate and surrounding regions in the Middle East

NASA Technical Reports Server (NTRS)

Toksoz, M. Nafi

1987-01-01

The primary effort in this study during the past year has been directed along two separate lines: (1) expanding finite element models to include the entire Anatolian plate, the Aegean Sea and the Northeastern Mediterranean Sea, and (2) investigating the relationship between fault geometry and earthquake activity for the North Anatolian and similar strike-slip faults (e.g., San Andreas Fault). Both efforts are designed to provide an improved basis for interpreting the Crustal Dynamics measurements NASA has planned for this region. The initial phases of both investigations have been completed and the results are being prepared for publication. These investigations are described briefly.

SAR-revealed slip partitioning on a bending fault plane for the 2014 Northern Nagano earthquake at the northern Itoigawa-Shizuoka tectonic line

NASA Astrophysics Data System (ADS)

Kobayashi, Tomokazu; Morishita, Yu; Yarai, Hiroshi

2018-05-01

By applying conventional cross-track synthetic aperture radar interferometry (InSAR) and multiple aperture InSAR techniques to ALOS-2 data acquired before and after the 2014 Northern Nagano, central Japan, earthquake, a three-dimensional ground displacement field has been successfully mapped. Crustal deformation is concentrated in and around the northern part of the Kamishiro Fault, which is the northernmost section of the Itoigawa-Shizuoka tectonic line. The full picture of the displacement field shows contraction in the northwest-southeast direction, but northeastward movement along the fault strike direction is prevalent in the northeast portion of the fault, which suggests that a strike-slip component is a significant part of the activity of this fault, in addition to a reverse faulting. Clear displacement discontinuities are recognized in the southern part of the source region, which falls just on the previously known Kamishiro Fault trace. We inverted the SAR and GNSS data to construct a slip distribution model; the preferred model of distributed slip on a two-plane fault surface shows a combination of reverse and left-lateral fault motions on a bending east-dipping fault surface with a dip of 30° in the shallow part and 50° in the deeper part. The hypocenter falls just on the estimated deeper fault plane where a left-lateral slip is inferred, whereas in the shallow part, a reverse slip is predominant, which causes surface ruptures on the ground. The slip partitioning may be accounted for by shear stress resulting from a reverse fault slip with left-lateral component at depth, for which a left-lateral slip is suppressed in the shallow part where the reverse slip is inferred. The slip distribution model with a bending fault surface, instead of a single fault plane, produces moment tensor solution with a non-double couple component, which is consistent with the seismically estimated mechanism.

Reinterpretation of Mesozoic and Cenozoic tectonic events, Mountain Pass area, northeastern San Bernardino County, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nance, M.A.

1993-04-01

Detailed mapping, stratigraphic structural analysis in the Mountain Pass area has resulted in a reinterpretation of Mesozoic and Cenozoic tectonic events in the area. Mesozoic events are characterized by north vergent folds and thrust faults followed by east vergent thrusting. Folding created two synclines and an anticline which were than cut at different stratigraphic levels by subsequent thrust faults. Thrusting created composite tectono-stratigraphic sections containing autochthonous, para-autothonous, and allochthonous sections. Normal faults cutting these composite sections including North, Kokoweef, White Line, and Piute fault must be post-thrusting, not pre-thrusting as in previous interpretations. Detailed study of these faults results inmore » differentiation of at least three orders of faults and suggest they represent Cenozoic extension correlated with regional extensional events between 11 and 19 my. Mesozoic stratigraphy reflects regional orogenic uplift, magmatic activity, and thrusting. Inclusion of Kaibab clasts in the Chinle, Kaibab and Chinle clasts in the Aztec, and Chinle, Aztec, and previously deposited Delfonte Volcanics clasts in the younger members of the Delfonte Volcanics suggest regional uplift prior to the thrusting of Cambrian Bonanza King over Delfonte Volcanics by the Mescal Thrust fault. The absence of clasts younger than Kaibab argues against pre-thrusting activity for the Kokoweef fault.« less

Fault Current Distribution and Pole Earth Potential Rise (EPR) Under Substation Fault

NASA Astrophysics Data System (ADS)

Nnassereddine, M.; Rizk, J.; Hellany, A.; Nagrial, M.

2013-09-01

New high-voltage (HV) substations are fed by transmission lines. The position of these lines necessitates earthing design to ensure safety compliance of the system. Conductive structures such as steel or concrete poles are widely used in HV transmission mains. The earth potential rise (EPR) generated by a fault at the substation could result in an unsafe condition. This article discusses EPR based on substation fault. The pole EPR assessment under substation fault is assessed with and without mutual impedance consideration. Split factor determination with and without the mutual impedance of the line is also discussed. Furthermore, a simplified formula to compute the pole grid current under substation fault is included. Also, it includes the introduction of the n factor which determines the number of poles that required earthing assessments under substation fault. A case study is shown.

Evidence for Active Westward Tilting of Fortymile Wash, Nye County, Nevada

NASA Astrophysics Data System (ADS)

McKague, H. L.; Sims, D. W.; Waiting, D. J.

2006-12-01

Fortymile Wash is located east and south of a potential high-level nuclear waste repository at Yucca Mountain, Nevada. Several lines of evidence suggest that this may be an area of active westward tilting associated with the continued development of Crater Flat basin and slip on the Bare Mountain normal fault. Near the southern end of Busted Butte, the incised channel of Fortymile Wash changes trend downgradient from south to south-southwest. Further southward, the incised main channel grades to a divergent distributary channel system that shows evidence of increasingly westward tilt. Viewed in profiles oriented normal to the incised channel and across the Fortymile Wash distributary system, topographic elevation of the western margin of the fan decreases southward, resulting in the elevation of the western margin of Fortymile Basin being as much as 18 m [59 ft] lower than the channel system on the eastern fan margin. Mapping of the surficial deposits within the distributary channel system (Pelletier, et al., 2005; Geophy. Res. Ltr., Vol. 32) may be interpreted to show a westward shift (downslope) of the locus of erosional activity toward the topographically lower western fan margin. Most of the older alluvium (Qa3 {86±40-16 ka}) has been eroded from the eastern portion, while incipient incision into the older alluvium is occurring on the western side of the distributary channel system. The results from level-line benchmark surveys (Gilmore, 1992; USGS OFR 92- 450) from 1915 and 1984 show gradual and systematic elevation changes east of the Bare Mountain fault to just east of Amargosa City, Nevada, where a step-like increase occurs. The level-line surveys are near and along the path of U.S. Highway 95, which traverses the distributary channel system of the Fortymile Wash alluvial fan in the southern portion of the Fortymile Wash basin. These lines of evidence indicate disequilibrium in the channel system that would result from active westward tilting of the Fortymile Wash basin. The active tilting in Fortymile Wash may be associated with continued development of Crater Flat basin and slip on the Bare Mountain fault, with the steeply dipping southern segment of the Bare Mountain fault not only controlling the southward-increasing subsidence in Southern Crater Flat, but also the changes observed in the southern Fortymile Wash basin 20 km [12.5 mi] to the southeast. An alternative interpretation is westward tilting, which is the result of active, but not evident, faulting beneath or near Fortymile Wash. Additional evidence indicating the presence of a fault beneath Fortymile Wash is the easterly dip of Miocene tuffs in Fran Ridge north of Busted Butte. This abstract is an independent product of the Center for Nuclear Waste Regulatory Analyses and does not necessarily reflect the view or regulatory position of the U.S. Nuclear Regulatory Commission.

Using the 3D active fault model to estimate the surface deformation, a study on HsinChu area, Taiwan.

NASA Astrophysics Data System (ADS)

Lin, Y. K.; Ke, M. C.; Ke, S. S.

2016-12-01

An active fault is commonly considered to be active if they have moved one or more times in the last 10,000 years and likely to have another earthquake sometime in the future. The relationship between the fault reactivation and the surface deformation after the Chi-Chi earthquake (M=7.2) in 1999 has been concerned up to now. According to the investigations of well-known disastrous earthquakes in recent years, indicated that surface deformation is controlled by the 3D fault geometric shape. Because the surface deformation may cause dangerous damage to critical infrastructures, buildings, roads, power, water and gas lines etc. Therefore it's very important to make pre-disaster risk assessment via the 3D active fault model to decrease serious economic losses, people injuries and deaths caused by large earthquake. The approaches to build up the 3D active fault model can be categorized as (1) field investigation (2) digitized profile data and (3) build the 3D modeling. In this research, we tracked the location of the fault scarp in the field first, then combined the seismic profiles (had been balanced) and historical earthquake data to build the underground fault plane model by using SKUA-GOCAD program. Finally compared the results come from trishear model (written by Richard W. Allmendinger, 2012) and PFC-3D program (Itasca) and got the calculated range of the deformation area. By analysis of the surface deformation area made from Hsin-Chu Fault, we concluded the result the damage zone is approaching 68 286m, the magnitude is 6.43, the offset is 0.6m. base on that to estimate the population casualties, building damage by the M=6.43 earthquake in Hsin-Chu area, Taiwan. In the future, in order to be applied accurately on earthquake disaster prevention, we need to consider further the groundwater effect and the soil structure interaction inducing by faulting.

High Resolution Magnetic surveys across the Emeelt and Hustaï faults near Ulaanbaatar, Mongolia

NASA Astrophysics Data System (ADS)

Fleury, S.; Munschy, M.; Schlupp, A.; Ferry, M.; Munkhuu, U.

2012-04-01

During the 20th century, Mongolia was one of the most seismic active intra-continental areas in the world. Some recent observations raise strong concern on still unidentified structures around Ulaanbaatar (1.5 M inhabitants). Near the city, instrumental seismicity shows continuous activity with five M 4+ events since 1974 and a M 5.4. Since 2005, the number of earthquake in the shallow crust (above 10-20 km) has significantly increased on the Emeelt fault area, west of Ulaanbaatar. A multi-disciplinary study - including GPR profiling, magnetic mapping, DGPS microtopography, morphotectonic observations and paleoseismic trenching - was carried out in the fault areas to assess their seismogenic potential. We present preliminary results of high resolution magnetic surveys using three axis fluxgate magnetic sensors. In Emeelt and Hustaï area, about 4 km2 were prospected with survey line spacing of 5 m to investigate the subsurface characteristic of the active faults. The main faults are clearly detected as well as secondary branches that affect buried paleo-channels. The combined approach of morphotectonic observations and magnetic measurements was used to select the location of paleoseismic trenches. The fluxgate equipment, being an easy, non-invasive and high-resolution way of mapping was used inside trenches to map exposures. Micro magnetic surveys were conducted on the walls of the trenches along 30 m, with a vertical extent of 2 m and a spacing of 0.1 m between each line. These measurements are used to define different units of sediments with a very high level of detail particularly where the stratigraphic interfaces are poorly visible. Magnetic mapping reveals a fault zone in recent units that consists of intense deformational patterns. Simultaneous use of horizontal and vertical maps may yield a 3D interpretation of the distribution of sedimentary layers. Faulted units related to recent depositional process attest for the ongoing activity of the Emeelt and Hustaï faults. This novel approach brings supplementary physical measurements to classic trench observations as well as access to physical properties not observable with the naked eye. It proves to be a useful complement to photologs and field observations. Finally, our multidisciplinary approach helps assess seismic hazard for the nearby capital of Mongolia, Ulaanbaatar.

Fiber Bragg grating sensor for fault detection in high voltage overhead transmission lines

NASA Astrophysics Data System (ADS)

Moghadas, Amin

2011-12-01

A fiber optic based sensor capable of fault detection in both radial and network overhead transmission power line systems is investigated. Bragg wavelength shift is used to measure the fault current and detect fault in power systems. Magnetic fields generated by currents in the overhead transmission lines cause a strain in magnetostrictive material which is then detected by fiber Bragg grating (FBG) sensors. The Fiber Bragg interrogator senses the reflected FBG signals, and the Bragg wavelength shift is calculated and the signals are processed. A broadband light source in the control room scans the shift in the reflected signals. Any surge in the magnetic field relates to an increased fault current at a certain location. Also, fault location can be precisely defined with an artificial neural network (ANN) algorithm. This algorithm can be easily coordinated with other protective devices. It is shown that the faults in the overhead transmission line cause a detectable wavelength shift on the reflected signal of FBG sensors and can be used to detect and classify different kind of faults. The proposed method has been extensively tested by simulation and results confirm that the proposed scheme is able to detect different kinds of fault in both radial and network system.

Fiber Bragg Grating Sensor for Fault Detection in Radial and Network Transmission Lines

PubMed Central

Moghadas, Amin A.; Shadaram, Mehdi

2010-01-01

In this paper, a fiber optic based sensor capable of fault detection in both radial and network overhead transmission power line systems is investigated. Bragg wavelength shift is used to measure the fault current and detect fault in power systems. Magnetic fields generated by currents in the overhead transmission lines cause a strain in magnetostrictive material which is then detected by Fiber Bragg Grating (FBG). The Fiber Bragg interrogator senses the reflected FBG signals, and the Bragg wavelength shift is calculated and the signals are processed. A broadband light source in the control room scans the shift in the reflected signal. Any surge in the magnetic field relates to an increased fault current at a certain location. Also, fault location can be precisely defined with an artificial neural network (ANN) algorithm. This algorithm can be easily coordinated with other protective devices. It is shown that the faults in the overhead transmission line cause a detectable wavelength shift on the reflected signal of FBG and can be used to detect and classify different kind of faults. The proposed method has been extensively tested by simulation and results confirm that the proposed scheme is able to detect different kinds of fault in both radial and network system. PMID:22163416

Fluid-controlled faulting process in the Asal Rift, Djibouti, from 8 yr of radar interferometry observations

NASA Astrophysics Data System (ADS)

Doubre, Cécile; Peltzer, Gilles

2007-01-01

The deformation in the Asal Rift (Djibouti) is characterized by magmatic inflation, diking, distributed extension, fissure opening, and normal faulting. An 8 yr time line of surface displacement maps covering the rift, constructed using radar interferometry data acquired by the Canadian satellite Radarsat between 1997 and 2005, reveals the aseismic behavior of faults and its relation with bursts of microseismicity. The observed ground movements show the asymmetric subsidence of the inner floor of the rift with respect to the bordering shoulders accommodated by slip on three of the main active faults. Fault slip occurs both as steady creep and during sudden slip events accompanied by an increase in the seismicity rate around the slipping fault and the Fieale volcanic center. Slip distribution along fault strike shows triangular sections, a pattern not explained by simple elastic dislocation theory. These observations suggest that the Asal Rift faults are in a critical failure state and respond instantly to small pressure changes in fluid-filled fractures connected to the faults, reducing the effective normal stress on their locked section at depth.

SOIL GAS RADON MEASUREMENT AROUND FAULT LINES ON THE WESTERN SECTION OF THE NORTH ANATOLIAN FAULT ZONE IN TURKEY.

PubMed

Yakut, Hakan; Tabar, Emre; Yildirim, Eray; Zenginerler, Zemine; Ertugral, Filiz; Demirci, Nilufer

2017-04-15

Soil gas radon activity measurements were made around the western section of the North Anatolian Fault Zone. In the study, the variation of radon concentration at 12 different locations along the fault line was monitored by using LR-115 (solid-state nuclear track detectors) detectors for 12-monthly periods. Twelve radon stations were determined in the study region, and in each station, LR-115 films were installed in the borehole of ∼50 cm. The recorded radon concentration varies from 29 to 7059 Bqm-3 with an average value of 1930 Bqm-3. The influence of meteorological parameters such as temperature, pressure, total rainfall and humidity on soil radon concentrations in the study area was also investigated. The positive and poor correlation was observed between average value of 222Rn concentration and temperature. There is a reverse proportion between radon level with other meteorological factors (humidity, pressure and rainfall). The results show that the measured soil gas radon activity concentration shows seasonal variation in a highly permeable sandy-gravelly soil with definite seasons without obvious long transitional periods. The summer (from June 2013 to September 2013) is characterised by 1.8 times higher average soil gas radon activity concentration (median is 2.372 kBqm-3) than the winter (from December 2012 to March 2013) (median is 1.298 kBqm-3). © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The design and implementation of on-line monitoring system for UHV compact shunt capacitors

NASA Astrophysics Data System (ADS)

Tao, Weiliang; Ni, Xuefeng; Lin, Hao; Jiang, Shengbao

2017-08-01

Because of the large capacity and compact structure of the UHV compact shunt capacitor, it is difficult to take effective measures to detect and prevent the faults. If the fault capacitor fails to take timely maintenance, it will pose a threat to the safe operation of the system and the life safety of the maintenance personnel. The development of UHV compact shunt capacitor on-line monitoring system can detect and record the on-line operation information of UHV compact shunt capacitors, analyze and evaluate the early fault warning signs, find out the fault capacitor or the capacitor with fault symptom, to ensure safe and reliable operation of the system.

Mise en évidence d'un nouveau front de chevauchement dans l'Atlas tunisien oriental de Tunisie par sismique réflexion. Contexte structural régional et rôle du Trias salifère

NASA Astrophysics Data System (ADS)

Khomsi, Sami; Bédir, Mourad; Ben Jemia, M. Ghazi; Zouari, Hédi

2004-11-01

Structural interpretations of newly acquired seismic lines in northeastern Tunisia allow us to highlight a new thrust front for the Atlasic range of Tunisia, in contrast to the previously Zaghouan fault thrust Dorsale zone. This new thrust front takes place on weakness tectonic zones, materialized by inherited faults anchored on the pre-Triassic basement. This front seems to be a paleogeographic trend controlling structural style and basin fill with a synsedimentary activity. The front is expressed by reverse faults, thrust faults, back thrusting, and decollement structures. To cite this article: S. Khomsi et al., C. R. Geoscience 336 (2004).

The Story of a Yakima Fold and How It Informs Late Neogene and Quaternary Backarc Deformation in the Cascadia Subduction Zone, Manastash Anticline, Washington, USA

NASA Astrophysics Data System (ADS)

Kelsey, Harvey M.; Ladinsky, Tyler C.; Staisch, Lydia; Sherrod, Brian L.; Blakely, Richard J.; Pratt, Thomas L.; Stephenson, William J.; Odum, Jack K.; Wan, Elmira

2017-10-01

The Yakima folds of central Washington, USA, are prominent anticlines that are the primary tectonic features of the backarc of the northern Cascadia subduction zone. What accounts for their topographic expression and how much strain do they accommodate and over what time period? We investigate Manastash anticline, a north vergent fault propagation fold typical of structures in the fold province. From retrodeformation of line- and area-balanced cross sections, the crust has horizontally shortened by 11% (0.8-0.9 km). The fold, and by inference all other folds in the fold province, formed no earlier than 15.6 Ma as they developed on a landscape that was reset to negligible relief following voluminous outpouring of Grande Ronde Basalt. Deformation is accommodated on two fault sets including west-northwest striking frontal thrust faults and shorter north to northeast striking faults. The frontal thrust fault system is active with late Quaternary scarps at the base of the range front. The fault-cored Manastash anticline terminates to the east at the Naneum anticline and fault; activity on the north trending Naneum structures predates emplacement of the Grande Ronde Basalt. The west trending Yakima folds and west striking thrust faults, the shorter north to northeast striking faults, and the Naneum fault together constitute the tectonic structures that accommodate deformation in the low strain rate environment in the backarc of the Cascadia Subduction Zone.

The story of a Yakima fold and how it informs Late Neogene and Quaternary backarc deformation in the Cascadia subduction zone, Manastash anticline, Washington, USA

USGS Publications Warehouse

Kelsey, Harvey M.; Ladinsky, Tyler C.; Staisch, Lydia; Sherrod, Brian; Blakely, Richard J.; Pratt, Thomas; Stephenson, William; Odum, Jackson K.; Wan, Elmira

2017-01-01

The Yakima folds of central Washington, USA, are prominent anticlines that are the primary tectonic features of the backarc of the northern Cascadia subduction zone. What accounts for their topographic expression and how much strain do they accommodate and over what time period? We investigate Manastash anticline, a north vergent fault propagation fold typical of structures in the fold province. From retrodeformation of line- and area-balanced cross sections, the crust has horizontally shortened by 11% (0.8–0.9 km). The fold, and by inference all other folds in the fold province, formed no earlier than 15.6 Ma as they developed on a landscape that was reset to negligible relief following voluminous outpouring of Grande Ronde Basalt. Deformation is accommodated on two fault sets including west-northwest striking frontal thrust faults and shorter north to northeast striking faults. The frontal thrust fault system is active with late Quaternary scarps at the base of the range front. The fault-cored Manastash anticline terminates to the east at the Naneum anticline and fault; activity on the north trending Naneum structures predates emplacement of the Grande Ronde Basalt. The west trending Yakima folds and west striking thrust faults, the shorter north to northeast striking faults, and the Naneum fault together constitute the tectonic structures that accommodate deformation in the low strain rate environment in the backarc of the Cascadia Subduction Zone.

Interacting faults

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

Current microseismicity and generating faults in the Gyeongju area, southeastern Korea

NASA Astrophysics Data System (ADS)

Han, Minhui; Kim, Kwang-Hee; Son, Moon; Kang, Su Young

2017-01-01

A study of microseismicity in a 15 × 20 km2 subregion of Gyeongju, southeastern Korea, establishes a direct link between minor earthquakes and known fault structures. The study area has a complex history of tectonic deformation and has experienced large historic earthquakes, with small earthquakes recorded since the beginning of modern instrumental monitoring. From 5 years of continuously recorded local seismic data, 311 previously unidentified microearthquakes can be reliably located using the double-difference algorithm. These newly discovered events occur in linear streaks that can be spatially correlated with active faults, which could pose a serious hazard to nearby communities. At-risk infrastructure includes the largest industrial park in South Korea, nuclear power plants, and disposal facilities for radioactive waste. The current work suggests that the southern segment of the Yeonil Tectonic Line and segments of the Seokup and Waup Basin boundary faults are active. For areas with high rates of microseismic activity, reliably located hypocenters are spatially correlated with mapped faults; in less active areas, earthquake clusters tend to occur at fault intersections. Microearthquakes in stable continental regions are known to exist, but have been largely ignored in assessments of seismic hazard because their magnitudes are well below the detection thresholds of seismic networks. The total number of locatable microearthquakes could be dramatically increased by lowering the triggering thresholds of network detection algorithms. The present work offers an example of how microearthquakes can be reliably detected and located with advanced techniques. This could make it possible to create a new database to identify subsurface fault geometries and modes of fault movement, which could then be considered in the assessments of seismic hazard in regions where major earthquakes are rare.

Multiwavelet packet entropy and its application in transmission line fault recognition and classification.

PubMed

Liu, Zhigang; Han, Zhiwei; Zhang, Yang; Zhang, Qiaoge

2014-11-01

Multiwavelets possess better properties than traditional wavelets. Multiwavelet packet transformation has more high-frequency information. Spectral entropy can be applied as an analysis index to the complexity or uncertainty of a signal. This paper tries to define four multiwavelet packet entropies to extract the features of different transmission line faults, and uses a radial basis function (RBF) neural network to recognize and classify 10 fault types of power transmission lines. First, the preprocessing and postprocessing problems of multiwavelets are presented. Shannon entropy and Tsallis entropy are introduced, and their difference is discussed. Second, multiwavelet packet energy entropy, time entropy, Shannon singular entropy, and Tsallis singular entropy are defined as the feature extraction methods of transmission line fault signals. Third, the plan of transmission line fault recognition using multiwavelet packet entropies and an RBF neural network is proposed. Finally, the experimental results show that the plan with the four multiwavelet packet energy entropies defined in this paper achieves better performance in fault recognition. The performance with SA4 (symmetric antisymmetric) multiwavelet packet Tsallis singular entropy is the best among the combinations of different multiwavelet packets and the four multiwavelet packet entropies.

Development of a Methodology for Hydrogeological Characterization of Faults: Progress of the Project in Berkeley, California

NASA Astrophysics Data System (ADS)

Goto, J.; Moriya, T.; Yoshimura, K.; Tsuchi, H.; Karasaki, K.; Onishi, T.; Ueta, K.; Tanaka, S.; Kiho, K.

2010-12-01

The Nuclear Waste Management Organization of Japan (NUMO), in collaboration with Lawrence Berkeley National Laboratory (LBNL), has carried out a project to develop an efficient and practical methodology to characterize hydrologic property of faults since 2007, exclusively for the early stage of siting a deep underground repository. A preliminary flowchart of the characterization program and a classification scheme of fault hydrology based on the geological feature have been proposed. These have been tested through the field characterization program on the Wildcat Fault in Berkeley, California. The Wildcat Fault is a relatively large non-active strike-slip fault which is believed to be a subsidiary of the active Hayward Fault. Our classification scheme assumes the contrasting hydrologic features between the linear northern part and the split/spread southern part of the Wildcat Fault. The field characterization program to date has been concentrated in and around the LBNL site on the southern part of the fault. Several lines of electrical and reflection seismic surveys, and subsequent trench investigations, have revealed the approximate distribution and near-surface features of the Wildcat Fault (see also Onishi, et al. and Ueta, et al.). Three 150m deep boreholes, WF-1 to WF-3, have been drilled on a line normal to the trace of the fault in the LBNL site. Two vertical holes were placed to characterize the undisturbed Miocene sedimentary formations at the eastern and western sides of the fault (WF-1 and WF-2 respectively). WF-2 on the western side intersected the rock formation, which was expected only in WF-1, and several of various intensities. Therefore, WF-3, originally planned as inclined to penetrate the fault, was replaced by the vertical hole further to the west. It again encountered unexpected rocks and faults. Preliminary results of in-situ hydraulic tests suggested that the transmissivity of WF-1 is ten to one hundred times higher than WF-2. The monitoring of hydraulic pressure displayed different head distribution patterns between WF-1 and WF-2 (see also Karasaki, et al.). Based on these results, three hypotheses on the distribution of the Wildcat Fault were proposed: (a) a vertical fault in between WF-1 and WF-2, (b) a more gently dipping fault intersected in WF-2 and WF-3, and (c) a wide zone of faults extending between WF-1 and WF-3. At present, WF-4, an inclined hole to penetrate the possible (eastern?) master fault, is ongoing to test these hypotheses. After the WF-4 investigation, hydrologic and geochemical analyses and modeling of the southern part of the fault will be carried out. A simpler field characterization program will also be carried out in the northern part of the fault. Finally, all the results will be synthesized to improve the comprehensive methodology.

A fault is born: The Landers-Mojave earthquake line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nur, A.; Ron, H.

1993-04-01

The epicenter and the southern portion of the 1992 Landers earthquake fell on an approximately N-S earthquake line, defined by both epicentral locations and by the rupture directions of four previous M>5 earthquakes in the Mojave: The 1947 Manix; 1975 Galway Lake; 1979 Homestead Valley: and 1992 Joshua Tree events. Another M 5.2 earthquake epicenter in 1965 fell on this line where it intersects the Calico fault. In contrast, the northern part of the Landers rupture followed the NW-SE trending Camp Rock and parallel faults, exhibiting an apparently unusual rupture kink. The block tectonic model (Ron et al., 1984) combiningmore » fault kinematic and mechanics, explains both the alignment of the events, and their ruptures (Nur et al., 1986, 1989), as well as the Landers kink (Nur et al., 1992). Accordingly, the now NW oriented faults have rotated into their present direction away from the direction of maximum shortening, close to becoming locked, whereas a new fault set, optimally oriented relative to the direction of shortening, is developing to accommodate current crustal deformation. The Mojave-Landers line may thus be a new fault in formation. During the transition of faulting from the old, well developed and wak but poorly oriented faults to the strong, but favorably oriented new ones, both can slip simultaneously, giving rise to kinks such as Landers.« less

Seismic Hazard and Fault Length

NASA Astrophysics Data System (ADS)

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

2005-12-01

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

Active tectonics of the northern Mojave Desert: The 2017 Desert Symposium field trip road log

USGS Publications Warehouse

Miller, David; Reynolds, R.E.; Phelps, Geoffrey; Honke, Jeff; Cyr, Andrew J.; Buesch, David C.; Schmidt, Kevin M.; Losson, G.

2017-01-01

The 2017 Desert Symposium field trip will highlight recent work by the U.S. Geological Survey geologists and geophysicists, who have been mapping young sediment and geomorphology associated with active tectonic features in the least well-known part of the eastern California Shear Zone (ECSZ). This area, stretching from Barstow eastward in a giant arc to end near the Granite Mountains on the south and the Avawatz Mountains on the north (Fig. 1-1), encompasses the two major structural components of the ECSZ—east-striking sinistral faults and northwest-striking dextral faults—as well as reverseoblique and normal-oblique faults that are associated with topographic highs and sags, respectively. In addition, folds and stepovers (both restraining stepovers that form pop-up structures and releasing stepovers that create narrow basins) have been identified. The ECSZ is a segment in the ‘soft’ distributed deformation of the North American plate east of the San Andreas fault (Fig. 1-1), where it takes up approximately 20-25% of plate motion in a broad zone of right-lateral shear (Sauber et al., 1994) The ECSZ (sensu strictu) begins in the Joshua Tree area and passes north through the Mojave Desert, past the Owens Valley-to-Death Valley swath and northward, where it is termed the Walker Lane. It has been defined as the locus of active faulting (Dokka and Travis, 1990), but when the full history from about 10 Ma forward is considered, it lies in a broader zone of right shear that passes westward in the Mojave Desert to the San Andreas fault (Mojave strike-slip province of Miller and Yount, 2002) and passes eastward to the Nevada state line or beyond (Miller, this volume).We will visit several accessible highlights for newly studied faults, signs of young deformation, and packages of syntectonic sediments. These pieces of a complex active tectonic puzzle have yielded some answers to longstanding questions such as: How is fault slip transfer in this area accommodated between northwest-striking dextral faults and eaststriking sinistral faults?How is active deformation on the Ludlow fault transferred northward, presumably to connect to the southern Death Valley fault zone?When were faults in this area of the central Mojave Desert initiated?Are faults in this area more or less active than faults in the ECSZ to the west?What is the role of NNW-striking faults and when did they form?How has fault slip changed over time? Locations and fault names are provided in figure 1-2. Important turns and locations are identified with locations in the projection: UTM, zone 11; datum NAD 83: (578530 3917335).

Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eisses, A.; Kell, A.; Kent, G.

Amy Eisses, Annie Kell, Graham Kent, Neal Driscoll, Robert Karlin, Rob Baskin, John Louie, and Satish Pullammanappallil, 2011, Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada: Geothermal Resources Council Transactions, 35, 7 pp. Preprint at http://crack.seismo.unr.edu/geothermal/Eisses-GRCpaper-sm.pdf The Pyramid Lake fault zone lies within a vitally important area of the northern Walker Lane where not only can transtension can be studied through a complex arrangement of strike-slip and normal faults but also geothermal activity can be examined in the extensional regime for productivity. This study used advanced and economical seismic methodsmore » in attempt to develop the Paiute Tribe’s geothermal reservoir and to expand upon the tectonics and earthquake hazard knowledge of the area. 500 line-kilometers of marine CHIRP data were collected on Pyramid Lake combined with 27 kilometers of vibrator seismic on-land data from the northwest side of the basin were collected in 2010 that highlighted two distinct phases of faulting. Preliminary results suggest that the geothermal fluids in the area are controlled by the late Pleistoceneto Holocene-aged faults and not through the mid-Miocene-aged conduits as originally hypothesized.« less

A seismic refraction and reflection study across the central San Jacinto Basin, Southern California

USGS Publications Warehouse

Lee, T.-C.; Biehler, S.; Park, S.K.; Stephenson, W.J.

1996-01-01

The San Jacinto Basin is a northwest-trending, pullapart basin in the San Jacinto fault zone of the San Andreas fault system in southern California. About 24 km long and 2 to 4 km wide, the basin sits on a graben bounded by two strands of the San Jacinto fault zone: the Claremont Fault on the northeast and the Casa Loma Fault on the southwest. We present a case study of shallow structure (less than 1 km) in the central basin. A 2.75-km refraction line running from the northeast to southwest across the regional structural trend reveals a groundwater barrier (Offset I). Another line, bent southward and continued for 1.65-km, shows a crystalline basement offset (Offset III) near an inferred trace of the Casa Loma Fault. Although a basement refractor was not observed along the 2.75-km line, a mismatch between the estimate of its minimum depth and the basement depth determined for the 1.65-km line suggests that an offset in the basement (greater than 260 m) exists around the junction of the two refraction lines (Offset II). By revealing more faults and subtle sedimentary structures, the reflection stack sections confirm the two refraction offsets as faults. Offsets I and III each separate sediments of contrasting structures and, in addition. Offset III disrupts an unconformity. However, the sense and amount of the offset across Offset III contradict what may be expected across the Casa Loma Fault, which has its basinward basement down-thrown to about 2.5 km in the better defined southeastern part of the graben. The Casa Loma Fault trace has been mislinked in the existing geological maps and the trace should be remapped to Offset II where the reflector disruptions spread over a 400-m wide zone. Our Offset III is an unnamed, concealed fault.

Using InSAR time series to identify geologic hazards associated with the Hayward and Calaveras faults along the South Bay Aqueduct

NASA Astrophysics Data System (ADS)

Jones, C. E.; Burgmann, R.; Hoirup, D. F., Jr.; Hawkins, B.

2016-12-01

We evaluated Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) data using InSAR time series analysis and documented ground movement along the Calaveras and Hayward faults near the South Bay Aqueduct (SBA). Images from seven different UAVSAR flight lines at 7m x 7m resolution were used for the study. A total of 132 acquisitions (between 12 and 51 per line) were acquired between 2009 and 2015. Each of the seven lines observed only part of the aqueduct, but all segments of the aqueduct were imaged in more than one line with some segments in up to four lines. This provided between one and three imaging geometries for every fault location along the aqueduct. The SBA transports water from the Sacramento-San Joaquin Delta (Delta) to communities east and south of San Francisco Bay through a combination of open canals, tunnels, and pipelines. From its starting point immediately west of the Delta at Bethany Reservoir, the SBA extends westward, crossing multiple faults, including Calaveras and Hayward faults. The aqueduct continues south, largely following the Hayward fault to its terminus east of San Jose. The SBA and associated infrastructure are at risk from landslides and from movement along any of these faults, with the landslides often spatially associated with the faults. We report linear rates of surface movement averaged across the six-year time period, and identify locations experiencing significant movement along the Calaveras and Hayward faults. Aseismic displacement is quantified and mapped for the two faults, including multiple traces of the Calaveras fault extending north and south of where it crosses the SBA. This work was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contracts with the California Dept. of Water Resources and with the National Aeronautics and Space Administration.

Coseismic fault zone deformation caused by the 2014 Mw=6.2 Nagano-ken-hokubu, Japan, earthquake on the Itoigawa-Shizuoka Tectonic Line revealed with differential LiDAR

NASA Astrophysics Data System (ADS)

Toda, S.; Ishimura, D.; Homma, S.; Mukoyama, S.; Niwa, Y.

2015-12-01

The Mw = 6.2 Nagano-ken-hokubu earthquake struck northern Nagano, central Japan, on November 22, 2014, and accompanied a 9-km-long surface rupture mostly along the previously mapped N-NW trending Kamishiro fault, one of the segments of the 150-km-long Itoigawa-Shizuoka Tectonic Line active fault system. While we mapped the rupture and measured vertical displacement of up to 80 cm at the field, interferometric synthetic aperture radar (InSAR) shows densely spaced fringes on the hanging wall side, suggesting westward or uplift movement associated with thrust faulting. The mainshock focal mechanism and aftershock hypocenters indicate the source fault dips to the east but the InSAR images cannot exactly differentiate between horizontal and vertical movements and also lose coherence within and near the fault zone itself. To reveal near-field deformation and shallow fault slip, here we demonstrate a differential LiDAR analysis using a pair of 1 m-resolution pre-event and post-event bare Earth digital terrain models (DTMs) obtained from commercial LiDAR provider. We applied particle image velocity (PIV) method incorporating elevation change to obtain 3-D vectors of coseismic displacements (Mukoyama, 2011, J. Mt. Sci). Despite sporadic noises mostly due to local landslides, we detected up to 1.5 m net movement at the tip of the hanging wall, more than the field measurement of 80 cm. Our result implies that a 9-km-long rupture zone is not a single continuous fault but composed of two bow-shaped fault strands, suggesting a combination of shallow fault dip and modest amount (< 1.5 m) of slip. Eastward movement without notable subsidence on the footwall also supports the low angle fault dip near the surface, and significant fault normal contraction, observed as buckled cultural features across the fault zone. Secondary features, such as subsidiary back-thrust faults confirmed at the field, are also visible as a significant contrast of vector directions and slip amounts.

Active faulting in low- to moderate-seismicity regions: the SAFE project

NASA Astrophysics Data System (ADS)

Sebrier, M.; Safe Consortium

2003-04-01

SAFE (Slow Active Faults in Europe) is an EC-FP5 funded multidisciplinary effort which proposes an integrated European approach in identifying and characterizing active faults as input for evaluating seismic hazard in low- to moderate-seismicity regions. Seismically active western European regions are generally characterized by low hazard but high risk, due to the concentration of human and material properties with high vulnerability. Detecting, and then analysing, tectonic deformations that may lead to destructive earthquakes in such areas has to take into account three major limitations: - the typical climate of western Europe (heavy vegetation cover and/or erosion) ; - the subdued geomorphic signature of slowly deforming faults ; - the heavy modification of landscape by human activity. The main objective of SAFE, i.e., improving the assessment of seismic hazard through understanding of the mechanics and recurrence of active faults in slowly deforming regions, is achieved through four major steps : (1) extending geologic and geomorphic investigations of fault activity beyond the Holocene to take into account various time-windows; (2) developing an expert system that combines diverse lines of geologic, seismologic, geomorphic, and geophysical evidence to diagnose the existence and seismogenic potential of slow active faults; (3) delineating and characterising high seismic risk areas of western Europe, either from historical or geological/geomorphic evidence; (4) demonstrating and discussing the impact of the project results on risk assessment through a seismic scenario in the Basel-Mulhouse pilot area. To take properly into account known differences in source behavior, these goals are pursued both in extensional (Lower and Upper Rhine Graben, Catalan Coast) and compressional tectonic settings (southern Upper Rhine Graben, Po Plain, and Provence). Two arid compressional regions (SE Spain and Moroccan High Atlas) have also been selected to address the limitations imposed by vegetation and human modified landscapes. The first results demonstrate that the strong added value provided by SAFE consists in its integrated multidisciplinary and multiscalar approach that allows robust diagnostic conclusions on fault activity and on the associated earthquake potential. This approach will be illustrated through selected methodological results.

Active Fault Topography and Fault Outcrops in the Central Part of the Nukumi fault, the 1891 Nobi Earthquake Fault System, Central Japan

NASA Astrophysics Data System (ADS)

Sasaki, T.; Ueta, K.; Inoue, D.; Aoyagi, Y.; Yanagida, M.; Ichikawa, K.; Goto, N.

2010-12-01

It is important to evaluate the magnitude of earthquake caused by multiple active faults, taking into account the simultaneous effects. The simultaneity of adjacent active faults are often decided on the basis of geometric distances except for known these paleoseismic records. We have been studied the step area between the Nukumi fault and the Neodani fault, which appeared as consecutive ruptures in the 1891 Nobi earthquake, since 2009. The purpose of this study is to establish innovation in valuation technique of the simultaneity of adjacent active faults in addition to the paleoseismic record and the geometric distance. Geomorphological, geological and reconnaissance microearthquake surveys are concluded. The present work is intended to clarify the distribution of tectonic geomorphology along the Nukumi fault and the Neodani fault by high-resolution interpretations of airborne LiDAR DEM and aerial photograph, and the field survey of outcrops and location survey. The study area of this work is the southeastern Nukumi fault and the northwestern Neodani fault. We interpret DEM using shaded relief map and stereoscopic bird's-eye view made from 2m mesh DEM data which is obtained by airborne laser scanner of Kokusai Kogyo Co., Ltd. Aerial photographic survey is for confirmation of DEM interpretation using 1/16,000 scale photo. As a result of topographic survey, we found consecutive tectonic topography which is left lateral displacement of ridge and valley lines and reverse scarplets along the Nukumi fault and the Neodani fault . From Ogotani 2km southeastern of Nukumi pass which is located at the southeastern end of surface rupture along the Nukumi fault by previous study to Neooppa 9km southeastern of Nukumi pass, we can interpret left lateral topographies and small uphill-facing fault scarps on the terrace surface by detail DEM investigation. These topographies are unrecognized by aerial photographic survey because of heavy vegetation. We have found several new outcrops in this area where the surface ruptures of the 1891 Nobi earthquake have not been known. These outcrops have active fault which cut the layer of terrace deposit and slope deposit to the bottom of present soil layer in common. At the locality of Ogotani outcrop, the humic layer which age is from14th century to 15th century by 14C age dating is deformed by the active fault. The vertical displacement of the humic layer is 0.8-0.9m and the terrace deposit layer below the humic layer is ca. 1.3m. For this reason and the existence of fain grain deposit including AT tephra (28ka) in the footwall of the fault, this fault movement occurred more than once since the last glacial age. We conclude that the surface rupture of Nukumi fault in the 1891 Nobi earthquake is continuous to 9km southeast of Nukumi pass. In other words, these findings indicate that there is 10km parallel overlap zone between the surface rupture of the southeastern end of Nukumi fault and the northwestern end of Neodani fault.

NASA ground terminal communication equipment automated fault isolation expert systems

NASA Technical Reports Server (NTRS)

Tang, Y. K.; Wetzel, C. R.

1990-01-01

The prototype expert systems are described that diagnose the Distribution and Switching System I and II (DSS1 and DSS2), Statistical Multiplexers (SM), and Multiplexer and Demultiplexer systems (MDM) at the NASA Ground Terminal (NGT). A system level fault isolation expert system monitors the activities of a selected data stream, verifies that the fault exists in the NGT and identifies the faulty equipment. Equipment level fault isolation expert systems are invoked to isolate the fault to a Line Replaceable Unit (LRU) level. Input and sometimes output data stream activities for the equipment are available. The system level fault isolation expert system compares the equipment input and output status for a data stream and performs loopback tests (if necessary) to isolate the faulty equipment. The equipment level fault isolation system utilizes the process of elimination and/or the maintenance personnel's fault isolation experience stored in its knowledge base. The DSS1, DSS2 and SM fault isolation systems, using the knowledge of the current equipment configuration and the equipment circuitry issues a set of test connections according to the predefined rules. The faulty component or board can be identified by the expert system by analyzing the test results. The MDM fault isolation system correlates the failure symptoms with the faulty component based on maintenance personnel experience. The faulty component can be determined by knowing the failure symptoms. The DSS1, DSS2, SM, and MDM equipment simulators are implemented in PASCAL. The DSS1 fault isolation expert system was converted to C language from VP-Expert and integrated into the NGT automation software for offline switch diagnoses. Potentially, the NGT fault isolation algorithms can be used for the DSS1, SM, amd MDM located at Goddard Space Flight Center (GSFC).

Faulting processes in active faults - Evidences from TCDP and SAFOD drill core samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janssen, C.; Wirth, R.; Wenk, H. -R.

The microstructures, mineralogy and chemistry of representative samples collected from the cores of the San Andreas Fault drill hole (SAFOD) and the Taiwan Chelungpu-Fault Drilling project (TCDP) have been studied using optical microscopy, TEM, SEM, XRD and XRF analyses. SAFOD samples provide a transect across undeformed host rock, the fault damage zone and currently active deforming zones of the San Andreas Fault. TCDP samples are retrieved from the principal slip zone (PSZ) and from the surrounding damage zone of the Chelungpu Fault. Substantial differences exist in the clay mineralogy of SAFOD and TCDP fault gouge samples. Amorphous material has beenmore » observed in SAFOD as well as TCDP samples. In line with previous publications, we propose that melt, observed in TCDP black gouge samples, was produced by seismic slip (melt origin) whereas amorphous material in SAFOD samples was formed by comminution of grains (crush origin) rather than by melting. Dauphiné twins in quartz grains of SAFOD and TCDP samples may indicate high seismic stress. The differences in the crystallographic preferred orientation of calcite between SAFOD and TCDP samples are significant. Microstructures resulting from dissolution–precipitation processes were observed in both faults but are more frequently found in SAFOD samples than in TCDP fault rocks. As already described for many other fault zones clay-gouge fabrics are quite weak in SAFOD and TCDP samples. Clay-clast aggregates (CCAs), proposed to indicate frictional heating and thermal pressurization, occur in material taken from the PSZ of the Chelungpu Fault, as well as within and outside of the SAFOD deforming zones, indicating that these microstructures were formed over a wide range of slip rates.« less

Integration of On-Line and Off-Line Diagnostic Algorithms for Aircraft Engine Health Management

NASA Technical Reports Server (NTRS)

Kobayashi, Takahisa; Simon, Donald L.

2007-01-01

This paper investigates the integration of on-line and off-line diagnostic algorithms for aircraft gas turbine engines. The on-line diagnostic algorithm is designed for in-flight fault detection. It continuously monitors engine outputs for anomalous signatures induced by faults. The off-line diagnostic algorithm is designed to track engine health degradation over the lifetime of an engine. It estimates engine health degradation periodically over the course of the engine s life. The estimate generated by the off-line algorithm is used to update the on-line algorithm. Through this integration, the on-line algorithm becomes aware of engine health degradation, and its effectiveness to detect faults can be maintained while the engine continues to degrade. The benefit of this integration is investigated in a simulation environment using a nonlinear engine model.

Central Japan's Atera Active Fault's Wide-Fractured Zone: An Examination of the Structure and In-situ Crustal Stress

NASA Astrophysics Data System (ADS)

Ikeda, R.; Omura, K.; Matsuda, T.; Mizuochi, Y.; Uehara, D.; Chiba, A.; Kikuchi, A.; Yamamoto, T.

2001-12-01

In-situ downhole measurements and coring within and around an active fault zone are needed to better understand the structure and material properties of fault rocks as well as the physical state of active faults and intra-plate crust. Particularly, the relationship between the stress concentration state and the heterogeneous strength of an earthquake fault zone is important to estimate earthquake occurrence mechanisms which correspond to the prediction of an earthquake. It is necessary to compare some active faults in different conditions of the chrysalis stage and their relation to subsequent earthquake occurrence. To better understand such conditions, "Active Fault Zone Drilling Project" has been conducted in the central part of Japan by the National Research Institute for Earth Science and Disaster Prevention. The Nojima fault which appeared on the surface by the 1995 Great Kobe earthquake (M=7.2) and the Neodani fault created by the 1981 Nobi earthquake, the greatest inland earthquake M=8.0 in Japan, have been drilled through the fault fracture zones. During these past four years, a similar experiment and research at the Atera fault, of which some parts seem to have been dislocated by the 1586 Tensyo earthquake, has been undertaken. The features of the Atera fault are as follows: (1) total length is about 70 km, (2) general trend is NW45_Kwith a left-lateral strike slip, (3) slip rate is estimated as 3-5 m/1000 yrs. and the average recurrence time as 1700 yrs., (4) seismicity is very low at present, and (5) lithologies around the fault are basically granitic rocks and rhyolite. We have conducted integrated investigations by surface geophysical survey and drilling around the Atera fault. Six boreholes have been drilled from the depth of 400 m to 630 m. Four of these boreholes are located on a line crossing the fracture zone of the Atera fault. Resistivity and gravity structures inferred from surface geophysical surveys were compared with the physical properties determined from the borehole logging data and core samples. These results were also compared with in situ stress data by the hydraulic fracturing stress measurements in the boreholes. We obtained characteristic states on crustal stress and strength of the fault from these investigations. Our findings are as follows: (1) The fracture zone around the Atera fault shows a very wide and complex fracture structure, from approximately 1 km to 4 km wide. The average slip rate was estimated to be 5.3 m /1000 yrs. by the distribution of basalt in age of 1.5 Ma by radioactive dating. We inferred that the Atera fault has been repeatedly active in recent geologic time; however, it is in a very weak state at present. (2) The stress magnitude decreases in the area closer to the center of the fracture zone. Furthermore the orientation of the maximum horizontal compressive stress was almost in a North-South direction, just reverse of the fault moving direction. These are important results to evaluate fault activity. We argue that the stress state observed in these sites exists only when the faults are quite "weak," and thus does not reach to a critical level of fault activation in the present situation.

Faulting along the southern margin of Reelfoot Lake, Tennessee

USGS Publications Warehouse

Van Arsdale, R.; Purser, J.; Stephenson, W.; Odum, J.

1998-01-01

The Reelfoot Lake basin, Tennessee, is structurally complex and of great interest seismologically because it is located at the junction of two seismicity trends of the New Madrid seismic zone. To better understand the structure at this location, a 7.5-km-long seismic reflection profile was acquired on roads along the southern margin of Reelfoot Lake. The seismic line reveals a westerly dipping basin bounded on the west by the Reelfoot reverse fault zone, the Ridgely right-lateral transpressive fault zone on the east, and the Cottonwood Grove right-lateral strike-slip fault in the middle of the basin. The displacement history of the Reelfoot fault zone appears to be the same as the Ridgely fault zone, thus suggesting that movement on these fault zones has been synchronous, perhaps since the Cretaceous. Since the Reelfoot and Ridgely fault systems are believed responsible for two of the mainshocks of 1811-1812, the fault history revealed in the Reelfoot Lake profile suggests that multiple mainshocks may be typical of the New Madrid seismic zone. The Ridgely fault zone consists of two northeast-striking faults that lie at the base of and within the Mississippi Valley bluff line. This fault zone has 15 m of post-Eocene, up-to-the-east displacement and appears to locally control the eastern limit of Mississippi River migration. The Cottonwood Grove fault zone passes through the center of the seismic line and has approximately 5 m up-to-the-east displacement. Correlation of the Cottonwood Grove fault with a possible fault scarp on the floor of Reelfoot Lake and the New Markham fault north of the lake suggests the Cottonwood Grove fault may change to a northerly strike at Reelfoot Lake, thereby linking the northeast-trending zones of seismicity in the New Madrid seismic zone.

A Generalised Fault Protection Structure Proposed for Uni-grounded Low-Voltage AC Microgrids

NASA Astrophysics Data System (ADS)

Bui, Duong Minh; Chen, Shi-Lin; Lien, Keng-Yu; Jiang, Jheng-Lun

2016-04-01

This paper presents three main configurations of uni-grounded low-voltage AC microgrids. Transient situations of a uni-grounded low-voltage (LV) AC microgrid (MG) are simulated through various fault tests and operation transition tests between grid-connected and islanded modes. Based on transient simulation results, available fault protection methods are proposed for main and back-up protection of a uni-grounded AC microgrid. In addition, concept of a generalised fault protection structure of uni-grounded LVAC MGs is mentioned in the paper. As a result, main contributions of the paper are: (i) definition of different uni-grounded LVAC MG configurations; (ii) analysing transient responses of a uni-grounded LVAC microgrid through line-to-line faults, line-to-ground faults, three-phase faults and a microgrid operation transition test, (iii) proposing available fault protection methods for uni-grounded microgrids, such as: non-directional or directional overcurrent protection, under/over voltage protection, differential current protection, voltage-restrained overcurrent protection, and other fault protection principles not based on phase currents and voltages (e.g. total harmonic distortion detection of currents and voltages, using sequence components of current and voltage, 3I0 or 3V0 components), and (iv) developing a generalised fault protection structure with six individual protection zones to be suitable for different uni-grounded AC MG configurations.

The Salton Seismic Imaging Project: Seismic velocity structure of the Brawley Seismic Zone, Salton Buttes and Geothermal Field, Salton Trough, California

NASA Astrophysics Data System (ADS)

Delph, J.; Hole, J. A.; Fuis, G. S.; Stock, J. M.; Rymer, M. J.

2011-12-01

The Salton Trough is an active rift in southern California in a step-over between the plate-bounding Imperial and San Andreas Faults. In March 2011, the Salton Seismic Imaging Project (SSIP) investigated the rift's crustal structure by acquiring several seismic refraction and reflection lines. One of the densely sampled refraction lines crosses the northern-most Imperial Valley, perpendicular to the strike-slip faults and parallel to a line of small Quaternary rhyolitic volcanoes. The line crosses the obliquely extensional Brawley Seismic Zone and goes through one of the most geothermally productive areas in the United States. Well logs indicate the valley is filled by several kilometers of late Pliocene-recent lacustrine, fluvial, and shallow marine sediment. The 42-km long seismic line was comprised of eleven 110-460 kg explosive shots and receivers at a 100 m spacing. First arrival travel times were used to build a tomographic seismic velocity image of the upper crust. Velocity in the valley increases smoothly from <2 km/s to >5 km/s, indicating diagenesis and gradational metamorphism of rift sediments at very shallow depth due to an elevated geotherm. The velocity gradient is much smaller in the relatively low velocity (<6 km/s) crystalline basement comprised of recently metamorphosed sediment reaching greenschist to lower amphibolite facies. The depth of this basement is about 4-km below the aseismic region of the valley west of the Brawley Seismic Zone, but rises sharply to ~2 km depth beneath the seismically, geothermally, and volcanically active area of the Brawley Seismic Zone. The basement deepens to the northeast of the active tectonic zone and then is abruptly offset to shallower depth on the northeast side of the valley. This offset may be the subsurficial expression of a paleofault, most likely an extension of the Sand Hills Fault, which bounds the basin to the east. Basement velocity east of the fault is ~5.7 km/s, consistent with the granitic rocks of the Chocolate Mountains. The tomographic model shows that the shallow metasedimentary basement as well as the geothermal and volcanic activity seem to be bounded by the sharp western and eastern margins of the Brawley Seismic Zone. At this location, strongly fractured crust allows both hydrothermal and magmatic fluids to rise to the surface in the most rapidly extending portion of the rift basin.

Structural characteristics of epicentral areas in Central Europe: study case Cheb Basin (Czech Republic)

NASA Astrophysics Data System (ADS)

Bankwitz, P.; Schneider, G.; Kämpf, H.; Bankwitz, E.

2003-03-01

The earthquake distribution pattern of Central Europe differs systematically from the neighbouring areas of NW and southern Europe regarding the fault plane kinematics. Within a belt between the French Massif Central and the northern part of the Bohemian Massif (1000 km) sinistral faulting along N-S zones dominates on the contrary to the Alps and their foreland with common bookshelf shears. One of the prominent N-S structures is the Regensburg-Leipzig-Rostock Zone (A) with several epicentral areas, where the main seismic center occurs in the northern Cheb Basin (NW Bohemia). The study demonstrates new structural results for the swarm-quake region in NW-Bohemia, especially for the Nový Kostel area in the Cheb Basin. There the N-S-trending newly found Počatky-Plesná zone (PPZ) is identical with the main earthquake line. The PPZ is connected with a mofette line between Hartušov and Bublák with evidence for CO 2 degassing from the subcrustal mantle. The morphologically more prominent Mariánské Lázně fault (MLF) intersects the PPZ obliquely under an acuate angle. In the past the MLF was supposed to be the tectonic structure connected with the epicentral area of Nový Kostel. But evidence from the relocated hypocentres along the PPZ (at 7-12 kms depth) indicate that the MLF is seismically non-active. Asymmetric drainage patterns of the Cheb Basin are caused by fault related movement along Palaeozoic basement faults which initiate a deformation of the cover (Upper Pliocene to Holocene basin filling). The PPZ forms an escarpment in Pliocene and Pleistocene soft rock and is supposingly acting as an earthquake zone since late Pleistocene time. The uppermost Pleistocene of 0.12-0.01 Ma deposited only in front of the fault scarp dates the fault activity. The crossing faults envelope crustal wedges under different local stress conditions. Their intersection line forms a zone beginning at the surface near Nový Kostel, dipping south with increasing depth, probably down to about 12 km. The intersection zone represents a crustal anomaly. There fault movements can be blocked up and peculiar stress condition influence the behaviour of the adjacent crust. An ENE-WNW striking dextral wrench fault was detected which is to expect as kinematic counterpart to the ca. N-S striking sinistral shear zones. Nearly E-W striking fracture segments were formerly only known as remote sensing lineaments or as joint density zones. The ENE shear zone is characterized by a set of compressional m-scale folds and dm-scale faults scattered within a 20 m wide wrench zone. It is built up of different sets of cleavage-like clay plate pattern of microscopical scale. The associated shear planes fit into a Riedel shear system. One characteristic feature are tiny channels of micrometer scale. They have originated after shear plane bending and are the sites of CO 2 mantle degassing.

Long term landscape evolution within central Apennines (Italy): Marsica and Peligna region morphotectonics and surface processes

NASA Astrophysics Data System (ADS)

Miccadei, E.; Piacentini, T.; Berti, C.

2010-12-01

The relief features of the Apennines have been developed in a complex geomorphological and geological setting from Neogene to Quaternary. Growth of topography has been driven by active tectonics (thrust-related crustal shortening and high-angle normal faulting related to crustal extension), regional rock uplift, and surface processes, starting from Late Miocene(?) - Early Pliocene. At present a high-relief landscape is dominated by morphostructures including high-standing, resistant Mesozoic and early Tertiary carbonates ridges (i.e. thrust ridges, faulted homocline ridges) and intervening, erodible Tertiary siliciclastics valleys (i.e. fault line valleys) and Quaternary continental deposits filled basins (i.e. tectonic valleys, tectonic basins). This study tries to identify paleo-uplands that may be linked to paleo-base levels and aims at the reconstruction of ancient landscapes since the incipient phases of morphogenesis. It analyzes the role of tectonics and morphogenic processes in the long term temporal scale landscape evolution (i.e. Mio?-Pliocene to Quaternary). It is focused on the marsicano-peligna region, located along the main drainage divide between Adriatic side and Tyrrhenian side of Central Apennines, one of the highest average elevation area of the whole chain. The work incorporates GIS-based geomorphologic field mapping of morphostructures and Quaternary continental deposits, and plano-altimetric analysis and morphometry (DEM-, map-based) of the drainage network (i.e. patterns, hypsometry, knick points, Ks). Field mapping give clues on the definition of paleo-landscapes related to different paleo-morpho-climatic environments (i.e. karst, glacial, slope, fluvial). Geomorphological evidence of tectonics and their cross-cutting relationships with morphostructures, continental deposits and faults, provide clues on the deciphering of the reciprocal relationship of antecedence of the paleo-landscapes and on the timing of morphotectonics. Morphotectonic features are related to Neogene thrusts, reactivated or displaced by complex kinematic strike slip and followed by extensional tectonic features (present surface evidence given by fault line scarps, fault line valleys, fault scarps, fault slopes, wind gaps, etc.). Geomorphic evidence of faults is provided also by morphometry of the drainage network: highest long slope of the main streams (knick points and Ks) are located where the streams cut across or run along recent faults. Correlation of tectonic elements, paleosurfaces, Quaternary continental deposits, by means of morphotectonic cross sections, lead to the identification, in the marsicano-peligna region, of areas in which morphotectonics acted in the same period, becoming younger moving from the West to the East. In conclusion, recognition of different morphotectonic features, identification of different paleo-landscapes, and reconstruction of their migration history, contribute to define the main phases of syn and post orogenic, Apennine chain landscape evolution: it results from the link of alternating morphotectonics and surface processes, due to migrating fault activity, rock uplift processes and alternating karst, glacial, slope, fluvial processes.

Spatial Relationship Between Crustal Structure and Mantle Seismicity in the Vrancea Seismogenic Zone of Romania

NASA Astrophysics Data System (ADS)

Knapp, C. C.; Enciu, D. M.; Knapp, J. H.

2007-12-01

Active crustal deformation and subsidence in the Southeast Carpathian foreland has previously been attributed to active foundering of thickened continental lithosphere beneath the Carpathian bend region (Knapp et al, 2005). The present study involves integration of active and passive-source seismic data in order to place constraints on the duration, timing, and scale of crustal deformation in the Carpathian foreland, and in particular to assess the genetic relationship with the Vrancea intermediate-depth seismogenic zone (VSZ). Relocated crustal earthquakes and focal mechanisms were correlated with four deep industry seismic profiles, the reprocessed DACIA PLAN deep seismic profile, and the DRACULA (Deep Reflection Acquisition Constraining Unusual Lithospheric Activity) II and III profiles. Projection of foreland crustal hypocenters onto the deep seismic lines correlates well with previously identified crustal faults such as the Trotus and Sinaia, as well as the newly identified Ialomita Fault. Specifically, results of this study (1) image the full crustal and uppermost mantle structure of the Focsani Basin in the close proximity of the VSZ, (2) show evidence for a sub-horizontal, slightly east-dipping Moho in the vicinity of the VSZ and thinning of the crust towards the Carpathian orogen, (3) illustrate the conspicuous absence of west-dipping fabrics or structures in the crust and across the Moho, (4) present evidence that the Trotus Fault is a crustal-scale active fault with a dextral sense of motion, (5) suggest that the Paleozoic age Peceneaga-Camena and Capidava-Ovidiu Faults have not been active in post-Paleozoic time, and (6) show evidence for a new active crustal scale sinistral fault, named the Ialomita fault. Both the seismogenic Vrancea body and deformation in the Focsani Basin appear to be concentrically bound by the Trotus Fault in the north and east and the Sinaia-Ialomita Fault in the south, suggesting a coupled deformation between the VSZ and the foreland deformation, possibly accommodated on these two major fault systems. These results contradict both the "subduction-in-place" and "slab- break-off" hypotheses as feasible explanations for VSZ intermediate-depth seismicity, and lend additional support to a lithospheric delamination model to explain both the origin of the VSZ and the crustal architecture of the Southeast Carpathian foreland.

Energy budget and propagation of faults via shearing and opening using work optimization

NASA Astrophysics Data System (ADS)

Madden, Elizabeth H.; Cooke, Michele L.; McBeck, Jessica

2017-08-01

We present numerical models of faults propagating by work optimization in a homogeneous medium. These simulations allow quantification and comparison of the energy budgets of fault growth by shear versus tensile failure. The energy consumed by growth of a fault, Wgrow, propagating by in-line shearing is 76% of the total energy associated with that growth, while 24% is spent on frictional work during propagation. Wgrow for a fault propagating into intact rock by tensile failure, at an angle to the parent fault, consumes 60% of the work budget, while only 6% is consumed by frictional work associated with propagation. Following the conservation of energy, this leaves 34% of the energy budget available for other activities and suggests that out-of-plane propagation of faults in Earth's crust may release energy for other processes, such as permanent damage zone formation or rupture acceleration. Comparison of these estimates of Wgrow with estimates of the critical energy release rate and earthquake fracture energy at several scales underscores their theoretical similarities and their dependence on stress drop.

Subsurface geometry of the San Andreas fault in southern California: Results from the Salton Seismic Imaging Project (SSIP) and strong ground motion expectations

USGS Publications Warehouse

Fuis, Gary S.; Bauer, Klaus; Goldman, Mark R.; Ryberg, Trond; Langenheim, Victoria; Scheirer, Daniel S.; Rymer, Michael J.; Stock, Joann M.; Hole, John A.; Catchings, Rufus D.; Graves, Robert; Aagaard, Brad T.

2017-01-01

The San Andreas fault (SAF) is one of the most studied strike‐slip faults in the world; yet its subsurface geometry is still uncertain in most locations. The Salton Seismic Imaging Project (SSIP) was undertaken to image the structure surrounding the SAF and also its subsurface geometry. We present SSIP studies at two locations in the Coachella Valley of the northern Salton trough. On our line 4, a fault‐crossing profile just north of the Salton Sea, sedimentary basin depth reaches 4 km southwest of the SAF. On our line 6, a fault‐crossing profile at the north end of the Coachella Valley, sedimentary basin depth is ∼2–3  km">∼2–3  km and centered on the central, most active trace of the SAF. Subsurface geometry of the SAF and nearby faults along these two lines is determined using a new method of seismic‐reflection imaging, combined with potential‐field studies and earthquakes. Below a 6–9 km depth range, the SAF dips ∼50°–60°">∼50°–60° NE, and above this depth range it dips more steeply. Nearby faults are also imaged in the upper 10 km, many of which dip steeply and project to mapped surface fault traces. These secondary faults may join the SAF at depths below about 10 km to form a flower‐like structure. In Appendix D, we show that rupture on a northeast‐dipping SAF, using a single plane that approximates the two dips seen in our study, produces shaking that differs from shaking calculated for the Great California ShakeOut, for which the southern SAF was modeled as vertical in most places: shorter‐period (T<1  s">T<1  s) shaking is increased locally by up to a factor of 2 on the hanging wall and is decreased locally by up to a factor of 2 on the footwall, compared to shaking calculated for a vertical fault.

Structural localization and origin of compartmentalized fluid flow, Comstock lode, Virginia City, Nevada

USGS Publications Warehouse

Berger, B.R.; Tingley, J.V.; Drew, L.J.

2003-01-01

Bonanza-grade orebodies in epithermal-style mineral deposits characteristically occur as discrete zones within spatially more extensive fault and/or fracture systems. Empirically, the segregation of such systems into compartments of higher and lower permeability appears to be a key process necessary for high-grade ore formation and, most commonly, it is such concentrations of metals that make an epithermal vein district world class. In the world-class silver- and gold-producing Comstock mining district, Nevada, several lines of evidence lead to the conclusion that the Comstock lode is localized in an extensional stepover between right-lateral fault zones. This evidence includes fault geometries, kinematic indicators of slip, the hydraulic connectivity of faults as demonstrated by veins and dikes along faults, and the opening of a normal-fault-bounded, asymmetric basin between two parallel and overlapping northwest-striking, lateral- to lateral-oblique-slip fault zones. During basin opening, thick, generally subeconomic, banded quartz-adularia veins were deposited in the normal fault zone, the Comstock fault, and along one of the bounding lateral fault zones, the Silver City fault. As deformation continued, the intrusion of dikes and small plugs into the hanging wall of the Comstock fault zone may have impeded the ability of the stepover to accommodate displacement on the bounding strike-slip faults through extension within the stepover. A transient period of transpressional deformation of the Comstock fault zone ensued, and the early-stage veins were deformed through boudinaging and hydraulic fragmentation, fault-motion inversion, and high- and low-angle axial rotations of segments of the fault planes and some fault-bounded wedges. This deformation led to the formation of spatially restricted compartments of high vertical permeability and hydraulic connectivity and low lateral hydraulic connectivity. Bonanza orebodies were formed in the compartmentalized zones of high permeability and hydraulic connectivity. As heat flow and related hydrothermal activitv waned along the Comstock fault zone, extension was reactivated in the stepover along the Occidental zone of normal faults east of the Comstock fault zone. Volcanic and related intrusive activity in this part of the stepover led to a new episode of hydrothermal activity and formation of the Occidental lodes.

Elevation changes in the central transverse ranges near Ventura, California

USGS Publications Warehouse

Buchanan-Banks, J. M.; Castle, R.O.; Ziony, J.I.

1975-01-01

Profiles of elevation changes developed from repeated levelings in the east-trending Transverse Ranges near Ventura, California, reveal three general types of vertical movements: 1. (1) broadly defined regional tilting; 2. (2) sharply defined differential movements across recently active faults; and 3. (3) differential subsidence centering on producing oil fields. Down-to-the-southeast tilting is evident in profiles along the coast this sense of movement, however, is the inverse of that that may have prevailed during late Pleistocene time. Profiles along lines extending north and northwest from Ventura show prominent inflections formed by up-to-the-north differential movements that coincide roughly with the Red Mountain fault; this fault is a north-dipping reverse fault that displaces a Holocene(?) soil zone and along which scarps and sag ponds are preserved. A similar inflection coincides with the Padre Juan fault; post-Pleistocene activity on the Padre Juan, however, is uniquely indicated by the geodetic data. Contemporary integrity of the structural block extending northward from the Red Mountain fault is suggested by the apparent absence of differential movements across the Munson Creek, Tule Creek, Santa Ynez, and Arroyo Parida faults since at least 1934. Subsidence is recognized over both the Ventura and Rincon oil fields; although maximum subsidence has not been recorded in either case, 277 mm of differential subsidence was measured within the Ventura field between 1934 and 1968. ?? 1975.

A review of recently active faults in Taiwan

USGS Publications Warehouse

Bonilla, Manuel G.

1975-01-01

Six faults associated with five large earthquakes produced surface displacements ranging from 1 to 3 m in the period 1906 through 1951. Four of the ruptures occurred in the western coastal plain and foothills, and two occurred in the Longitudinal Valley of eastern Taiwan. Maps are included showing the locations and dimensions of the displacements. The published geological literature probably would not lead one to infer the existence of a fault along most of the 1906 rupture, except for descriptions of the rupture itself. Over most of its length the 1935 rupture on the Chihhu fault is parallel to but more than 0.5 km from nearby faults shown on geologic maps published in 1969 and 1971; only about 1.5 km of its 15 km length coincides with a mapped fault. The coastal plain part of the Tuntzuchio fault which ruptured in 1935 is apparently not revealed by landforms, and only suggested by other data. Part of the 1946 Hsinhua faulting coincides with a fault identified in the subsurface by seismic work but surface indications of the fault are obscure. The 1951 Meilun faulting occurred along a conspicuous pre-1951 scarp and the 1951 Yuli faulting occurred near or in line with pre-1951 scarps. More than 40 faults which, according to the published literature, have had Pleistocene or later movement are shown on a small-scale map. Most of these faults are in the densely-populated western part of Taiwan. The map and text calls attention to faults that may be active and therefore may be significant in planning important structures. Equivocal evidence suggestive of fault creep was found on the Yuli fault and the Hsinhua fault. Fault creep was not found at several places examined along the 1906 fault trace. Tectonic uplift has occurred in Taiwan in the last 10,000 years and application of eustatic sea level curves to published radiocarbon dates shows that the minimum rate of uplift is considerably different in different parts of the island. Incomplete data indicate that the rate is high near Hualien, where an uplift of at least 0.6 m and probably more than 1 m occurred in the 1951 earthquake, and near and south of the 1946 faulting. Sudden uplifts can have serious consequences for installations near the shore. Investigation of this process, study of recently active faults, and continuing study of seismicity are necessary parts of a practical earthquake-hazard reduction program.

Active intra-basin faulting in the Northern Basin of Lake Malawi from seismic reflection data

NASA Astrophysics Data System (ADS)

Shillington, D. J.; Chindandali, P. R. N.; Scholz, C. A.; Ebinger, C. J.; Onyango, E. A.; Peterson, K.; Gaherty, J. B.; Nyblade, A.; Accardo, N. J.; McCartney, T.; Oliva, S. J.; Kamihanda, G.; Ferdinand, R.; Salima, J.; Mruma, A. H.

2016-12-01

Many questions remain about the development and evolution of fault systems in weakly extended rifts, including the relative roles of border faults and intra-basin faults, and segmentation at various scales. The northern Lake Malawi (Nyasa) rift in the East African Rift System is an early stage rift exhibiting pronounced tectonic segmentation, which is defined by 100-km-long border faults. The basins also contain a series of intrabasinal faults and associated synrift sediments. The occurrence of the 2009 Karonga Earthquake Sequence on one of these intrabasinal faults indicates that some of them are active. Here we present new multichannel seismic reflection data from the Northern Basin of the Malawi Rift collected in 2015 as a part of the SEGMeNT (Study of Extension and maGmatism in Malawi aNd Tanzania) project. This rift basin is bound on its east side by the west-dipping Livingstone border fault. Over 650 km of seismic reflection profiles were acquired in the Northern Basin using a 500 to 1540 cu in air gun array and a 1200- to 1500-m seismic streamer. Dip lines image a series of north-south oriented west-dipping intra-basin faults and basement reflections up to 5 s twtt near the border fault. Cumulative offsets on intra-basin faults decrease to the west. The largest intra-basin fault has a vertical displacement of >2 s two-way travel time, indicating that it has accommodated significant total extension. Some of these intra-basin faults offset the lake bottom and the youngest sediments by up to 50 s twtt ( 37 m), demonstrating they are still active. The two largest intra-basin faults exhibit the largest offsets of young sediments and also correspond to the area of highest seismicity based on analysis of seismic data from the 89-station SEGMeNT onshore/offshore network (see Peterson et al, this session). Fault patterns in MCS profiles vary along the basin, suggesting a smaller scale of segmentation of faults within the basin; these variations in fault patterns appear to correlate with variations in the distribution of aftershocks from the 2009 and 2014 Karonga earthquakes and in background seismicity beneath the lake, providing new constraints on length-displacement scaling for predictive models and earthquake hazards.

Landforms along transverse faults parallel to axial zone of folded mountain front, north-eastern Kumaun Sub-Himalaya, India

NASA Astrophysics Data System (ADS)

Luirei, Khayingshing; Bhakuni, S. S.; Negi, Sanjay S.

2017-02-01

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-Tanakpur faults cause the neotectonic activities as observed. The role of transverse fault tectonics in the formation of the curvature cannot be ruled out.

Marine and land active-source seismic investigation of geothermal potential, tectonic structure, and earthquake hazards in Pyramid Lake, Nevada

NASA Astrophysics Data System (ADS)

Eisses, A.; Kell, A. M.; Kent, G.; Driscoll, N. W.; Karlin, R. E.; Baskin, R. L.; Louie, J. N.; Smith, K. D.; Pullammanappallil, S.

2011-12-01

Preliminary slip rates measured across the East Pyramid Lake fault, or the Lake Range fault, help provide new estimates of extension across the Pyramid Lake basin. Multiple stratigraphic horizons spanning 48 ka were tracked throughout the lake, with layer offsets measured across all significant faults in the basin. A chronstratigraphic framework acquired from four sediment cores allows slip rates of the Lake Range and other faults to be calculated accurately. This region of the northern Walker Lake, strategically placed between the right-lateral strike-slip faults of Honey and Eagle Lakes to the north, and the normal fault bounded basins to the southwest (e.g., Tahoe, Carson), is critical in understanding the underlying structural complexity that is not only necessary for geothermal exploration, but also earthquake hazard assessment due to the proximity of the Reno-Sparks metropolitan area. In addition, our seismic CHIRP imaging with submeter resolution allows the construction of the first fault map of Pyramid Lake. The Lake Range fault can be obviously traced west of Anahoe Island extending north along the east end of the lake in numerous CHIRP lines. Initial drafts of the fault map reveal active transtension through a series of numerous, small, northwest striking, oblique-slip faults in the north end of the lake. A previously field mapped northwest striking fault near Sutcliff can be extended into the west end of Pyramid Lake. This fault map, along with the calculated slip rate of the Lake Range, and potentially multiple other faults, gives a clearer picture into understanding the geothermal potential, tectonic regime and earthquake hazards in the Pyramid Lake basin and the northern Walker Lane. These new results have also been merged with seismicity maps, along with focal mechanisms for the larger events to begin to extend our fault map in depth.

Transmission line relay mis-operation detection based on time-synchronized field data

DOE PAGES

Esmaeilian, Ahad; Popovic, Tomo; Kezunovic, Mladen

2015-05-04

In this paper, a real-time tool to detect transmission line relay mis-operation is implemented. The tool uses time-synchronized measurements obtained from both ends of the line during disturbances. The proposed fault analysis tool comes into the picture only after the protective device has operated and tripped the line. The proposed methodology is able not only to detect, classify, and locate transmission line faults, but also to accurately confirm whether the line was tripped due to a mis-operation of protective relays. The analysis report includes either detailed description of the fault type and location or detection of relay mis-operation. As such,more » it can be a source of very useful information to support the system restoration. The focus of the paper is on the implementation requirements that allow practical application of the methodology, which is illustrated using the field data obtained the real power system. Testing and validation is done using the field data recorded by digital fault recorders and protective relays. The test data included several hundreds of event records corresponding to both relay mis-operations and actual faults. The discussion of results addresses various challenges encountered during the implementation and validation of the presented methodology.« less

Subsurface structures of the active reverse fault zones in Japan inferred from gravity anomalies.

NASA Astrophysics Data System (ADS)

Matsumoto, N.; Sawada, A.; Hiramatsu, Y.; Okada, S.; Tanaka, T.; Honda, R.

2016-12-01

The object of our study is to examine subsurface features such as continuity, segmentation and faulting type, of the active reverse fault zones. We use the gravity data published by the Gravity Research Group in Southwest Japan (2001), the Geographical Survey Institute (2006), Yamamoto et al. (2011), Honda et al. (2012), and the Geological Survey of Japan, AIST (2013) in this study. We obtained the Bouguer anomalies through terrain corrections with 10 m DEM (Sawada et al. 2015) under the assumed density of 2670 kg/m3, a band-pass filtering, and removal of linear trend. Several derivatives and structural parameters calculated from a gravity gradient tensor are applied to highlight the features, such as a first horizontal derivatives (HD), a first vertical derivatives (VD), a normalized total horizontal derivative (TDX), a dip angle (β), and a dimensionality index (Di). We analyzed 43 reverse fault zones in northeast Japan and the northern part of southwest Japan among major active fault zones selected by Headquarters for Earthquake Research Promotion. As the results, the subsurface structural boundaries clearly appear along the faults at 21 faults zones. The weak correlations appear at 13 fault zones, and no correlations are recognized at 9 fault zones. For example, in the Itoigawa-Shizuoka tectonic line, the subsurface structure boundary seems to extend further north than the surface trace. Also, a left stepping structure of the fault around Hakuba is more clearly observed with HD. The subsurface structures, which detected as the higher values of HD, are distributed on the east side of the surface rupture in the north segments and on the west side in the south segments, indicating a change of the dip direction, the east dipping to the west dipping, from north to south. In the Yokote basin fault zone, the subsurface structural boundary are clearly detected with HD, VD and TDX along the fault zone in the north segment, but less clearly in the south segment. Also, Di implies the existence of 3D-like structure with E-W trend around the segment boundary. The distribution of dip angle β along the fault zone implies a reverse faulting, corresponding to the faulting type of this fault zone reported by previous studies.

Probabilistic seismic hazard assessments of Sabah, east Malaysia: accounting for local earthquake activity near Ranau

NASA Astrophysics Data System (ADS)

Khalil, Amin E.; Abir, Ismail A.; Ginsos, Hanteh; Abdel Hafiez, Hesham E.; Khan, Sohail

2018-02-01

Sabah state in eastern Malaysia, unlike most of the other Malaysian states, is characterized by common seismological activity; generally an earthquake of moderate magnitude is experienced at an interval of roughly every 20 years, originating mainly from two major sources, either a local source (e.g. Ranau and Lahad Dato) or a regional source (e.g. Kalimantan and South Philippines subductions). The seismicity map of Sabah shows the presence of two zones of distinctive seismicity, these zones are near Ranau (near Kota Kinabalu) and Lahad Datu in the southeast of Sabah. The seismicity record of Ranau begins in 1991, according to the international seismicity bulletins (e.g. United States Geological Survey and the International Seismological Center), and this short record is not sufficient for seismic source characterization. Fortunately, active Quaternary fault systems are delineated in the area. Henceforth, the seismicity of the area is thus determined as line sources referring to these faults. Two main fault systems are believed to be the source of such activities; namely, the Mensaban fault zone and the Crocker fault zone in addition to some other faults in their vicinity. Seismic hazard assessments became a very important and needed study for the extensive developing projects in Sabah especially with the presence of earthquake activities. Probabilistic seismic hazard assessments are adopted for the present work since it can provide the probability of various ground motion levels during expected from future large earthquakes. The output results are presented in terms of spectral acceleration curves and uniform hazard curves for periods of 500, 1000 and 2500 years. Since this is the first time that a complete hazard study has been done for the area, the output will be a base and standard for any future strategic plans in the area.

Feasibility analysis of a novel hybrid-type superconducting circuit breaker in multi-terminal HVDC networks

NASA Astrophysics Data System (ADS)

Khan, Umer Amir; Lee, Jong-Geon; Seo, In-Jin; Amir, Faisal; Lee, Bang-Wook

2015-11-01

Voltage source converter-based HVDC systems (VSC-HVDC) are a better alternative than conventional thyristor-based HVDC systems, especially for developing multi-terminal HVDC systems (MTDC). However, one of the key obstacles in developing MTDC is the absence of an adequate protection system that can quickly detect faults, locate the faulty line and trip the HVDC circuit breakers (DCCBs) to interrupt the DC fault current. In this paper, a novel hybrid-type superconducting circuit breaker (SDCCB) is proposed and feasibility analyses of its application in MTDC are presented. The SDCCB has a superconducting fault current limiter (SFCL) located in the main current path to limit fault currents until the final trip signal is received. After the trip signal the IGBT located in the main line commutates the current into a parallel line where DC current is forced to zero by the combination of IGBTs and surge arresters. Fault simulations for three-, four- and five-terminal MTDC were performed and SDCCB performance was evaluated in these MTDC. Passive current limitation by SFCL caused a significant reduction of fault current interruption stress in the SDCCB. It was observed that the DC current could change direction in MTDC after a fault and the SDCCB was modified to break the DC current in both the forward and reverse directions. The simulation results suggest that the proposed SDCCB could successfully suppress the DC fault current, cause a timely interruption, and isolate the faulty HVDC line in MTDC.

Structural development of the onshore Otway passive margin (Australia): the interaction of rotating syn-sedimentary faults

NASA Astrophysics Data System (ADS)

Tanner, David C.; Ziesch, Jennifer; Krawczyk, Charlotte M.

2017-04-01

Within the context of long-term CO2 storage integrity, we interpreted the faults within the 2.2 km thick, syn-rift, Late Cretaceous to Recent sediments below the CO2CRC Otway Project site in Australia using a detailed interpretation of a 3-D reflection seismic cube (32.3 km×14.35 km × 4100 ms TWT). All the faults in the onshore Otway passive margin basin in this area were active to varying degrees during sedimentation, between ca. 120 and 50 Ma, before they died out. From analysis of fault juxtaposition and fault tip-line propagation maps, as well as analysis of individual stratigraphic thickness maps, we determine the direction and incremental amount of syn-sedimentary movement on each fault. Thickening of the hanging-walls of the faults occurred, as is typical for syn-sedimentary faults. However, we also determine that substantial local footwall thinning took place. Although the syn-sedimentary behaviour of the faults was constantly maintained until 50 Ma, there were two main phases of footwall thinning, separated by a quiescent phase. We postulate that these phases of footwall thinning represent rotation of the fault blocks that correlate with prograding sediment pulses within the passive margin. The rotation of the fault blocks occurred simultaneously, i.e., they could only rotate if they interacted.

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

NASA Astrophysics Data System (ADS)

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

2016-09-01

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).

On-line diagnosis of sequential systems, 2

NASA Technical Reports Server (NTRS)

Sundstrom, R. J.

1974-01-01

The theory and techniques applicable to the on-line diagnosis of sequential systems, were investigated. A complete model for the study of on-line diagnosis is developed. First an appropriate class of system models is formulated which can serve as a basis for a theoretical study of on-line diagnosis. Then notions of realization, fault, fault-tolerance and diagnosability are formalized which have meaningful interpretations in the the context of on-line diagnosis. The diagnosis of systems which are structurally decomposed and are represented as a network of smaller systems is studied. The fault set considered is the set of faults which only affect one component system is the network. A characterization of those networks which can be diagnosed using a purely combinational detector is achieved. A technique is given which can be used to realize any network by a network which is diagnosable in the above sense. Limits are found on the amount of redundancy involved in any such technique.

The Gabbs Valley, Nevada, geothermal prospect: Exploring for a potential blind geothermal resource

NASA Astrophysics Data System (ADS)

Payne, J.; Bell, J. W.; Calvin, W. M.

2012-12-01

The Gabbs Valley prospect in west-central Nevada is a potential blind geothermal resource system. Possible structural controls on this system were investigated using high-resolution LiDAR, low sun-angle aerial (LSA) photography, exploratory fault trenching and a shallow temperature survey. Active Holocene faults have previously been identified at 37 geothermal systems with indication of temperatures greater than 100° C in the western Nevada region. Active fault controls in Gabbs Valley include both Holocene and historical structures. Two historical earthquakes occurring in 1932 and 1954 have overlapping surface rupture patterns in Gabbs Valley. Three active fault systems identified through LSA and LiDAR mapping have characteristics of Basin and Range normal faulting and Walker Lane oblique dextral faulting. The East Monte Cristo Mountains fault zone is an 8.5 km long continuous NNE striking, discrete fault with roughly 0.5 m right-normal historic motion and 3 m vertical Quaternary separation. The Phillips Wash fault zone is an 8.2 km long distributed fault system striking NE to N, with Quaternary fault scarps of 1-3 m vertical separation and a 500 m wide graben adjacent to the Cobble Cuesta anticline. This fault displays ponded drainages, an offset terrace riser and right stepping en echelon fault patterns suggestive of left lateral offset, and fault trenching exposed non-matching stratigraphy typical of a significant component of lateral offset. The unnamed faults of Gabbs Valley are a 10.6 km long system of normal faults striking NNE and Quaternary scarps are up to 4 m high. These normal faults largely do not have historic surface rupture, but a small segment of 1932 rupture has been identified. A shallow (2 m deep) temperature survey of 80 points covering roughly 65 square kilometers was completed. Data were collected over approximately 2 months, and continual base station temperature measurements were used to seasonally correct temperature measurements. A 2.5 km long temperature anomaly greater than 3° C above background temperatures forms west-northwest trending zone between terminations of the Phillips Wash fault zone and unnamed faults of Gabbs Valley to the south. Rupture segments of two young active faults bracket the temperature anomaly. The temperature anomaly may be due to several possible causes. 1. Increases in stress near the rupture segments or tip-lines of these faults, or where multiple fault splays exist, can increase fault permeability. The un-ruptured segments of these faults may be controlling the location of the Gabbs Valley thermal anomaly between ruptured segments of the 1932 Cedar Mountain and 1954 Fairview Peak earthquakes. 2. Numerous unnamed normal faults may interact and the hanging wall of these faults is hosting the thermal anomaly. The size and extent of the anomaly may be due to its proximity to a flat playa and not the direct location of the shallow heat anomaly. 3. The linear northwest nature of the thermal anomaly may reflect a hydrologic barrier in the subsurface controlling where heated fluids rise. A concealed NW- striking fault is possible, but has not been identified in previous studies or in the LiDAR or LSA fault mapping.

Plio Quaternary tectonic evolution and structure of the Catania foredeep, the northern Hyblean Plateau and the Ionian shelf (SE Sicily)

NASA Astrophysics Data System (ADS)

Torelli, Luigi; Grasso, Mario; Mazzoldi, Glauco; Peis, Davide

1998-11-01

Available multi- and single-channel seismic reflection profiles, calibrated by onshore borehole data, have been used for defining the structural styles in the shelf and slope of the Ionian Sea between Catania and Augusta (SE Sicily). The geological and geophysical data suggest that this area represents a segment of the foredeep-foreland system which collapsed after Late Pliocene times. The foundering was controlled by normal faults trending NE-SW, which flank the southern margin of the Catania foredeep. Onland, in outcrop, these faults appear largely to be post-dated by Lower Pleistocene sediments, nearshore carbonates passing laterally into basinal clays, which lie unconformably upon older substrata. Offshore, close to the southern edge of the foredeep, seismic lines allow recognition of two distinct units: a syn-rift wedge (Upper Pliocene submarine tholeiites and sediments), and a post-rift sequence which can be correlated with Lower Pleistocene carbonates, sands and clays recognisable on land, both in outcrop and by borehole data. The true frontal part of the thrust belt, as detected by the seismic lines, occupies the inner part of the area investigated and is buried by Upper Pliocene and Lower Pleistocene sediments. However, the compressive deformation seems to propagate toward the south-southeast by means of growing detachment levels developing at depth within Pleistocene marine clays, for a length of about 10 km, ahead of the present-day thrust front. Offshore, the faults trending NE-SW are dissected towards the east by faults trending NNW-SSE, subparallel to the Malta Escarpment, which flank the edge of the submerged Messina Rise. These faults, originating in a steep scarp which drops eastwards to the deep Ionian basin, have triggered submarine slides and affected the present-day seafloor sediments. As shown by seismic lines and as stressed by the modern seismicity of the area, some of the faults along the Malta Escarpment could be still active.

Seismic Reflection Images of Deep Lithospheric Faults and Thin Crust at the Actively Deforming Indo-Australian Plate Boundary in the Indian Ocean

NASA Astrophysics Data System (ADS)

Singh, S. C.; Carton, H.; Chauhan, A.; Dyment, J.; Cannat, M.; Hananto, N.; Hartoyo, D.; Tapponnier, P.; Davaille, A.

2007-12-01

Recently, we acquired deep seismic reflection data using a state-of-the-art technology of Schlumberger having a powerful source (10,000 cubic inch) and a 12 km long streamer along a 250 km long trench parallel line offshore Sumatra in the Indian Ocean deformation zone that provides seismic reflection image down to 40 km depth over the old oceanic lithosphere formed at Wharton spreading centre about 55-57 Ma ago. We observe deep penetrating faults that go down to 37 km depth (~24 km in the oceanic mantle), providing the first direct evidence for full lithospheric-scale deformation in an intra-plate oceanic domain. These faults dip NE and have dips between 25 and 40 degrees. The majority of faults are present in the mantle and are spaced at about 5 km, and do not seem cut through the Moho. We have also imaged active strike-slip fault zones that seem to be associated with the re-activation of ancient fracture zones, which is consistent with previous seismological and seafloor observations. The geometries of the deep penetrating faults neither seem to correspond to faulting associated with the plate bending at the subduction front nor with the re-activation of fracture zone that initiated about 7.5 Ma ago, and therefore, we suggest that these deep mantle faults were formed due to compressive stress at the beginning of the hard collision between India and Eurasia, soon after the cessation of seafloor spreading in the Wharton basin. We also find that the crust generated at the fast Wharton spreading centre 55-57 Ma ago is only 3.5-4.5 km thick, the thinnest crust ever observed in a fast spreading environment. We suggest that this extremely thin crust is due to 40-50°C lower than normal mantle temperature in this part of the Indian Ocean during its formation.

PWM-switching pattern-based diagnosis scheme for single and multiple open-switch damages in VSI-fed induction motor drives.

PubMed

Trabelsi, Mohamed; Boussak, Mohamed; Gossa, Moncef

2012-03-01

This paper deals with a fault detection technique for insulated-gate bipolar transistors (IGBTs) open-circuit faults in voltage source inverter (VSI)-fed induction motor drives. The novelty of this idea consists in analyzing the pulse-width modulation (PWM) switching signals and the line-to-line voltage levels during the switching times, under both healthy and faulty operating conditions. The proposed method requires line-to-line voltage measurement, which provides information about switching states and is not affected by the load. The fault diagnosis scheme is achieved using simple hardware and can be included in the existing inverter system without any difficulty. In addition, it allows not only accurate single and multiple faults diagnosis but also minimization of the fault detection time to a maximum of one switching period (T(c)). Simulated and experimental results on a 3-kW squirrel-cage induction motor drive are displayed to validate the feasibility and the effectiveness of the proposed strategy. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Fault ride-through enhancement using an enhanced field oriented control technique for converters of grid connected DFIG and STATCOM for different types of faults.

PubMed

Ananth, D V N; Nagesh Kumar, G V

2016-05-01

With increase in electric power demand, transmission lines were forced to operate close to its full load and due to the drastic change in weather conditions, thermal limit is increasing and the system is operating with less security margin. To meet the increased power demand, a doubly fed induction generator (DFIG) based wind generation system is a better alternative. For improving power flow capability and increasing security STATCOM can be adopted. As per modern grid rules, DFIG needs to operate without losing synchronism called low voltage ride through (LVRT) during severe grid faults. Hence, an enhanced field oriented control technique (EFOC) was adopted in Rotor Side Converter of DFIG converter to improve power flow transfer and to improve dynamic and transient stability. A STATCOM is coordinated to the system for obtaining much better stability and enhanced operation during grid fault. For the EFOC technique, rotor flux reference changes its value from synchronous speed to zero during fault for injecting current at the rotor slip frequency. In this process DC-Offset component of flux is controlled, decomposition during symmetric and asymmetric faults. The offset decomposition of flux will be oscillatory in a conventional field oriented control, whereas in EFOC it was aimed to damp quickly. This paper mitigates voltage and limits surge currents to enhance the operation of DFIG during symmetrical and asymmetrical faults. The system performance with different types of faults like single line to ground, double line to ground and triple line to ground was applied and compared without and with a STATCOM occurring at the point of common coupling with fault resistance of a very small value at 0.001Ω. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

A soft computing scheme incorporating ANN and MOV energy in fault detection, classification and distance estimation of EHV transmission line with FSC.

PubMed

Khadke, Piyush; Patne, Nita; Singh, Arvind; Shinde, Gulab

2016-01-01

In this article, a novel and accurate scheme for fault detection, classification and fault distance estimation for a fixed series compensated transmission line is proposed. The proposed scheme is based on artificial neural network (ANN) and metal oxide varistor (MOV) energy, employing Levenberg-Marquardt training algorithm. The novelty of this scheme is the use of MOV energy signals of fixed series capacitors (FSC) as input to train the ANN. Such approach has never been used in any earlier fault analysis algorithms in the last few decades. Proposed scheme uses only single end measurement energy signals of MOV in all the 3 phases over one cycle duration from the occurrence of a fault. Thereafter, these MOV energy signals are fed as input to ANN for fault distance estimation. Feasibility and reliability of the proposed scheme have been evaluated for all ten types of fault in test power system model at different fault inception angles over numerous fault locations. Real transmission system parameters of 3-phase 400 kV Wardha-Aurangabad transmission line (400 km) with 40 % FSC at Power Grid Wardha Substation, India is considered for this research. Extensive simulation experiments show that the proposed scheme provides quite accurate results which demonstrate complete protection scheme with high accuracy, simplicity and robustness.

Surface fault rupture during the Mw 7.8 Kaikoura earthquake, New Zealand, with specific comment on the Kekerengu Fault - one of the country's fastest slipping onland active faults

NASA Astrophysics Data System (ADS)

Van Dissen, Russ; Little, Tim

2017-04-01

The Mw 7.8 Kaikoura earthquake of 14 November, 2016 (NZDT) was a complex event. It involved ground-surface (or seafloor) fault rupture on at least a dozen onland or offshore faults, and subsurface rupture on a handful of additional faults. Most of the surface ruptures involved previously known (or suspected) active faults, as well as surface rupture on at least two hitherto unrecognised active faults. The southwest to northeast extent of surface fault rupture, as generalised by two straight-line segments, is approximately 180 km, though this is a minimum for the collective length of surface rupture due to multiple overlapping faults with various orientations. Surface rupture displacements on specific faults involved in the Kaikoura Earthquake span approximately two orders of magnitude. For example, maximum surface displacement on the Heaver's Creek Fault is cm- to dm-scale in size; whereas, maximum surface displacement on the nearby Kekerengu Fault is approximately 10-12 m (predominantly in a dextral sense). The Kekerengu Fault has a Late Pleistocene slip-rate rate of 20-26 mm/yr, and is possibly the second fastest slipping onland fault in New Zealand, behind the Alpine Fault. Located in the northeastern South Island of New Zealand, the Kekerengu Fault - along with the Hope Fault to the southwest and the Needles Fault offshore to the northeast - comprise the fastest slipping elements of the Pacific-Australian plate boundary in this part of the country. In January 2016 (about ten months prior to the Kaikoura earthquake) three paleo-earthquake investigation trenches were excavated across pronounced traces of the Kekerengu Fault at two locations. These were the first such trenches dug and evaluated across the fault. All three trenches displayed abundant evidence of past surface fault ruptures (three surface ruptures in the last approximately 1,200 years, four now including the 2016 rupture). An interesting aspect of the 2016 rupture is that two of the trenches received surface fault rupture, and are now dextrally offset by about 9 m, while the third trench did not have any 2016 surface rupture pass through it. In this instance, ground-surface rupture along this trace of the fault died out within tens of metres of the trench. Another salient aspect of the Kaikoura earthquake is that the determined (or estimated) recurrence intervals of the faults that ruptured the ground surface vary by an order of magnitude or more. This strongly implies that the ensemble of faults that ruptured with the Kekerengu Fault in the 2016 earthquake has not always been the same for past earthquakes. Possible reasons for this could include the state of stress at the time of a specific earthquake, the direction of rupture propagation, and whether or not rupture on one fault system cascades into rupture on another as is suspected to have happened in the Kaikoura earthquake.

Seismic images of an extensional basin, generated at the hangingwall of a low-angle normal fault: The case of the Sansepolcro basin (Central Italy)

NASA Astrophysics Data System (ADS)

Barchi, Massimiliano R.; Ciaccio, Maria Grazia

2009-12-01

The study of syntectonic basins, generated at the hangingwall of regional low-angle detachments, can help to gain a better knowledge of these important and mechanically controversial extensional structures, constraining their kinematics and timing of activity. Seismic reflection images constrain the geometry and internal structure of the Sansepolcro Basin (the northernmost portion of the High Tiber Valley). This basin was generated at the hangingwall of the Altotiberina Fault (AtF), an E-dipping low-angle normal fault, active at least since Late Pliocene, affecting the upper crust of this portion of the Northern Apennines. The dataset analysed consists of 5 seismic reflection lines acquired in the 80s' by ENI-Agip for oil exploration and a portion of the NVR deep CROP03 profile. The interpretation of the seismic profiles provides a 3-D reconstruction of the basin's shape and of the sedimentary succession infilling the basin. This consisting of up to 1200 m of fluvial and lacustrine sediments: this succession is much thicker and possibly older than previously hypothesised. The seismic data also image the geometry at depth of the faults driving the basin onset and evolution. The western flank is bordered by a set of E-dipping normal faults, producing the uplifting and tilting of Early to Middle Pleistocene succession along the Anghiari ridge. Along the eastern flank, the sediments are markedly dragged along the SW-dipping Sansepolcro fault. Both NE- and SW-dipping faults splay out from the NE-dipping, low-angle Altotiberina fault. Both AtF and its high-angle splays are still active, as suggested by combined geological and geomorphological evidences: the historical seismicity of the area can be reasonably associated to these faults, however the available data do not constrain an unambiguous association between the single structural elements and the major earthquakes.

Probabilistic evaluation of on-line checks in fault-tolerant multiprocessor systems

NASA Technical Reports Server (NTRS)

Nair, V. S. S.; Hoskote, Yatin V.; Abraham, Jacob A.

1992-01-01

The analysis of fault-tolerant multiprocessor systems that use concurrent error detection (CED) schemes is much more difficult than the analysis of conventional fault-tolerant architectures. Various analytical techniques have been proposed to evaluate CED schemes deterministically. However, these approaches are based on worst-case assumptions related to the failure of system components. Often, the evaluation results do not reflect the actual fault tolerance capabilities of the system. A probabilistic approach to evaluate the fault detecting and locating capabilities of on-line checks in a system is developed. The various probabilities associated with the checking schemes are identified and used in the framework of the matrix-based model. Based on these probabilistic matrices, estimates for the fault tolerance capabilities of various systems are derived analytically.

Sequential Test Strategies for Multiple Fault Isolation

NASA Technical Reports Server (NTRS)

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

1997-01-01

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

On-line experimental validation of a model-based diagnostic algorithm dedicated to a solid oxide fuel cell system

NASA Astrophysics Data System (ADS)

Polverino, Pierpaolo; Esposito, Angelo; Pianese, Cesare; Ludwig, Bastian; Iwanschitz, Boris; Mai, Andreas

2016-02-01

In the current energetic scenario, Solid Oxide Fuel Cells (SOFCs) exhibit appealing features which make them suitable for environmental-friendly power production, especially for stationary applications. An example is represented by micro-combined heat and power (μ-CHP) generation units based on SOFC stacks, which are able to produce electric and thermal power with high efficiency and low pollutant and greenhouse gases emissions. However, the main limitations to their diffusion into the mass market consist in high maintenance and production costs and short lifetime. To improve these aspects, the current research activity focuses on the development of robust and generalizable diagnostic techniques, aimed at detecting and isolating faults within the entire system (i.e. SOFC stack and balance of plant). Coupled with appropriate recovery strategies, diagnosis can prevent undesired system shutdowns during faulty conditions, with consequent lifetime increase and maintenance costs reduction. This paper deals with the on-line experimental validation of a model-based diagnostic algorithm applied to a pre-commercial SOFC system. The proposed algorithm exploits a Fault Signature Matrix based on a Fault Tree Analysis and improved through fault simulations. The algorithm is characterized on the considered system and it is validated by means of experimental induction of faulty states in controlled conditions.

Validation of gravity data from the geopotential field model for subsurface investigation of the Cameroon Volcanic Line (Western Africa)

NASA Astrophysics Data System (ADS)

Marcel, Jean; Abate Essi, Jean Marcel; Nouck, Philippe Njandjock; Sanda, Oumarou; Manguelle-Dicoum, Eliézer

2018-03-01

Belonging to the Cameroon Volcanic Line (CVL), the western part of Cameroon is an active volcanic zone with volcanic eruptions and deadly gas emissions. The volcanic flows generally cover areas and bury structural features like faults. Terrestrial gravity surveys can hardly cover entirely this mountainous area due to difficult accessibility. The present work aims to evaluate gravity data derived from the geopotential field model, EGM2008 to investigate the subsurface of the CVL. The methodology involves upward continuation, horizontal gradient, maxima of horizontal gradient-upward continuation combination and Euler deconvolution techniques. The lineaments map inferred from this geopotential field model confirms several known lineaments and reveals new ones covered by lava flows. The known lineaments are interpreted as faults or geological contacts such as the Foumban fault and the Pan-African Belt-Congo craton contact. The lineaments highlighted coupled with the numerous maar lakes identified in this volcanic sector attest of the vulnerability of the CVL where special attention should be given for geohazard prevention.

Static air-gap eccentricity fault diagnosis using rotor slot harmonics in line neutral voltage of three-phase squirrel cage induction motor

NASA Astrophysics Data System (ADS)

Oumaamar, Mohamed El Kamel; Maouche, Yassine; Boucherma, Mohamed; Khezzar, Abdelmalek

2017-02-01

The mixed eccentricity fault detection in a squirrel cage induction motor has been thoroughly investigated. However, a few papers have been related to pure static eccentricity fault and the authors focused on the RSH harmonics presented in stator current. The main objective of this paper is to present an alternative method based on the analysis of line neutral voltage taking place between the supply and the stator neutrals in order to detect air-gap static eccentricity, and to highlight the classification of all RSH harmonics in line neutral voltage. The model of squirrel cage induction machine relies on the rotor geometry and winding layout. Such developed model is used to analyze the impact of the pure static air-gap eccentricity by predicting the related frequencies in the line neutral voltage spectrum. The results show that the line neutral voltage spectrum are more sensitive to the air-gap static eccentricity fault compared to stator current one. The theoretical analysis and simulated results are confirmed by experiments.

A Novel Transient Fault Current Sensor Based on the PCB Rogowski Coil for Overhead Transmission Lines

PubMed Central

Liu, Yadong; Xie, Xiaolei; Hu, Yue; Qian, Yong; Sheng, Gehao; Jiang, Xiuchen

2016-01-01

The accurate detection of high-frequency transient fault currents in overhead transmission lines is the basis of malfunction detection and diagnosis. This paper proposes a novel differential winding printed circuit board (PCB) Rogowski coil for the detection of transient fault currents in overhead transmission lines. The interference mechanism of the sensor surrounding the overhead transmission line is analyzed and the guideline for the interference elimination is obtained, and then a differential winding printed circuit board (PCB) Rogowski coil is proposed, where the branch and return line of the PCB coil were designed to be strictly symmetrical by using a joining structure of two semi-rings and collinear twisted pair differential windings in each semi-ring. A serial test is conducted, including the frequency response, linearity, and anti-interference performance as well as a comparison with commercial sensors. Results show that a PCB Rogowski coil has good linearity and resistance to various external magnetic field interferences, thus enabling it to be widely applied in fault-current-collecting devices. PMID:27213402

Fault kinematics and tectonic stress in the seismically active Manyara Dodoma Rift segment in Central Tanzania Implications for the East African Rift

NASA Astrophysics Data System (ADS)

Macheyeki, Athanas S.; Delvaux, Damien; De Batist, Marc; Mruma, Abdulkarim

2008-07-01

The Eastern Branch of the East African Rift System is well known in Ethiopia (Main Ethiopian Rift) and Kenya (Kenya or Gregory Rift) and is usually considered to fade away southwards in the North Tanzanian Divergence, where it splits into the Eyasi, Manyara and Pangani segments. Further towards the south, rift structures are more weakly expressed and this area has not attracted much attention since the mapping and exploratory works of the 1950s. In November 4, 2002, an earthquake of magnitude Mb = 5.5 struck Dodoma, the capital city of Tanzania. Analysis of modern digital relief, seismological and geological data reveals that ongoing tectonic deformation is presently affecting a broad N-S trending belt, extending southward from the North Tanzanian Divergence to the region of Dodoma, forming the proposed "Manyara-Dodoma Rift segment". North of Arusha-Ngorongoro line, the rift is confined to a narrow belt (Natron graben in Tanzania) and south of it, it broadens into a wide deformation zone which includes both the Eyasi and Manyara grabens. The two-stage rifting model proposed for Kenya and North Tanzania also applies to the Manyara-Dodoma Rift segment. In a first stage, large, well-expressed topographic and volcanogenic structures were initiated in the Natron, Eyasi and Manyara grabens during the Late Miocene to Pliocene. From the Middle Pleistocene onwards, deformations related to the second rifting stage propagated southwards to the Dodoma region. These young structures have still limited morphological expressions compared to the structures formed during the first stage. However, they appear to be tectonically active as shown by the high concentration of moderate earthquakes into earthquake swarms, the distribution of He-bearing thermal springs, the morphological freshness of the fault scarps, and the presence of open surface fractures. Fault kinematic and paleostress analysis of geological fault data in basement rocks along the active fault lines show that recent faults often reactivate older fault systems that were formed under E-W to NW-SE horizontal compression, compatible with late Pan-African tectonics. The present-day stress inverted from earthquake focal mechanisms shows that the Manyara-Dodoma Rift segment is presently subjected to an extensional stress field with a N080°E direction of horizontal principal extension. Under this stress field, the rift develops by: (1) reactivation of the pre-existing tectonic planes of weakness, and (2) progressive development of a new fault system in a more N-S trend by the linkage of existing rift faults. This process started about 1.2 Ma ago and is still ongoing.

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

NASA Astrophysics Data System (ADS)

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

2015-05-01

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

A distributed fault-detection and diagnosis system using on-line parameter estimation

NASA Technical Reports Server (NTRS)

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

1991-01-01

The development of a model-based fault-detection and diagnosis system (FDD) is reviewed. The system can be used as an integral part of an intelligent control system. It determines the faults of a system from comparison of the measurements of the system with a priori information represented by the model of the system. The method of modeling a complex system is described and a description of diagnosis models which include process faults is presented. There are three distinct classes of fault modes covered by the system performance model equation: actuator faults, sensor faults, and performance degradation. A system equation for a complete model that describes all three classes of faults is given. The strategy for detecting the fault and estimating the fault parameters using a distributed on-line parameter identification scheme is presented. A two-step approach is proposed. The first step is composed of a group of hypothesis testing modules, (HTM) in parallel processing to test each class of faults. The second step is the fault diagnosis module which checks all the information obtained from the HTM level, isolates the fault, and determines its magnitude. The proposed FDD system was demonstrated by applying it to detect actuator and sensor faults added to a simulation of the Space Shuttle Main Engine. The simulation results show that the proposed FDD system can adequately detect the faults and estimate their magnitudes.

Contradicting Estimates of Location, Geometry, and Rupture History of Highly Active Faults in Central Japan

NASA Astrophysics Data System (ADS)

Okumura, K.

2011-12-01

Accurate location and geometry of seismic sources are critical to estimate strong ground motion. Complete and precise rupture history is also critical to estimate the probability of the future events. In order to better forecast future earthquakes and to reduce seismic hazards, we should consider over all options and choose the most likely parameter. Multiple options for logic trees are acceptable only after thorough examination of contradicting estimates and should not be a result from easy compromise or epoche. In the process of preparation and revisions of Japanese probabilistic and deterministic earthquake hazard maps by Headquarters for Earthquake Research Promotion since 1996, many decisions were made to select plausible parameters, but many contradicting estimates have been left without thorough examinations. There are several highly-active faults in central Japan such as Itoigawa-Shizuoka Tectonic Line active fault system (ISTL), West Nagano Basin fault system (WNBF), Inadani fault system (INFS), and Atera fault system (ATFS). The highest slip rate and the shortest recurrence interval are respectively ~1 cm/yr and 500 to 800 years, and estimated maximum magnitude is 7.5 to 8.5. Those faults are very hazardous because almost entire population and industries are located above the fault within tectonic depressions. As to the fault location, most uncertainties arises from interpretation of geomorphic features. Geomorphological interpretation without geological and structural insight often leads to wrong mapping. Though non-existent longer fault may be a safer estimate, incorrectness harm reliability of the forecast. Also this does not greatly affect strong motion estimates, but misleading to surface displacement issues. Fault geometry, on the other hand, is very important to estimate intensity distribution. For the middle portion of the ISTL, fast-moving left-lateral strike-slip up to 1 cm/yr is obvious. Recent seismicity possibly induced by 2011 Tohoku earthquake show pure strike-slip. However, thrusts are modeled from seismic profiles and gravity anomalies. Therefore, two contradicting models are presented for strong motion estimates. There should be a unique solution of the geometry, which will be discussed. As to the rupture history, there is plenty of paleoseismological evidence that supports segmentation of those faults above. However, in most fault zones, the largest and sometimes possibly less frequent earthquakes are modeled. Segmentation and modeling of coming earthquakes should be more carefully examined without leaving them in contradictions.

Fuzzy-Wavelet Based Double Line Transmission System Protection Scheme in the Presence of SVC

NASA Astrophysics Data System (ADS)

Goli, Ravikumar; Shaik, Abdul Gafoor; Tulasi Ram, Sankara S.

2015-06-01

Increasing the power transfer capability and efficient utilization of available transmission lines, improving the power system controllability and stability, power oscillation damping and voltage compensation have made strides and created Flexible AC Transmission (FACTS) devices in recent decades. Shunt FACTS devices can have adverse effects on distance protection both in steady state and transient periods. Severe under reaching is the most important problem of relay which is caused by current injection at the point of connection to the system. Current absorption of compensator leads to overreach of relay. This work presents an efficient method based on wavelet transforms, fault detection, classification and location using Fuzzy logic technique which is almost independent of fault impedance, fault distance and fault inception angle. The proposed protection scheme is found to be fast, reliable and accurate for various types of faults on transmission lines with and without Static Var compensator at different locations and with various incidence angles.

A comparison of long-baseline strain data and fault creep records obtained near Hollister, California

USGS Publications Warehouse

Slater, L.E.; Burford, R.O.

1979-01-01

A comparison of creepmeter records from nine sites along a 12-km segment of the Calaveras fault near Hollister, California and long-baseline strain changes for nine lines in the Hollister multiwavelength distance-measuring (MWDM) array has established that episodes of large-scale deformation both preceded and accompanied periods of creep activity monitored along the fault trace during 1976. A concept of episodic, deep-seated aseismic slip that contributes to loading and subsequent aseismic failure of shallow parts of the fault plane seems attractive, implying that the character of aseismic slip sensed along the surface trace may be restricted to a relatively shallow (~ 1-km) region on the fault plane. Preliminary results from simple dislocation models designed to test the concept demonstrate that extending the time-histories and amplitudes of creep events sensed along the fault trace to depths of up to 10 km on the fault plane cannot simulate adequately the character and amplitudes of large-scale episodic movements observed at points more than 1 km from the fault. Properties of a 2-3-km-thick layer of unconsolidated sediments present in Hollister Valley, combined with an essentially rigid-block behavior in buried basement blocks, might be employed in the formulation of more appropriate models that could predict patterns of shallow fault creep and large-scale displacements much more like those actually observed. ?? 1979.

15 years of zooming in and zooming out: Developing a new single scale national active fault database of New Zealand

NASA Astrophysics Data System (ADS)

Ries, William; Langridge, Robert; Villamor, Pilar; Litchfield, Nicola; Van Dissen, Russ; Townsend, Dougal; Lee, Julie; Heron, David; Lukovic, Biljana

2014-05-01

In New Zealand, we are currently reconciling multiple digital coverages of mapped active faults into a national coverage at a single scale (1:250,000). This seems at first glance to be a relatively simple task. However, methods used to capture data, the scale of capture, and the initial purpose of the fault mapping, has produced datasets that have very different characteristics. The New Zealand digital active fault database (AFDB) was initially developed as a way of managing active fault locations and fault-related features within a computer-based spatial framework. The data contained within the AFDB comes from a wide range of studies, from plate tectonic (1:500,000) to cadastral (1:2,000) scale. The database was designed to allow capture of field observations and remotely sourced data without a loss in data resolution. This approach has worked well as a method for compiling a centralised database for fault information but not for providing a complete national coverage at a single scale. During the last 15 years other complementary projects have used and also contributed data to the AFDB, most notably the QMAP project (a national series of geological maps completed over 19 years that include coverage of active and inactive faults at 1:250,000). AFDB linework and attributes was incorporated into this series but simplification of linework and attributes has occurred to maintain map clarity at 1:250,000 scale. Also, during this period on-going mapping of active faults has improved upon these data. Other projects of note that have used data from the AFDB include the National Seismic Hazard Model of New Zealand and the Global Earthquake Model (GEM). The main goal of the current project has been to provide the best digital spatial representation of a fault trace at 1:250,000 scale and combine this with the most up to date attributes. In some areas this has required a simplification of very fine detailed data and in some cases new mapping to provide a complete coverage. Where datasets have conflicting line work and/or attributes, data was reviewed through consultation with authors or review of published research to ensure the most to date representation was maintained. The current project aims to provide a coverage that will be consistent between the AFDB and QMAP digital and provide a free download of these data on the AFDB website (http://data.gns.cri.nz/af/).

Extensional Fault Evolution and its Flexural Isostatic Response During Iberia-Newfoundland Rifted Margin Formation

NASA Astrophysics Data System (ADS)

Gómez-Romeu, J.; Kusznir, N.; Manatschal, G.; Roberts, A.

2017-12-01

During the formation of magma-poor rifted margins, upper lithosphere thinning and stretching is achieved by extensional faulting, however, there is still debate and uncertainty how faults evolve during rifting leading to breakup. Seismic data provides an image of the present-day structural and stratigraphic configuration and thus initial fault geometry is unknown. To understand the geometric evolution of extensional faults at rifted margins it is extremely important to also consider the flexural response of the lithosphere produced by fault displacement resulting in footwall uplift and hangingwall subsidence. We investigate how the flexural isostatic response to extensional faulting controls the structural development of rifted margins. To achieve our aim, we use a kinematic forward model (RIFTER) which incorporates the flexural isostatic response to extensional faulting, crustal thinning, lithosphere thermal loads, sedimentation and erosion. Inputs for RIFTER are derived from seismic reflection interpretation and outputs of RIFTER are the prediction of the structural and stratigraphic consequences of recursive sequential faulting and sedimentation. Using RIFTER we model the simultaneous tectonic development of the Iberia-Newfoundland conjugate rifted margins along the ISE01-SCREECH1 and TGS/LG12-SCREECH2 seismic lines. We quantitatively test and calibrate the model against observed target data restored to breakup time. Two quantitative methods are used to obtain this target data: (i) gravity anomaly inversion which predicts Moho depth and continental lithosphere thinning and (ii) reverse post-rift subsidence modelling to give water and Moho depths at breakup time. We show that extensional faulting occurs on steep ( 60°) normal faults in both proximal and distal parts of rifted margins. Extensional faults together with their flexural isostatic response produce not only sub-horizontal exhumed footwall surfaces (i.e. the rolling hinge model) and highly rotated (60° or more) pre- and syn-rift stratigraphy, but also extensional allochthons underlain by apparent horizontal detachments. These detachment faults were never active in this sub-horizontal geometry; they were only active as steep faults which were isostatically rotated to their present sub-horizontal position.

Origin and late quaternary tectonism of a western Canadian continental shelf trough

NASA Astrophysics Data System (ADS)

Moslow, Thomas F.; Luternauer, John L.; Rohr, Kristin

1991-08-01

Analyses of high resolution and multi-channel seismic profiles from the central continental shelf of western Canada ascribe a late Quaternary glacial origin to large-scale troughs. Along the margins of Moresby Trough, one of three large-scale cross-shelf bathymetric depressions in Queen Charlotte Sound, seismic profiles within Quaternary sediments show a divergence of reflectors, thickening and folding of seismic units, and concavity of reflectors suggestive of drag. Compactional subsidence, growth faulting, and compaction faulting are also observed. Fault traces commonly terminate below the seabed. Deformation of Quaternary sediments due to faulting is plastic in nature and maximum offset of reflectors is 2.5 m. The observed Quaternary deformation appears to be a product of rapid deposition, loading and subsidence of late Quaternary sediment, which is unrelated to seismic activity. In addition, Quaternary faulting was probably activated by post-glacial loading and isostatic rebound of consolidated Tertiary strata along the margins of continental shelf troughs. The presence of mass movement (slump or debris flow) deposits overlying lithified Tertiary strata along the flanks of Moresby Trough provides the only evidence of seismic activity in the study area. The lack of a mud drape over these deposits implies a late Holocene age for the timing of their emplacement. The Quaternary troughs are incised into Tertiary-aged sedimentary fill of the Queen Charlotte basin. Previous workers had interpreted seafloor escarpments paralleling the trough margins to indicate that the location of Moresby Trough was controlled by renewed or continued activity on Tertiary-aged faults. A multi-channel seismic line across Moresby Trough shows that such an escarpment on the seafloor does not correlate to faults either in the Tertiary basin fill or the underlying basement. Tertiary reflectors are continuous underneath Moresby Trough; the seafloor escarpment is an erosional feature and was not created by reactivation of Tertiary structures. Trough erosion and subsequent fill (up to 175 m thick) are entirely of Quaternary age.

An improved fault detection classification and location scheme based on wavelet transform and artificial neural network for six phase transmission line using single end data only.

PubMed

Koley, Ebha; Verma, Khushaboo; Ghosh, Subhojit

2015-01-01

Restrictions on right of way and increasing power demand has boosted development of six phase transmission. It offers a viable alternative for transmitting more power, without major modification in existing structure of three phase double circuit transmission system. Inspite of the advantages, low acceptance of six phase system is attributed to the unavailability of a proper protection scheme. The complexity arising from large number of possible faults in six phase lines makes the protection quite challenging. The proposed work presents a hybrid wavelet transform and modular artificial neural network based fault detector, classifier and locator for six phase lines using single end data only. The standard deviation of the approximate coefficients of voltage and current signals obtained using discrete wavelet transform are applied as input to the modular artificial neural network for fault classification and location. The proposed scheme has been tested for all 120 types of shunt faults with variation in location, fault resistance, fault inception angles. The variation in power system parameters viz. short circuit capacity of the source and its X/R ratio, voltage, frequency and CT saturation has also been investigated. The result confirms the effectiveness and reliability of the proposed protection scheme which makes it ideal for real time implementation.

Decadal strain along creeping faults in the Needles District, Paradox Basin Utah determined with InSAR Time Series Analysis

NASA Astrophysics Data System (ADS)

Kravitz, K.; Furuya, M.; Mueller, K. J.

2013-12-01

The Needles District, in Canyonlands National Park in Utah exposes an array of actively creeping normal faults that accommodate gravity-driven extension above a plastically deforming substrate of evaporite deposits. Previous interferogram stacking and InSAR analysis of faults in the Needles District using 35 ERS satellite scenes from 1992 to 2002 showed line-of-sight deformation rates of ~1-2 mm/yr along active normal faults, with a wide strain gradient along the eastern margin of the deforming region. More rapid subsidence of ~2-2.5 mm/yr was also evident south of the main fault array across a broad platform bounded by the Colorado River and a single fault scarp to the south. In this study, time series analysis was performed on SAR scenes from Envisat, PALSAR, and ERS satellites ranging from 1992 to 2010 to expand upon previous results. Both persistent scatterer and small baseline methods were implemented using StaMPS. Preliminary results from Envisat data indicate equally distributed slip rates along the length of faults within the Needles District and very little subsidence in the broad region further southwest identified in previous work. A phase ramp that appears to be present within the initial interferograms creates uncertainty in the current analysis and future work is aimed at removing this artifact. Our new results suggest, however that a clear deformation signal is present along a number of large grabens in the northern part of the region at higher rates of up to 3-4 mm/yr. Little to no creep is evident along the single fault zone that bounds the southern Needles, in spite of the presence of a large and apparently active fault. This includes a segment of this fault that is instrumented by a creepmeter that yields slip rates on the order of ~1mm/yr. Further work using time series analysis and a larger sampling of SAR scenes will be used in an effort to determine why differences exist between previous and current work and to test mechanics-based modeling of extension in the region.

The Investigation of Active Tectonism Offshore Cide-Sinop, Southern Black Sea by Seismic Reflection and Bathymetric Data

NASA Astrophysics Data System (ADS)

Alp, Y. I.; Ocakoglu, N.; Kılıc, F.; Ozel, A. O.

2017-12-01

The active tectonism offshore Cide-Sinop at the Southern Black Sea shelf area was first time investigated by multi-beam bathymetric and multi-channel seismic reflection data under the Research Project of The Scientific and Technological Research Council of Turkey (TUBİTAK-ÇAYDAG-114Y057). The multi-channel seismic reflection data of about 700 km length were acquired in 1991 by Turkish Petroleum Company (TP). Multibeam bathymetric data were collected between 2002-2008 by the Turkish Navy, Department of Navigation, Hydrography and Oceanography (TN-DNHO). Conventional data processing steps were applied as follows: in-line geometry definition, shot-receiver static correction, editing, shot muting, gain correction, CDP sorting, velocity analysis, NMO correction, muting, stacking, predictive deconvolution, band-pass filtering, finite-difference time migration, and automatic gain correction. Offshore area is represented by a quite smooth and large shelf plain with an approx. 25 km wide and the water depth of about -100 m. The shelf gently deepens and it is limited by the shelf break with average of -120 m contour. The seafloor morphology is charasterised by an erosional surface. Structurally, E-W trending strike-slip faults with generally compression components and reverse/thrust faults have been regionally mapped for the first time. Most of these faults deform all seismic units and reach the seafloor delimiting the morphological highs and submarine plains. Thus, these faults are intepreted as active faults. These results support the idea that the area is under the active compressional tectonic regime

Strike-slip faulting at Thebes Gap, Missouri and Illinois; implications for New Madrid tectonism

USGS Publications Warehouse

Harrison, Richard W.; Schultz, Art

1994-01-01

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.

The regional structural setting of the 2008 Wells earthquake and Town Creek Flat Basin: implications for the Wells earthquake fault and adjacent structures

USGS Publications Warehouse

Henry, Christopher S.; Colgan, Joseph P.

2011-01-01

The 2008 Wells earthquake occurred on a northeast-striking, southeast-dipping fault that is clearly delineated by the aftershock swarm to a depth of 10-12 km below sea level. However, Cenozoic rocks and structures around Wells primarily record east-west extension along north- to north-northeast-striking, west-dipping normal faults that formed during the middle Miocene. These faults are responsible for the strong eastward tilt of most basins and ranges in the area, including the Town Creek Flat basin (the location of the earthquake) and the adjacent Snake Mountains and western Windermere Hills. These older west-dipping faults are locally overprinted by a younger generation of east-dipping, high-angle normal faults that formed as early as the late Miocene and have remained active into the Quaternary. The most prominent of these east-dipping faults is the set of en-échelon, north-striking faults that bounds the east sides of the Ruby Mountains, East Humboldt Range, and Clover Hill (about 5 km southwest of Wells). The northeastern-most of these faults, the Clover Hill fault, projects northward along strike toward the Snake Mountains and the approximately located surface projection of the Wells earthquake fault as defined by aftershock locations. The Clover Hill fault also projects toward a previously unrecognized, east-facing Quaternary fault scarp and line of springs that appear to mark a significant east-dipping normal fault along the western edge of Town Creek Flat. Both western and eastern projections may be northern continuations of the Clover Hill fault. The Wells earthquake occurred along this east-dipping fault system. Two possible alternatives to rupture of a northern continuation of the Clover Hill fault are that the earthquake fault (1) is antithetic to an active west-dipping fault or (2) reactivated a Mesozoic thrust fault that dips east as a result of tilting by the west-dipping faults along the west side of the Snake Mountains. Both alternatives are precluded by the depths of the earthquake and aftershocks, about 8 km and as deep as 12 km, respectively. These depths are below where an antithetic fault would intersect any main fault, and a tilted, formerly shallow and sub-horizontal thrust fault would not extend to depths of more than about 5–6 km. The east-dipping, high-angle, earthquake fault cuts older west-dipping faults rather than reactivating them, highlighting a change in the structural style of Basin and Range extension in this region from closely-spaced, west-dipping faults that rotated significantly during slip and accommodated large-magnitude extension, to widely-spaced, high-angle faults that accommodate much less total strain over a long time span.

Model-Based Fault Diagnosis for Turboshaft Engines

NASA Technical Reports Server (NTRS)

Green, Michael D.; Duyar, Ahmet; Litt, Jonathan S.

1998-01-01

Tests are described which, when used to augment the existing periodic maintenance and pre-flight checks of T700 engines, can greatly improve the chances of uncovering a problem compared to the current practice. These test signals can be used to expose and differentiate between faults in various components by comparing the responses of particular engine variables to the expected. The responses can be processed on-line in a variety of ways which have been shown to reveal and identify faults. The combination of specific test signals and on-line processing methods provides an ad hoc approach to the isolation of faults which might not otherwise be detected during pre-flight checkout.

Geophysical Survey of Proposed Construction Site with Possible Faulting, East San Francisco Bay Hills, California

NASA Astrophysics Data System (ADS)

Galvin, J. L.; Deqiang, C.; Abimbola, A.; Shuler, S.; Hayashi, K.; Fox, J.; Craig, M. S.; Strayer, L. M.; Drumm, P.

2015-12-01

We conducted a geophysical study at a site proposed for a new dorm building prior to trenching planned as part of a separate fault investigation study. The study area was located on the south side of the CSU East Bay campus, roughly 100 - 300 m SSE of the current dorm complex. In addition to its proximity to the Hayward Fault, several smaller faults have been previously mapped within the proposed location, including the East and West Dibblee Faults. These faults are thought to represent contacts between the Leona Rhyolite and the Knoxville Formation. Data acquisition included seismic, resistivity, and GPS data collected in an effort to develop a better understanding of the geological and structural profile of this area, including the location of lithologic contacts, faults, and the thickness of soil and fill. Geophysical profiles were collected over the locations of future trenches. The survey included geophysical lines that were located coincident with two planned trenching sites, which were chosen to intersect mapped faults. Survey positions were recorded using differential GPS. Seismic refraction and MASW (multichannel analysis of surface waves) surveys were performed over two of the planned trench sites using a 48-channel seismographic system with 4.5 Hz geophones and a 10-lb sledgehammer. For one of the lines, geophones were spaced every 3 m with a total spread length of 141 m and a shot spacing of 9 m. For the second line, geophones were spaced every 4 m with a total spread length of 188 m. Shots were taken every 12 m. Resistivity surveys were also performed along one of the line locations using both a capacitively-coupled dipole (CCD) system and 48-electrode system. Geospatial data for the survey area were compiled, including 0.3 m color orthoimagery and vector line files for geologic unit boundaries and presumed fault locations. The products of this study will include the geophysical response of geologic formations, location of unit contacts and faults, thickness of soil and fill, shear wave velocity (VS and VS30). The results of this study will enable improved seismic hazard assessment of the site and will contribute to a better understanding of the overall geologic profile of this area.

University Autonomy: Two Fault-Lines

ERIC Educational Resources Information Center

Evans, G. R.

2010-01-01

The doctrine of university autonomy in the UK contains a least two major "fault-lines" where the structure is inherently weak and there is danger of functional breakdown. The first occurs at the junction between the institution and the state, the second within the institution, where the unity in policy-making between academic and…

Research on Fault Characteristics and Line Protections Within a Large-scale Photovoltaic Power Plant

NASA Astrophysics Data System (ADS)

Zhang, Chi; Zeng, Jie; Zhao, Wei; Zhong, Guobin; Xu, Qi; Luo, Pandian; Gu, Chenjie; Liu, Bohan

2017-05-01

Centralized photovoltaic (PV) systems have different fault characteristics from distributed PV systems due to the different system structures and controls. This makes the fault analysis and protection methods used in distribution networks with distributed PV not suitable for a centralized PV power plant. Therefore, a consolidated expression for the fault current within a PV power plant under different controls was calculated considering the fault response of the PV array. Then, supported by the fault current analysis and the on-site testing data, the overcurrent relay (OCR) performance was evaluated in the collection system of an 850 MW PV power plant. It reveals that the OCRs at downstream side on overhead lines may malfunction. In this case, a new relay scheme was proposed using directional distance elements. In the PSCAD/EMTDC, a detailed PV system model was built and verified using the on-site testing data. Simulation results indicate that the proposed relay scheme could effectively solve the problems under variant fault scenarios and PV plant output levels.

Vertical displacements inherited from pre-Neogene time in the Gulfes of Sigacik and Kusadasi (Western Anatolia) by multi channel seismic and chirp data

NASA Astrophysics Data System (ADS)

Gurcay, S.; Cifci, G.; Dondurur, D.; Sozbilir, H.

2012-12-01

Gulfes of Sigacik and Kusadasi (Western Anatolia) are located south of the Middle Eastern Aegean depression which formed by vertical displacements along the NB- to N-trending structural planes. This study consists of the results of the multi-channel seismic reflection and chirp data acquisition by K. Piri Reis, research vessel of Dokuz Eylül University (Izmir-TURKEY), in Sigacik Gulf and Kusadasi Gulf (West Anatolia) in August-2005 and in March-2008. Data were acquired approximately along the 1300km seismic lines. Two main seismic units, lower unit (Pre-Neogene) and upper unit (Neogene), can easily be determined on multi channel seismic sections. It is also observed on seismic sections that there are many active faults deform these units. Two main submarine basins can be determined from multi-channel seismic sections, Sigacik Basin and Kusadasi Basin. The upper unit in Sigacik Basin is deformed generally by strike slip faults. But there are some faults that have sharp vertical movements on lower unit. Some of these vertical movements are followed by strike-slip active faults along the upper unit indicating that these normal movements have changed to lateral movements, recently.

Evidence of a major fault zone along the California-Nevada state line 35 deg 30 min to 36 deg 30 min north latitude

NASA Technical Reports Server (NTRS)

Liggett, M. A.; Childs, J. F.

1973-01-01

The author has identified the following significant results. Geologic reconnaissance guided by analysis of ERTS-1 and Apollo-9 satellite imagery and intermediate scale photography from X-15 and U-2 aircraft has confirmed the presence of a major fault zone along the California-Nevada state line, between 35 deg 30 min and 36 deg 30 min north latitude. The name Pahrump Fault Zone has been suggested for this feature after the valley in which it is best exposed. Field reconnaissance has indicated the existence of previously unreported faults cutting bedrock along range fronts, and displacing Tertiary and Quaternary basin sediments. Gravity data support the interpretation of regional structural discontinuity along this zone. Individual fault traces within the Pahrump Fault Zone form generally left-stepping en echelon patterns. These fault patterns, the apparent offset of a Laramide age thrust fault, and possible drag folding along a major fault break suggest a component of right lateral displacement. The trend and postulated movement of the Pahrump Fault Zone are similar to the adjacent Las Vegas Shear Zone and Death Valley-Furnace Creek Faults, which are parts of a regional strike slip system in the southern Basin-Range Province.

Fault Analysis in Solar Photovoltaic Arrays

NASA Astrophysics Data System (ADS)

Zhao, Ye

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

Evaluation of potential surface rupture and review of current seismic hazards program at the Los Alamos National Laboratory. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1991-12-09

This report summarizes the authors review and evaluation of the existing seismic hazards program at Los Alamos National Laboratory (LANL). The report recommends that the original program be augmented with a probabilistic analysis of seismic hazards involving assignment of weighted probabilities of occurrence to all potential sources. This approach yields a more realistic evaluation of the likelihood of large earthquake occurrence particularly in regions where seismic sources may have recurrent intervals of several thousand years or more. The report reviews the locations and geomorphic expressions of identified fault lines along with the known displacements of these faults and last knowmore » occurrence of seismic activity. Faults are mapped and categorized into by their potential for actual movement. Based on geologic site characterization, recommendations are made for increased seismic monitoring; age-dating studies of faults and geomorphic features; increased use of remote sensing and aerial photography for surface mapping of faults; the development of a landslide susceptibility map; and to develop seismic design standards for all existing and proposed facilities at LANL.« less

Analysis of tectonic features in US southwest from Skylab photographs

NASA Technical Reports Server (NTRS)

Abdel-Gawad, M. (Principal Investigator); Tubbesing, L.

1975-01-01

The author has identified the following significant results. Skylab photographs were utilized to study faults and tectonic lines in selected areas of the U.S. Southwest. Emphasis was on elements of the Texas Zone in the Mojave Desert and the tectonic intersection in southern Nevada. Transverse faults believed to represent the continuation of the Texas Zone were found to be anomalous in strike. This suggests that the Mojave Desert block was rotated counterclockwise as a unit with the Sierra Nevada. Left-lateral strike-slip faults in Lake Mead area are interpreted as elements of the Wasatch tectonic zone; their anomalous trend indicates that the Lake Mead area has rotated clockwise with the Colorado Plateau. A tectonic model relating major fault zones to fragmentation and rotation of crustal blocks was developed. Detailed correlation of the high resolution S190B metric camera photographs with U-2 photographs and geologic maps demonstrates the feasibility of utilizing S190B photographs for the identification of geomorphic features associated with recent and active faults and for the assessment of seismic hazards.

Imaging the Crust in the Northern Sector of the 2009 L'Aquila Seismic Sequence through Oil Exploration Data Interpretation

NASA Astrophysics Data System (ADS)

Grazia Ciaccio, Maria; Improta, Luigi; Patacca, Etta; Scandone, Paolo; Villani, Fabio

2010-05-01

The 2009 L'Aquila seismic sequence activated a complex, about 40 km long, NW-trending and SW-dipping normal fault system, consisting of three main faults arranged in right-lateral en-echelon geometry. While the northern sector of the epicentral area was extensively investigated by oil companies, only a few scattered, poor-quality commercial seismic profiles are available in the central and southern sector. In this study we interpret subsurface commercial data from the northern sector, which is the area where is located the source of the strong Mw5.4 aftershock occurred on the 9th April 2009. Our primary goals are: (1) to define a reliable framework of the upper crust structure, (2) to investigate how the intense aftershock activity, the bulk of which is clustered in the 5-10 km depth range, relates to the Quaternary extensional faults present in the area. The investigated area lies between the western termination of the W-E trending Gran Sasso thrust system to the south, the SW-NE trending Mt. Sibillini thrust front (Ancona-Anzio Line Auctt.) to the north and west, and by the NNW-SSE trending, SW-dipping Mt. Gorzano normal fault to the east. In this area only middle-upper Miocene deposits are exposed (Laga Flysch and underlying Cerrogna Marl), but commercial wells have revealed the presence of a Triassic-Miocene sedimentary succession identical to the well known Umbria-Marche stratigraphic sequence. We have analyzed several confidential seismic reflection profiles, mostly provided by ENI oil company. Seismic lines are tied to two public wells, 5766 m and 2541 m deep. Quality of the reflection imaging is highly variable. A few good quality stack sections contain interpretable signal down to 4.5-5.5 s TWT, corresponding to depths exceeding 10-12 km and thus allowing crustal imaging at seismogenic depths. Key-reflectors for the interpretation correspond to: (1) the top of the Miocene Cerrogna marls, (2) the top of the Upper Albian-Oligocene Scaglia Group, (3) the Aptian-Albian Fucoid Marl horizon, (4) the top of the upper Jurassic "Calcari ad Aptici" Formation, (5) the top of the upper Triassic dolomites plus evaporites of the Burano Formation. Strong but discontinuous deep reflectors can be reasonably attributed to the Paleozoic-Trassic clastic sequence underlying the evaporites. Neogene compression is responsible for a system of NNW-SSE trending fault-propagation folds which have often grown on top of popup-like structures. Extensional features include shallow-seated low-angle faults, likely related to gravitational readjustments on top of compressional features, and younger NNW-SSE trending high-angle faults. The major high-angle fault in the investigated area is represented by the Mt. Gorzano Fault, a regional structure the surface trace of which is at least 20 km long. The Mt. Gorzano Fault is a listric fault that dips around 60° in the first 2 s TWT and flattens at greater depths until it becomes sub-horizontal at about 5 s TWT, i.e. at a depth averaging 12 kilometers. Depth converted sections, calibrated by well data, indicate that the bulk of the aftershock activity is confined between the Triassic dolomites plus evaporites and the underlying Paleozoic-Triassic terrigenous deposits, without affecting the overlying carbonates. Events alignment revealed by accurate Double-Difference relative locations suggests that the Mw5.4 aftershock activated a 12 km-long segment of the Mt. Gorzano Fault at depths ranging from 5 to 10-12 kilometers. Aftershocks cluster in the hanging-wall of the deep portion of the fault recognized in the stack sections, whose geometry is consistent with the fault plane highlighted by earthquakes alignment.

Performance analysis of microcomputer based differential protection of UHV lines under selective phase switching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhatti, A.A.

1990-04-01

This paper examines the effects of primary and secondary fault quantities as well s of mutual couplings of neighboring circuits on the sensitivity of operation and threshold settings of a microcomputer based differential protection of UHV lines under selective phase switching. Microcomputer based selective phase switching allows the disconnection of minimum number of phases involved in a fault and requires the autoreclosing of these phases immediately after the extinction of secondary arc. During a primary fault a heavy current contribution to the healthy phases tends to cause an unwanted tripping. Faulty phases physically disconnected constitute an isolated fault which beingmore » coupled to the system affects the current and voltage levels of the healthy phases still retained in the system and may cause an unwanted tripping. The microcomputer based differential protection, appears to have poor performance when applied to uncompensated lines employing selective pole switching.« less

Tidal-Induced Ocean Dynamics as Cause of Enceladus' Tiger Stripe Pattern

NASA Astrophysics Data System (ADS)

Vermeersen, B. L.; Maas, L. R.; van Oers, S.; Rabitti, A.; Jara-Orue, H.

2013-12-01

One of the most peculiar features on Saturn moon Enceladus is its so-called tiger stripe pattern at the geologically active South Polar Terrain (SPT), as first observed in detail by the Cassini spacecraft early 2005. It is generally assumed that the four almost parallel surface lines that constitute this pattern are faults in the icy surface overlying a confined salty water reservoir. Indeed, later Cassini observations have shown that salty water jets originate from the tiger stripes [e.g., Hansen et al., Science, 311, 1422-1425, 2006; Postberg et al., Nature, 474, 620-622, 2011]. The periodic activity of the tiger stripe faults shows a strong correlation with tidal forcing. Jets emanating from specific fault lines seem to be triggered at those places of the faults where tidal-induced stresses are largest immediately following closest orbital approach with Saturn [e.g., Hurford et al., Nature, 447, 292-294, 2007]. Thus jet activity seems to be directly induced by tidal forcing. However, this does not explain the characteristic regular pattern of the stripes themselves. Here we explore the possibility that this pattern is formed and maintained by induced, tidally and rotationally driven, fluid motions in the ocean underneath the icy surface of the tiger-stripe region. The remarkable spatial regularity of Enceladus' SPT fault lines is reminiscent of that observed at the surface of confined density-stratified fluids by the action of induced internal gravity waves. Theoretical analysis, numerical simulations and laboratory water tank experiments all indicate that wave attractors - particular limit orbits to which waves are focused in a fluid basin - naturally emerge in gravitationally (radial salt concentration or temperature differences) or rotationally stratified confined fluids as a function of forcing periodicity and fluid basin geometry [Maas et al., Nature, 338, 557-561, 1997]. We have found that ocean dynamical wave attractors induced by tidal-effective forcing of Enceladus' SPT salty water basin can reproduce the general characteristics of the observed tiger stripe pattern and even offer the possibility of constraining the 3D-form of the salty water basin underlying Enceladus' SPT. Vertical cross section of one of the water tank experiments. The tank is uniformly stratified with salty water and harmonically shaken. Wave attractors impinge at the surface of the tank at A, B and C, which are places where an overlying plate experiences enhanced stress levels. Distances A-B and B-C are not the same due to a sloping floor of the fluid tank. The length of the tank is about 1.5 m. Numbers at the bottom indicate mm.

Lightning Overvoltage on Low-Voltage Distribution System

NASA Astrophysics Data System (ADS)

Michishita, Koji

The portion of the faults of a medium-voltage line, cause by lightning, tends to increase with often reaching beyond 30%. However, due to the recent progress of the lightning protection design, the number of faults has decreased to 1/3 of that at 30 years ago. As for the low-voltage distribution line, the fault rate has been estimated primarily, although the details of the overvoltages have not been studied yet. For the further development of highly information-oriented society, improvement of reliability of electric power supply to the appliance in a low-voltage customer will be socially expected. Therefore, it is important to establish effective lightning protection design of the low-voltage distribution system, defined to be composed of lines having mutual interaction on the customers' electric circuits, such as a low-voltage distribution line, an antenna line and a telecommunication line. In this report, the author interprets the recent research on the lightning overvoltage on a low-voltage distribution system.

Active tectonics at the Lower Yarmouk Gorge?

NASA Astrophysics Data System (ADS)

Inbar, Nimrod; Raggad, Marwan; Siebert, Christian; Möller, Peter; Rödiger, Tino; Rosenthal, Eliyaho; Guttman, Josseph; Magri, Fabien

2017-04-01

The Lower Yarmouk Gorge (LYG) extends on the eastern margin of the Jordan Rift Valley (JRV) adjacent to the Kinneret basin which makes part in the chain of pull-apart basins along the Dead Sea Transform (DST). The LYG is bounded to the south by the Ajloun Plateau (northern Jordan) and to the north by the Golan Heights (Israel). It acts as the outflow of the Yarmouk drainage basin into the Jordan River a few kilometers south of Lake Tiberias. Although topographically the Golan Heights and the Ajloun seem to be different provinces separated by the LYG, the northern Ajloun and southern Golan form the southern flank of a major synclinal structure. Morphologically, the LYG resembles the Sheikh-Ali strike-slip fault and other NE-SW striking faults related to the DST. However, the existence of faulting along that line is debatable. As the gorge serves also as state boundary, no seismic lines cross the LYG. Quaternary landslides, mostly on the southern flank of the LYG cover possible surface evidence of faulting although Quaternary basalts located at the gorge path may indicate possible vertical pathways. Moreover, hydrological studies (Siebert et al., 2014, Goretzki et al., 2016) show that permeability anisotropy along the LYG line allows heated groundwater to emerge along the gorge with temperatures rising up to 60°C. The presented study uses well data from northern Jordan and southern Golan Heights as well as seismic data from the southern Golan Heights to bridge over the information gap. Based on the available information we present our hypothesis on the geology of the LYG aiming to contribute to the discussion regarding active tectonics at the Lower Yarmouk Gorge. Our preliminary results show that a major fault along the gorge path is dubious however, perpendicular faulting is more likely to occur. We expect the results of current research to contribute to the understanding of the local complex geohydrological system. Furthermore, results are expected to deepen our understanding of pull-apart basin tectonics effect on the evolution of marginal structures. Reference: Goretzki, N. et al., 2016. Inverse Problem to Constrain Hydraulic and Thermal Parameters Inducing Anomalous Heat Flow in the Lower Yarmouk Gorge. Energy Procedia, 97: 419-426. DOI:http://dx.doi.org/10.1016/j.egypro.2016.10.038 Siebert, C. et al., 2014. Thermal waters in the Lower Yarmouk Gorge and their relation to surrounding aquifers. Chemie der Erde - Geochemistry, 74(3): 425-441. DOI:http://dx.doi.org/10.1016/j.chemer.2014.04.002

A global tectonic activity map with orbital photographic supplement

NASA Technical Reports Server (NTRS)

Lowman, P. D., Jr.

1981-01-01

A three part map showing equatorial and polar regions was compiled showing tectonic and volcanic activity of the past one million years, including the present. Features shown include actively spreading ridges, spreading rates, major active faults, subduction zones, well defined plates, and volcanic areas active within the past one million years. Activity within this period was inferred from seismicity (instrumental and historic), physiography, and published literature. The tectonic activity map was used for planning global geodetic programs of satellite laser ranging and very long base line interferometry and for geologic education.

Comparative study of two active faults in different stages of the earthquake cycle in central Japan -The Atera fault (with 1586 Tensho earthquake) and the Nojima fault (with 1995 Kobe earthquake)-

NASA Astrophysics Data System (ADS)

Matsuda, T.; Omura, K.; Ikeda, R.

2003-12-01

National Research Institute for Earth Science and Disaster Prevention (NIED) has been conducting _gFault zone drilling_h. Fault zone drilling is especially important in understanding the structure, composition, and physical properties of an active fault. In the Chubu district of central Japan, large active faults such as the Atotsugawa (with 1858 Hietsu earthquake) and the Atera (with 1586 Tensho earthquake) faults exist. After the occurrence of the 1995 Kobe earthquake, it has been widely recognized that direct measurements in fault zones by drilling. This time, we describe about the Atera fault and the Nojima fault. Because, these two faults are similar in geological situation (mostly composed of granitic rocks), so it is easy to do comparative study of drilling investigation. The features of the Atera fault, which have been dislocated by the 1586 Tensho earthquake, are as follows. Total length is about 70 km. That general trend is NW45 degree with a left-lateral strike slip. Slip rate is estimated as 3-5 m / 1000 years. Seismicity is very low at present and lithologies around the fault are basically granitic rocks and rhyolite. Six boreholes have been drilled from the depth of 400 m to 630 m. Four of these boreholes (Hatajiri, Fukuoka, Ueno and Kawaue) are located on a line crossing in a direction perpendicular to the Atera fault. In the Kawaue well, mostly fractured and alternating granitic rock continued from the surface to the bottom at 630 m. X-ray fluorescence analysis (XRF) is conducted to estimate the amount of major chemical elements using the glass bead method for core samples. The amounts of H20+ are about from 0.5 to 2.5 weight percent. This fractured zone is also characterized by the logging data such as low resistivity, low P-wave velocity, low density and high neutron porosity. The 1995 Kobe (Hyogo-ken Nanbu) earthquake occurred along the NE-SW-trending Rokko-Awaji fault system, and the Nojima fault appeared on the surface on Awaji Island when this rupture occurred. It is more than 10 km long with 1-2 m offset along the Nojima fault. About one year after the earthquake, NIED drilled a borehole (the Hirabayashi NIED borehole) and penetrated the Nojima fault. The Hirabayashi NIED borehole was drilled to a depth of 1838 m and recovered the drill core. The main types of rock intersected by the borehole are granodiorite and cataclastic fault rocks. Three fracture zones were recognized in cores at approximate depth of 1140 m, 1300 m and 1800 m. There is remarkable foliated blue-gray gouge at a depth of 1140 m. We investigate chemical compositions by XRF analysis in the fracture zone. The amounts of H20+ are about from 1.0 to 15.0 weight percent. We investigate mineral assemblage in both drilling cores by X-ray powder diffraction analysis. From the results, we can_ft recognize so difference between the two faults. But the amount of H2O+ is very different. In the Hirabayashi NIED core at a depth of 1140 m, there is about ten times as much as the average of the Kawaue core. This is probably due to the greater degree of wall-rock fracturing in the fracture zone. We suggest that this characteristic is associated with the fault activity at the time of the 1995 Kobe earthquake and the nature of fluid-rock interactions in the fracture zone.

Power in the Production of Spaces Transformed by Rural Tourism

ERIC Educational Resources Information Center

Frisvoll, Svein

2012-01-01

The article critiques Halfacree's conceptualisation of rural space for masking the workings of power within "black boxes" such as "structural coherence" and "trial by space". One consequence is that rural change's social activities and also their social and personal consequences are cloaked, thereby rendering the localised fault lines of rurality…

Detection of High-impedance Arcing Faults in Radial Distribution DC Systems

NASA Technical Reports Server (NTRS)

Gonzalez, Marcelo C.; Button, Robert M.

2003-01-01

High voltage, low current arcing faults in DC power systems have been researched at the NASA Glenn Research Center in order to develop a method for detecting these 'hidden faults', in-situ, before damage to cables and components from localized heating can occur. A simple arc generator was built and high-speed and low-speed monitoring of the voltage and current waveforms, respectively, has shown that these high impedance faults produce a significant increase in high frequency content in the DC bus voltage and low frequency content in the DC system current. Based on these observations, an algorithm was developed using a high-speed data acquisition system that was able to accurately detect high impedance arcing events induced in a single-line system based on the frequency content of the DC bus voltage or the system current. Next, a multi-line, radial distribution system was researched to see if the arc location could be determined through the voltage information when multiple 'detectors' are present in the system. It was shown that a small, passive LC filter was sufficient to reliably isolate the fault to a single line in a multi-line distribution system. Of course, no modification is necessary if only the current information is used to locate the arc. However, data shows that it might be necessary to monitor both the system current and bus voltage to improve the chances of detecting and locating high impedance arcing faults

Characteristic investigation and control of a modular multilevel converter-based HVDC system under single-line-to-ground fault conditions

DOE PAGES

Shi, Xiaojie; Wang, Zhiqiang; Liu, Bo; ...

2014-05-16

This paper presents the analysis and control of a multilevel modular converter (MMC)-based HVDC transmission system under three possible single-line-to-ground fault conditions, with special focus on the investigation of their different fault characteristics. Considering positive-, negative-, and zero-sequence components in both arm voltages and currents, the generalized instantaneous power of a phase unit is derived theoretically according to the equivalent circuit model of the MMC under unbalanced conditions. Based on this model, a novel double-line frequency dc-voltage ripple suppression control is proposed. This controller, together with the negative-and zero-sequence current control, could enhance the overall fault-tolerant capability of the HVDCmore » system without additional cost. To further improve the fault-tolerant capability, the operation performance of the HVDC system with and without single-phase switching is discussed and compared in detail. Lastly, simulation results from a three-phase MMC-HVDC system generated with MATLAB/Simulink are provided to support the theoretical analysis and proposed control schemes.« less

New Evidence for Quaternary Strain Partitioning Along the Queen Charlotte Fault System, Southeastern Alaska

NASA Astrophysics Data System (ADS)

Walton, M. A. L.; Miller, N. C.; Brothers, D. S.; Kluesner, J.; Haeussler, P. J.; Conrad, J. E.; Andrews, B. D.; Ten Brink, U. S.

2017-12-01

The Queen Charlotte Fault (QCF) is a fast-moving ( 53 mm/yr) transform plate boundary fault separating the Pacific Plate from the North American Plate along western Canada and southeastern Alaska. New high-resolution bathymetric data along the fault show that the QCF main trace accommodates nearly all strike-slip plate motion along a single narrow deformation zone, though questions remain about how and where smaller amounts of oblique convergence are accommodated along-strike. Obliquity and convergence rates are highest in the south, where the 2012 Haida Gwaii, British Columbia MW 7.8 thrust earthquake was likely caused by Pacific underthrusting. In the north, where obliquity is lower, aftershocks from the 2013 Craig, Alaska MW 7.5 strike-slip earthquake also indicate active convergent deformation on the Pacific (west) side of the plate boundary. Off-fault structures previously mapped in legacy crustal-scale seismic profiles may therefore be accommodating part of the lesser amounts of Quaternary convergence north of Haida Gwaii. Between 2015 and 2017, the USGS acquired more than 8,000 line-km of offshore high-resolution multichannel seismic (MCS) data along the QCF to better understand plate boundary deformation. The new MCS data show evidence for Quaternary deformation associated with a series of elongate ridges located within 30 km of the QCF main trace on the Pacific side. These ridges are anticlinal structures flanked by growth faults, with recent deformation and active fluid flow characterized by seafloor scarps and seabed gas seeps at ridge crests. Structural and morphological evidence for contractional deformation decreases northward along the fault, consistent with a decrease in Pacific-North America obliquity along the plate boundary. Preliminary interpretations suggest that plate boundary transpression may be partitioned into distinctive structural domains, in which convergent stress is accommodated by margin-parallel thrust faulting, folding, and ridge formation within the Pacific Plate, with strike-slip faulting localized to the primary trace of the QCF. Contractional structures may be occupying zones of pre-existing crustal weakness and/or re-activated fabrics in the oceanic crust, possibly explaining strain partitioning behavior in areas with a low convergence angle (<15°).

Retrodeformable cross sections and Oak Ridge fault, Ventura basin, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeats, R.S.; Huftile, G.F.

1988-03-01

A retrodeformable (balanced) cross section is constructed such that stratified rocks are restored to their undeformed state without loss or gain of bed length or bed thickness. Ductile strata may be area-balanced if original thickness is known. Near Ventura, folds in Pliocene-Pleistocene turbidites and Miocene-early Pliocene shales (Rincon, Monterey, Sisquoc) overlie an unfolded competent Paleogene sequence. The basal decollement of the foldbelt is in the ductile Rincon Formation (lower Miocene). The overlying Sulphur Mountain, Ventura Avenue, San Miguelito, and Rincon anticlines are fault-propagation folds developing from south-dipping, largely late Quaternary frontal ramp thrusts (Sisar-Big Canyon-Lion fault set, Barnard fault set,more » padre Juan fault, and C-3 fault, respectively) that rise from the decollement. Cross-section balancing shows that the overlying fold-thrust belt has shortened 2.5-6 km more than subjacent Paleogene competent strata. This excess bed length is taken up in the Paleogene sequence on the Oak Ridge fault as a ramp from the brittle-plastic transition zone through the upper crust. This implies that the basal decollement is the frontal active thrust of the Oak Ridge fault. The decollement dies out southeast of a line between Timber Canyon oil field and the west end of Oak Ridge, possibly because of decreased ductility in the Miocene decollement sequence due to appearance of sandstone interbeds. Farther southeast, late Quaternary displacement concentrated on the Oak Ridge fault itself at rates greater than 10 mm/year.« less

Fault Lines in American Culture: The Case for Civic Debate

ERIC Educational Resources Information Center

Hartoonian, H. Michael; Van Scotter, Richard D.

2012-01-01

The social landscape of the United States can be mapped by using a series of cultural fault lines. This topography portrays conditions that descriptions of the surface fail to illuminate. Many of these schisms are the by-product of ideological positions that diminish personal responsibility and thoughtful civic discourse. If left unattended, these…

Use of TCSR with Split Windings for Shortening the Spar Cycle Time in 500 kV Lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matinyan, A. M., E-mail: al-drm@mail.ru; Peshkov, M. V.; Karpov, V. N.

The arc-fault recharge phenomenon in single-phase automatic reclosure (SPAR) of a line is examined. Abrief description is given of the design of a 500 kV thyristor controlled shunt reactor (TCSR) with split valve-side windings. This type of TCSR is shown to effectively quench a single-phase arc fault in a power transmission line and shortens the SPAR cycle time.

Development of a pin-post insulator with built-in metal oxide varistors for distribution lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujiwara, N.; Yoneyama, T.; Hamada, Y.

1996-04-01

A 6.6 kV pin-post insulator, incorporating ZnO varistors, has been developed in order to reduce line faults caused by direct lighting strikes, thereby reducing and simplifying maintenance work on distribution systems. The developed insulators are interchangeable with conventional pin insulators and can withstand internal fault currents twice upon their failures. The simulated results regarding the response of the developed insulators to direct lightning strikes on an overhead ground wire agreed well with the experimental results. Simulation studies also revealed that installing the developed insulators on every two poles reduces the line-fault rate of present distribution lines in case of directmore » lightning strikes by 33%, while installing them on every pole reduces the rate by 97.5% or about 1/40 of the original value.« less

High-resolution Geophysical Constraints on Fault Structure and Morphology in the Catalina Basin, Southern California Inner Continental Borderland

NASA Astrophysics Data System (ADS)

Walton, M. A. L.; Roland, E. C.; Brothers, D. S.; Kluesner, J.; Maier, K. L.; Conrad, J. E.; Hart, P. E.; Balster-Gee, A. F.

2016-12-01

Southern California's Inner Continental Borderland, offshore of Los Angeles and San Diego, contains a complex arrangement of basins, ridges, and active faults that present seismic hazards to the region. In 2014 and 2016, the U.S. Geological Survey and University of Washington collected new geophysical data throughout the Catalina Basin (CB), including multibeam bathymetry, Chirp sub-bottom profiles, and more than 2000 line-km of high-resolution multi-channel seismic reflection profiles. These data provide the first detailed imaging of the San Clemente and Catalina faults, which border the CB. We now have improved constraints on the seabed morphology, fault structure, and deformation history along significant length of the San Clemente and Catalina fault systems, as well as insights into sediment deposition and basin development in the CB since the late Miocene. New multibeam data image the Catalina Fault as a continuous linear seafloor feature along the base of Catalina Island, and subsurface imaging indicates dominantly strike-slip motion. We also image the San Clemente Fault as a straight lineament along the seafloor downslope of San Clemente Island; the fault offsets several gullies and ridges, suggesting recent strike-slip motion. In the northwest region of the CB, the San Clemente Fault's main trace splits into several transpressional splays, as indicated by a series of uplifted, fault-bounded blocks. Growth strata throughout the CB suggest that oblique transform motion along the Catalina and San Clemente faults has affected regional sedimentation patterns and depocenters over time, providing a fundamental control on sediment distribution within the CB. Buried folds, faults, and unconformities within basin strata, including a prominent surface that is likely late Miocene based on regional geology, indicate multiple episodes of deformation throughout the CB's history.

Structural and Tectonic Map Along the Pacific-North America Plate Boundary in Northern Gulf of California, Sonora Desert and Valle de Mexicali, Mexico, from Seismic Reflection Evidence

NASA Astrophysics Data System (ADS)

Gonzalez-Escobar, M.; Suarez-Vidal, F.; Mendoza-Borunda, R.; Martin Barajas, A.; Pacheco-Romero, M.; Arregui-Estrada, S.; Gallardo-Mata, C.; Sanchez-Garcia, C.; Chanes-Martinez, J.

2012-12-01

Between 1978 and 1983, Petróleos Mexicanos (PEMEX) carried on an intense exploration program in the northern Gulf of California, the Sonora Desert and the southern part of the Mexicali Valley. This program was supported by a seismic reflection field operation. The collected seismic data was 2D, with travel time of 6 s recording, in 48 channels, and the source energy was: dynamite, vibroseis and air guns. Since 2007 to present time, the existing seismic data has been re-processing and ire-interpreting as part of a collaboration project between the PEMEX's Subdirección de Exploración (PEMEX) and CICESE. The study area is located along a large portion of the Pacific-North America plate boundary in the northern Gulf of California and the Southern part of the Salton Trough tectonic province (Mexicali Valley). We present the result of the processes reflection seismic lines. Many of the previous reported known faults were identify along with the first time described located within the study region. We identified regions with different degree of tectonic activity. In structural map it can see the location of many of these known active faults and their associated seismic activity, as well as other structures with no associated seismicity. Where some faults are mist placed they were deleted or relocated based on new information. We included historical seismicity for the region. We present six reflection lines that cross the aftershocks zone of the El Mayor-Cucapah earthquake of April 4, 2010 (Mw7.2). The epicenter of this earthquake and most of the aftershocks are located in a region where pervious to this earthquake no major earthquakes are been reported. A major result of this study is to demonstrate that there are many buried faults that increase the seismic hazard.

Product quality management based on CNC machine fault prognostics and diagnosis

NASA Astrophysics Data System (ADS)

Kozlov, A. M.; Al-jonid, Kh M.; Kozlov, A. A.; Antar, Sh D.

2018-03-01

This paper presents a new fault classification model and an integrated approach to fault diagnosis which involves the combination of ideas of Neuro-fuzzy Networks (NF), Dynamic Bayesian Networks (DBN) and Particle Filtering (PF) algorithm on a single platform. In the new model, faults are categorized in two aspects, namely first and second degree faults. First degree faults are instantaneous in nature, and second degree faults are evolutional and appear as a developing phenomenon which starts from the initial stage, goes through the development stage and finally ends at the mature stage. These categories of faults have a lifetime which is inversely proportional to a machine tool's life according to the modified version of Taylor’s equation. For fault diagnosis, this framework consists of two phases: the first one is focusing on fault prognosis, which is done online, and the second one is concerned with fault diagnosis which depends on both off-line and on-line modules. In the first phase, a neuro-fuzzy predictor is used to take a decision on whether to embark Conditional Based Maintenance (CBM) or fault diagnosis based on the severity of a fault. The second phase only comes into action when an evolving fault goes beyond a critical threshold limit called a CBM limit for a command to be issued for fault diagnosis. During this phase, DBN and PF techniques are used as an intelligent fault diagnosis system to determine the severity, time and location of the fault. The feasibility of this approach was tested in a simulation environment using the CNC machine as a case study and the results were studied and analyzed.

A Solid-State Fault Current Limiting Device for VSC-HVDC Systems

NASA Astrophysics Data System (ADS)

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

2013-08-01

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

The detection error of thermal test low-frequency cable based on M sequence correlation algorithm

NASA Astrophysics Data System (ADS)

Wu, Dongliang; Ge, Zheyang; Tong, Xin; Du, Chunlin

2018-04-01

The problem of low accuracy and low efficiency of off-line detecting on thermal test low-frequency cable faults could be solved by designing a cable fault detection system, based on FPGA export M sequence code(Linear feedback shift register sequence) as pulse signal source. The design principle of SSTDR (Spread spectrum time-domain reflectometry) reflection method and hardware on-line monitoring setup figure is discussed in this paper. Testing data show that, this detection error increases with fault location of thermal test low-frequency cable.

Coulomb Stress Change and Seismic Hazard of Rift Zones in Southern Tibet after the 2015 Mw7.8 Nepal Earthquake and Its Mw7.3 Aftershock

NASA Astrophysics Data System (ADS)

Dai, Z.; Zha, X.; Lu, Z.

2015-12-01

In southern Tibet (30~34N, 80~95E), many north-trending rifts, such as Yadong-Gulu and Lunggar rifts, are characterized by internally drained graben or half-graben basins bounded by active normal faults. Some developed rifts have become a portion of important transportation lines in Tibet, China. Since 1976, eighty-seven >Mw5.0 earthquakes have happened in the rift regions, and fifty-five events have normal faulting focal mechanisms according to the GCMT catalog. These rifts and normal faults are associated with both the EW-trending extension of the southern Tibet and the convergence between Indian and Tibet. The 2015 Mw7.8 Nepal great earthquake and its Mw7.3 aftershock occurred at the main Himalayan Thrust zone and caused tremendous damages in Kathmandu region. Those earthquakes will lead to significant viscoelastic deformation and stress changes in the southern Tibet in the future. To evaluate the seismic hazard in the active rift regions in southern Tibet, we modeled the slip distribution of the 2015 Nepal great earthquakes using the InSAR displacement field from the ALOS-2 satellite SAR data, and calculated the Coulomb failure stress (CFS) on these active normal faults in the rift zones. Because the estimated CFS depends on the geometrical parameters of receiver faults, it is necessary to get the accurate fault parameters in the rift zones. Some historical earthquakes have been studied using the field data, teleseismic data and InSAR observations, but results are in not agreement with each other. In this study, we revaluated the geometrical parameters of seismogenic faults occurred in the rift zones using some high-quality coseismic InSAR observations and teleseismic body-wave data. Finally, we will evaluate the seismic hazard in the rift zones according to the value of the estimated CFS and aftershock distribution.

Shipborne Magnetic Survey of San Pablo Bay and Implications on the Hayward-Rodgers Creek Fault Junction

NASA Astrophysics Data System (ADS)

Ponce, D. A.; Athens, N. D.; Denton, K.

2012-12-01

A shipborne magnetic survey of San Pablo Bay reveals a steep magnetic gradient as well as several prominent magnetic anomalies along the offshore extension of the Hayward Fault. The Hayward Fault enters San Pablo Bay at Pinole Point and potentially extends beneath San Pablo Bay for 15 km. About 1,000 line-km of shipborne magnetometer data were collected in San Pablo Bay along approximately north-east and north-west trending traverses. Shiptrack lines were spaced 200-m apart in a N55oE direction and tie-lines were spaced 500- and 1,000-m apart in a N145oE direction. Magnetometer and Geographic Positioning System (GPS) data were collected simultaneously at one-second intervals using a Geometrics G858 cesium vapor magnetometer with the sensor attached to a nonmagnetic pole extended about 2 m over the bow. Diurnal variations of the Earth's magnetic field were recorded at a ground magnetic base station and shipborne data were corrected for diurnal variations, International Geomagnetic Reference Field, cultural noise, heading errors, and leveling errors. The heading correction applied to the shipborne magnetic data accounts for a systematic shift in the magnetic readings due to the magnetic field produced by the boat and the orientation of the boat. The heading correction was determined by traversing several shiptrack lines in various azimuths in opposite directions. Magnetic measurements off the main survey lines (e.g., turns) were removed from the survey. After applying the heading correction, crossing values or the difference in values where two survey lines intersect were compared and the survey was leveled. Shipborne magnetic data reveal a prominent magnetic anomaly immediately offshore of Point Pinole that probably reflects ultramafic rocks (e.g. serpentinite), similar to those exposed in the northern part of the onshore Hayward Fault. Further to the northwest, shipborne magnetic data enhance two prominent aeromagnetic anomalies along the Hayward Fault in the central part of San Pablo Bay. These magnetic anomalies appear to represent two separate features, one on either side of the Hayward Fault. Likely sources for these anomalies are probably mafic, ultramafic, or volcanic rocks along the fault. Indeed, the more prominent, higher amplitude anomaly, which occurs on the west side of the Hayward Fault, could reflect an offset counterpart to the San Leandro gabbro body in the central part of the onshore portion of the Hayward Fault (Jachens et al., 2002). If so, the apparent offset is about 43 km. Although a magnetic ridge of possible volcanic rock origin (Wright and Smith, 1992) occurs between the Hayward and Rodgers Creek Faults, the Rodgers Creek Fault itself may be expressed by a steep gradient in the shipborne magnetic data. Analysis of these high-resolution shipborne magnetic data afford us the opportunity to image the detailed structure beneath San Pablo Bay and its implications on earthquake hazards.

Shallow high-resolution geophysical investigation along the western segment of the Victoria Lines Fault (island of Malta)

NASA Astrophysics Data System (ADS)

Villani, Fabio; D'Amico, Sebastiano; Panzera, Francesco; Vassallo, Maurizio; Bozionelos, George; Farrugia, Daniela; Galea, Pauline

2018-01-01

The Victoria Lines Fault (island of Malta) is a >15 km-long and N260°-striking segmented normal fault-system, which is probably inactive since the late Pliocene. In the westernmost part, the Fomm Ir-Rih segment displays comparable geologic throw and escarpment height ( 150-170 m), moreover its hangingwall hosts thin patches of Middle Pleistocene clastic continental deposits (red beds), which are poorly preserved elsewhere. We acquired two seismic transects, by collecting ambient vibration recordings, processed by using horizontal-to-vertical spectral ratios, complemented by one high-resolution 2-D refraction tomography survey crossing this fault where it is locally covered by red beds and recent colluvial deposits. We found a resonance peak at 1.0 Hz in the hangingwall block, whereas clear peaks in the range 5.0-10.0 Hz appear when approaching the subsurface fault, and we relate them to the fractured bedrock within the fault zone. The best-fit tomographic model shows a relatively high-Vp shallow body (Vp 2200-2400 m/s) that we relate to the weathered top of the Miocene Upper Coralline Limestone Fm., bounded on both sides by low-Vp regions (<1400 m/s). The latter are the smeared images of steep fault zones. Tomography further reveals a thick ( 15-20 m) low-Vp (<1000 m/s) zone, which could be a syn-tectonic wedge of colluvial deposits developed in the downthrown block. Surface waves analysis indicates lateral changes of the average shallow shear wave velocity, with Vs 130 m/s within the inferred fault zone, and Vs >230 m/s above the weathered top-bedrock. Our results depict a clear seismic signature of the Victoria Lines Fault, characterized by low seismic velocity and high amplification of ground motion. We hypothesize that, during the Middle Pleistocene, faulting may have affected the basal part of the red beds, so that this part of the investigated complex fault-system may be considered inactive since 0.6 Myr ago.

Delivery and application of precise timing for a traveling wave powerline fault locator system

NASA Technical Reports Server (NTRS)

Street, Michael A.

1990-01-01

The Bonneville Power Administration (BPA) has successfully operated an in-house developed powerline fault locator system since 1986. The BPA fault locator system consists of remotes installed at cardinal power transmission line system nodes and a central master which polls the remotes for traveling wave time-of-arrival data. A power line fault produces a fast rise-time traveling wave which emanates from the fault point and propagates throughout the power grid. The remotes time-tag the traveling wave leading edge as it passes through the power system cardinal substation nodes. A synchronizing pulse transmitted via the BPA analog microwave system on a wideband channel sychronizes the time-tagging counters in the remote units to a different accuracy of better than one microsecond. The remote units correct the raw time tags for synchronizing pulse propagation delay and return these corrected values to the fault locator master. The master then calculates the power system disturbance source using the collected time tags. The system design objective is a fault location accuracy of 300 meters. BPA's fault locator system operation, error producing phenomena, and method of distributing precise timing are described.

The correlation of 2D-resistivity and magnetic methods in fault verification at northern Sumatra, Indonesia

NASA Astrophysics Data System (ADS)

Kamaruddin, Nur Aminuda; Saad, Rosli; Nordiana, M. M.; Azwin, I. N.

2015-04-01

The Great Sumatra Fault system was split into two sub-parallel lines or segments at the Northern Sumatra. This event is one of the impacts of powerful earthquakes that hit Sumatra Island especially one that occurred in 2004. These two sub-parallel segments known as Aceh and Seulimeum fault. The study is focused on the Seulimeum fault and two geophysical methods chosen aimed to compare and verified the result obtained respectively. 2-D resistivity method is a common geophysical method used in determination of near surface structures such as faults, cavities, voids and sinkholes. Meanwhile, the magnetic method often chosen to delineate subsurface structures, determine depth of magnetic source bodies and possibly sediment thickness. Three survey lines of resistivity method and randomly magnetic stations were carried out covering Krueng district. The resistivity data processed using Res2Dinv and result presented using Surfer software. The fault identified by the contrast of low and high resistivity value. Meanwhile, the magnetic data were presented in magnetic residual contour map and the extended fault system is suspected represent by the contrast value of the magnetic anomalies. Within suspected fault zone, the results of resistivity are tally with magnetic result.

Monitoring transmitted waves across a fault with a high potential for mining induced earthquakes -the Ezulwini gold mine in South Africa

NASA Astrophysics Data System (ADS)

Kawakata, H.; Yoshimitsu, N.; Nakatani, M.; Philipp, J.; Doi, I.; Naoi, M. M.; Ward, T.; Visser, V.; Morema, G.; Khambule, S.; Masakale, T.; Milev, A.; Durrheim, R. J.; Ribeiro, L.; Ward, M.; Ogasawara, H.

2011-12-01

It gives us important information about earthquake processes to monitor transmitted waves across a fault with a high potential for earthquake generation. In laboratory experiments, the decreases in elastic wave speed (e.g., Yoshimitsu et al., 2009) and attenuation parameter Q (Yoshimitsu and Kawakata, 2011) have been found prior to the faulting. In South African gold mines, we can specify a fault with a high potential for mining induced earthquakes of relatively large magnitude based on mining plans. In addition, the seismic line can be set at the depth of a few kilometers, so that the transmitted waves propagate through only hard rock. Hence, we started to monitor transmitted waves across a fault that has a high potential for an M˜2 earthquake at about 1 km deep in the Ezulwini gold mine. We installed a piezoelectric transmitter as a wave source about 20 m away from the fault in the hanging wall. Three accelerometers of 3-component were also installed in alignment with the transmitter; one is about 7 m away from the fault in the hanging wall, and the other two are about 7 m and 13 m away from the fault in the footwall, respectively. Then, the total length of our seismic line is ˜ 33 m long. The frequency response of accelerometers is within ±3 dB from 1 Hz to 10 kHz. For 10 minutes from midnight everyday, when there is no blasting, the elastic waves are transmitted every 0.05 seconds, and the received waves are recorded at 400 ksps on 14bit. Transmitted signals can be clearly recognized in stacked waveforms of all channels, although signal-to-noise ratios are high enough only in a frequency range from 3 kHz up to 10 kHz. The waveforms of three components are rotated so that one component (radial component) is parallel to the seismic line. Then, P waves are dominant in radial components for two sites in the footwall. On the other hand, at the nearest site in the hanging wall, near field term and/or intermediate term seem to be included. In addition to the transmission monitoring, ambient noise recording at 200 ksps for 50 minutes is carried out every day after the 10-minute transmission for the analysis of seismic noise interferometry. Further, from 1 AM to the next midnight everyday, earthquake trigger recording at 200 ksps is held for the analysis of coda-wave interferometry. These enable us not only to monitor the fault properties but to compare active imaging using transmission signals with passive imaging with seismic interferometry.

Chocolate tablet aspects of cytherean Meshkenet Tessera

NASA Technical Reports Server (NTRS)

Raitala, J.

1993-01-01

Meshkenet Tessera structures were mapped from Magellan data and several resemblances to chocolate tablet boudinage were found. The complex fault sets display polyphase tectonic sequences of a few main deformation phases. Shear and tension have contributed to the areal deformation. Main faults cut the 1600-km long Meshkenet Tessera highland into bar-like blocks which have ridge and groove pattern oriented along or at high angles to the faults. The first approach to the surface block deformation is an assumption of initial parallel shear faulting followed by a chocolate tablet boudinage. Major faults which cut Meshkenet Tessera into rectangular blocks have been active repetitively while two progressive or superposed boudinage set formations have taken place at high angles during the relaxational or flattening type deformation of the area. Chocolate tablet boudinage is caused by a layer-parallel two-dimensional extension resulting in fracturing of the competent layer. Such structures, defined by two sets of boudin neck lines at right angles to each other, have been described by a number of authors. They develop in a flattening type of bulk deformation or during superposed deformation where the rock is elongated in two dimensions parallel to the surface. This is an attempt to describe and understand the formation and development of structures of Meshkenet Tessera which has complicated fault structures.

The Potential of Research-Based Learning for the Creation of Truly Inclusive Academic Communities of Practice

ERIC Educational Resources Information Center

Smith, Pete; Rust, Chris

2011-01-01

The academic community in higher education is becoming increasingly fragmented, with arguably the greatest fault line between research and teaching. This paper argues that, through the reinvention of the undergraduate curriculum to focus on student engagement in research and research-type activities, a truly inclusive community of academic…

21 CFR 880.5725 - Infusion pump.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Infusion pump. 880.5725 Section 880.5725 Food and... Infusion pump. (a) Identification. An infusion pump is a device used in a health care facility to pump... means to detect a fault condition, such as air in, or blockage of, the infusion line and to activate an...

21 CFR 880.5725 - Infusion pump.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Infusion pump. 880.5725 Section 880.5725 Food and... Infusion pump. (a) Identification. An infusion pump is a device used in a health care facility to pump... means to detect a fault condition, such as air in, or blockage of, the infusion line and to activate an...

Complementary Ruptures of Surface Ruptures and Deep Asperity during the 2014 Northern Nagano, Japan, Earthquake (MW 6.3)

NASA Astrophysics Data System (ADS)

Asano, K.; Iwata, T.; Kubo, H.

2015-12-01

A thrust earthquake of MW 6.3 occurred along the northern part of the Itoigawa-Shizuoka Tectonic Line (ISTL) in the northern Nagano prefecture, central Japan, on November 22, 2014. This event was reported to be related to an active fault, the Kamishiro fault belonging to the ISTL (e.g., HERP, 2014). The surface rupture is observed along the Kamishiro fault (e.g., Lin et al., 2015; Okada et al., 2015). We estimated the kinematic source rupture process of this earthquake through the multiple time-window linear waveform inversion method (Hartzell and Heaton, 1983). We used velocity waveforms in 0.05-1 Hz from 12 strong motion stations of K-NET, KiK-net (NIED), JMA, and Nagano prefecture (SK-net, ERI). In order to enhance the reliability in Green's functions, we assumed one-dimensional velocity structure models different for the different stations, which were extracted from the nation-wide three-dimensional velocity structure model, Japan Integrated Velocity Structure Model (JIVSM, Koketsu et al., 2012). Considering the spatial distribution of aftershocks (Sakai et al., 2015) and surface ruptures, the assumed fault model consisted of two dip-bending fault segments with different dip angles between the northern and southern segments. The total length and width of the fault plane is 20 km and 13 km, relatively, and the fault model is divided into 260 subfaults of 1 km × 1 km in space and six smoothed ramp functions in time. An asperity or large slip area with a peak slip of 1.9 m was estimated in the lower plane of the northern segment in the approximate depth range of 4 to 8 km. The depth extent of this asperity is consistent with the seismogenic zone revealed by past studies (e.g., Panayotopoulos et al., 2014). In contrast, the slip in the southern segment is relatively concentrated in the shallow portion of the segment where the surface ruptures were found along the Kamishiro fault. The overall spatial rupture pattern of the source fault, in which the deep asperity was located on the northern segment and surface rupture was found on the southern segment, seems to be spatially consistent with the mapped active faults. These findings suggest characteristic and repeating features of fault ruptures along active faults where static offsets have accumulated over past events, and it would be a good constraint on earthquake scenarios along it.

Aircraft Engine On-Line Diagnostics Through Dual-Channel Sensor Measurements: Development of a Baseline System

NASA Technical Reports Server (NTRS)

Kobayashi, Takahisa; Simon, Donald L.

2008-01-01

In this paper, a baseline system which utilizes dual-channel sensor measurements for aircraft engine on-line diagnostics is developed. This system is composed of a linear on-board engine model (LOBEM) and fault detection and isolation (FDI) logic. The LOBEM provides the analytical third channel against which the dual-channel measurements are compared. When the discrepancy among the triplex channels exceeds a tolerance level, the FDI logic determines the cause of the discrepancy. Through this approach, the baseline system achieves the following objectives: (1) anomaly detection, (2) component fault detection, and (3) sensor fault detection and isolation. The performance of the baseline system is evaluated in a simulation environment using faults in sensors and components.

On-line diagnosis of sequential systems, 3

NASA Technical Reports Server (NTRS)

Sundstrom, R. J.

1975-01-01

A formal model is introduced which can serve as the basis for a theoretical investigation of on-line diagnosis. Within this model a fault of a system S is considered to be a transformation of S into another system S prime at some time tau. The resulting faulty system is taken to be the system which looks like S up to time tau and like S prime thereafter. The on-line diagnosis of systems which are structurally decomposed and represented as a network of smaller systems is also investigated. The fault set considered is the set of unrestricted component faults; namely, the set of faults which only affect one component of the network. A characterization of networks which can be diagnosed using a combinational detector is obtained. It is further shown that any network can be made diagnosable in the above sense through the addition of one component. In addition, a lower bound is obtained on the complexity of any component, the addition of which is sufficient to make a particular network combinationally diagnosable.

Distribution of Hydrothermal Activity at the Lau ISS: Possible Controlling Parameters

NASA Astrophysics Data System (ADS)

Martinez, F.; Baker, E. T.; Resing, J. A.; Edwards, M. H.; Walker, S. L.; Buck, N.

2008-12-01

Seismic tomographic studies of intermediate to fast spreading rate mid-ocean ridges (MORs) interpret zones of rapid crustal cooling a few (3-4) km off axis surrounding the axial seismic low velocity zone (LVZ). These zones of rapid cooling also broadly correlate with the initiation and growth of large abyssal hill faults. The close association of both high thermal gradients and development of fault permeability at crustal scales suggests the hypothesis that these areas may be favorable locations for off-axis high temperature hydrothermal activity. In March-May 2008 on R/V Kilo Moana we conducted a near-bottom sidescan sonar and oceanographic survey along the Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR) in the Lau back-arc basin to map the distribution of hydrothermal activity within this region. The survey utilized the deep-towed DSL120A (IMI120) sonar, an array of miniature autonomous plume recorders (MAPRs) attached to the tow cable and tethered beneath the sonar's depressor weight, an in situ chemical scanner (VISA) and 23 CTD hydrocasts (see Baker et al., this session). At the ELSC the survey spanned ~100 x 10 km area encompassing the ABE, Tow Cam and Kilo Moana vent fields with ~ 1 km spaced lines overall and ~500 m spaced lines in the area of the ABE vent field. On the VFR the survey spanned a distance of ~100 km along axis by ~5 km across axis with 700 m spaced lines encompassing the Vai Lili, Mariner and Tui Malila vent sites. Initial results identified particle plumes, indicative of high temperature venting, only within about a km of the ridge axis at the ELSC and VFR with possible diffuse venting indicated by MAPR oxidation-reduction potential (ORP) measurements at flank sites at VFR. The expanded sonar coverage better defines the volcano-tectonic context of the hydrothermal signals and previously mapped vent sites. Initial results suggest, however, no high-T venting more than about 1 km from the ridge axis, an apparently negative test of the above hypothesis. This may suggest that hydrothermal fluids are efficiently channeled to the axis even if cooling off-axis crustal regions. Alternatively, at the back-arc VFR/ELSC subduction controls on magmatic productivity may play an important role in modifying the usual relationships observed at MORs among spreading rate, seismic low velocity zone width, faulting, sedimentation and hydrothermal activity. For example, the fast spreading ELSC is magmatically deficient for its spreading rate, forms a deep faulted axial floor and has no continuous axial magma lens seismic reflector. This may lead to a narrower LVZ at the ELSC relative to MORs spreading at the same rate. At the intermediate rate and arc- proximal VFR excess magmatic productivity and volatile-rich volcanics form a peaked shallow axis, few flanking faults and a sediment drape of volcaniclastics from the ridge axis (and nearby arc volcanoes). These effects may act to suppress fault-related permeability on ridge flanks or may rapidly blanket ridge-flanking hydrothermal systems. Some of these issues may be further clarified when planned seismic tomographic and moored hydrophone studies are carried out beginning next year at the ELSC/VFR.

Geophysical characterization of transtensional fault systems in the Eastern California Shear Zone-Walker Lane Belt

NASA Astrophysics Data System (ADS)

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

2011-12-01

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 ~2.0 km/sec in the basin fill to 4.5-5.5 km/sec in the footwall) across the basin-bounding normal fault system. Very fast (approaching 6.0 km/sec) basement underlies the basin fill. The residual gravity anomaly indicates that Clayton Valley is divided into a shallower northern basin, imaged by the seismic lines, and a deeper, more asymmetric southern basin. Faults within Clayton Valley are curvilinear in nature, similar to faults observed in other step-over systems (e.g., the Mina Deflection). Gravity profiles support the seismic reflection interpretation and indicate a high angle fault (>60 degrees) bounding the northern sub-basin on its southeast margin, with a shallower fault bounding it to the northwest. A basement high trends west-northwest and separates the northern and southern basins, and is likely bounded on its southern edge by a predominantly strike-slip fault crossing the valley. Much of the strain accommodated within the southern sub-basin appears to be transferred into southern Big Smoky Valley, northwest of Clayton Valley, via these dextral strike-slip faults that obliquely cross Clayton Valley.

High resolution seismics methods in application to fault zone detection

NASA Astrophysics Data System (ADS)

Matula, Rafal; Czaja, Klaudia; Mahmod, Adam Ahmed

2014-05-01

Surveys were carried out along border line between Outer Carpathians, Inner Carpathians and Pieniny Klippen Belt. Main point of interest was imaging transition zone structured by para-conglomerates, sandstone and clays lenses, crossing in near neighbourhood of Stare Bystre, village in the southern part of Poland. Actually geological works states existence of two hypothetical faults, first at the direction NE-SW and second NNW-SSE. Main aim of geological and geophysical investigation was to prove that mentioned fault has a system of smaller discontinuities connected with previous main fault activity. Para-conglomerate exposures, which is localized close to discussed fault is cut by visible system of cracks. That fact provide geological evidences that this system could be the effect of previous fault activity so in other words, it has a continuation up to main discontinuities. What is more part of the same formation para-conglomerates is covered by Neogen river sediments, so non-direct detection methods of cracks azimuth must be applied. Geophysical investigation was located near mentioned exposure and conducted in 3-D variant. Measurements were extremely focused on determining any changes of elevation buried para-conglomerates and velocity variation inside studied sediments. Seismic methods such as refraction and refraction tomography were used to imaging bedrock. Surveys were carried out in non typical acquisition, azimuthal schema. During field works 24- channels seismograph and 4 Hz, 10 Hz and 100 Hz geophones were used. Hypothetical discontinuities were estimated after analysing seismic records and expressed by velocity variation in bedding rocks and additionally evaluated changes in its elevation. Furthermore, in this study attempt of use refraction wave attributes related to loosing rock - para-conglomerates continuity were exposed. The presentation of geophysical data had a volumetric character what was easier to interpret and better related to assumptions about geological structure of mentioned zone. Correlation between geophysical and geological results seems to be very effective in reconstruction the forming processes of fault zones. Better understanding phenomena, which rules of young fault activities, reduce incorporated hazards and simultaneously bring information about presence geodynamics processes.

Intelligent on-line fault tolerant control for unanticipated catastrophic failures.

PubMed

Yen, Gary G; Ho, Liang-Wei

2004-10-01

As dynamic systems become increasingly complex, experience rapidly changing environments, and encounter a greater variety of unexpected component failures, solving the control problems of such systems is a grand challenge for control engineers. Traditional control design techniques are not adequate to cope with these systems, which may suffer from unanticipated dynamic failures. In this research work, we investigate the on-line fault tolerant control problem and propose an intelligent on-line control strategy to handle the desired trajectories tracking problem for systems suffering from various unanticipated catastrophic faults. Through theoretical analysis, the sufficient condition of system stability has been derived and two different on-line control laws have been developed. The approach of the proposed intelligent control strategy is to continuously monitor the system performance and identify what the system's current state is by using a fault detection method based upon our best knowledge of the nominal system and nominal controller. Once a fault is detected, the proposed intelligent controller will adjust its control signal to compensate for the unknown system failure dynamics by using an artificial neural network as an on-line estimator to approximate the unexpected and unknown failure dynamics. The first control law is derived directly from the Lyapunov stability theory, while the second control law is derived based upon the discrete-time sliding mode control technique. Both control laws have been implemented in a variety of failure scenarios to validate the proposed intelligent control scheme. The simulation results, including a three-tank benchmark problem, comply with theoretical analysis and demonstrate a significant improvement in trajectory following performance based upon the proposed intelligent control strategy.

The role of E-W basement faults in the Mesozoic geodynamic evolution of the Gafsa and Chotts basins, south-central Tunisia

NASA Astrophysics Data System (ADS)

Amri, Dorra Tanfous; Dhahri, Ferid; Soussi, Mohamed; Gabtni, Hakim; Bédir, Mourad

2017-10-01

The Gafsa and Chotts intracratonic basins in south-central Tunisia are transitional zones between the Atlasic domain to the north and the Saharan platform to the south. The principal aim of this paper is to unravel the geodynamic evolution of these basins following an integrated approach including seismic, well log and gravity data. These data are used to highlight the tectonic control on the deposition of Jurassic and Lower Cretaceous series and to discuss the role of the main faults that controlled the basin architecture and Cretaceous-Tertiary inversion. The horizontal gravity gradient map of the study area highlights the pattern of discontinuities within the two basins and reveals the presence of deep E-W basement faults. Primary attention is given to the role played by the E-W faults system and that of the NW-SE Gafsa fault which was previously considered active since the Jurassic. Facies and thickness analyses based on new seismic interpretation and well data suggest that the E-W-oriented faults controlled the subsidence distribution especially during the Jurassic. The NW-SE faults seem to be key structures that controlled the basins paleogeography during Late Cretaceous-Cenozoic time. The upper Triassic evaporite bodies, which locally outline the main NW-SE Gafsa fault, are regarded as intrusive salt bodies rather than early diapiric extrusions as previously interpreted since they are rare and occurred only along main strike-slip faults. In addition, seismic lines show that Triassic rocks are deep and do not exhibit true diapiric features.

Architecture and tectono-stratigraphic evolution of the intramontane Baza Basin (Bétics, SE-Spain): Constraints from seismic imaging

NASA Astrophysics Data System (ADS)

Haberland, Christian; Gibert, Luis; Jurado, María José; Stiller, Manfred; Baumann-Wilke, Maria; Scott, Gary; Mertz, Dieter F.

2017-07-01

The Baza basin is a large Neogene intramontane basin in the Bétic Cordillera of southern Spain that formed during the Tortonian (late Miocene). The Bétic Cordillera was produced by NW-SE oblique convergence between the Eurasian and African Plates. Three seismic reflection lines (each 18 km long; vibroseis method) were acquired across the Baza basin to reveal the architecture of the sedimentary infill and faulting during basin formation. We applied rather conventional CDP data processing followed by first arrival P-wave tomography to provide complementary structural information and establish velocity models for the post-stack migration. These images show a highly asymmetric structure for the Basin with sediments thickening westward, reaching a maximum observed thickness of > 2200 m near the governing Baza Fault zone (BFZ). Three major seismic units (including several subunits) on top of the acoustic basement could be identified. We use stratigraphic information from the uplifted block of the BFZ and other outcrops at the basin edges together with available information from neighboring Bétic basins to tentatively correlate the seismic units to the known stratigraphy in the area. Until new drilling or surface outcrop data is not available, this interpretation is preliminary. The seismic units could be associated to Tortonian marine deposits, and latest Miocene to Pleistocene continental fluvio-lacustrine sediments. Individual strands of the BFZ truncate the basin sediments. Strong fault reflections imaged in two lines are the product of the large impedance contrast between sedimentary fill and basement. In the central part of the Basin several basement faults document strong deformation related to the early stages of basin formation. Some of these faults can be traced up to the shallowest imaged depth levels indicating activity until recent times.

Episodic strain accumulation in southern california.

PubMed

Thatcher, W

1976-11-12

Reexamination of horizontal geodetic data in the region of recently discovered aseismic uplift has demonstrated that equally unusual horizontal crustal deformation accompanied the development of the uplift. During this time interval compressive strains were oriented roughly normal to the San Andreas fault, suggesting that the uplift produced little shear strain accumulation across this fault. On the other hand, the orientation of the anomalous shear straining is consistent with strain accumulation across northdipping range-front thrusts like the San Fernando fault. Accordingly, the horizontal and vertical crustal deformation disclosed by geodetic observation is interpreted as a short epoch of rapid strain accumulation on these frontal faults. If this interpretation is correct, thrust-type earthquakes will eventually release the accumulated strains, but the geodetic data examined here cannot be used to estimate when these events might occur. However, observation of an unusual sequence of tilts prior to 1971 on a level line lying to the north of the magnitude 6.4 San Fernando earthquake offers some promise for precursor monitoring. The data are adequately explained by a simple model of up-dip aseismic slip propagation toward the 1971 epicentral region. These observations and the simple model that accounts for them suggest a conceptually straightforward monitoring scheme to search for similar uplift and tilt precursors within the uplifted region. Such premonitory effects could be detected by a combination of frequenlty repeated short (30 to 70 km in length) level line measurements, precise gravity traverses, and continuously recording gravimeters sited to the north of the active frontal thrust faults. Once identified, such precursors could be closely followed in space and time, and might then provide effective warnings of impending potentially destructive earth-quakes.

Fault Lines in Our Democracy: Civic Knowledge, Voting Behavior, and Civic Engagement in the United States

ERIC Educational Resources Information Center

Coley, Richard J.; Sum, Andrew

2012-01-01

As the 21st century unfolds, the United States faces historic challenges, including a struggling economy, an aging infrastructure and global terrorism. Solutions will have to come from educated, skilled citizens who understand and believe in our democratic system and are civically engaged. This incisive new report examines these fault lines and…

Fault Lines in Our Democracy: Civic Knowledge, Voting Behavior, and Civic Engagement in the United States. Highlights

ERIC Educational Resources Information Center

Coley, Richard J.; Sum, Andrew

2012-01-01

As the 21st century unfolds, the United States faces historic challenges, including a struggling economy, an aging infrastructure and global terrorism. Solutions will have to come from educated, skilled citizens who understand and believe in our democratic system and are civically engaged. This incisive new report examines these fault lines and…

An update of Quaternary faults of central and eastern Oregon

USGS Publications Warehouse

Weldon, Ray J.; Fletcher, D.K.; Weldon, E.M.; Scharer, K.M.; McCrory, P.A.

2002-01-01

This is the online version of a CD-ROM publication. We have updated the eastern portion of our previous active fault map of Oregon (Pezzopane, Nakata, and Weldon, 1992) as a contribution to the larger USGS effort to produce digital maps of active faults in the Pacific Northwest region. The 1992 fault map has seen wide distribution and has been reproduced in essentially all subsequent compilations of active faults of Oregon. The new map provides a substantial update of known active or suspected active faults east of the Cascades. Improvements in the new map include (1) many newly recognized active faults, (2) a linked ArcInfo map and reference database, (3) more precise locations for previously recognized faults on shaded relief quadrangles generated from USGS 30-m digital elevations models (DEM), (4) more uniform coverage resulting in more consistent grouping of the ages of active faults, and (5) a new category of 'possibly' active faults that share characteristics with known active faults, but have not been studied adequately to assess their activity. The distribution of active faults has not changed substantially from the original Pezzopane, Nakata and Weldon map. Most faults occur in the south-central Basin and Range tectonic province that is located in the backarc portion of the Cascadia subduction margin. These faults occur in zones consisting of numerous short faults with similar rates, ages, and styles of movement. Many active faults strongly correlate with the most active volcanic centers of Oregon, including Newberry Craters and Crater Lake.

"3D_Fault_Offsets," a Matlab Code to Automatically Measure Lateral and Vertical Fault Offsets in Topographic Data: Application to San Andreas, Owens Valley, and Hope Faults

NASA Astrophysics Data System (ADS)

Stewart, N.; Gaudemer, Y.; Manighetti, I.; Serreau, L.; Vincendeau, A.; Dominguez, S.; Mattéo, L.; Malavieille, J.

2018-01-01

Measuring fault offsets preserved at the ground surface is of primary importance to recover earthquake and long-term slip distributions and understand fault mechanics. The recent explosion of high-resolution topographic data, such as Lidar and photogrammetric digital elevation models, offers an unprecedented opportunity to measure dense collections of fault offsets. We have developed a new Matlab code, 3D_Fault_Offsets, to automate these measurements. In topographic data, 3D_Fault_Offsets mathematically identifies and represents nine of the most prominent geometric characteristics of common sublinear markers along faults (especially strike slip) in 3-D, such as the streambed (minimum elevation), top, free face and base of channel banks or scarps (minimum Laplacian, maximum gradient, and maximum Laplacian), and ridges (maximum elevation). By calculating best fit lines through the nine point clouds on either side of the fault, the code computes the lateral and vertical offsets between the piercing points of these lines onto the fault plane, providing nine lateral and nine vertical offset measures per marker. Through a Monte Carlo approach, the code calculates the total uncertainty on each offset. It then provides tools to statistically analyze the dense collection of measures and to reconstruct the prefaulted marker geometry in the horizontal and vertical planes. We applied 3D_Fault_Offsets to remeasure previously published offsets across 88 markers on the San Andreas, Owens Valley, and Hope faults. We obtained 5,454 lateral and vertical offset measures. These automatic measures compare well to prior ones, field and remote, while their rich record provides new insights on the preservation of fault displacements in the morphology.

Ground-Truth On The CSUEB Campus: Results From Integrating Geophysical, Geological And Geospatial Methods And Fault Trench Studies.

NASA Astrophysics Data System (ADS)

Abimbola, A.; Strayer, L. M.; McEvilly, A.

2015-12-01

A major (>M6) earthquake on the Hayward fault would be catastrophic, resulting in wide-ranging structural damage and potential loss of life. California State University, East Bay (CSUEB), in Hayward lies within the Hayward fault zone and is home to student residents. The campus is bound to the west by the Hayward and on the east by Chabot (CF) fault and is pervasively cut by anastomosing secondary splay faults. In June 2015 three exploratory trenches were opened on CSUEB campus to evaluate faulting within the proposed construction area of new student housing. Previous work by Dibblee found minor faulting in this area that we consider to be splays of the CF. We took the opportunity to conduct an active seismic survey, coincident with two of these three trenches. The purpose of our survey was to compare the results of these two methods, to further assess seismic hazard on campus, and to contribute to the ongoing effort to create a 3D model of the campus area. P-waves were generated by plate and 3.5kg sledgehammer, recorded on a 48-channel single component array for P-wave tomography and multichannel analysis of surface waves (MASW). Line 1 was 141m long with 3m receiver spacing and 9m shot spacing, and Line 2 was 188m long with 4m receivers spacing and 12m spacing. Initial P-wave tomography models show two velocity structures. To a depth of 25m, velocities ranged from 750-3000 m/s. At depths below 25m, we recorded P-wave velocities up to 6500 m/s, flanked by lower velocities, suggesting a bedrock unit bound by tectonically sheared material. Trench results indicate that faults and shears are indeed present in the top 2m. Additional near-surface seismic surveys are planned for the fall of 2015 to extend the trace of these faults, as they appear to cut across the entire campus. Furthermore, additional analysis of current and future seismic surveys will provide data on strong ground motion and offer insight into seismic hazards on the CSUEB campus. These new data will be integrated into an ongoing effort to create a 3D model of the geologic and tectonic setting of the CSUEB campus.

The fault lines of academic medicine.

PubMed

Schafer, Andrew I

2002-01-01

Unprecedented advances in biomedical research and the upheaval in health care economics have converged to cause seismic changes in the traditional organization of medical schools and academic health centers. This process is particularly evident in departments of internal medicine. The activities and functions of academic medicine are in the midst of separation and realignment along lines that do not honor historical departmental and divisional boundaries. The organization of a successful medical school or department must be dynamic, constantly serving its constituents to accommodate progress and change and to promote optimal structure for academic productivity.

Distribution of Subsurface Flexure zone caused by Uemachi Fault, Japan and its activity

NASA Astrophysics Data System (ADS)

Kitada, N.; Inoue, N.; Takemura, K.; Ito, H.; Mitamura, M.

2012-12-01

In Osaka, Uemachi Fault is one of the famous active faults. It across the center of Osaka and lies in N-S direction mainly and is more than 40 km in length. The faults bound sedimentary basins, where thick sedimentary deposits of the Pliocene-Quaternary Osaka Group have accumulated. The deposits consist primarily of sand and marine and non-marine clay, and the clay layers are key markers for the interpretation of glacial and interglacial cycles. In this study, we estimate the width of the flexure zone using a geotechnical borehole database. GI database collects more than 40,000 boreholes and includes both geological information and soil properties around Osaka by the Geo-database Information Committee of Kansai Area. Our results indicate that the deformation associated with the flexure zone is distributed primarily along the splay fault (NE-SW) and not along the main fault, suggesting that the splay fault might be the primary fault at present. We first examined the borehole data along the seismic reflection line and then considered the surrounding area. An Upper Pleistocene marine clay (Ma12) is a good indicator of the flexure zone. We constructed many cross sections in and around the fault zone and classified the deformation form into three categories around the flexure zone. The results of this study allowed us to map the distribution of folding in a zone in the west of the Osaka area. Folding can be classified into three types: (1) Ma12 folding, (2) Ma12 folding that does not continue toward the hanging wall, and (3) folding or displacement of old marine clay. These folding zone trends are N-W strike however these trace are serpentine. These folding zone information are not in worth to estimate the source fault, however these zone will be more serious damaged when the earthquake occurred. Our result agrees well with the average displacement speed of about 0.4 m/ka that was derived by the Headquarters for Earthquake Research Promotion of the Ministry of Education, Culture, Sports, Science and Technology.

Semi-automated fault system extraction and displacement analysis of an excavated oyster reef using high-resolution laser scanned data

NASA Astrophysics Data System (ADS)

Molnár, Gábor; Székely, Balázs; Harzhauser, Mathias; Djuricic, Ana; Mandic, Oleg; Dorninger, Peter; Nothegger, Clemens; Exner, Ulrike; Pfeifer, Norbert

2015-04-01

In this contribution we present a semi-automated method for reconstructing the brittle deformation field of an excavated Miocene oyster reef, in Stetten, Korneuburg Basin, Lower Austria. Oyster shells up to 80 cm in size were scattered in a shallow estuarine bay forming a continuous and almost isochronous layer as a consequence of a catastrophic event in the Miocene. This shell bed was preserved by burial of several hundred meters of sandy to silty sediments. Later the layers were tilted westward, uplifted and erosion almost exhumed them. An excavation revealed a 27 by 17 meters area of the oyster covered layer. During the tectonic processes the sediment volume suffered brittle deformation. Faults mostly with some centimeter normal component and NW-SE striking affected the oyster covered volume, dissecting many shells and the surrounding matrix as well. Faults and displacements due to them can be traced along the site typically at several meters long, and as fossil oysters are broken and parts are displaced due to the faulting, along some faults it is possible to follow these displacements in 3D. In order to quantify these varying displacements and to map the undulating fault traces high-resolution scanning of the excavated and cleaned surface of the oyster bed has been carried out using a terrestrial laser scanner. The resulting point clouds have been co-georeferenced at mm accuracy and a 1mm resolution 3D point cloud of the surface has been created. As the faults are well-represented in the point cloud, this enables us to measure the dislocations of the dissected shell parts along the fault lines. We used a semi-automatic method to quantify these dislocations. First we manually digitized the fault lines in 2D as an initial model. In the next step we estimated the vertical (i.e. perpendicular to the layer) component of the dislocation along these fault lines comparing the elevations on two sides of the faults with moving averaging windows. To estimate the strike-slip dislocation component, the surface points of the dissected shells on both sides of the fault planes were compared and displacement vectors were derived. The exact orientation of the fault planes cannot be accurately extracted automatically, so the distinction between normal and reverse fault is difficult. This makes the third component of the dislocation to be estimated inaccurately. These derived dislocation values are regarded as components of the dislocation vectors and were transformed back to the real world spatial coordinate system. Interpolating these dislocation vectors along fault lines we calculated and visualized the deformation field along the whole surface of the oyster reef. Although this deformation field is only a 2D section of the real 3D deformation field, its elaboration reveals the spatial variability of the deformation according to sediment inhomogeneity. The project is supported by the Austrian Science Fund (FWF P 25883-N29).

Adjustable direct current and pulsed circuit fault current limiter

DOEpatents

Boenig, Heinrich J.; Schillig, Josef B.

2003-09-23

A fault current limiting system for direct current circuits and for pulsed power circuit. In the circuits, a current source biases a diode that is in series with the circuits' transmission line. If fault current in a circuit exceeds current from the current source biasing the diode open, the diode will cease conducting and route the fault current through the current source and an inductor. This limits the rate of rise and the peak value of the fault current.

Can compliant fault zones be used to measure absolute stresses in the upper crust?

NASA Astrophysics Data System (ADS)

Hearn, E. H.; Fialko, Y.

2009-04-01

Geodetic and seismic observations reveal long-lived zones with reduced elastic moduli along active crustal faults. These fault zones localize strain from nearby earthquakes, consistent with the response of a compliant, elastic layer. Fault zone trapped wave studies documented a small reduction in P and S wave velocities along the Johnson Valley Fault caused by the 1999 Hector Mine earthquake. This reduction presumably perturbed a permanent compliant structure associated with the fault. The inferred changes in the fault zone compliance may produce a measurable deformation in response to background (tectonic) stresses. This deformation should have the same sense as the background stress, rather than the coseismic stress change. Here we investigate how the observed deformation of compliant zones in the Mojave Desert can be used to constrain the fault zone structure and stresses in the upper crust. We find that gravitational contraction of the coseismically softened zones should cause centimeters of coseismic subsidence of both the compliant zones and the surrounding region, unless the compliant fault zones are shallow and narrow, or essentially incompressible. We prefer the latter interpretation because profiles of line of sight displacements across compliant zones cannot be fit by a narrow, shallow compliant zone. Strain of the Camp Rock and Pinto Mountain fault zones during the Hector Mine and Landers earthquakes suggests that background deviatoric stresses are broadly consistent with Mohr-Coulomb theory in the Mojave upper crust (with μ ≥ 0.7). Large uncertainties in Mojave compliant zone properties and geometry preclude more precise estimates of crustal stresses in this region. With improved imaging of the geometry and elastic properties of compliant zones, and with precise measurements of their strain in response to future earthquakes, the modeling approach we describe here may eventually provide robust estimates of absolute crustal stress.

Analysis of typical fault-tolerant architectures using HARP

NASA Technical Reports Server (NTRS)

Bavuso, Salvatore J.; Bechta Dugan, Joanne; Trivedi, Kishor S.; Rothmann, Elizabeth M.; Smith, W. Earl

1987-01-01

Difficulties encountered in the modeling of fault-tolerant systems are discussed. The Hybrid Automated Reliability Predictor (HARP) approach to modeling fault-tolerant systems is described. The HARP is written in FORTRAN, consists of nearly 30,000 lines of codes and comments, and is based on behavioral decomposition. Using the behavioral decomposition, the dependability model is divided into fault-occurrence/repair and fault/error-handling models; the characteristics and combining of these two models are examined. Examples in which the HARP is applied to the modeling of some typical fault-tolerant systems, including a local-area network, two fault-tolerant computer systems, and a flight control system, are presented.

Delineating Crustal Deformation by Onshore/Offshore Seismic Experiments in the Backstop Region of the Mediterranean Ridge

NASA Astrophysics Data System (ADS)

Papoulia, J. E.; Makris, J.

2009-12-01

In order to define the velocity structure of the crust and the sedimentary basins offshore western Peloponnese,we observed 5 seismic profiles. We used 65 4-Component Ocean Bottom Seismographs (OBS) and spaced them inline at 3 Km intervals. Line lengths varied between 60 and 180 Km. Four lines were oriented perpendicular to the coast (NE-SW orientation) and one parallel to it (NW-SE orientation) crossing three out of four NE-SW lines. The seismic energy was generated by a tuned 42 l air gun array that was fired at 125 m intervals. The evaluation procedure of the velocity modeling followed the sequence: First break tomography, layered tomography, forward modeling by two-point ray tracing and finally the Common Station Gathers were depth migrated using the velocity models. In this way we were able to develop the geometry of the crust and sediments and also map the major faults. The crust in the complete area is continental ranging between 27 Km in the north (island of Zakynthos), and 22 to 24 Km in the Kyparissiakos and Messiniakos gulfs to the south. Sedimentary thickness in these basins is significant and in the order of 8 to 10 Km. The “backstop” area that extends to the eastern limit of the Mediterranean Ridge is floored by thinned continental crust of about 20 Km, thickening to about 22 Km to the east. The sediments here are less thick and vary between 5 and 7 Km. Oceanic crust was mapped only along the western part of the two southern lines, beyond the backstop limit, under the Mediterranean Ridge. In the oceanic domain crustal thickness is about 16 Km in water depth of nearly 4 Km. The down dipping of the oceanic layer at the beginning of the subduction has strong reflectivity and clearly marks the border of the continental to the oceanic domains. The Preapulian zone is exposed on Zakynthos and the Strophades islands that tectonically build large thrusts and define the western limit of the offshore folded Ionian zone. High velocity limestone marking the Preapulian zone was observed under all five seismic lines and seems to dominate at least at the western part of the Backstop. Since the metamorphic limestone of the Ionian zone was not observed west of the three major thrusts, we have concluded that all the northern part of the backstop region is part of Preapulia. Tectonically, the main elements are thrusts that are still active and are marked by high seismicity and dextral strike slip faults. The main one, called the “Andravida fault” was followed deep into the Ionian Sea, building a large transtensional basin in the Kyparissiakos gulf. The Andravida fault system is of the same orientation as the Cephalonia fault, accommodating the expansion of the Aegean Microplate to the west. It is also marked by significant seismicity. Several normal faults were also mapped, usually associated with the thrust systems. Since most of the faults can be followed to the sea bottom, deforming also the most recent sediments, and are associated with high seismicity, we concluded that the recent tectonisation is very active and prone to seismic hazard.

Spatial and Temporal Variation of in-situ Stress in and around Active Fault zones in Central Japan

NASA Astrophysics Data System (ADS)

Ikeda, R.; Omura, K.; Matsuda, T.; Iio, Y.

2002-12-01

In the "Active Fault Zone Drilling Project in Japan," we have compared the relationship between the stress concentration state and the heterogeneous strength of an earthquake fault zone in different conditions. The Nojima fault which appeared on the surface by the 1995 Great Kobe earthquake (M=7.2) and the Neodani fault which appeared by the 1891 Nobi earthquake (M=8.0), have been drilled through their fault fracture zones. A similar experiment conducted on and research of the Atera fault, of which some parts have seemed to be dislocated by the 1586 Tensyo earthquake (M=7.9). We can use a deep borehole as a reliable tool to understand overall fault structure and composed materials directly. Additionally, the stress states in and around the fault fractured zones were obtained from in-situ stress measurements by the hydraulic fracturing method. Important phenomena such as rapid stress drop in the fault fracture zones were observed in the Neodani well (1300 m deep) and the Nojima well (1800 m) of the fault zone drillings, as well as in the Ashio well (2,000 m) in the focal area. In the Atera fault project, we have conducted integrated investigations by surface geophysical survey and drilling around the Atera fault. Four boreholes (400 m to 600 m deep) were located on a line crossing the fracture zone of the Atera fault. We noted that the stress magnitude decreases in the area closer to the center of the fracture zone. Furthermore the orientation of the maximum horizontal compressive stress was almost reverse of the fault moving direction. These results support the idea that the differential stress is extremely small at narrow zones adjoining fracture zones. We also noted that the frictional strength of the crust adjacent to the faults is high and the level of shear stress in the crust adjacent to the faults is principally controlled by the frictional strength of rock. We argue that the stress state observed in these sites exists only if the faults are quite "weak." As a temporal variation of stresses, crustal stress was recorded from 1978 to before the Kobe earthquake in and around the area where the earthquake occurred. By examining this data, the change in tectonic stress gradually increased prior to the earthquake. After the earthquake, the same boreholes were once again used to obtain new data. From these measurements, we were able to determine that there was a definite drop in the crustal stress in the area and that there was a change in the direction of the principal stresses. The continual measuring is essential to estimate the absolute stress magnitude that initiate earthquakes and control their propagation.

Improvement in operational characteristics of KEPCO’s line-commutation-type superconducting hybrid fault current limiter

NASA Astrophysics Data System (ADS)

Yim, S.-W.; Park, B.-C.; Jeong, Y.-T.; Kim, Y.-J.; Yang, S.-E.; Kim, W.-S.; Kim, H.-R.; Du, H.-I.

2013-01-01

A 22.9 kV class hybrid fault current limiter (FCL) developed by Korea Electric Power Corporation and LS Industrial Systems in 2006 operates using the line commutation mechanism and begins to limit the fault current after the first half-cycle. The first peak of the fault current is available for protective coordination in the power system. However, it also produces a large electromagnetic force and imposes a huge stress on power facilities such as the main transformer and gas-insulated switchgear. In this study, we improved the operational characteristics of the hybrid FCL in order to reduce the first peak of the fault current. While maintaining the structure of the hybrid FCL system, we developed a superconducting module that detects and limits the fault current during the first half-cycle. To maintain the protective coordination capacity, the hybrid FCL was designed to reduce the first peak value of the fault current by up to approximately 30%. The superconducting module was also designed to produce a minimum AC loss, generating a small, uniform magnetic field distribution during normal operation. Performance tests confirmed that when applied to the hybrid FCL, the superconducting module showed successful current limiting operation without any damage.

The Active Fault Parameters for Time-Dependent Earthquake Hazard Assessment in Taiwan

NASA Astrophysics Data System (ADS)

Lee, Y.; Cheng, C.; Lin, P.; Shao, K.; Wu, Y.; Shih, C.

2011-12-01

Taiwan is located at the boundary between the Philippine Sea Plate and the Eurasian Plate, with a convergence rate of ~ 80 mm/yr in a ~N118E direction. The plate motion is so active that earthquake is very frequent. In the Taiwan area, disaster-inducing earthquakes often result from active faults. For this reason, it's an important subject to understand the activity and hazard of active faults. The active faults in Taiwan are mainly located in the Western Foothills and the Eastern longitudinal valley. Active fault distribution map published by the Central Geological Survey (CGS) in 2010 shows that there are 31 active faults in the island of Taiwan and some of which are related to earthquake. Many researchers have investigated these active faults and continuously update new data and results, but few people have integrated them for time-dependent earthquake hazard assessment. In this study, we want to gather previous researches and field work results and then integrate these data as an active fault parameters table for time-dependent earthquake hazard assessment. We are going to gather the seismic profiles or earthquake relocation of a fault and then combine the fault trace on land to establish the 3D fault geometry model in GIS system. We collect the researches of fault source scaling in Taiwan and estimate the maximum magnitude from fault length or fault area. We use the characteristic earthquake model to evaluate the active fault earthquake recurrence interval. In the other parameters, we will collect previous studies or historical references and complete our parameter table of active faults in Taiwan. The WG08 have done the time-dependent earthquake hazard assessment of active faults in California. They established the fault models, deformation models, earthquake rate models, and probability models and then compute the probability of faults in California. Following these steps, we have the preliminary evaluated probability of earthquake-related hazards in certain faults in Taiwan. By accomplishing active fault parameters table in Taiwan, we would apply it in time-dependent earthquake hazard assessment. The result can also give engineers a reference for design. Furthermore, it can be applied in the seismic hazard map to mitigate disasters.

Evolution of the Median Tectonic Line fault zone, SW Japan, during exhumation

NASA Astrophysics Data System (ADS)

Shigematsu, Norio; Kametaka, Masao; Inada, Noriyuki; Miyawaki, Masahiro; Miyakawa, Ayumu; Kameda, Jun; Togo, Tetsuhiro; Fujimoto, Koichiro

2017-01-01

Like many crustal-scale fault zones, the Median Tectonic Line (MTL) fault zone in Japan preserves fault rocks that formed across a broad range of physical conditions. We examined the architecture of the MTL at a large new outcrop in order to understand fault behaviours under different crustal levels. The MTL here strikes almost E-W, dips to the north, and juxtaposes the Sanbagawa metamorphic rocks to the south against the Izumi Group sediments to the north. The fault core consists mainly of Sanbagawa-derived fault gouges. The fault zone can be divided into several structural units, including two slip zones (upper and lower slip zones), where the lower slip zone is more conspicuous. Crosscutting relationships among structures and kinematics indicate that the fault zone records four stages of deformation. Microstructures and powder X-ray diffraction (XRD) analyses indicate that the four stages of deformation occurred under different temperature conditions. The oldest deformation (stage 1) was widely distributed, and had a top-to-the-east (dextral) sense of slip at deep levels of the seismogenic zone. Deformation with the same sense of slip, then became localised in the lower slip zone (stage 2). Subsequently, the slip direction in the lower slip zone changed to top-to-the-west (sinistral-normal) (stage 3). The final stage of deformation (stage 4) involved top-to-the-north normal faulting along the two slip zones within the shallow crust (near the surface). The widely distributed stage 1 damage zone characterises the deeper part of the seismogenic zone, while the sets of localised principal slip zones and branching faults of stage 4 characterise shallow depths. The fault zone architecture described in this paper leads us to suggest that fault zones display different behaviours at different crustal levels.

Preliminary 3d depth migration of a network of 2d seismic lines for fault imaging at a Pyramid Lake, Nevada geothermal prospect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frary, R.; Louie, J.; Pullammanappallil, S.

Roxanna Frary, John N. Louie, Sathish Pullammanappallil, Amy Eisses, 2011, Preliminary 3d depth migration of a network of 2d seismic lines for fault imaging at a Pyramid Lake, Nevada geothermal prospect: presented at American Geophysical Union Fall Meeting, San Francisco, Dec. 5-9, abstract T13G-07.

Telegraph Canyon Creek, City of Chula Vista, San Diego County, California. Detailed Report for Flood Control. Volume 2. Technical Appendixes.

DTIC Science & Technology

1983-07-01

occurred within 40 miles of’ the site. Most of these earthquakes appear to be related to activity on the Elsinore, Agua Caliente, and offshore faults. The...device would be required by the Sweetwater Authority to prevent contamination of potable water lines. TELEGRAPH CANYON CREEK - - Recommended Plant List A

Neotectonic interpretations and PS-InSAR monitoring of crustal deformations in the Fujian area of China

NASA Astrophysics Data System (ADS)

Guo, Jianming; Xu, Shiyang; Fan, Hailong

2017-05-01

A neotectonic structural interpretation was conducted in the Fujian Province, west of the Taiwan Strait, by using computer image processing and 3D visualizations to enhance linear structural traces. The major faults in this area can be grouped into two conjugate shear fracture zones, with one trending to the northeast and the other trending to the northwest. PS-InSAR technology uses stable permanent target scatterer points to determine deformation rates and can effectively reduce the influence of spatiotemporal decorrelations and atmospheric anomalies that affect conventional D-InSAR techniques and prevent the formation of interference fringes. This study focuses on the fault zones located in the Quanzhou area of Fujian Province, where the 1604 M7.5-8.0 historic earthquake occurred. In total, 22 scenes of ERS SAR data from 1996 to 1999 were processed using PS-InSAR methods. The results show that the line of sight direction displacement rate of the main fault in the study area is 3-5 mm/yr, which indicates that the faults in this area are still active and subject to earthquake risk.

Gas Path On-line Fault Diagnostics Using a Nonlinear Integrated Model for Gas Turbine Engines

NASA Astrophysics Data System (ADS)

Lu, Feng; Huang, Jin-quan; Ji, Chun-sheng; Zhang, Dong-dong; Jiao, Hua-bin

2014-08-01

Gas turbine engine gas path fault diagnosis is closely related technology that assists operators in managing the engine units. However, the performance gradual degradation is inevitable due to the usage, and it result in the model mismatch and then misdiagnosis by the popular model-based approach. In this paper, an on-line integrated architecture based on nonlinear model is developed for gas turbine engine anomaly detection and fault diagnosis over the course of the engine's life. These two engine models have different performance parameter update rate. One is the nonlinear real-time adaptive performance model with the spherical square-root unscented Kalman filter (SSR-UKF) producing performance estimates, and the other is a nonlinear baseline model for the measurement estimates. The fault detection and diagnosis logic is designed to discriminate sensor fault and component fault. This integration architecture is not only aware of long-term engine health degradation but also effective to detect gas path performance anomaly shifts while the engine continues to degrade. Compared to the existing architecture, the proposed approach has its benefit investigated in the experiment and analysis.

Probing the frontal deformation zone of the Chihshang Fault with boreholes and high-resolution electrical resistivity imaging methods: A case study at the Dapo site in eastern Taiwan

NASA Astrophysics Data System (ADS)

Chang, Ping-Yu; Huang, Wen-Jeng; Chen, Chien-Chih; Hsu, Han-lun; Yen, I.-Chin; Ho, Gong-Ruei; Lee, Jian-Cheng; Lu, Shih-Ting; Chen, Po-Tsun

2018-06-01

Not only direct fault ruptures but also later mass movement may result in complicated frontal deformation of the faults. Consequently, the deformation front or the contacts between the unconsolidated materials from the hanging wall and footwall of the thrust fault may indicate the toe of the mass movement instead of the actual fault zone. In this study, we used a combination of surface electrical resistivity imaging methods and borehole records in order to investigate the geometries of the structures in the frontal deformation zone of the Chihshang Fault at the Dapo elementary school. From the cores, we observed three different geological components at the Dapo site: the conductive Lichi mélange of the hanging wall, the colluvial gravels and the underlying fluvial-gravel layer at the footwall. The resistivity images from two parallel survey lines reveal that the position where the fault trace was thought to be is actually the toe of the slumping body's surface ruptures consisting of materials from the Lichi mélange. On the basis of the resistivity images, we also found that the actual fault plane is located on the southeastern side of the resistivity survey line near the hilltop. As a result, we conclude that mass movement induced by the inter-seismic creeping, not direct faulting, is the main factor affecting the frontal deformation zone of the Chihshang fault at the Dapo site.

Developing sub 5-m LiDAR DEMs for forested sections of the Alpine and Hope faults, South Island, New Zealand: Implications for structural interpretations

NASA Astrophysics Data System (ADS)

Langridge, R. M.; Ries, W. F.; Farrier, T.; Barth, N. C.; Khajavi, N.; De Pascale, G. P.

2014-07-01

Kilometre-wide airborne light detection and ranging (LiDAR) surveys were collected along portions of the Alpine and Hope faults in New Zealand to assess the potential for generating sub 5-m bare earth digital elevation models (DEMs) from ground return data in areas of dense rainforest (bush) cover as an aid to mapping these faults. The 34-km long Franz-Whataroa LiDAR survey was flown along the densely-vegetated central-most portion of the transpressive Alpine Fault. Six closely spaced flight lines (200 m apart) yielded survey coverage with double overlap of swath collection, which was considered necessary due to the low density of ground returns (0.16 m-2 or a point every 6 m2) under mature West Coast podocarp-broadleaf rainforest. This average point spacing (˜2.5 m) allowed for the generation of a robust, high quality 3-m bare earth DEM. The DEM confirmed the zigzagged form of the surface trace of the Alpine Fault in this area, originally recognised by Norris and Cooper (1995, 1997) and highlights that the surface strike variations are more variant than previously mapped. The 29-km long Hurunui-Hope LiDAR survey was flown east of the Main Divide of the Southern Alps along the dextral-slip Hope Fault, where the terrain is characterised by lower rainfall and more open beech forest. Flight line spacings of ˜275 m were used to generate a DEM from the ground return data. The average ground return values under beech forest were 0.27 m-2 and yielded an estimated cell size suitable for a 2-m DEM. In both cases the LiDAR revealed unprecedented views of the surface geomorphology of these active faults. Lessons learned from our survey methodologies can be employed to plan cost-effective, high-gain airborne surveys to yield bare earth DEMs underneath vegetated terrain and multi-storeyed canopies from densely forested environments across New Zealand and worldwide.

A tectonic model for the Tertiary evolution of strike slip faults and rift basins in SE Asia

NASA Astrophysics Data System (ADS)

Morley, C. K.

2002-04-01

Models for the Tertiary evolution of SE Asia fall into two main types: a pure escape tectonics model with no proto-South China Sea, and subduction of proto-South China Sea oceanic crust beneath Borneo. A related problem is which, if any, of the main strike-slip faults (Mae Ping, Three Pagodas and Aliao Shan-Red River (ASRR)) cross Sundaland to the NW Borneo margin to facilitate continental extrusion? Recent results investigating strike-slip faults, rift basins, and metamorphic core complexes are reviewed and a revised tectonic model for SE Asia proposed. Key points of the new model include: (1) The ASRR shear zone was mainly active in the Eocene-Oligocene in order to link with extension in the South China Sea. The ASRR was less active during the Miocene (tens of kilometres of sinistral displacement), with minor amounts of South China Sea spreading centre extension transferred to the ASRR shear zone. (2) At least three important regions of metamorphic core complex development affected Indochina from the Oligocene-Miocene (Mogok gneiss belt; Doi Inthanon and Doi Suthep; around the ASRR shear zone). Hence, Paleogene crustal thickening, buoyancy-driven crustal collapse, and lower crustal flow are important elements of the Tertiary evolution of Indochina. (3) Subduction of a proto-South China Sea oceanic crust during the Eocene-Early Miocene is necessary to explain the geological evolution of NW Borneo and must be built into any model for the region. (4) The Eocene-Oligocene collision of NE India with Burma activated extrusion tectonics along the Three Pagodas, Mae Ping, Ranong and Klong Marui faults and right lateral motion along the Sumatran subduction zone. (5) The only strike-slip fault link to the NW Borneo margin occurred along the trend of the ASRR fault system, which passes along strike into a right lateral transform system including the Baram line.

Reclosing operation characteristics of the flux-coupling type SFCL in a single-line-to ground fault

NASA Astrophysics Data System (ADS)

Jung, B. I.; Cho, Y. S.; Choi, H. S.; Ha, K. H.; Choi, S. G.; Chul, D. C.; Sung, T. H.

2011-11-01

The recloser that is used in distribution systems is a relay system that behaves sequentially to protect power systems from transient and continuous faults. This reclosing operation of the recloser can improve the reliability and stability of the power supply. For cooperation with this recloser, the superconducting fault current limiter (SFCL) must properly perform the reclosing operation. This paper analyzed the reclosing operation characteristics of the three-phase flux-coupling type SFCL in the event of a ground fault. The fault current limiting characteristics according to the changing number of turns of the primary and secondary coils were examined. As the number of turns of the first coil increased, the first maximum fault current decreased. Furthermore, the voltage of the quenched superconducting element also decreased. This means that the power burden of the superconducting element decreases based on the increasing number of turns of the primary coil. The fault current limiting characteristic of the SFCL according to the reclosing time limited the fault current within a 0.5 cycles (8 ms), which is shorter than the closing time of the recloser. In other words, the superconducting element returned to the superconducting state before the second fault and normally performed the fault current limiting operation. If the SFCL did not recover before the recloser reclosing time, the normal current that was flowing in the transmission line after the recovery of the SFCL from the fault would have been limited and would have caused losses. Therefore, the fast recovery time of a SFCL is critical to its cooperation with the protection system.

Mountain Meadows Dacite: Oligocene intrusive complex that welds together the Los Angeles Basin, northwestern Peninsular Ranges, and central Transverse Ranges, California

USGS Publications Warehouse

McCulloh, Thane H.; Beyer, Larry A.; Morin, Ronald W.

2001-01-01

Dikes and irregular intrusive bodies of distinctive Oligocene biotite dacite and serially related hornblende latite and felsite occur widely in the central and eastern San Gabriel Mountains, southern California, and are related to the Telegraph Peak granodiorite pluton. Identical dacite is locally present beneath Middle Miocene Topanga Group Glendora Volcanics at the northeastern edge of the Los Angeles Basin, where it is termed Mountain Meadows Dacite. This study mapped the western and southwestern limits of the dacite distribution to understand the provenance of derived redeposited clasts, to perceive Neogene offsets on several large strike-slip faults, to test published palinspastic reconstructions, and to better understand the tectonic boundaries that separate contrasting pre-Tertiary rock terranes where the Peninsular Ranges meet the central and western Transverse Ranges and the Los Angeles Basin. Transported and redeposited clasts of dacite-latite occur in deformed lower Miocene and lower middle Miocene sandy conglomerates (nonmarine, nearshore, and infrequent upper bathyal) close to the northern and northeastern margins of the Los Angeles Basin for a distance of nearly 60 km. Tie-lines between distinctive source suites and clast occurrences indicate that large tracts of the ancestral San Gabriel Mountains were elevated along range-bounding faults as early as 16–15 Ma. The tie-lines prohibit very large strike-slip offsets on those faults. Transport of eroded dacite began south of the range as early as 18 Ma. Published and unpublished data about rocks adjacent to the active Santa Monica-Hollywood-Raymond oblique reverse left-lateral fault indicate that cumulative left slip totals 13–14 km and total offset postdates 7 Ma. This cumulative slip, with assembly of stratigraphic and paleogeographic data, invalidates prior estimates of 60 to 90 km of left slip on these faults beginning about 17–16 Ma. A new and different palinspastic reconstruction of a region southwest of the San Andreas Fault Zone is proposed. Our reconstruction incorporates 20° of clockwise rotation of tracts north of the Raymond Fault from the easternmost Santa Monica Mountains to the Vasquez Creek Fault (San Gabriel south branch). We interpret the Vasquez Creek Fault as a reverse and right-lateral tear fault. Right slip on the tear becomes reverse dip slip on the northeast-striking Clamshell-Sawpit fault complex, interpreted as an offset part of the Mount Lukens Fault. This explains the absence of evidence for lateral offset of the Glendora Volcanics and associated younger marine strata where those are broken farther east by the eastern Sierra Madre reverse fault system. About 34 km of right slip is suggested for all breaks of the San Gabriel fault system. New paleogeographic maps of the Paleogene basin margin and of a Middle Miocene marine embayment and strandline derive in part from our palinspastic reconstruction. These appealingly simple maps fit well with data from the central Los Angeles Basin to the south and southwest.

Geomorphic indices indicated differential active tectonics of the Longmen Shan

NASA Astrophysics Data System (ADS)

Gao, M.; Xu, X.; Tan, X.

2012-12-01

The Longmen Shan thrust belt is located at the eastern margin of the Tibetan Plateau. It is a region of rapid active tectonics with high erosion rates and dense vegetation. The structure of the Longmen Shan region is dominated by northeast-trending thrusts and overturned folds that verge to the east and southeast (Burchfiel et al. 1995, Chen and Wilson 1996). The Longmen Shan thrust belt consists of three major faults from west to east: back-range fault, central fault, and frontal-range fault. The Mw 7.9 Wenchuan earthquake ruptured two large thrust faults along the Longmen Shan thrust belt (Xiwei et al., 2009). In this paper, we focus on investigating the spatial variance of tectonic activeness from the back-range fault to the frontal-range fault, particular emphasis on the differential recent tectonic activeness reflected by the hypsometry and the asymmetric factor of the drainage. Results from asymmetric factor indicate the back-rannge thrust fault on the south of the Maoxian caused drainage basins tilted on the hanging wall. For the north of the Maoxian, the strike-slip fault controlled the shapes of the drainage basins. Constantly river capture caused the expansion of the drainage basins which traversed by the fault. The drainages on the central fault and the frontal-range fault are also controlled by the fault slip. The drainage asymmetric factor suggested the central and southern segments of the Longmen Shan are more active than the northern segment, which is coherence with results of Huiping et al. (2010). The results from hypsometry show the back-range fault is the most active fault among the three major faults. Central fault is less active than the back-range fault but more active than the frontal-range fault. Beichuan is identified as the most active area along the central fault. Our geomorphic indices reflect an overall eastward decreasing of tectonic activeness of the Longmen Shan thrust belt.

Building a risk-targeted regional seismic hazard model for South-East Asia

NASA Astrophysics Data System (ADS)

Woessner, J.; Nyst, M.; Seyhan, E.

2015-12-01

The last decade has tragically shown the social and economic vulnerability of countries in South-East Asia to earthquake hazard and risk. While many disaster mitigation programs and initiatives to improve societal earthquake resilience are under way with the focus on saving lives and livelihoods, the risk management sector is challenged to develop appropriate models to cope with the economic consequences and impact on the insurance business. We present the source model and ground motions model components suitable for a South-East Asia earthquake risk model covering Indonesia, Malaysia, the Philippines and Indochine countries. The source model builds upon refined modelling approaches to characterize 1) seismic activity from geologic and geodetic data on crustal faults and 2) along the interface of subduction zones and within the slabs and 3) earthquakes not occurring on mapped fault structures. We elaborate on building a self-consistent rate model for the hazardous crustal fault systems (e.g. Sumatra fault zone, Philippine fault zone) as well as the subduction zones, showcase some characteristics and sensitivities due to existing uncertainties in the rate and hazard space using a well selected suite of ground motion prediction equations. Finally, we analyze the source model by quantifying the contribution by source type (e.g., subduction zone, crustal fault) to typical risk metrics (e.g.,return period losses, average annual loss) and reviewing their relative impact on various lines of businesses.

Fault detection and classification in electrical power transmission system using artificial neural network.

PubMed

Jamil, Majid; Sharma, Sanjeev Kumar; Singh, Rajveer

2015-01-01

This paper focuses on the detection and classification of the faults on electrical power transmission line using artificial neural networks. The three phase currents and voltages of one end are taken as inputs in the proposed scheme. The feed forward neural network along with back propagation algorithm has been employed for detection and classification of the fault for analysis of each of the three phases involved in the process. A detailed analysis with varying number of hidden layers has been performed to validate the choice of the neural network. The simulation results concluded that the present method based on the neural network is efficient in detecting and classifying the faults on transmission lines with satisfactory performances. The different faults are simulated with different parameters to check the versatility of the method. The proposed method can be extended to the Distribution network of the Power System. The various simulations and analysis of signals is done in the MATLAB(®) environment.

Interpretations from multichannel seismic-reflection profiles of the deep crust crossing South Carolina and Georgia from the Appalachian Mountains to the Atlantic Coast

USGS Publications Warehouse

Behrendt, John C.

1985-01-01

The Appalachian décollement does not appear continuous from the Appalachian Mountains to the coast but rather appears to extend southeastward only to the Carolina slate belt. A series of reflections on lines S4, S6, and S8 and on the COCORP line is interpreted as evidence of southeastward-dipping imbricate faults, from the Brevard fault on the northwest to beyond the Augusta fault, which marks the southeastern extent of the Eastern Piedmont fault zone. The Carolina slate belt is characterized on the four seismic profiles by a complex series of diffractions and reflections extending from less than 1 s to 8 s. These arrivals are possibly the result of layering in the metasedimentary rocks complexly disrupted by the imbricate faults. A number of Triassic (?) basins are apparent in the reflection data for the rifted Charleston terrane identified from low-gradient magnetic anomalies.

DOD Strategic Religious Engagement: A Luxury or a Necessity?

DTIC Science & Technology

2013-03-01

prepared to conduct religious engagement along tense, international religious fault lines. This paper explores how , in a season of declining resources...tense, international religious fault lines. This paper explores how , in a season of declining resources, the U.S. Government can leverage the Combatant...later, it is easier to see how mistakes made in identifying and understanding the intelligence on the cultural dynamics at work in the Middle East led

San Andreas-sized Strike-slip Fault on Europa

NASA Technical Reports Server (NTRS)

1998-01-01

This mosaic of the south polar region of Jupiter's moon Europa shows the northern 290 kilometers (180 miles) of a strike-slip fault named Astypalaea Linea. The entire fault is about 810 kilometers (500 miles) long, about the size of the California portion of the San Andreas fault, which runs from the California-Mexico border north to the San Francisco Bay.

In a strike-slip fault, two crustal blocks move horizontally past one another, similar to two opposing lanes of traffic. Overall motion along the fault seems to have followed a continuous narrow crack along the feature's entire length, with a path resembling steps on a staircase crossing zones that have been pulled apart. The images show that about 50 kilometers (30 miles) of displacement have taken place along the fault. The fault's opposite sides can be reconstructed like a puzzle, matching the shape of the sides and older, individual cracks and ridges broken by its movements.

[figure removed for brevity, see original site]

The red line marks the once active central crack of the fault. The black line outlines the fault zone, including material accumulated in the regions which have been pulled apart.

Bends in the fault have allowed the surface to be pulled apart. This process created openings through which warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean, could reach the surface. This upwelling of material formed large areas of new ice within the boundaries of the original fault. A similar pulling-apart phenomenon can be observed in the geological trough surrounding California's Salton Sea, in Death Valley and the Dead Sea. In those cases, the pulled-apart regions can include upwelled materials, but may be filled mostly by sedimentary and eroded material from above.

One theory is that fault motion on Europa is induced by the pull of variable daily tides generated by Jupiter's gravitational tug on Europa. Tidal tension opens the fault and subsequent tidal stress causes it to move lengthwise in one direction. Then tidal forces close the fault again, preventing the area from moving back to its original position. Daily tidal cycles produce a steady accumulation of lengthwise offset motions. Here on Earth, unlike Europa, large strike-slip faults like the San Andreas are set in motion by plate tectonic forces.

North is to the top of the picture and the sun illuminates the surface from the top. The image, centered at 66 degrees south latitude and 195 degrees west longitude, covers an area approximately 300 by 203 kilometers(185 by 125 miles). The pictures were taken on September 26, 1998by Galileo's solid-state imaging system.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

Recent tectonic stress field, active faults and geothermal fields (hot-water type) in China

NASA Astrophysics Data System (ADS)

Wan, Tianfeng

1984-10-01

It is quite probable that geothermal fields of the hot-water type in China do not develop in the absence of recently active faults. Such active faults are all controlled by tectonic stress fields. Using the data of earthquake fault-plane solutions, active faults, and surface thermal manifestations, a map showing the recent tectonic stress field, and the location of active faults and geothermal fields in China is presented. Data collected from 89 investigated prospects with geothermal manifestations indicate that the locations of geothermal fields are controlled by active faults and the recent tectonic stress field. About 68% of the prospects are controlled by tensional or tensional-shear faults. The angle between these faults and the direction of maximum compressive stress is less than 45°, and both tend to be parallel. About 15% of the prospects are controlled by conjugate faults. Another 14% are controlled by compressive-shear faults where the angle between these faults and the direction maximum compressive stress is greater than 45°.

Revisiting the Borah Peak Leveling Line: 30+ years of interseismic deformation across the Lost River fault

NASA Astrophysics Data System (ADS)

Crosby, B. T.; Rodgers, D. W.; Lauer, I. H.

2017-12-01

The 1983 Borah Peak, Idaho, earthquake (M 7.0) produced both local ground surface rupture and notable far-field geodetic elevation changes that inspired a suite of investigations into coseismic flexural response. Shortly after the earthquake, Stein and Barrientos revisited a 50 km leveling line that runs roughly perpendicular to and spanning the Lost River normal fault. They found 1 meter of surface subsidence adjacent to the fault on the hanging wall that decays to no detectable change over 25 km distance from the fault. On the footwall, 20 cm of surface uplift was observed adjacent to the fault, decaying to zero change over 17 km. Though the changes in elevation are calculated as a difference between the first leveling in 1933 and the post-event leveling in 1984, they treat this change as the coseismic period, assuming little change between 1933 and 1983. A subsequent survey in 1985 revealed no significant change, suggesting that postseismic relaxation was complete. We evaluate the assumption that no detectable interseismic slip occurred between 1933 and the Borah Peak event by resurveying the line and differencing elevations between 2017 and 1985. If interseismic slip is insignificant, then there should be no detectable change over these 32 years. Using RTK GNSS with a 3D error ellipse of 0.9 cm, we resurveyed all leveling monuments in June, 2017. Significant deformation was observed. Between 1985 and 2017, 28 cm of displacement occurred across the fault. The hanging wall, adjacent to the fault, subsided 8 cm while the footwall rose 20 cm. Subsidence on the hanging wall increases slightly with distance away from the fault, reaching a maximum of 10 cm at a distance of 4 km from the fault and decaying to zero by 17 km. On the footwall surface uplift increases from 20 cm at the fault to 42 cm by 6.5 km before decaying. Clearly interseismic deformation has occurred over the last 32 years, including both discrete slip at the fault and distributed subsidence or surface uplift with distance away from the fault. A difference between the 2017 and 1933 data reveal that the opposing patterns of deformation pre and post event at on the footwall largely balance each other out, creating block-like surface uplift. These vertical changes are complemented by observations from continuous geodetic GNSS that corroborate the interseismic extension.

Sedimentary and tectonic evolution of Plio Pleistocene alluvial and lacustrine deposits of Fucino Basin (central Italy)

NASA Astrophysics Data System (ADS)

Cavinato, Gian Paolo; Carusi, Claudio; Dall'Asta, Massimo; Miccadei, Enrico; Piacentini, Tommaso

2002-04-01

The Fucino Basin was the greatest lake of the central Italy, which was completely drained at the end of 19th century. The basin is an intramontane half-graben filled by Plio-Quaternary alluvial and lacustrine deposits located in the central part of the Apennines chain, which was formed in Upper Pliocene and in Quaternary time by the extensional tectonic activity. The analysis of the geological surface data allows the definition of several stratigraphic units grouped in Lower Units and Upper Units. The Lower Units (Upper Pliocene) are exposed along the northern and north-eastern basin margins. They consist of open to marginal lacustrine deposits, breccia deposits and fluvial deposits. The Upper Units (Lower Pliocene-Holocene) consist of interbedded marginal lacustrine deposits and fluvial deposits; thick coarse-grained fan-delta deposits are interfingered at the foot of the main relief with fluvial-lacustrine deposits. Most of the thickness of the lacustrine sequences (more than 1000-m thick) is buried below the central part of the Fucino Plain. The basin is bounded by E-W, WSW-ENE and NW-SE fault systems: Velino-Magnola Fault (E-W) and Tremonti-Celano-Aielli Fault (WSW-ENE) and S. Potito-Celano Fault (NW-SE) in the north; the Trasacco Fault, the Pescina-Celano Fault and the Serrone Fault (NW-SE) in the south-east. The geometry and kinematic indicators of these faults indicate normal or oblique movements. The study of industrial seismic profiles across the Fucino Basin gives a clear picture of the subsurface basin geometry; the basin shows triangular-shaped basin-fill geometry, with the maximum deposits thickness toward the main east boundary fault zones that dip south-westward (Serrone Fault, Trasacco Fault, Pescina-Celano Fault). On the basis of geological surface data, borehole stratigraphy and seismic data analysis, it is possible to recognize and to correlate sedimentary and seismic facies. The bottom of the basin is well recognized in the seismic lines available from the good and continuous signals of the top of Meso-Cenozoic carbonate rocks. The shape of sedimentary bodies indicates that the filling of the basin was mainly controlled by normal slip along the NW-SE boundary faults. In fact, the continental deposits are frequently in on-lap contact over the carbonate substratum; several disconformable contacts occurred during the sedimentary evolution of the basin. The main faults (with antithetic and synthetic fault planes) displace the whole sedimentary sequence up to the surface indicating a recent faults' activity (1915 Avezzano earthquake, Ms=7.0). The stratigraphic and tectonic setting of the Fucino Basin and neighboring areas indicates that the extensional tectonic events have had an important role in driving the structural-sedimentary evolution of the Plio-Quaternary deposits. The geometry of the depositional bodies, of the fault planes and their relationships indicate that the Fucino Basin was formed as a half-graben type structure during Plio-Quaternary extensional events. Some internal complexities are probably related to the fold-and-thrust structures of the Apenninic orogeny formed in Messinian time, in this area, and to a different activity timing of the E-W and WSW-ENE fault systems and the NW-SE fault systems. We believe, based on the similarity of the surface characteristics, that the structural setting of the Fucino Basin can be extrapolated to the other great intramontane basins in Central Italy (e.g. Rieti, L'Aquila, Sulmona, Sora, Isernia basins).

A Vibration-Based Approach for Stator Winding Fault Diagnosis of Induction Motors: Application of Envelope Analysis

DTIC Science & Technology

2014-10-02

takes it either as auxiliary to magnetic flux, or is not able to detect the winding faults unless severity is already quite significant. This paper...different loads, speeds and severity levels. The experimental results show that the proposed method was able to detect inter-turn faults in the...maintenance strategy requires the technologies of: (a) on- line condition monitoring, (b) fault detection and diagnosis, and (c) prognostics. Figure 1

Double-layer rotor magnetic shield performance analysis in high temperature superconducting synchronous generators under short circuit fault conditions

NASA Astrophysics Data System (ADS)

Hekmati, Arsalan; Aliahmadi, Mehdi

2016-12-01

High temperature superconducting, HTS, synchronous machines benefit from a rotor magnetic shield in order to protect superconducting coils against asynchronous magnetic fields. This magnetic shield, however, suffers from exerted Lorentz forces generated in light of induced eddy currents during transient conditions, e.g. stator windings short-circuit fault. In addition, to the exerted electromagnetic forces, eddy current losses and the associated effects on the cryogenic system are the other consequences of shielding HTS coils. This study aims at investigating the Rotor Magnetic Shield, RMS, performance in HTS synchronous generators under stator winding short-circuit fault conditions. The induced eddy currents in different circumferential positions of the rotor magnetic shield along with associated Joule heating losses would be studied using 2-D time-stepping Finite Element Analysis, FEA. The investigation of Lorentz forces exerted on the magnetic shield during transient conditions has also been performed in this paper. The obtained results show that double line-to-ground fault is of the most importance among different types of short-circuit faults. It was revealed that when it comes to the design of the rotor magnetic shields, in addition to the eddy current distribution and the associated ohmic losses, two phase-to-ground fault should be taken into account since the produced electromagnetic forces in the time of fault conditions are more severe during double line-to-ground fault.

Plate tectonics and crustal deformation around the Japanese Islands

NASA Technical Reports Server (NTRS)

Hashimoto, Manabu; Jackson, David D.

1993-01-01

We analyze over a century of geodetic data to study crustal deformation and plate motion around the Japanese Islands, using the block-fault model for crustal deformation developed by Matsu'ura et al. (1986). We model the area including the Japanese Islands with 19 crustal blocks and 104 faults based on the distribution of active faults and seismicity. Geodetic data are used to obtain block motions and average slip rates of faults. This geodetic model predicts that the Pacific plate moves N deg 69 +/- 2 deg W at about 80 +/- 3 mm/yr relative to the Eurasian plate which is much lower than that predicted in geologic models. Substantial aseismic slip occurs on the subduction boundaries. The block containing the Izu Peninsula may be separated from the rigid part of the Philippine Sea plate. The faults on the coast of Japan Sea and the western part of the Median Tectonic Line have slip rates exceeding 4 mm/yr, while the Fossa Magna does not play an important role in the tectonics of the central Japan. The geodetic model requires the division of northeastern Japan, contrary to the hypothesis that northeastern Japan is a part of the North American plate. Owing to rapid convergence, the seismic risk in the Nankai trough may be larger than that of the Tokai gap.

Off-line, built-in test techniques for VLSI circuits

NASA Technical Reports Server (NTRS)

Buehler, M. G.; Sievers, M. W.

1982-01-01

It is shown that the use of redundant on-chip circuitry improves the testability of an entire VLSI circuit. In the study described here, five techniques applied to a two-bit ripple carry adder are compared. The techniques considered are self-oscillation, self-comparison, partition, scan path, and built-in logic block observer. It is noted that both classical stuck-at faults and nonclassical faults, such as bridging faults (shorts), stuck-on x faults where x may be 0, 1, or vary between the two, and parasitic flip-flop faults occur in IC structures. To simplify the analysis of the testing techniques, however, a stuck-at fault model is assumed.

Subsurface imaging in a sector of Cerro Prieto transform fault near to pull-apart basin, Mexicali Valley, Baja California, Mexico, based on crooked lines 2D seismic reflection.

NASA Astrophysics Data System (ADS)

Mares-Agüero, M. A.; González-Escobar, M.; Arregui, S.

2016-12-01

In the transition zone between San Andres continental transformation system and the coupled transform faults system and rifting of Gulf of California is located the Cerro Prieto pull-apart basin delimitated by Imperial fault (northeast) and Cerro Prieto fault (CPF) (southwest), this last, is the limit west of Cerro Prieto geothermic field (CPGF). Crooked lines 2D seismic reflection, covering a portion near the intersection of CPF and CPGF are processed and interpreted. The seismic data were obtained in the early 80's by Petróleos Mexicanos (PEMEX). By decades, technical and investigation works in Cerro Prieto geothermic field and its vicinity had mapped faults at several depths but do not stablish a clear limit where this faults and CPF interact due the complex hydrothermal effects imaging the subsurface. The profiles showing the presence of a zone of uplift effect due to CPF. Considering the proximity of the profiles to CPF, it is surprising almost total absence of faults. A strong reflector around 2 km of depth, it is present in all profiles. This seismic reflector is considered a layer of shale, result of the correlation with a well located in the same region.

Geologic and paleoseismic study of the Lavic Lake fault at Lavic Lake Playa, Mojave Desert, Southern California

USGS Publications Warehouse

Rymer, M.J.; Seitz, G.G.; Weaver, K.D.; Orgil, A.; Faneros, G.; Hamilton, J.C.; Goetz, C.

2002-01-01

Paleoseismic investigations of the Lavic Lake fault at Lavic Lake playa place constraints on the timing of a possible earlier earthquake along the 1999 Hector Mine rupture trace and reveal evidence of the timing of the penultimate earthquake on a strand of the Lavic Lake fault that did not rupture in 1999. Three of our four trenches, trenches A, B, and C, were excavated across the 1999 Hector Mine rupture; a fourth trench, D, was excavated across a vegetation lineament that had only minor slip at its southern end in 1999. Trenches A-C exposed strata that are broken only by the 1999 rupture; trench D exposed horizontal bedding that is locally warped and offset by faults. Stratigraphic evidence for the timing of an earlier earthquake along the 1999 rupture across Lavic Lake playa was not exposed. Thus, an earlier event, if there was one along that rupture trace, predates the lowest stratigraphic level exposed in our trenches. Radiocarbon dating of strata near the bottom of trenches constrains a possible earlier event to some time earlier than about 4950 B.C. Buried faults revealed in trench D are below a vegetation lineament at the ground surface. A depositional contact about 80 cm below the ground surface acts as the upward termination of fault breaks in trench D. Thus, this contact may be the event horizon for a surface-rupturing earthquake prior to 1999-the penultimate earthquake on the Lavic Lake fault. Radiocarbon ages of detrital charcoal samples from immediately below the event horizon indicate that the earthquake associated with the faulting occurred later than A.D. 260. An approximately 1300-year age difference between two samples at about the same stratigraphic level below the event horizon suggests the potential for a long residence time of detrital charcoal in the area. Coupled with a lack of bioturbation that could introduce young organic material into the stratigraphic section, the charcoal ages provide only a maximum bounding age; thus, the recognized event may be younger. There is abundant, subtle evidence for pre-1999 activity of the Lavic Lake fault in the playa area, even though the fault was not mapped near the playa prior to the Hector Mine earthquake. The most notable indicators for long-term presence of the fault are pronounced, persistent vegetation lineaments and uplifted basalt exposures. Primary and secondary slip occurred in 1999 on two southern vegetation lineaments, and minor slip locally formed on a northern lineament; trench exposures across the northern vegetation lineament revealed the post-A.D. 260 earthquake, and a geomorphic trough extends northward into alluvial fan deposits in line with this lineament. The presence of two basalt exposures in Lavic lake playa indicates the presence of persistent compressional steps and uplift along the fault. Fault-line scarps are additional geomorphic markers of repeated slip events in basalt exposures.

Structural and Sequence Stratigraphic Analysis of the Onshore Nile Delta, Egypt.

NASA Astrophysics Data System (ADS)

Barakat, Moataz; Dominik, Wilhelm

2010-05-01

The Nile Delta is considered the earliest known delta in the world. It was already described by Herodotus in the 5th Century AC. Nowadays; the Nile Delta is an emerging giant gas province in the Middle East with proven gas reserves which have more than doubled in size in the last years. The Nile Delta basin contains a thick sedimentary sequence inferred to extend from Jurassic to recent time. Structural styles and depositional environments varied during this period. Facies architecture and sequence stratigraphy of the Nile Delta are resolved using seismic stratigraphy based on (2D seismic lines) including synthetic seismograms and tying in well log data. Synthetic seismograms were constructed using sonic and density logs. The combination of structural interpretation and sequence stratigraphy of the development of the basin was resolved. Seven chrono-stratigraphic boundaries have been identified and correlated on seismic and well log data. Several unconformity boundaries also identified on seismic lines range from angular to disconformity type. Furthermore, time structure maps, velocity maps, depth structure maps as well as Isopach maps were constructed using seismic lines and log data. Several structural features were identified: normal faults, growth faults, listric faults, secondary antithetic faults and large rotated fault blocks of manly Miocene age. In some cases minor rollover structures could be identified. Sedimentary features such as paleo-channels were distinctively recognized. Typical Sequence stratigraphic features such as incised valley, clinoforms, topsets, offlaps and onlaps are identified and traced on the seismic lines allowing a good insight into sequence stratigraphic history of the Nile Delta most especially in the Miocene to Pliocene clastic sedimentary succession.

Shallow seismic structure of Kunlun fault zone in northern Tibetan Plateau, China: Implications for the 2001 M s8.1 Kunlun earthquake

USGS Publications Warehouse

Wang, Chun-Yong; Mooney, W.D.; Ding, Z.; Yang, J.; Yao, Z.; Lou, H.

2009-01-01

The shallow seismic velocity structure of the Kunlun fault zone (KLFZ) was jointly deduced from seismic refraction profiling and the records of trapped waves that were excited by five explosions. The data were collected after the 2001 Kunlun M s8.1 earthquake in the northern Tibetan Plateau. Seismic phases for the in-line record sections (26 records up to a distance of 15 km) along the fault zone were analysed, and 1-D P- and S-wave velocity models of shallow crust within the fault zone were determined by using the seismic refraction method. Sixteen seismic stations were deployed along the off-line profile perpendicular to the fault zone. Fault-zone trapped waves appear clearly on the record sections, which were simulated with a 3-D finite difference algorithm. Quantitative analysis of the correlation coefficients of the synthetic and observed trapped waveforms indicates that the Kunlun fault-zone width is 300 m, and S-wave quality factor Q within the fault zone is 15. Significantly, S-wave velocities within the fault zone are reduced by 30-45 per cent from surrounding rocks to a depth of at least 1-2 km, while P-wave velocities are reduced by 7-20 per cent. A fault-zone with such P- and S-low velocities is an indication of high fluid pressure because Vs is affected more than Vp. The low-velocity and low-Q zone in the KLFZ model is the effect of multiple ruptures along the fault trace of the 2001 M s8.1 Kunlun earthquake. ?? 2009 The Authors Journal compilation ?? 2009 RAS.

Determination of the gaseous hydrogen ductile-brittle transition in copper-nickel alloys

NASA Technical Reports Server (NTRS)

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

1985-01-01

A series of copper-nickel alloys were fabricated, notched tensile specimens machined for each alloy, and the specimens tested in 34.5 MPa hydrogen and in air. A notched tensile ratio was determined for each alloy and the hydrogen environment embrittlement (HEE) determined for the alloys of 47.7 weight percent nickel to 73.5 weight percent nickel. Stacking fault probability and stacking fault energies were determined for each alloy using the x ray diffraction line shift and line profiles technique. Hydrogen environment embrittlement was determined to be influenced by stacking fault energies; however, the correlation is believed to be indirect and only partially responsible for the HEE behavior of these alloys.

The wister mud pot lineament: Southeastward extension or abandoned strand of the San Andreas fault?

USGS Publications Warehouse

Lynch, D.K.; Hudnut, K.W.

2008-01-01

We present the results of a survey of mud pots in the Wister Unit of the Imperial Wildlife Area. Thirty-three mud pots, pot clusters, or related geothermal vents (hundreds of pots in all) were identified, and most were found to cluster along a northwest-trending line that is more or less coincident with the postulated Sand Hills fault. An extrapolation of the trace of the San Andreas fault southeastward from its accepted terminus north of Bombay Beach very nearly coincides with the mud pot lineament and may represent a surface manifestation of the San Andreas fault southeast of the Salton Sea. Additionally, a recent survey of vents near Mullet Island in the Salton Sea revealed eight areas along a northwest-striking line where gas was bubbling up through the water and in two cases hot mud and water were being violently ejected.

Stacking fault related luminescence in GaN nanorods.

PubMed

Forsberg, M; Serban, A; Poenaru, I; Hsiao, C-L; Junaid, M; Birch, J; Pozina, G

2015-09-04

Optical and structural properties are presented for GaN nanorods (NRs) grown in the [0001] direction on Si(111) substrates by direct-current reactive magnetron sputter epitaxy. Transmission electron microscopy (TEM) reveals clusters of dense stacking faults (SFs) regularly distributed along the c-axis. A strong emission line at ∼3.42 eV associated with the basal-plane SFs has been observed in luminescence spectra. The optical signature of SFs is stable up to room temperatures with the activation energy of ∼20 meV. Temperature-dependent time-resolved photoluminescence properties suggest that the recombination mechanism of the 3.42 eV emission can be understood in terms of multiple quantum wells self-organized along the growth axis of NRs.

Steady-state analysis of a faulted three-phase four-wire system supplying induction motors with neutrals connected and other single-phase line-to-neutral loads

NASA Technical Reports Server (NTRS)

Wood, M. E.

1980-01-01

Four wire Wye connected ac power systems exhibit peculiar steady state fault characteristics when the fourth wire of three phase induction motors is connected. The loss of one phase of power source due to a series or shunt fault results in currents higher than anticipated on the remaining two phases. A theoretical approach to compute the fault currents and voltages is developed. A FORTRAN program is included in the appendix.

How to build and teach with QuakeCaster: an earthquake demonstration and exploration tool

USGS Publications Warehouse

Linton, Kelsey; Stein, Ross S.

2015-01-01

QuakeCaster is an interactive, hands-on teaching model that simulates earthquakes and their interactions along a plate-boundary fault. QuakeCaster contains the minimum number of physical processes needed to demonstrate most observable earthquake features. A winch to steadily reel in a line simulates the steady plate tectonic motions far from the plate boundaries. A granite slider in frictional contact with a nonskid rock-like surface simulates a fault at a plate boundary. A rubber band connecting the line to the slider simulates the elastic character of the Earth’s crust. By stacking and unstacking sliders and cranking in the winch, one can see the results of changing the shear stress and the clamping stress on a fault. By placing sliders in series with rubber bands between them, one can simulate the interaction of earthquakes along a fault, such as cascading or toggling shocks. By inserting a load scale into the line, one can measure the stress acting on the fault throughout the earthquake cycle. As observed for real earthquakes, QuakeCaster events are not periodic, time-predictable, or slip-predictable. QuakeCaster produces rare but unreliable “foreshocks.” When fault gouge builds up, the friction goes to zero and fault creep is seen without large quakes. QuakeCaster events produce very small amounts of fault gouge that strongly alter its behavior, resulting in smaller, more frequent shocks as the gouge accumulates. QuakeCaster is designed so that students or audience members can operate it and record its output. With a stopwatch and ruler one can measure and plot the timing, slip distance, and force results of simulated earthquakes. People of all ages can use the QuakeCaster model to explore hypotheses about earthquake occurrence. QuakeCaster takes several days and about $500.00 in materials to build.

View of portion of South Island, New Zealand as seen from Skylab

NASA Image and Video Library

1973-12-22

SL4-137-3700 (22 Dec. 1973) --- A near vertical view of a portion of South Island, New Zealand, as see from the Skylab space station in Earth orbit. This picture was taken by one of the Skylab 4 crew members with a handheld 70mm Hasselblad camera using a 100mm lens. The picture should be held with the largest body of water (Tasman Sea) on the left. Cape Foulwind is at the upper left. The City of Christchurch is under clouds at the center right margin. Note the movement of sediment by alongshore currents, especially on the east (right) side of the island. The Alpine Fault, which is part of the circum-Pacific volcanic-tectonic belt, is clearly visible on the left (west) side of the island. The fault line is marked by a scarp, which appears very distinct from orbital altitude. Differences in topography and vegetation on either side of the fault are also sharp. Streams change direction at the fault line, and the change in slope at the fault line is evident in the widening of stream channels. The left side of the fault has moved northeast (upward) relative to the right side; some stream offsets indicate the direction of relative movement, but others are controlled by local topography. The Alpine Fault, which also transects New Zealand's North Island, was photographed and described more than a dozen times by the Skylab 4 crewmen. The circum-Pacific volcanic-tectonic belt is a feature of the Earth's crust which is related to sea floor spreading and continental drift. Though the Alpine Fault is sharply delineated in this photograph, other major crustal features are subtle that their existence was unknown before their observation from orbit. The distance from top to bottom is about 290 kilometers (175 miles). Photo credit: NASA

Observations of Static Coulomb Stress Triggering During the Mw 5.7 Pawnee Earthquake Sequence

NASA Astrophysics Data System (ADS)

Pennington, C.; Chen, X.; Nakata, N.; Chang, J. C.

2016-12-01

The Pawnee earthquake occurred at 12:02 UTC on September 3 and was felt throughout Oklahoma and is the largest event recorded in Oklahoma instrumented history. The earthquake occurred near the junction of two previously mapped faults (Watchorn Fault and Labette Fault), but the actual fault that ruptured was a left-lateral unmapped basement fault (now known as the Sooner Lake Fault) with a strike of 107°, which is conjugate to a segment of the Labette fault that is optimally oriented (referred as OOF). We located 634 events from both before and after the mainshock (updated on September 15, 2016) and use these locations to map other seismogenic faults in the area. Examining the catalog, we found two episodes of seismicity, which started at 100 days and 40 days prior to mainshock, each episode has two clusters occurring two days apart on both OOF and near the mainshock. The near-simultaneous occurrence of clusters suggests possible stress interaction between the Sooner Lake Fault and the Labette fault. We examined the Coulomb stress changes on the surrounding faults caused by the mainshock and have found an increase of coulomb stress along the rakes of mapped faults in the area, the highest being along the Sooner Lake fault and the OOF segment of the Labette fault (see fig 1). These faults experienced up to 5 bars of positive coulomb stress increase, which matched the areas that experience the most aftershocks. To better understand the effect of the coulomb stress on the aftershocks, we plan on refining the catalogs for both aftershocks over a longer period and focal mechanisms to obtain accurate nodal planes, which will be used to see how and if the aftershocks were triggered by the Coulomb stress changes. We will also examine and refine the focal mechanisms that were produced for the events that occurred both before and after the main shock to investigate Coulomb stress interaction. Fig 1. (a) Is a map of faults in the Pawnee area with the red line being the source fault, which is part of the Sooner Lake Fault (green and red line segments.) The opitimally oriented segment of the Labette Fault (OOF) is shown in blue. (b) Shows the coulomb stress change for individual rakes after the rupture along the source fault.

Upper-crustal structure beneath the strait of Georgia, Southwest British Columbia

USGS Publications Warehouse

Dash, R.K.; Spence, G.D.; Riedel, M.; Hyndman, R.D.; Brocher, T.M.

2007-01-01

We present a new three-dimensional (3-D) P-wave velocity model for the upper-crustal structure beneath the Strait of Georgia, southwestern British Columbia based on non-linear tomographic inversion of wide-angle seismic refraction data. Our study, part of the Georgia Basin Geohazards Initiative (GBGI) is primarily aimed at mapping the depth of the Cenozoic sedimentary basin and delineating the near-surface crustal faults associated with recent seismic activities (e.g. M = 4.6 in 1997 and M = 5.0 in 1975) in the region. Joint inversion of first-arrival traveltimes from the 1998 Seismic Hazards Investigation in Puget Sound (SHIPS) and the 2002 Georgia Basin experiment provides a high-resolution velocity model of the subsurface to a depth of ???7 km. In the southcentral Georgia Basin, sedimentary rocks of the Cretaceous Nanaimo Group and early Tertiary rocks have seismic velocities between 3.0 and 5.5 km s-1. The basin thickness increases from north to south with a maximum thickness of 7 (??1) km (depth to velocities of 5.5 km s-1) at the southeast end of the strait. The underlying basement rocks, probably representing the Wrangellia terrane, have velocities of 5.5-6.5 km-1 with considerable lateral variation. Our tomographic model reveals that the Strait of Georgia is underlain by a fault-bounded block within the central Georgia Basin. It also shows a correlation between microearthquakes and areas of rapid change in basin thickness. The 1997/1975 earthquakes are located near a northeast-trending hinge line where the thicknesses of sedimentary rocks increase rapidly to the southeast. Given its association with instrumentally recorded, moderate sized earthquakes, we infer that the hinge region is cored by an active fault that we informally name the Gabriola Island fault. A northwest-trending, southwest dipping velocity discontinuity along the eastern side of Vancouver Island correlates spatially with the surface expression of the Outer Island fault. The Outer Island fault as mapped in our seismic tomography model is a thrust fault that projects directly into the Lummi Island fault, suggesting that they are related structures forming a fault system that is continuous for nearly 90 km. Together, these inferred thrust faults may account for at least a portion of the basement uplift at the San Juan Islands. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

Constraints on Shallow Crustal Structure across the San Andreas Fault Zone, Coachella Valley, Southern California: Results from the Salton Seismic Imaging Project (SSIP)

NASA Astrophysics Data System (ADS)

Hernandez, A.; Persaud, P.; Bauer, K.; Stock, J. M.; Fuis, G. S.; Hole, J. A.; Goldman, M.

2015-12-01

The strong influence of basin structure and crustal heterogeneities on seismic wave propagation suggests that these factors should be included in calculations of strong ground shaking. Knowledge of the shallow subsurface is thus essential for an accurate seismic hazard estimate for the densely populated Coachella Valley, the region north of the potential M7.8 rupture near the Salton Sea. Using SSIP data, we analyzed first arrivals from nine 65-911 kg explosive shots recorded along a profile in the Coachella Valley in order to evaluate the interpretation of our 2D tomographic results and give added details on the structural complexity of the shallow crust. The line extends 37 km from the Peninsular Ranges to the Little San Bernardino Mountains crossing the major strands of the San Andreas Fault Zone. We fit traveltime curves to our picks with forward modeling ray tracing, and determined 1D P-wave velocity models for traveltime arrivals east and west of each shot, and a 2D model for the line. We also inferred the geometry of near-vertical faults from the pre-stack line migration method of Bauer et al. (2013). In general, the 1D models east of individual shots have deeper basement contacts and lower apparent velocities, ~5 km/s at 4 km depth, whereas the models west of individual shots have shallower basement and velocities up to 6 km/s at 2 km depth. Mismatches in basement depths (assuming 5-6 km/s) between individual 1D models indicate a shallowly dipping basement, deepening eastward towards the Banning Fault and shoaling abruptly farther east. An east-dipping structure in the 2D model also gives a better fit than horizontal layers. Based on high velocity zones derived from traveltimes at 9-20 km from the western end of the line, we included an offset from ~2 km to 4 km depth near the middle of the line, which significantly improved the 2D model fit. If fault-related, this offset could represent the Garnet Hill Fault if it continues southward in the subsurface.

Data-based hybrid tension estimation and fault diagnosis of cold rolling continuous annealing processes.

PubMed

Liu, Qiang; Chai, Tianyou; Wang, Hong; Qin, Si-Zhao Joe

2011-12-01

The continuous annealing process line (CAPL) of cold rolling is an important unit to improve the mechanical properties of steel strips in steel making. In continuous annealing processes, strip tension is an important factor, which indicates whether the line operates steadily. Abnormal tension profile distribution along the production line can lead to strip break and roll slippage. Therefore, it is essential to estimate the whole tension profile in order to prevent the occurrence of faults. However, in real annealing processes, only a limited number of strip tension sensors are installed along the machine direction. Since the effects of strip temperature, gas flow, bearing friction, strip inertia, and roll eccentricity can lead to nonlinear tension dynamics, it is difficult to apply the first-principles induced model to estimate the tension profile distribution. In this paper, a novel data-based hybrid tension estimation and fault diagnosis method is proposed to estimate the unmeasured tension between two neighboring rolls. The main model is established by an observer-based method using a limited number of measured tensions, speeds, and currents of each roll, where the tension error compensation model is designed by applying neural networks principal component regression. The corresponding tension fault diagnosis method is designed using the estimated tensions. Finally, the proposed tension estimation and fault diagnosis method was applied to a real CAPL in a steel-making company, demonstrating the effectiveness of the proposed method.

Assessment on the influence of resistive superconducting fault current limiter in VSC-HVDC system

NASA Astrophysics Data System (ADS)

Lee, Jong-Geon; Khan, Umer Amir; Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Park, Byung-Bae; Lee, Bang-Wook

2014-09-01

Due to fewer risk of commutation failures, harmonic occurrences and reactive power consumptions, Voltage Source Converter (VSC) based HVDC system is known as the optimum solution of HVDC power system for the future power grid. However, the absence of suitable fault protection devices for HVDC system hinders the efficient VSC-HVDC power grid design. In order to enhance the reliability of the VSC-HVDC power grid against the fault current problems, the application of resistive Superconducting Fault Current Limiters (SFCLs) could be considered. Also, SFCLs could be applied to the VSC-HVDC system with integrated AC Power Systems in order to enhance the transient response and the robustness of the system. In this paper, in order to evaluate the role of SFCLs in VSC-HVDC systems and to determine the suitable position of SFCLs in VSC-HVDC power systems integrated with AC power System, a simulation model based on Korea Jeju-Haenam HVDC power system was designed in Matlab Simulink/SimPowerSystems. This designed model was composed of VSC-HVDC system connected with an AC microgrid. Utilizing the designed VSC-HVDC systems, the feasible locations of resistive SFCLs were evaluated when DC line-to-line, DC line-to-ground and three phase AC faults were occurred. Consequently, it was found that the simulation model was effective to evaluate the positive effects of resistive SFCLs for the effective suppression of fault currents in VSC-HVDC systems as well as in integrated AC Systems. Finally, the optimum locations of SFCLs in VSC-HVDC transmission systems were suggested based on the simulation results.

Propulsion Health Monitoring for Enhanced Safety

NASA Technical Reports Server (NTRS)

Butz, Mark G.; Rodriguez, Hector M.

2003-01-01

This report presents the results of the NASA contract Propulsion System Health Management for Enhanced Safety performed by General Electric Aircraft Engines (GE AE), General Electric Global Research (GE GR), and Pennsylvania State University Applied Research Laboratory (PSU ARL) under the NASA Aviation Safety Program. This activity supports the overall goal of enhanced civil aviation safety through a reduction in the occurrence of safety-significant propulsion system malfunctions. Specific objectives are to develop and demonstrate vibration diagnostics techniques for the on-line detection of turbine rotor disk cracks, and model-based fault tolerant control techniques for the prevention and mitigation of in-flight engine shutdown, surge/stall, and flameout events. The disk crack detection work was performed by GE GR which focused on a radial-mode vibration monitoring technique, and PSU ARL which focused on a torsional-mode vibration monitoring technique. GE AE performed the Model-Based Fault Tolerant Control work which focused on the development of analytical techniques for detecting, isolating, and accommodating gas-path faults.

Earthquakes in the Orozco transform zone: seismicity, source mechanisms, and tectonics

USGS Publications Warehouse

Tréhu, Anne M.; Solomon, Sean C.

1983-01-01

As part of the Rivera Ocean Seismic Experiment, a network of ocean bottom seismometers and hydrophones was deployed in order to determine the seismic characteristics of the Orozco transform fault in the central eastern Pacific. We present hypocentral locations and source mechanisms for 70 earthquakes recorded by this network. All epicenters are within the transform region of the Orozco Fracture Zone and clearly delineate the active plate boundary. About half of the epicenters define a narrow line of activity parallel to the spreading direction and situated along a deep topographic trough that forms the northern boundary of the transform zone (region 1). Most focal depths for these events are very shallow, within 4 km of the seafloor; several well-determined focal depths, however, are as great as 7 km. No shallowing of seismic activity is observed as the rise-transform intersection is approached; to the contrary, the deepest events are within 10 km of the intersection. First motion polarities for most of the earthquakes in region 1 are compatible with right-lateral strike slip faulting along a nearly vertical plane, striking parallel to the spreading direction. Another zone of activity is observed in the central part of the transform (region 2). The apparent horizontal and vertical distribution of activity in this region is more scattered than in the first, and the first motion radiation patterns of these events do not appear to be compatible with any known fault mechanism. Pronounced lateral variations in crustal velocity structure are indicated for the transform region from refraction data and measurements of wave propagation directions. The effect of this lateral heterogeneity on hypocenters and fault plane solutions is evaluated by tracing rays through a three-dimensional velocity grid. While findings for events in region 1 are not significantly affected, in region 2, epicentral mislocations of up to 10 km and azimuthal deflections of up to 45° may result from assuming a laterally homogeneous velocity structure. When corrected for the effects of lateral heterogeneity, the epicenters and fault plane solutions for earthquakes in region 2 are compatible with predominantly normal faulting along a topographic trough trending NW–SE; the focal depths, however, are poorly constrained. These results suggest an en echelon spreading center or leaky transform regime in the central transform region.

A modular neural network scheme applied to fault diagnosis in electric power systems.

PubMed

Flores, Agustín; Quiles, Eduardo; García, Emilio; Morant, Francisco; Correcher, Antonio

2014-01-01

This work proposes a new method for fault diagnosis in electric power systems based on neural modules. With this method the diagnosis is performed by assigning a neural module for each type of component comprising the electric power system, whether it is a transmission line, bus or transformer. The neural modules for buses and transformers comprise two diagnostic levels which take into consideration the logic states of switches and relays, both internal and back-up, with the exception of the neural module for transmission lines which also has a third diagnostic level which takes into account the oscillograms of fault voltages and currents as well as the frequency spectrums of these oscillograms, in order to verify if the transmission line had in fact been subjected to a fault. One important advantage of the diagnostic system proposed is that its implementation does not require the use of a network configurator for the system; it does not depend on the size of the power network nor does it require retraining of the neural modules if the power network increases in size, making its application possible to only one component, a specific area, or the whole context of the power system.

A Modular Neural Network Scheme Applied to Fault Diagnosis in Electric Power Systems

PubMed Central

Flores, Agustín; Morant, Francisco

2014-01-01

This work proposes a new method for fault diagnosis in electric power systems based on neural modules. With this method the diagnosis is performed by assigning a neural module for each type of component comprising the electric power system, whether it is a transmission line, bus or transformer. The neural modules for buses and transformers comprise two diagnostic levels which take into consideration the logic states of switches and relays, both internal and back-up, with the exception of the neural module for transmission lines which also has a third diagnostic level which takes into account the oscillograms of fault voltages and currents as well as the frequency spectrums of these oscillograms, in order to verify if the transmission line had in fact been subjected to a fault. One important advantage of the diagnostic system proposed is that its implementation does not require the use of a network configurator for the system; it does not depend on the size of the power network nor does it require retraining of the neural modules if the power network increases in size, making its application possible to only one component, a specific area, or the whole context of the power system. PMID:25610897

On boundary-element models of elastic fault interaction

NASA Astrophysics Data System (ADS)

Becker, T. W.; Schott, B.

2002-12-01

We present the freely available, modular, and UNIX command-line based boundary-element program interact. It is yet another implementation of Crouch and Starfield's (1983) 2-D and Okada's (1992) half-space solutions for constant slip on planar fault segments in an elastic medium. Using unconstrained or non-negative, standard-package matrix routines, the code can solve for slip distributions on faults given stress boundary conditions, or vice versa, both in a local or global reference frame. Based on examples of complex fault geometries from structural geology, we discuss the effects of different stress boundary conditions on the predicted slip distributions of interacting fault systems. Such one-step calculations can be useful to estimate the moment-release efficiency of alternative fault geometries, and so to evaluate the likelihood which system may be realized in nature. A further application of the program is the simulation of cyclic fault rupture based on simple static-kinetic friction laws. We comment on two issues: First, that of the appropriate rupture algorithm. Cellular models of seismicity often employ an exhaustive rupture scheme: fault cells fail if some critical stress is reached, then cells slip once-only by a given amount, and subsequently the redistributed stress is used to check for triggered activations on other cells. We show that this procedure can lead to artificial complexity in seismicity if time-to-failure is not calculated carefully because of numerical noise. Second, we address the question if foreshocks can be viewed as direct expressions of a simple statistical distribution of frictional strength on individual faults. Repetitive failure models based on a random distribution of frictional coefficients initially show irregular seismicity. By repeatedly selecting weaker patches, the fault then evolves into a quasi-periodic cycle. Each time, the pre-mainshock events build up the cumulative moment release in a non-linear fashion. These temporal seismicity patterns roughly resemble the accelerated moment-release features which are sometimes observed in nature.

Reevaluation of 1935 M 7.0 earthquake fault, Miaoli-Taichung Area, western Taiwan: a DEM and field study

NASA Astrophysics Data System (ADS)

Lin, Y. N.; Chen, Y.; Ota, Y.

2003-12-01

A large earthquake (M 7.0) took place in Miaoli area, western Taiwan on April 21st, 1935. Right to its south is the 1999 Chi-Chi earthquake fault, indicating it is not only tectonically but seismically active. As the previous study, the study area is located in the mature zone of a tectonic collision that occurred between Philippine sea Plate and Eurasia continental Plate. The associated surface ruptures of 1935 earthquake daylighted Tungtsichiao Fault, a tear fault trending NE in the south and Chihhu Fault, a back thrust trending N-S in the north, but no ruptures occurred in between. Strike-slip component was identified by the horizontal offset observed along Tungtsichiao Fault; however, there are still disputes on the reported field evidence. Our purposes are (1) to identify the structural behaviors of these two faults, (2) to find out what the seismogenic structure is, and (3) to reconstruct the regional geology by information given by this earthquake. By DEM interpretation and field survey, we can clearly recognize a lot of the 1935 associated features. In the west of Chihhu Fault, a series of N-S higher terraces can be identified with eastward tilted surfaces and nearly 200 m relative height. Another lower terrace is also believed being created during the 1935 earthquake, showing an east-facing scarp with a height of ca. 1.5~2 m. Outcrop investigation reveals that the late-Miocene bedrock has been easterly thrusted over the Holocene conglomerates, indicating a west-dipping fault plane. The Tungtsichiao Fault cuts through a lateritic terrace at Holi, which is supposed developed in Pleistocene. The fault scarp is only discernible in the northeastern ending. Other noticeable features are the fault related antiforms that line up along the surface rupture. There is no outcrop to show the fault geometry among bedrocks. We re-interpret the northern Chihhu Fault as the back thrust generated from a main subsurface detachment, which may be the actual seismogenic fault. Due to the bend geometry normally existing between ramp and detachment, stress accumulated and earthquake happened right on it. The fault tip of this main thrust may be blind on land or break out offshore, which explains why no surface ruptures related to the main thrust were found.

Solar Photovoltaic (PV) Distributed Generation Systems - Control and Protection

NASA Astrophysics Data System (ADS)

Yi, Zhehan

This dissertation proposes a comprehensive control, power management, and fault detection strategy for solar photovoltaic (PV) distribution generations. Battery storages are typically employed in PV systems to mitigate the power fluctuation caused by unstable solar irradiance. With AC and DC loads, a PV-battery system can be treated as a hybrid microgrid which contains both DC and AC power resources and buses. In this thesis, a control power and management system (CAPMS) for PV-battery hybrid microgrid is proposed, which provides 1) the DC and AC bus voltage and AC frequency regulating scheme and controllers designed to track set points; 2) a power flow management strategy in the hybrid microgrid to achieve system generation and demand balance in both grid-connected and islanded modes; 3) smooth transition control during grid reconnection by frequency and phase synchronization control between the main grid and microgrid. Due to the increasing demands for PV power, scales of PV systems are getting larger and fault detection in PV arrays becomes challenging. High-impedance faults, low-mismatch faults, and faults occurred in low irradiance conditions tend to be hidden due to low fault currents, particularly, when a PV maximum power point tracking (MPPT) algorithm is in-service. If remain undetected, these faults can considerably lower the output energy of solar systems, damage the panels, and potentially cause fire hazards. In this dissertation, fault detection challenges in PV arrays are analyzed in depth, considering the crossing relations among the characteristics of PV, interactions with MPPT algorithms, and the nature of solar irradiance. Two fault detection schemes are then designed as attempts to address these technical issues, which detect faults inside PV arrays accurately even under challenging circumstances, e.g., faults in low irradiance conditions or high-impedance faults. Taking advantage of multi-resolution signal decomposition (MSD), a powerful signal processing technique based on discrete wavelet transformation (DWT), the first attempt is devised, which extracts the features of both line-to-line (L-L) and line-to-ground (L-G) faults and employs a fuzzy inference system (FIS) for the decision-making stage of fault detection. This scheme is then improved as the second attempt by further studying the system's behaviors during L-L faults, extracting more efficient fault features, and devising a more advanced decision-making stage: the two-stage support vector machine (SVM). For the first time, the two-stage SVM method is proposed in this dissertation to detect L-L faults in PV system with satisfactory accuracies. Numerous simulation and experimental case studies are carried out to verify the proposed control and protection strategies. Simulation environment is set up using the PSCAD/EMTDC and Matlab/Simulink software packages. Experimental case studies are conducted in a PV-battery hybrid microgrid using the dSPACE real-time controller to demonstrate the ease of hardware implementation and the controller performance. Another small-scale grid-connected PV system is set up to verify both fault detection algorithms which demonstrate promising performances and fault detecting accuracies.

Interpretation of the Seattle uplift, Washington, as a passive-roof duplex

USGS Publications Warehouse

Brocher, T.M.; Blakely, R.J.; Wells, R.E.

2004-01-01

We interpret seismic lines and a wide variety of other geological and geophysical data to suggest that the Seattle uplift is a passive-roof duplex. A passive-roof duplex is bounded top and bottom by thrust faults with opposite senses of vergence that form a triangle zone at the leading edge of the advancing thrust sheet. In passive-roof duplexes the roof thrust slips only when the floor thrust ruptures. The Seattle fault is a south-dipping reverse fault forming the leading edge of the Seattle uplift, a 40-km-wide fold-and-thrust belt. The recently discovered, north-dipping Tacoma reverse fault is interpreted as a back thrust on the trailing edge of the belt, making the belt doubly vergent. Floor thrusts in the Seattle and Tacoma fault zones, imaged as discontinuous reflections, are interpreted as blind faults that flatten updip into bedding plane thrusts. Shallow monoclines in both the Seattle and Tacoma basins are interpreted to overlie the leading edges of thrust-bounded wedge tips advancing into the basins. Across the Seattle uplift, seismic lines image several shallow, short-wavelength folds exhibiting Quaternary or late Quaternary growth. From reflector truncation, several north-dipping thrust faults (splay thrusts) are inferred to core these shallow folds and to splay upward from a shallow roof thrust. Some of these shallow splay thrusts ruptured to the surface in the late Holocene. Ages from offset soils in trenches across the fault scarps and from abruptly raised shorelines indicate that the splay, roof, and floor thrusts of the Seattle and Tacoma faults ruptured about 1100 years ago.

Rifting and subduction in the papuan peninsula, papua new guinea: The significance of the trobriand tough, the nubara strike-slip fault, and the woodlark rift to the present configuration of papua new guinea

NASA Astrophysics Data System (ADS)

Cameron, Milo Louis

The calculated extension (~111 km) across the Woodlark rift is incompatible with the > 130 km needed to exhume the Metamorphic Core Complexes on shallow angle faults (< 30°) using N-S extension in the Woodlark Basin. High resolution bathymetry, seismicity, and seismic reflection data indicate that the Nubara Fault continues west of the Trobriand Trough, intersects the Woodlark spreading center, and forms the northern boundary of the Woodlark plate and the southern boundary of the Trobriand plate. The newly defined Trobriand plate, to the north of this boundary, has moved SW-NE along the right lateral Nubara Fault, creating SW-NE extension in the region bounded by the MCC's of the D'Entrecasteaux Islands and Moresby Seamount. Gravity and bathymetry data extracted along four transect lines were used to model the gravity and flexure across the Nubara Fault boundary. Differences exist in the elastic thickness between the northern and southern parts of the lines at the Metamorphic Core Complexes of Goodenough Island (Te_south = 5.7 x 103 m; Te_north = 6.1 x 103 m) and Fergusson Island (Te_south = 1.2 x 103 m; Te_north = 5.5 x 103 m). Differences in the elastic strength of the lithosphere also exist at Moresby Seamount (Te_south = 4.2 x 103 m; Te_north = 4.7 x 103 m) and Egum Atoll (Te_south =7.5 x 103 m; Te_north = 1.3 x 104 m). The differences between the northern and southern parts of each transect line imply an east-west boundary that is interpreted to be the Nubara Fault. The opening of the Woodlark Basin resulted in the rotation of the Papuan Peninsula and the Woodlark Rise, strike slip motion between the Solomon Sea and the Woodlark Basin at the Nubara Fault, and the formation of the PAC-SOL-WLK; SOL-WLK-TRB triple junctions. The intersection of the Woodlark Spreading Center with the Nubara Fault added the AUS-WLK-TRB triple junction and established the Nubara Fault as the northern boundary of the Woodlark plate.

Site-to-Source Finite Fault Distance Probability Distribution in Probabilistic Seismic Hazard and the Relationship Between Minimum Distances

NASA Astrophysics Data System (ADS)

Ortega, R.; Gutierrez, E.; Carciumaru, D. D.; Huesca-Perez, E.

2017-12-01

We present a method to compute the conditional and no-conditional probability density function (PDF) of the finite fault distance distribution (FFDD). Two cases are described: lines and areas. The case of lines has a simple analytical solution while, in the case of areas, the geometrical probability of a fault based on the strike, dip, and fault segment vertices is obtained using the projection of spheres in a piecewise rectangular surface. The cumulative distribution is computed by measuring the projection of a sphere of radius r in an effective area using an algorithm that estimates the area of a circle within a rectangle. In addition, we introduce the finite fault distance metrics. This distance is the distance where the maximum stress release occurs within the fault plane and generates a peak ground motion. Later, we can apply the appropriate ground motion prediction equations (GMPE) for PSHA. The conditional probability of distance given magnitude is also presented using different scaling laws. A simple model of constant distribution of the centroid at the geometrical mean is discussed, in this model hazard is reduced at the edges because the effective size is reduced. Nowadays there is a trend of using extended source distances in PSHA, however it is not possible to separate the fault geometry from the GMPE. With this new approach, it is possible to add fault rupture models separating geometrical and propagation effects.

Frictional properties of saponite-rich gouge from a serpentinite-bearing fault zone along the Gokasho-Arashima Tectonic Line, central Japan

USGS Publications Warehouse

Sone, Hiroki; Shimamoto, Toshihiko; Moore, Diane E.

2012-01-01

We studied a serpentinite-bearing fault zone in Gokasho-Arashima Tectonic Line, Mie Prefecture, central Japan, characterizing its internal structures, mineral assemblage, permeability, and frictional properties. The fault core situated between the serpentinite breccia and the adjacent sedimentary rocks is characterized by a zone locally altered to saponite. The clayey gouge layer separates fault rocks of serpentinite origin containing talc and tremolite from fault rocks of sedimentary origin containing chlorite but no quartz. The minerals that formed within the fault are the products of metasomatic reaction between the serpentinite and the siliceous rocks. Permeability measurements show that serpentinite breccia and fault gouge have permeability of 10−14–10−17 m2 and 10−15–10−18 m2, respectively, at 5–120 MPa confining pressure. Frictional coefficient of the saponite-rich clayey fault gouge ranged between 0.20 and 0.35 under room-dry condition, but was reduced to 0.06–0.12 when saturated with water. The velocity dependence of friction was strongly positive, mostly ranging between 0.005 and 0.006 in terms of a–b values. The governing friction law is not constrained yet, but we find that the saponite-rich gouge possesses an evolutional behavior in the opposite direction to that suggested by the rate and state friction law, in addition to its direct velocity dependence.

Investigation of Aceh Segment and Seulimeum Fault by using seismological data; A preliminary result

NASA Astrophysics Data System (ADS)

Muksin, U.; Irwandi; Rusydy, I.; Muzli; Erbas, K.; Marwan; Asrillah; Muzakir; Ismail, N.

2018-04-01

The Seulimeum Fault has not generated large earthquake after last large earthquake with magnitude of M 7.3 occured in 1936. The Seulimeum Fault is accompanied by the Seulawah volcano that reported to be active in 1839, 1975 and 2010. The activity of the Seulimeum Fault could be related with the existence of the Seulawah volcano and the Seulawah volcano activity could also triggered by the Seulumeum Fault activity. The objective of the longterm research is to investigate the relation between the Seulimeum Fault and the Seulawah Volcano. The aim of this paper is to present the first result of the investigation of the Seulimeum Fault based on the seismicity and geomorphology. A seismic network consisting of 17 seismometers (Trilium Compact) and data logger (DSS Cube) were deployed in Aceh Besar. The seismic network was installed for 3 months to record earthquakes along the Seulimeum and the Aceh Faults. The Seulimeum Fault is considered to be active as several local earthquakes were recorded. The Seulimeum Fault is much more active in the region of the bifurcation of the The Aceh Segment and the Seulimeum Fault. The mechanisms of earthquakes along the Seulimeum Fault were mostly strike slip following similar to the Sumatran Fault characteristics.

Reply to the "Comment on "The May 1 20 (MW 6.1) and 29 (MW 6.0), 2012, Emilia (Po Plain, northern Italy) earthquakes: New seismotectonic implications from subsurface geology and high-quality hypocenter location" by Carannante et al., 2015" by Bonini L., et al.

NASA Astrophysics Data System (ADS)

Argnani, Andrea; Carannante, Simona; Massa, Marco; Lovati, Sara; D'Alema, Ezio

2016-12-01

In their comments Bonini et al. argue that our seismotectonic interpretation of the Emilia 2012 seismic sequence does not agree with observations, and follow three lines of arguments to support their statement. These concern the structural interpretation of seismic reflection profiles, the relationship between seismogenic sources and seismicity patterns, and the fit of inferred fault geometry to InSAR observations. These lines of arguments are mostly repeating what has been previously presented by the same authors, and none of them, as discussed in detail in our reply, presents a strong case against our structural interpretation, that, we are convinced, does not conflict with the available data. The two adjacent rupture surfaces outlined by accurately relocated aftershocks are an indication of the presence of two different active fault planes. Interpretation of seismic profiles supports seismological observation and indicates the occurrence of relevant along-strike changes in structural style. These pieces of information have been integrated to build a new seismotectonic interpretation for the area of the Emilia 2012 seismic sequence. Analysis of geodetic data from the area of the Emilia earthquakes has produced very different models of the fault planes; unlike what has been stated by Bonini et al., who see a difficult fit to InSAR data for the fault planes we have identified, the most recent results are consistent with our interpretation that see a steep fault in the upper 8-10 km under the Mirandola anticline. We point out that the geological structures in the subsurface of the Ferrara Arc do change along strike, and the attempt of Bonini et al. to explain both the May 20 and May 29 sequences using a single cross section is not appropriate.

Short-Circuit Fault Detection and Classification Using Empirical Wavelet Transform and Local Energy for Electric Transmission Line.

PubMed

Huang, Nantian; Qi, Jiajin; Li, Fuqing; Yang, Dongfeng; Cai, Guowei; Huang, Guilin; Zheng, Jian; Li, Zhenxin

2017-09-16

In order to improve the classification accuracy of recognizing short-circuit faults in electric transmission lines, a novel detection and diagnosis method based on empirical wavelet transform (EWT) and local energy (LE) is proposed. First, EWT is used to deal with the original short-circuit fault signals from photoelectric voltage transformers, before the amplitude modulated-frequency modulated (AM-FM) mode with a compactly supported Fourier spectrum is extracted. Subsequently, the fault occurrence time is detected according to the modulus maxima of intrinsic mode function (IMF₂) from three-phase voltage signals processed by EWT. After this process, the feature vectors are constructed by calculating the LE of the fundamental frequency based on the three-phase voltage signals of one period after the fault occurred. Finally, the classifier based on support vector machine (SVM) which was constructed with the LE feature vectors is used to classify 10 types of short-circuit fault signals. Compared with complementary ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and improved CEEMDAN methods, the new method using EWT has a better ability to present the frequency in time. The difference in the characteristics of the energy distribution in the time domain between different types of short-circuit faults can be presented by the feature vectors of LE. Together, simulation and real signals experiment demonstrate the validity and effectiveness of the new approach.

Short-Circuit Fault Detection and Classification Using Empirical Wavelet Transform and Local Energy for Electric Transmission Line

PubMed Central

Huang, Nantian; Qi, Jiajin; Li, Fuqing; Yang, Dongfeng; Cai, Guowei; Huang, Guilin; Zheng, Jian; Li, Zhenxin

2017-01-01

In order to improve the classification accuracy of recognizing short-circuit faults in electric transmission lines, a novel detection and diagnosis method based on empirical wavelet transform (EWT) and local energy (LE) is proposed. First, EWT is used to deal with the original short-circuit fault signals from photoelectric voltage transformers, before the amplitude modulated-frequency modulated (AM-FM) mode with a compactly supported Fourier spectrum is extracted. Subsequently, the fault occurrence time is detected according to the modulus maxima of intrinsic mode function (IMF2) from three-phase voltage signals processed by EWT. After this process, the feature vectors are constructed by calculating the LE of the fundamental frequency based on the three-phase voltage signals of one period after the fault occurred. Finally, the classifier based on support vector machine (SVM) which was constructed with the LE feature vectors is used to classify 10 types of short-circuit fault signals. Compared with complementary ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and improved CEEMDAN methods, the new method using EWT has a better ability to present the frequency in time. The difference in the characteristics of the energy distribution in the time domain between different types of short-circuit faults can be presented by the feature vectors of LE. Together, simulation and real signals experiment demonstrate the validity and effectiveness of the new approach. PMID:28926953

Fault location method for unexposed gas trunk line insulation at stray current constant effect area

NASA Astrophysics Data System (ADS)

Tsenev, A. N.; Nosov, V. V.; Akimova, E. V.

2017-10-01

For the purpose of gas trunk lines safe operation, two types of pipe wall metal anticorrosion protection are generally used - the passive (insulation coating) protection and the active (electrochemical) protection. In the process of a pipeline long-term operation, its insulation is subject to wear and damage. Electrochemical protection means of a certain potential value prevent metal dissolution in the soil. When insulation wear and tear attains a level of insufficiency of the protection potential value, the insulating coating needs repair which is a labor-consuming procedure. To reduce the risk of such situation, it is necessary to make inspection rounds to monitor the condition of pipe insulation. A method for pipeline insulation coating unexposed fault location based on Pearson method is considered, wherein a working cathodic protection station signal of 100 Hz frequency is used, which makes installation of a generator unnecessary, and also a specific generator signal of 1 kHz frequency is used at high noise immunity and sensitivity of the instrument complex. This method enables detection and sizing of unexposed pipeline defects within the zones of earth current permanent action. High noise immunity of selective indicators allows for operation in proximity to 110 kV, 220 kV, and 500 kV power transmission lines in action.

A 3D modeling approach to complex faults with multi-source data

NASA Astrophysics Data System (ADS)

Wu, Qiang; Xu, Hua; Zou, Xukai; Lei, Hongzhuan

2015-04-01

Fault modeling is a very important step in making an accurate and reliable 3D geological model. Typical existing methods demand enough fault data to be able to construct complex fault models, however, it is well known that the available fault data are generally sparse and undersampled. In this paper, we propose a workflow of fault modeling, which can integrate multi-source data to construct fault models. For the faults that are not modeled with these data, especially small-scale or approximately parallel with the sections, we propose the fault deduction method to infer the hanging wall and footwall lines after displacement calculation. Moreover, using the fault cutting algorithm can supplement the available fault points on the location where faults cut each other. Increasing fault points in poor sample areas can not only efficiently construct fault models, but also reduce manual intervention. By using a fault-based interpolation and remeshing the horizons, an accurate 3D geological model can be constructed. The method can naturally simulate geological structures no matter whether the available geological data are sufficient or not. A concrete example of using the method in Tangshan, China, shows that the method can be applied to broad and complex geological areas.

Interface For Fault-Tolerant Control System

NASA Technical Reports Server (NTRS)

Shaver, Charles; Williamson, Michael

1989-01-01

Interface unit and controller emulator developed for research on electronic helicopter-flight-control systems equipped with artificial intelligence. Interface unit interrupt-driven system designed to link microprocessor-based, quadruply-redundant, asynchronous, ultra-reliable, fault-tolerant control system (controller) with electronic servocontrol unit that controls set of hydraulic actuators. Receives digital feedforward messages from, and transmits digital feedback messages to, controller through differential signal lines or fiber-optic cables (thus far only differential signal lines have been used). Analog signals transmitted to and from servocontrol unit via coaxial cables.

Security Police Career Ladders AFSCs 811X0, 811X2, and 811X2A.

DTIC Science & Technology

1984-11-01

MONITORS (GRP658) PERCENT MEMBERS PERFORMING TASKS (N=186) J424 PERFORM SPCDS OPERATOR REACTIONS TO SENSOR ALARM, LINE FAULT, OR UNIQUE LINE FAULT...MESSAGES 96 J426 PERFORM SPCDS VERIFICATION PROCEDURES 96 J423 PERFORM SMALL PERMANENT COMMUNICATIONS DISPLAY SEGMENT ( SPCDS ) SHUT-DOWN PROCEDURES 92 J425...PERFORM SPCDS START-UP PROCEDURES 91 J419 PERFORM BISS OPERATOR REACTION TO PRIME POWER LOSS OR SEVERE WEATHER WARNINGS 91 E192 MAKE ENTRIES ON AF

Development of Murray Loop Bridge for High Induced Voltage

NASA Astrophysics Data System (ADS)

Isono, Shigeki; Kawasaki, Katsutoshi; Kobayashi, Shin-Ichi; Ishihara, Hayato; Chiyajo, Kiyonobu

In the case of the cable fault that ground fault resistance is less than 10MΩ, Murray Loop Bridge is excellent as a fault locator in location accuracy and the convenience. But, when the induction of several hundred V is taken from the single core cable which adjoins it, a fault location with the high voltage Murray Loop Bridge becomes difficult. Therefore, we developed Murray Loop Bridge, which could be applied even when the induced voltage of several hundred V occurs in the measurement cable. The evaluation of the fault location accuracy was done with the developed prototype by the actual line and the training equipment.

Understanding strain transfer and basin evolution complexities in the Salton pull-apart basin near the Southern San Andreas Fault

NASA Astrophysics Data System (ADS)

Kell, A. M.; Sahakian, V. J.; Kent, G. M.; Driscoll, N. W.; Harding, A. J.; Baskin, R. L.; Barth, M.; Hole, J. A.; Stock, J. M.; Fuis, G. S.

2015-12-01

Active source seismic data in the Salton Sea provide insight into the complexity of the pull-apart system development. Seismic reflection data combined with tomographic cross sections give constraints on the timing of basin development and strain partitioning between the two dominant dextral faults in the region; the Imperial fault to the southwest and the Southern San Andreas fault (SSAF) to the northeast. Deformation associated with this step-over appears young, having formed in the last 20-40 k.a. The complexity seen in the Salton Sea is similar to that seen in pull-apart basins worldwide. In the southern basin of the Salton Sea, a zone of transpression is noted near the southern termination of the San Andreas fault, though this stress regime quickly transitions to a region of transtension in the northern reaches of the sea. The evolution seen in the basin architecture is likely related to a transition of the SSAF dying to the north, and giving way to youthful segments of the Brawley seismic zone and Imperial fault. Stratigraphic signatures seen in seismic cross-sections also reveal a long-term component of slip to the southwest on a fault 1-2 km west of the northeastern Salton Sea shoreline. Numerous lines of evidence, including seismic reflection data, high-resolution bathymetry within the Salton Sea, and folding patterns in the Borrego Formation to the east of the sea support an assertion of a previously unmapped fault, the Salton Trough fault (STF), parallel to the SAF and just offshore within the Salton Sea. Seismic observations are seen consistently within two datasets of varying vertical resolutions, up to depths of 4-5 km, suggesting that this fault strand is much longer-lived than the evolution seen in the southern sub-basin. The existence of the STF unifies discrepancies between the onshore seismic studies and data collected within the sea. The STF likely serves as the current bounding fault to the active pull-apart system, as it aligns with the "rung-and-ladder" seismicity seen within the Salton Sea. Additionally, the presence of the STF may explain the gaps seen in the paleoseismic record along the SSAF (i.e. Philibosian et al., 2011), which shows an extended period of non-rupture. The STF may play a role in strain release along the SSAF, so a combined history may yield improved insight to the long periods of quiescence.

A high-resolution aftershock seismicity image of the 2002 Sultandaği-Çay earthquake (Mw = 6.2), Turkey

NASA Astrophysics Data System (ADS)

Ergin, Mehmet; Aktar, Mustafa; Özalaybey, Serdar; Tapirdamaz, Mustafa C.; Selvi, Oguz; Tarancioglu, Adil

2009-10-01

A moderate-size earthquake (Mw = 6.2) occurred on 3 February 2002 (07:11:28 GMT) in the Sultandağı-Çay region of southwest Turkey. The mainshock was followed by a strong aftershock of Mw = 6.0 just 2 h after the mainshock, at 09:26:49 GMT. A temporary seismic network of 27 vertical component seismometers was installed to monitor aftershock activity. One thousand sixty nine aftershocks (0.2 < ML < 3.3) were recorded during the period from 5 to 10 February 2002. We analyzed the P and S arrival times and P wave first motion data to obtain high-quality hypocenters and focal mechanisms, which revealed fine details of the fault zone. We infer that the mainshock has ruptured a segment of the Sultandağ Fault Zone that is approximately 37 km long and 7 km wide at depth. The average slip over the rupture plane during the mainshock is estimated to be 32 cm. The linear distribution of the aftershocks and the location of the mainshock epicenter suggest that rupture has initiated in the eastern bending of the fault and propagated unilaterally to the west. The majority of fault plane solutions indicate E-W to ESE-WNW striking oblique-normal faulting mechanisms with an average dip angle of 62° N ± 10° . The high-resolution aftershock seismicity image also shows that faulting involved a complex array of synthetic and possibly antithetic structures during the evolution of the aftershock sequence. The steady increase of the b value towards the west implies that the highest moment release of the mainshock occurred to the west of the epicenter. The study clearly shows the activation of the WNW-ESE-trending Sultandağ Fault Zone along the southern margin of the Akşehir-Afyon Graben (AAG). The westernmost end of the aftershock activity corresponds to a structurally complex zone distinct from the main rupture. It is characterized by both ENE-WSW- and NNE-SSW-trending oblique-slip normal faulting mechanisms, the latter being associated with the NNE-SSW-trending Karamık Graben. The intersection of these two grabens, AAG and Karamık Graben, provides abundant faults available for failure in this region. The occurrence pattern of large events in recent years indicates a possible migration of earthquakes from east to west. Thus, we conclude that this has an important implication for earthquake hazard for the city of Afyon, which lies along the same fault line and only 20 km west of the termination point of the aftershock zone.

Subsurface signature of North Anatolian Fault Zone and its relation with old sutures: New insight from receiver function analysis.

NASA Astrophysics Data System (ADS)

Özacar, Arda A.; Abgarmi, Bizhan

2017-04-01

The North Anatolian Fault Zone (NAFZ) is an active continental transform plate boundary that accommodates the westward extrusion of the Anatolian plate. The central segment of NAFZ displays northward convex surface trace which coincides partly with the Paleo-Tethyan suture formed during the early Cenozoic. The depth extent and detailed structure of the actively deforming crust along the NAF is still under much debate and processes responsible from rapid uplift are enigmatic. In this study, over five thousand high quality P receiver functions are computed using teleseismic earthquakes recorded by permanent stations of national agencies and temporary North Anatolian Fault Passive Seismic experiment (2005-2008). In order to map the crustal thickness and Vp/Vs variations accurately, the study area is divided into grids with 20 km spacing and along each grid line Moho phase and its multiples are picked through constructed common conversion point (CCP) profiles. According to our results, nature of discontinuities and crustal thickness display sharp changes across the main strand of NAFZ supporting a lithospheric scale faulting that offsets Moho discontinuity. In the southern block, crust is relatively thin in the west ( 35 km) and becomes thicker gradually towards east ( 40 km). In contrast, the northern block displays a strong lateral change in crustal thickness reaching up to 10 km across a narrow roughly N-S oriented zone which is interpreted as the subsurface signature of the ambiguous boundary between Istanbul Block and Pontides located further west at the surface.

Crustal strain near the Big Bend of the San Andreas Fault: Analysis of the Los Padres-Tehachapi Trilateration Networks, California

NASA Astrophysics Data System (ADS)

Eberhart-Phillips, Donna; Lisowski, Michael; Zoback, Mark D.

1990-02-01

In the region of the Los Padres-Tehachapi geodetic network, the San Andreas fault (SAF) changes its orientation by over 30° from N40°W, close to that predicted by plate motion for a transform boundary, to N73°W. The strain orientation near the SAF is consistent with right-lateral shear along the fault, with maximum shear rate of 0.38±0.01 μrad/yr at N63°W. In contrast, away from the SAF the strain orientations on both sides of the fault are consistent with the plate motion direction, with maximum shear rate of 0.19±0.01 μrad/yr at N44°W. The strain rate does not drop off rapidly away from the fault, and thus the area is fit by either a broad shear zone below the SAF or a single fault with a relatively deep locking depth. The fit to the line length data is poor for locking depth d less than 25 km. For d of 25 km a buried slip rate of 30 ± 6 mm/yr is estimated. We also estimated buried slip for models that included the Garlock and Big Pine faults, in addition to the SAF. Slip rates on other faults are poorly constrained by the Los Padres-Tehachapi network. The best fitting Garlock fault model had computed left-lateral slip rate of 11±2 mm/yr below 10 km. Buried left-lateral slip of 15±6 mm/yr on the Big Pine fault, within the Western Transverse Ranges, provides significant reduction in line length residuals; however, deformation there may be more complicated than a single vertical fault. A subhorizontal detachment on the southern side of the SAF cannot be well constrained by these data. We investigated the location of the SAF and found that a vertical fault below the surface trace fits the data much better than either a dipping fault or a fault zone located south of the surface trace.

Staged-Fault Testing of Distance Protection Relay Settings

NASA Astrophysics Data System (ADS)

Havelka, J.; Malarić, R.; Frlan, K.

2012-01-01

In order to analyze the operation of the protection system during induced fault testing in the Croatian power system, a simulation using the CAPE software has been performed. The CAPE software (Computer-Aided Protection Engineering) is expert software intended primarily for relay protection engineers, which calculates current and voltage values during faults in the power system, so that relay protection devices can be properly set up. Once the accuracy of the simulation model had been confirmed, a series of simulations were performed in order to obtain the optimal fault location to test the protection system. The simulation results were used to specify the test sequence definitions for the end-to-end relay testing using advanced testing equipment with GPS synchronization for secondary injection in protection schemes based on communication. The objective of the end-to-end testing was to perform field validation of the protection settings, including verification of the circuit breaker operation, telecommunication channel time and the effectiveness of the relay algorithms. Once the end-to-end secondary injection testing had been completed, the induced fault testing was performed with three-end lines loaded and in service. This paper describes and analyses the test procedure, consisting of CAPE simulations, end-to-end test with advanced secondary equipment and staged-fault test of a three-end power line in the Croatian transmission system.

Study of Stand-Alone Microgrid under Condition of Faults on Distribution Line

NASA Astrophysics Data System (ADS)

Malla, S. G.; Bhende, C. N.

2014-10-01

The behavior of stand-alone microgrid is analyzed under the condition of faults on distribution feeders. During fault since battery is not able to maintain dc-link voltage within limit, the resistive dump load control is presented to do so. An inverter control is proposed to maintain balanced voltages at PCC under the unbalanced load condition and to reduce voltage unbalance factor (VUF) at load points. The proposed inverter control also has facility to protect itself from high fault current. Existing maximum power point tracker (MPPT) algorithm is modified to limit the speed of generator during fault. Extensive simulation results using MATLAB/SIMULINK established that the performance of the controllers is quite satisfactory under different fault conditions as well as unbalanced load conditions.

Variation of the fractal dimension anisotropy of two major Cenozoic normal fault systems over space and time around the Snake River Plain, Idaho and SW Montana

NASA Astrophysics Data System (ADS)

Davarpanah, A.; Babaie, H. A.

2012-12-01

The interaction of the thermally induced stress field of the Yellowstone hotspot (YHS) with existing Basin and Range (BR) fault blocks, over the past 17 m.y., has produced a new, spatially and temporally variable system of normal faults around the Snake River Plain (SRP) in Idaho and Wyoming-Montana area. Data about the trace of these new cross faults (CF) and older BR normal faults were acquired from a combination of satellite imageries, DEM, and USGS geological maps and databases at scales of 1:24,000, 1:100,000, 1:250,000, 1:1000, 000, and 1:2,500, 000, and classified based on their azimuth in ArcGIS 10. The box-counting fractal dimension (Db) of the BR fault traces, determined applying the Benoit software, and the anisotropy intensity (ellipticity) of the fractal dimensions, measured with the modified Cantor dust method applying the AMOCADO software, were measured in two large spatial domains (I and II). The Db and anisotropy of the cross faults were studied in five temporal domains (T1-T5) classified based on the geologic age of successive eruptive centers (12 Ma to recent) of the YHS along the eastern SRP. The fractal anisotropy of the CF system in each temporal domain was also spatially determined in the southern part (domain S1), central part (domain S2), and northern part (domain S3) of the SRP. Line (fault trace) density maps for the BR and CF polylines reveal a higher linear density (trace length per unit area) for the BR traces in the spatial domain I, and a higher linear density of the CF traces around the present Yellowstone National Park (S1T5) where most of the seismically active faults are located. Our spatio-temporal analysis reveals that the fractal dimension of the BR system in domain I (Db=1.423) is greater than that in domain II (Db=1.307). It also shows that the anisotropy of the fractal dimension in domain I is less eccentric (axial ratio: 1.242) than that in domain II (1.355), probably reflecting the greater variation in the trend of the BR system in domain I. The CF system in the S1T5 domain has the highest fractal dimension (Db=1.37) and the lowest anisotropy eccentricity (1.23) among the five temporal domains. These values positively correlate with the observed maxima on the fault trace density maps. The major axis of the anisotropy ellipses is consistently perpendicular to the average trend of the normal fault system in each domain, and therefore approximates the orientation of extension for normal faulting in each domain. This fact gives a NE-SW and NW-SE extension direction for the BR system in domains I and II, respectively. The observed NE-SW orientation of the major axes of the anisotropy ellipses in the youngest T4 and T5 temporal domains, oriented perpendicular to the mean trend of the normal faults in the these domains, suggests extension along the NE-SW direction for cross faulting in these areas. The spatial trajectories (form lines) of the minor axes of the anisotropy ellipses, and the mean trend of fault traces in the T4 and T5 temporal domains, define a large parabolic pattern about the axis of the eastern SRP, with its apex at the Yellowstone plateau.

Wavelet Based Protection Scheme for Multi Terminal Transmission System with PV and Wind Generation

NASA Astrophysics Data System (ADS)

Manju Sree, Y.; Goli, Ravi kumar; Ramaiah, V.

2017-08-01

A hybrid generation is a part of large power system in which number of sources usually attached to a power electronic converter and loads are clustered can operate independent of the main power system. The protection scheme is crucial against faults based on traditional over current protection since there are adequate problems due to fault currents in the mode of operation. This paper adopts a new approach for detection, discrimination of the faults for multi terminal transmission line protection in presence of hybrid generation. Transient current based protection scheme is developed with discrete wavelet transform. Fault indices of all phase currents at all terminals are obtained by analyzing the detail coefficients of current signals using bior 1.5 mother wavelet. This scheme is tested for different types of faults and is found effective for detection and discrimination of fault with various fault inception angle and fault impedance.

Identification of the seismogenic source of the 1875 Cucuta earthquake on the basis of a combination of neotectonic, paleoseismologic and historic seismicity studies

NASA Astrophysics Data System (ADS)

Rodríguez, Luz; Diederix, Hans; Torres, Eliana; Audemard, Franck; Hernández, Catalina; Singer, André; Bohórquez, Olga; Yepez, Santiago

2018-03-01

An interesting variety of field evidence that collectively cover the three branches of Earthquake Geology: Neotectonics, Paleoseismology and Historical seismicity, has been collected in the border area between Venezuela and Colombia, near the town of San José de Cúcuta, as part of a study aimed at establishing the seismic source of the great Cucuta Earthquake, that occurred on May 18th, 1875, and that caused heavy losses of life and destruction on both sides of the border, between the Department of Norte de Santander in Colombia and Táchira state in Venezuela. This region is affected by the activity of several cross-border fault systems that converge in the zone of the so-called Pamplona Indenter. Among these seismic sources, the potential candidates of this destructive seismic event in 1875 are those related to the Boconó Fault System, of the northwestern foothills of the Mérida Andes and in particular it's most northwestern expression, the Aguas Calientes Fault System, as suggested by previous research carried out by FUNVISIS for the Venezuelan oil industry in the late 80s. In order to confirm whether this was the responsible system for the earthquake or not, the following studies were carried out: 1) In Neotectonics, a detailed binational surface mapping of the active faults of this system was carried out. This system consists of three branches referred to in this paper as: the North, Central and South branch respectively; 2) In Paleoseismology, two trenches were excavated. The first trench was excavated across the South branch and the second one across the North branch, which confirmed fault activity during the Holocene epoch; 3) In historical seismicity the direct coseismic surface effects that occurred in the epicentral area of the earthquake were assessed. All evidence collected and integrated in these three lines of research, made it possible to conclude that the Central branch of the Aguas Calientes fault system is the most likely candidate to have been the cause of this seismic event.

Active Structures as Deduced from Geomorphic Features: A case in Hsinchu Area, northwestern Taiwan

NASA Astrophysics Data System (ADS)

Chen, Y.; Shyu, J.; Ota, Y.; Chen, W.; Hu, J.; Tsai, B.; Wang, Y.

2002-12-01

Hsinchu area is located in the northwestern Taiwan, the fold-and thrust belt created by arc-continent collision between Eurasian and Philippine. Since the collision event is still ongoing, the island is tectonically active and full of active faults. According to the historical records, some of the faults are seismically acting. In Hsinchuarea two active faults, the Hsinchu and Hsincheng, have been previously mapped. To evaluate the recent activities, we studied the related geomorphic features by using newly developed Digital Elevation Model (DEM), the aerial photos and field investigation. Geologically, both of the faults are coupled with a hanging wall anticline. The anticlines are recently active due to the deformation of the geomorphic surfaces. The Hsinchu fault system shows complicate corresponding scarps, distributed sub-parallel to the fault trace previously suggested by projection of subsurface geology. This is probably caused by its strike-slip component tearing the surrounding area along the main trace. The scarps associated with the Hsincheng fault system are rather simple and unique. It offsets a flight of terraces all the way down to recent flood plain, indicating its long lasting activity. One to two kilometers to east of main trace a back-thrust is found, showing coupled vertical surface offsets with the main fault. The striking discovery in this study is that the surface deformation is only distributed in the southern bank of Touchien river, also suddenly decreasing when crossing another tear fault system, which is originated from Hsincheng fault in the west and extending southeastward parallel to the Touchien river. The strike-slip fault system mentioned above not only bisects the Hsinchu fault, but also divides the Hsincheng fault into segments. The supporting evidence found in this study includes pressure ridges and depressions. As a whole, the study area is tectonically dominated by three active fault systems and two actively growing anticlines. The interactions between active structural systems formed the complicate geomorphic features presented in this paper.

The application of active-source seismic imaging techniques to transtensional problems the Walker Lane and Salton Trough

NASA Astrophysics Data System (ADS)

Kell, Anna Marie

The plate margin in the western United States is an active tectonic region that contains the integrated deformation between the North American and Pacific plates. Nearly focused plate motion between the North American and Pacific plates within the northern Gulf of California gives way north of the Salton Trough to more diffuse deformation. In particular a large fraction of the slip along the southernmost San Andreas fault ultimately bleeds eastward, including about 20% of the total plate motion budget that finds its way through the transtensional Walker Lane Deformation Belt just east of the Sierra Nevada mountain range. Fault-bounded ranges combined with intervening low-lying basins characterize this region; the down-dropped features are often filled with water, which present opportunities for seismic imaging at unprecedented scales. Here I present active-source seismic imaging from the Salton Sea and Walker Lane Deformation Belt, including both marine applications in lakes and shallow seas, and more conventional land-based techniques along the Carson range front. The complex fault network beneath the Salton Trough in eastern California is the on-land continuation of the Gulf of California rift system, where North American-Pacific plate motion is accommodated by a series of long transform faults, separated by small pull-apart, transtensional basins; the right-lateral San Andreas fault bounds this system to the north where it carries, on average, about 50% of total plate motion. The Salton Sea resides within the most youthful and northerly "spreading center" in this several thousand-kilometer-long rift system. The Sea provides an ideal environment for the use of high-data-density marine seismic techniques. Two active-source seismic campaigns in 2010 and 2011 show progression of the development of the Salton pull-apart sub-basin and the northerly propagation of the Imperial-San Andreas system through time at varying resolutions. High fidelity seismic imagery documents the timing of strain transfer from the Imperial fault onto the San Andreas fault through the application of sequence stratigraphy. Evidence shows that the formation of the Salton and Mesquite sub-basins and the associated change of strain partitioning occurred within the last 20-40 k.y., essentially modifying a broader zone of transtension bounding the Imperial and San Andreas faults into two smaller zones of focused extension. The north-central Walker Lane contains a diffuse network of both strike-slip and normal faults, with some degree of strain partitioning characterized by normal faulting to the west along the eastern edge of the Sierra Nevada mountain range, and strike-slip faults to the east that define a diffuse boundary against the Basin and Range proper. A seismic study across the Mount Rose fault zone, bounding the Carson Range near Reno, Nevada, was carried out to investigate slip across a potential low-angle normal fault. A hammer seismic reflection and refraction profile combined with airborne LiDAR (light detection and ranging) imagery highlights fault scarp modification through minor slumping/landslides, providing a better understanding of the nature of slip on this fault. The northeastern margin of the Walker Lane is a region where both "Basin and Range" style normal faults and dextral strike-slip faults contribute to the northward propagation of the Walker Lane (essentially parallel to an equivalent northward propagation of the Mendocino triple junction). Near this intersection lies Pyramid Lake, bounded to the southwest by the dextral Pyramid Lake fault and to the northeast by the normal Lake Range fault. A high-resolution (sub-meter) seismic CHIRP survey collected in 2010 shows intriguing relationships into fault architecture beneath Pyramid Lake. Over 500 line-km of seismic data reveal a polarity flip in basin structure as down-to-the-east motion at the northern end of the Pyramid Lake fault rapidly gives way to down-to-the-west normal motion along the Lake Range fault. Alternating patterns of asymmetric and symmetric stratal patterns west of the Lake Range fault provides some evidence for segmentation of total slip along this large normal fault. Using dated sediment cores, slip rate for the Lake Range fault was found to be approximately 1 mm/yr during the Holocene. A complex zone of transtenstion was also observed in seismic CHIRP data in the northwest quadrant of the lake, where short, discontinuous faults hint at the development of a nascent shear zone trending to the northwest. (Abstract shortened by UMI.)

Tectonic and Structural Controls of Geothermal Activity in the Great Basin Region, Western USA

NASA Astrophysics Data System (ADS)

Faulds, J. E.; Hinz, N.; Kreemer, C. W.

2012-12-01

We are conducting a thorough inventory of structural settings of geothermal systems (>400 total) in the extensional to transtensional Great Basin region of the western USA. Most of the geothermal systems in this region are not related to upper crustal magmatism and thus regional tectonic and local structural controls are the most critical factors controlling the locations of the geothermal activity. A system of NW-striking dextral faults known as the Walker Lane accommodates ~20% of the North American-Pacific plate motion in the western Great Basin and is intimately linked to N- to NNE-striking normal fault systems throughout the region. Overall, geothermal systems are concentrated in areas with the highest strain rates within or proximal to the eastern and western margins of the Great Basin, with the high temperature systems clustering in transtensional areas of highest strain rate in the northwestern Great Basin. Enhanced extension in the northwestern Great Basin probably results from the northwestward termination of the Walker Lane and the concomitant transfer of dextral shear into west-northwest directed extension, thus producing a broad transtensional region. The capacity of geothermal power plants also correlates with strain rates, with the largest (hundreds of megawatts) along the Walker Lane or San Andreas fault system, where strain rates range from 10-100 nanostrain/yr to 1,000 nanostrain/yr, respectively. Lesser systems (tens of megawatts) reside in the Basin and Range (outside the Walker Lane), where local strain rates are typically < 10 nanostrain/yr. Of the 250+ geothermal fields catalogued, step-overs or relay ramps in normal fault zones serve as the most favorable setting, hosting ~32% of the systems. Such areas have multiple, overlapping fault strands, increased fracture density, and thus enhanced permeability. Other common settings include a) intersections between normal faults and strike-slip or oblique-slip faults (27%), where multiple minor faults connect major structures and fluids can flow readily through highly fractured, dilational quadrants, and b) normal fault terminations or tip-lines (22%), where horse-tailing generates closely-spaced faults and increased permeability. Other settings include accommodation zones (i.e., belts of intermeshing, oppositely dipping normal faults; 8%), major range-front faults (5-6%), and pull-aparts in strike-slip faults (4%). In addition, Quaternary faults lie within or near most systems. The relative scarcity of geothermal systems along displacement-maxima of major normal faults may be due to reduced permeability in thick zones of clay gouge and periodic release of stress in major earthquakes. Step-overs, terminations, intersections, and accommodation zones correspond to long-term, critically stressed areas, where fluid pathways are more likely to remain open in networks of closely-spaced, breccia-dominated fractures. These findings may help guide future exploration efforts, especially for blind geothermal systems, which probably comprise the bulk of the geothermal resources in the Great Basin.

Implications of seismic reflection and potential field geophysical data on the structural framework of the Yucca Mountain-Crater Flat region, Nevada

USGS Publications Warehouse

Brocher, T.M.; Hunter, W.C.; Langenheim, V.E.

1998-01-01

Seismic reflection and gravity profiles collected across Yucca Mountain, Nevada, together with geologic data, provide evidence against proposed active detachment faults at shallow depth along the pre-Tertiary-Tertiary contact beneath this potential repository for high-level nuclear waste. The new geophysical data show that the inferred pre-Tertiary-Tertiary contact is offset by moderate- to high-angle faults beneath Crater Flat and Yucca Mountain, and thus this shallow surface cannot represent an active detachment surface. Deeper, low-angle detachment surface(s) within Proterozoic-Paleozoic bedrock cannot be ruled out by our geophysical data, but are inconsistent with other geologic and geophysical observations in this vicinity. Beneath Crater Flat, the base of the seismogenic crust at 12 km depth is close to the top of the reflective (ductile) lower crust at 14 to 15 km depth, where brittle fault motions in the upper crust may be converted to pure shear in the ductile lower crust. Thus, our preferred interpretation of these geophysical data is that moderate- to high-angle faults extend to 12-15-km depth beneath Yucca Mountain and Crater Flat, with only modest changes in dip. The reflection lines reveal that the Amargosa Desert rift zone is an asymmetric half-graben having a maximum depth of about 4 km and a width of about 25 km. The east-dipping Bare Mountain fault that bounds this graben to the west can be traced by seismic reflection data to a depth of at least 3.5 km and possibly as deep as 6 km, with a constant dip of 64????5??. Within Crater Flat, east-dipping high-angle normal faults offset the pre-Tertiary-Tertiary contact as well as a reflector within the Miocene tuff sequence, tilting both to the west. The diffuse eastern boundary of the Amargosa Desert rift zone is formed by a broad series of high-angle down-to-the-west normal faults extending eastward across Yucca Mountain. Along our profile the transition from east- to west-dipping faults occurs at or just west of the Solitario Canyon fault, which bounds the western side of Yucca Mountain. The interaction at depth of these east- and west-dipping faults, having up to hundreds of meters offset, is not imaged by the seismic reflection profile. Understanding potential seismic hazards at Yucca Mountain requires knowledge of the subsurface geometry of the faults near Yucca Mountain, since earthquakes generally nucleate and release the greatest amount of their seismic energy at depth. The geophysical data indicate that many fault planes near the potential nuclear waste facility dip toward Yucca Mountain, including the Bare Mountain range-front fault and several west-dipping faults east of Yucca Mountain. Thus, earthquake ruptures along these faults would lie closer to Yucca Mountain than is often estimated from their surface locations and could therefore be more damaging.

Three-dimensional models of elastostatic deformation in heterogeneous media, with applications to the Eastern California Shear Zone

NASA Astrophysics Data System (ADS)

Barbot, Sylvain; Fialko, Yuri; Sandwell, David

2009-10-01

We present a semi-analytic iterative procedure for evaluating the 3-D deformation due to faults in an arbitrarily heterogeneous elastic half-space. Spatially variable elastic properties are modelled with equivalent body forces and equivalent surface traction in a `homogenized' elastic medium. The displacement field is obtained in the Fourier domain using a semi-analytic Green function. We apply this model to investigate the response of 3-D compliant zones (CZ) around major crustal faults to coseismic stressing by nearby earthquakes. We constrain the two elastic moduli, as well as the geometry of the fault zones by comparing the model predictions to Synthetic Aperture Radar inferferometric (InSAR) data. Our results confirm that the CZ models for the Rodman, Calico and Pinto Mountain faults in the Eastern California Shear Zone (ECSZ) can explain the coseismic InSAR data from both the Landers and the Hector Mine earthquakes. For the Pinto Mountain fault zone, InSAR data suggest a 50 per cent reduction in effective shear modulus and no significant change in Poisson's ratio compared to the ambient crust. The large wavelength of coseismic line-of-sight displacements around the Pinto Mountain fault requires a fairly wide (~1.9 km) CZ extending to a depth of at least 9 km. Best fit for the Calico CZ, north of Galway Dry Lake, is obtained for a 4km deep structure, with a 60 per cent reduction in shear modulus, with no change in Poisson's ratio. We find that the required effective rigidity of the Calico fault zone south of Galway Dry Lake is not as low as that of the northern segment, suggesting along-strike variations of effective elastic moduli within the same fault zone. The ECSZ InSAR data is best explained by CZ models with reduction in both shear and bulk moduli. These observations suggest pervasive and widespread damage around active crustal faults.

Why is the central area of the Alburni Mts in southern Italy so full of caves?

NASA Astrophysics Data System (ADS)

Cafaro, Simona; Gueguen, Erwan; Parise, Mario; Schiattarella, Marcello

2016-04-01

The Alburni Mts represent one of the most important karst area of southern Italy, with about 250 registered caves. Located in the southern Apennines, they constitute an impressive carbonate massif within the Mesozoic-Cenozoic Campania-Lucania platform. The study area is located inside the National Park of Cilento, Vallo di Diano and Alburni, and is bounded by two major rivers: the Calore and Tanagro rivers. This area has been repeatedly affected during Pleistocene by the activity of a regional, partly blind, NW-SE-striking fault system responsible for several huge earthquakes. The massif is limited to the north by an important normal fault zone (Alburni Line), whereas towards the E-SE it is bounded by a complex fault system linking the Alburni Mts to the Maddalena Mts across the Auletta basin and the Vallo di Diano valley. The entire massif is structured by NW-SE trending transtensional faults delimiting half-graben basins, and offset also by NE-SW trending faults. In particular, structural and geomorphological data have shown that the central area of the calcareous ridge is characterized by a relative structural low rhombic-shaped in planimetric view. Approximately 180 karst caves of the known 250, including some of the most significant from a speleological viewpoint, are located in this area. Is this simply due to repeated exploration activity in the last 25 years in this specific sector or might it be related to geological matter? New morphometric and structural data suggest that a relevant transversal structure, consisting of a complex NE-SW fault system, responsible for the genesis of the downthrown area in the central sector of the flat-topped ridge, was able to create the tectonic framework for the development of a great number of karst caves which present peculiar features and hydrological behaviour due to such structural controls. In this contribution we present and discuss these data, aimed at contributing to increase the knowledge on an area of sure karst and speleological interest.

Postseismic Deformation following the 1995 Kobe, Japan, Earthquake Detected by Space Geodesy

NASA Astrophysics Data System (ADS)

Hashimoto, Manabu; Ozawa, Taku; Nishimura, Takuya; Munekane, Hiroshi; Tobita, Mikio

2017-04-01

A Mw 6.8 earthquake hit the city of Kobe, southwest Japan, and its surrounding area on January 17, 1995, and claimed more than 6,400 fatalities. The source faults, trending in the NE-SW direction, are estimated beneath the foothill of the Rokko Mountains, which are located north of the city and the highest peak is 931 m high, but it has a dominant right lateral strike slip components. The Rokko Mountains may have been built by the motion of active faults, but the uplift during the 1995 earthquake may not be enough. Therefore there is a possibility that postseismic deformation contributes to the building of the Rokko Mountains. In order to study the postseismic deformation following the Kobe earthquake, we collected all available space geodetic data during about 20 years, including ERS-1/2, Envisat, JERS-1, ALOS/PALSAR and ALOS-2/PALSAR-2 images and continuous GPS data, and reanalyzed them. Especially, temporal continuous GPS observation made by the Geographical Survey Institute (present the Geospatial Information Authority), Japan in and around the Kobe area is important. We recalculated coordinates of these continuous GPS stations with recent PPP procedure using reanalyzed orbits and clocks of satellites. We made DInSAR and PSInSAR analyses of SAR images using ASTER-GDEM ver.2 or GSI DEM. Time series analysis of JERS-1 images revealed line-of-sight (LOS) decrease of the Rokko Mountains. PS-InSAR results of ALOS/PALSAR also revealed slight uplift north of the Rokko Mountains that uplifted by 20 cm coseismically. These observations suggest that the Rokko Mountains might have uplifted during the postseismic period. LOS increase in a wedge shaped region between two active faults east of the Rokko Mountains in the vicinity of the NE terminus of the source fault of the Kobe earthquake. The LOS increase is also confirmed by ERS-1/2, Envisat and ALOS/PALSAR images. These facts indicate that the subsidence between these two faults continued up to 2010. Continuous GPS observation during the first two years of the postseismic period shows north-south extension with right lateral motion between these two faults. These observations suggest that the Rokko Mountains may have uplift till 2010. On the other hand, active faults near the NE terminus continued to slip with the formation of graben-like structure, due to coseismically loaded stress.

Surface faults in the gulf coastal plain between Victoria and Beaumont, Texas

USGS Publications Warehouse

Verbeek, Earl R.

1979-01-01

Displacement of the land surface by faulting is widespread in the Houston-Galveston region, an area which has undergone moderate to severe land subsidence associated with fluid withdrawal (principally water, and to a lesser extent, oil and gas). A causative link between subsidence and fluid extraction has been convincingly reported in the published literature. However, the degree to which fluid withdrawal affects fault movement in the Texas Gulf Coast, and the mechanism(s) by which this occurs are as yet unclear. Faults that offset the ground surface are not confined to the large (>6000-km2) subsidence “bowl” centered on Houston, but rather are common and characteristic features of Gulf Coast geology. Current observations and conclusions concerning surface faults mapped in a 35,000-km2 area between Victoria and Beaumont, Texas (which area includes the Houston subsidence bowl) may be summarized as follows: (1) Hundreds of faults cutting the Pleistocene and Holocene sediments exposed in the coastal plain have been mapped. Many faults lie well outside the Houston-Galveston region; of these, more than 10% are active, as shown by such features as displaced, fractured, and patched road surfaces, structural failure of buildings astride faults, and deformed railroad tracks. (2) Complex patterns of surface faults are common above salt domes. Both radial patterns (for example, in High Island, Blue Ridge, Clam Lake, and Clinton domes) and crestal grabens (for example, in the South Houston and Friendswood-Webster domes) have been recognized. Elongate grabens connecting several known and suspected salt domes, such as the fault zone connecting Mykawa, Friendswood-Webster, and Clear Lake domes, suggest fault development above rising salt ridges. (3) Surface faults associated with salt domes tend to be short (<5 km in length), numerous, curved in map view, and of diverse trend. Intersecting faults are common. In contrast, surface faults in areas unaffected by salt diapirism are frequently mappable for appreciable distances (>10 km), occur singly or in simple grabens, have gently sinuous traces, and tend to lie roughly parallel to the ENE-NE “coastwise” trend common to regional growth faults identified in subsurface Tertiary sediments. (4) Evidence to support the thesis that surface scarps are the shallow expression of faults extending downward into the Tertiary section is mostly indirect, but nonetheless reasonably convincing. Certainly the patterns of crestal grabens and radiating faults mapped on the surface above salt domes are more than happenstance; analogous fault patterns have been documented around these structures at depth. Similarly, some of the long surface faults not associated with salt domes seem to have subsurface counterparts among known regional growth faults documented through well logs and seismic data. Correlations between surface scarps and faults offsetting subsurface data are not conclusive because of the large vertical distances (1900- 3800 m) involved in making the most of the inferred connections. Nevertheless, the large number of successful correlations - in trend, movement sense, and position - suggests that many surface scarps represent merely the most recent displacements on faults formed during the Tertiary. (5) Upstream-facing fault scarps in this region of low relief can be significant impediments to streams. Locally, both abandoned, mud-filled Pleistocene distributary channels and, more commonly, Holocene drainage lines still occupied by perennial streams reflect the influence of faulting on their development. Some bend sharply near faults and have tended to flow along or pond against the base of scarps; others meander within topographically expressed grabens. Such evidence for Quaternary displacement of the ground surface is widespread in the Texas Gulf coast. In the general, however, streams in areas now offset by faulting show no disruption of their courses where they cross fault scarps. Such scarps are probably very young, and where they can be demonstrated to partly or wholly predate fluid withdrawal, very recent natural fault activity is indicated. (6) Early aerial photographs (1930) of the entire region and topographic maps (1915-16 surveys) of Harris County (Houston and vicinity) show that many faults had already displaced the land surface at a time when appreciable pressure declines in subjacent strata were localized to relatively few areas of large-scale pumping. Prehistoric faulting of the land surface, as noted above, appears to have affected much of the Texas Gulf Coast. (7) A relation between groundwater extraction and current motion on active faults is suspected because of the increased incidence of ground failure in the Houston-Galveston subsidence bowl. This argument is weakened somewhat by recognition of numerous surface faults, some of them active today, far beyond the periphery of the strongly subsiding area. Moreover, tilt beam records from two monitored faults in northwest Houston and accounts of fault damage from local residents demonstrate a complex, episodic nature of fault creep which can only partially be correlated with groundwater production. Nevertheless, although specific mechanisms are in doubt, the extraction of groundwater from shallow (<800-m) sands is probably a major factor in contributing to current displacement of the ground surface in the Houston-Galveston region. Within this large area, the number of faults recognizable from aerial photographs has increased at least tenfold between 1930 and 1970. Elsewhere in the Texas Gulf Coast only a moderate increase has been noted, some of which is possibly attributable to oil and gas production. Surface fault density in the Houston-Galveston region is far greater than in any other area of the Texas Gulf Coast investigated to date. A plausible explanation for these differences is that large overdrafts of groundwater over an extended period of time in the Houston-Galveston region have stimulated fault activity there. Throughout the Texas Gulf Coast, however, a natural contribution to fault motion remains a distinct possibility.

Mountain front migration and drainage captures related to fault segment linkage and growth: The Polopos transpressive fault zone (southeastern Betics, SE Spain)

NASA Astrophysics Data System (ADS)

Giaconia, Flavio; Booth-Rea, Guillermo; Martínez-Martínez, José Miguel; Azañón, José Miguel; Pérez-Romero, Joaquín; Villegas, Irene

2013-01-01

The Polopos E-W- to ESE-WNW-oriented dextral-reverse fault zone is formed by the North Alhamilla reverse fault and the North and South Gafarillos dextral faults. It is a conjugate fault system of the sinistral NNE-SSW Palomares fault zone, active from the late most Tortonian (≈7 Ma) up to the late Pleistocene (≥70 ky) in the southeastern Betics. The helicoidal geometry of the fault zone permits to shift SE-directed movement along the South Cabrera reverse fault to NW-directed shortening along the North Alhamilla reverse fault via vertical Gafarillos fault segments, in between. Since the Messinian, fault activity migrated southwards forming the South Gafarillos fault and displacing the active fault-related mountain-front from the north to the south of Sierra de Polopos; whilst recent activity of the North Alhamilla reverse fault migrated westwards. The Polopos fault zone determined the differential uplift between the Sierra Alhamilla and the Tabernas-Sorbas basin promoting the middle Pleistocene capture that occurred in the southern margin of the Sorbas basin. Continued tectonic uplift of the Sierra Alhamilla-Polopos and Cabrera anticlinoria and local subsidence associated to the Palomares fault zone in the Vera basin promoted the headward erosion of the Aguas river drainage that captured the Sorbas basin during the late Pleistocene.

A study of Quaternary structures in the Qom region, West Central Iran

NASA Astrophysics Data System (ADS)

Babaahmadi, A.; Safaei, H.; Yassaghi, A.; Vafa, H.; Naeimi, A.; Madanipour, S.; Ahmadi, M.

2010-12-01

West Central Iran comprises numerous Quaternary faults. Having either strike-slip or thrust mechanisms, these faults are potentially active and therefore capable of creating destructive earthquakes. In this paper, we use satellite images as well as field trips to identify these active faults in the Qom region. The Qom and Indes faults are the main NW-trending faults along which a Quaternary restraining step-over zone has formed. Kamarkuh, Mohsen Abad, and Ferdows anticlines are potentially active structures that formed in this restraining step-over zone. There are some thrusts and anticlines, such as the Alborz anticline and Alborz fault, which are parallel to strike-slip faults such as the Qom fault, indicating deformation partitioning in the area. In addition to NW-trending structures, there is an important NE-trending fault known as the Qomrud fault that has deformed Quaternary deposits and affected Kushk-e-Nosrat fault, Alborz anticline, and Qomrud River. The results of this study imply that the major Quaternary faults of West Central Iran and their restraining step-over zones are potentially active.

Aircraft Engine On-Line Diagnostics Through Dual-Channel Sensor Measurements: Development of an Enhanced System

NASA Technical Reports Server (NTRS)

Kobayashi, Takahisa; Simon, Donald L.

2008-01-01

In this paper, an enhanced on-line diagnostic system which utilizes dual-channel sensor measurements is developed for the aircraft engine application. The enhanced system is composed of a nonlinear on-board engine model (NOBEM), the hybrid Kalman filter (HKF) algorithm, and fault detection and isolation (FDI) logic. The NOBEM provides the analytical third channel against which the dual-channel measurements are compared. The NOBEM is further utilized as part of the HKF algorithm which estimates measured engine parameters. Engine parameters obtained from the dual-channel measurements, the NOBEM, and the HKF are compared against each other. When the discrepancy among the signals exceeds a tolerance level, the FDI logic determines the cause of discrepancy. Through this approach, the enhanced system achieves the following objectives: 1) anomaly detection, 2) component fault detection, and 3) sensor fault detection and isolation. The performance of the enhanced system is evaluated in a simulation environment using faults in sensors and components, and it is compared to an existing baseline system.

Distributed intrusion monitoring system with fiber link backup and on-line fault diagnosis functions

NASA Astrophysics Data System (ADS)

Xu, Jiwei; Wu, Huijuan; Xiao, Shunkun

2014-12-01

A novel multi-channel distributed optical fiber intrusion monitoring system with smart fiber link backup and on-line fault diagnosis functions was proposed. A 1× N optical switch was intelligently controlled by a peripheral interface controller (PIC) to expand the fiber link from one channel to several ones to lower the cost of the long or ultra-long distance intrusion monitoring system and also to strengthen the intelligent monitoring link backup function. At the same time, a sliding window auto-correlation method was presented to identify and locate the broken or fault point of the cable. The experimental results showed that the proposed multi-channel system performed well especially whenever any a broken cable was detected. It could locate the broken or fault point by itself accurately and switch to its backup sensing link immediately to ensure the security system to operate stably without a minute idling. And it was successfully applied in a field test for security monitoring of the 220-km-length national borderline in China.

The evolution of a Late Cretaceous-Cenozoic intraplate basin (Duaringa Basin), eastern Australia: evidence for the negative inversion of a pre-existing fold-thrust belt

NASA Astrophysics Data System (ADS)

Babaahmadi, Abbas; Sliwa, Renate; Esterle, Joan; Rosenbaum, Gideon

2017-12-01

The Duaringa Basin in eastern Australia is a Late Cretaceous?-early Cenozoic sedimentary basin that developed simultaneously with the opening of the Tasman and Coral Seas. The basin occurs on the top of an earlier (Permian-Triassic) fold-thrust belt, but the negative inversion of this fold-thrust belt, and its contribution to the development of the Duaringa Basin, are not well understood. Here, we present geophysical datasets, including recently surveyed 2D seismic reflection lines, aeromagnetic and Bouguer gravity data. These data provide new insights into the structural style in the Duaringa Basin, showing that the NNW-striking, NE-dipping, deep-seated Duaringa Fault is the main boundary fault that controlled sedimentation in the Duaringa Basin. The major activity of the Duaringa Fault is observed in the southern part of the basin, where it has undergone the highest amount of displacement, resulting in the deepest and oldest depocentre. The results reveal that the Duaringa Basin developed in response to the partial negative inversion of the pre-existing Permian-Triassic fold-thrust belt, which has similar orientation to the extensional faults. The Duaringa Fault is the negative inverted part of a single Triassic thrust, known as the Banana Thrust. Furthermore, small syn-depositional normal faults at the base of the basin likely developed due to the reactivation of pre-existing foliations, accommodation faults, and joints associated with Permian-Triassic folds. In contrast to equivalent offshore basins, the Duaringa Basin lacks a complex structural style and thick syn-rift sediments, possibly because of the weakening of extensional stresses away from the developing Tasman Sea.

Seismic evidence for arc segmentation, active magmatic intrusions and syn-rift fault system in the northern Ryukyu volcanic arc

NASA Astrophysics Data System (ADS)

Arai, Ryuta; Kodaira, Shuichi; Takahashi, Tsutomu; Miura, Seiichi; Kaneda, Yoshiyuki

2018-04-01

Tectonic and volcanic structures of the northern Ryukyu arc are investigated on the basis of multichannel seismic (MCS) reflection data. The study area forms an active volcanic front in parallel to the non-volcanic island chain in the eastern margin of the Eurasian plate and has been undergoing regional extension on its back-arc side. We carried out a MCS reflection experiment along two across-arc lines, and one of the profiles was laid out across the Tokara Channel, a linear bathymetric depression which demarcates the northern and central Ryukyu arcs. The reflection image reveals that beneath this topographic valley there exists a 3-km-deep sedimentary basin atop the arc crust, suggesting that the arc segment boundary was formed by rapid and focused subsidence of the arc crust driven by the arc-parallel extension. Around the volcanic front, magmatic conduits represented by tubular transparent bodies in the reflection images are well developed within the shallow sediments and some of them are accompanied by small fragments of dipping seismic reflectors indicating intruded sills at their bottoms. The spatial distribution of the conduits may suggest that the arc volcanism has multiple active outlets on the seafloor which bifurcate at crustal depths and/or that the location of the volcanic front has been migrating trenchward over time. Further distant from the volcanic front toward the back-arc (> 30 km away), these volcanic features vanish, and alternatively wide rift basins become predominant where rapid transitions from normal-fault-dominant regions to strike-slip-fault-dominant regions occur. This spatial variation in faulting patterns indicates complex stress regimes associated with arc/back-arc rifting in the northern Okinawa Trough.[Figure not available: see fulltext.

Active, capable, and potentially active faults - a paleoseismic perspective

USGS Publications Warehouse

Machette, M.N.

2000-01-01

Maps of faults (geologically defined source zones) may portray seismic hazards in a wide range of completeness depending on which types of faults are shown. Three fault terms - active, capable, and potential - are used in a variety of ways for different reasons or applications. Nevertheless, to be useful for seismic-hazards analysis, fault maps should encompass a time interval that includes several earthquake cycles. For example, if the common recurrence in an area is 20,000-50,000 years, then maps should include faults that are 50,000-100,000 years old (two to five typical earthquake cycles), thus allowing for temporal variability in slip rate and recurrence intervals. Conversely, in more active areas such as plate boundaries, maps showing faults that are <10,000 years old should include those with at least 2 to as many as 20 paleoearthquakes. For the International Lithosphere Programs' Task Group II-2 Project on Major Active Faults of the World our maps and database will show five age categories and four slip rate categories that allow one to select differing time spans and activity rates for seismic-hazard analysis depending on tectonic regime. The maps are accompanied by a database that describes evidence for Quaternary faulting, geomorphic expression, and paleoseismic parameters (slip rate, recurrence interval and time of most recent surface faulting). These maps and databases provide an inventory of faults that would be defined as active, capable, and potentially active for seismic-hazard assessments.

Interpretation of fault-controlled ramp structures in sedimentary basins - example from Caspian Sea using Landsat TM data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iranpanah, A.

1989-03-01

Lineaments on a series of edge-enhanced images (TM data) from a region around the Caspian Sea form a geomorphically significant linear trend along the major Caucasus-Kopeh Dagh fault line. This fault represents the line of collision between the Cimmerian continents and the Turan plate on the south and north, respectively. The lineament zone manifests a ramp structure that forms a relatively narrow topographic high in the Caspian Sea. Paleogeographic studies of the Caspian Sea suggest that the basin is part of the eastern Paratethys, which began to develop in the early Paleogene during the Alpine-Himalayan uplift. On the basis ofmore » the lineaments and associated geomorphic features, the Caspian Sea can be divided into southern, central, and the northern Caspian subbasins. The Caucasus-Kopeh Dagh fault line trends N80/degrees/W and separates the southern Caspian from the central subbasin, approximately along 40/degrees/N latitude. The boundary between the central and the northern subbasins is also a linear topographic high which trends N70/degrees/E and lies approximately at 44/degrees/N latitude. The southern and central subbasins have subequal areal extension covering 35.64% and the 36.63% of the whole sea, whereas the northern subbasin occupies only 27.73% of the basin.« less

Geophysical Characterization of Groundwater-Fault Dynamics at San Andreas Oasis

NASA Astrophysics Data System (ADS)

Faherty, D.; Polet, J.; Osborn, S. G.

2017-12-01

The San Andreas Oasis has historically provided a reliable source of fresh water near the northeast margin of the Salton Sea, although since the recent completion of the Coachella Canal Lining Project and persistent drought in California, surface water at the site has begun to disappear. This may be an effect of the canal lining, however, the controls on groundwater are complicated by the presence of the Hidden Springs Fault (HSF), a northeast dipping normal fault that trends near the San Andreas Oasis. Its surface expression is apparent as a lineation against which all plant growth terminates, suggesting that it may form a partial barrier to subsurface groundwater flow. Numerous environmental studies have detailed the chemical evolution of waters resources at San Andreas Spring, although there remains a knowledge gap on the HSF and its relation to groundwater at the site. To better constrain flow paths and characterize groundwater-fault interactions, we have employed resistivity surveys near the surface trace of the HSF to generate profiles of lateral and depth-dependent variations in resistivity. The survey design is comprised of lines installed in Wenner Arrays, using an IRIS Syscal Kid, with 24 electrodes, at a maximum electrode spacing of 5 meters. In addition, we have gathered constraints on the geometry of the HSF using a combination of ground-based magnetic and gravity profiles, conducted with a GEM walking Proton Precession magnetometer and a Lacoste & Romberg gravimeter. Seventeen gravity measurements were acquired across the surface trace of the fault. Preliminary resistivity results depict a shallow conductor localized at the oasis and discontinuous across the HSF. Magnetic data reveal a large contrast in subsurface magnetic susceptibility that appears coincident with the surface trace and trend of the HSF, while gravity data suggests a shallow, relatively high density anomaly centered near the oasis. These data also hint at a second, previously undocumented fault bounding the opposite margin of the oasis and trending subparallel to the HSF. We thus speculate that the Hidden Springs Fault and this possible secondary fault act as partial barriers to lateral subsurface flow and form a structural wedge, localizing groundwater beneath the oasis.

The buried active faults in southeastern China as revealed by the relocated background seismicity and fault plane solutions

NASA Astrophysics Data System (ADS)

Zhu, A.; Wang, P.; Liu, F.

2017-12-01

The southeastern China in the mainland corresponds to the south China block, which is characterized by moderate historical seismicity and low stain rate. Most faults are buried under thick Quaternary deposits, so it is difficult to detect and locate them using the routine geological methods. Only a few have been identified to be active in late Quaternary, which leads to relatively high potentially seismic risk to this region due to the unexpected locations of the earthquakes. We performed both hypoDD and tomoDD for the background seismicity from 2000 to 2016 to investigate the buried faults. Some buried active faults are revealed by the relocated seismicity and the velocity structure, no geologically known faults corresponding to them and no surface active evidence ever observed. The geometries of the faults are obtained by analyzing the hypocentral distribution pattern and focal mechanism. The focal mechanism solutions indicate that all the revealed faults are dominated in strike-slip mechanisms, or with some thrust components. While the previous fault investigation and detection results show that most of the Quaternary faults in southeastern China are dominated by normal movement. It suggests that there may exist two fault systems in deep and shallow tectonic regimes. The revealed faults may construct the deep one that act as the seismogenic faults, and the normal faults at shallow cannot generate the destructive earthquakes. The variation in the Curie-point depths agrees well with the structure plane of the revealed active faults, suggesting that the faults may have changed the deep structure.

Investigation of the relationship between radon anomalıes in deep water resources near Akşehir fault zone and the radial distances of the sources to an earthquake center

NASA Astrophysics Data System (ADS)

Gümüş, Ayla; Yalım, Hüseyin Ali

2018-02-01

Radon emanation occurs all the rocks and earth containing uranium element. Anomalies in radon concentrations before earthquakes are observed in fault lines, geothermal sources, uranium deposits, volcanic movements. The aim of this study is to investigate the relationship between the radon anomalies in water resources and the radial distances of the sources to the earthquake center. For this purpose, radon concentrations of 9 different deep water sources near Akşehir fault line were determined by taking samples with monthly periods for two years. The relationship between the radon anomalies and the radial distances of the sources to the earthquake center was obtained for the sources.

Fault Detection and Correction for the Solar Dynamics Observatory Attitude Control System

NASA Technical Reports Server (NTRS)

Starin, Scott R.; Vess, Melissa F.; Kenney, Thomas M.; Maldonado, Manuel D.; Morgenstern, Wendy M.

2007-01-01

The Solar Dynamics Observatory is an Explorer-class mission that will launch in early 2009. The spacecraft will operate in a geosynchronous orbit, sending data 24 hours a day to a devoted ground station in White Sands, New Mexico. It will carry a suite of instruments designed to observe the Sun in multiple wavelengths at unprecedented resolution. The Atmospheric Imaging Assembly includes four telescopes with focal plane CCDs that can image the full solar disk in four different visible wavelengths. The Extreme-ultraviolet Variability Experiment will collect time-correlated data on the activity of the Sun's corona. The Helioseismic and Magnetic Imager will enable study of pressure waves moving through the body of the Sun. The attitude control system on Solar Dynamics Observatory is responsible for four main phases of activity. The physical safety of the spacecraft after separation must be guaranteed. Fine attitude determination and control must be sufficient for instrument calibration maneuvers. The mission science mode requires 2-arcsecond control according to error signals provided by guide telescopes on the Atmospheric Imaging Assembly, one of the three instruments to be carried. Lastly, accurate execution of linear and angular momentum changes to the spacecraft must be provided for momentum management and orbit maintenance. In thsp aper, single-fault tolerant fault detection and correction of the Solar Dynamics Observatory attitude control system is described. The attitude control hardware suite for the mission is catalogued, with special attention to redundancy at the hardware level. Four reaction wheels are used where any three are satisfactory. Four pairs of redundant thrusters are employed for orbit change maneuvers and momentum management. Three two-axis gyroscopes provide full redundancy for rate sensing. A digital Sun sensor and two autonomous star trackers provide two-out-of-three redundancy for fine attitude determination. The use of software to maximize chances of recovery from any hardware or software fault is detailed. A generic fault detection and correction software structure is used, allowing additions, deletions, and adjustments to fault detection and correction rules. This software structure is fed by in-line fault tests that are also able to take appropriate actions to avoid corruption of the data stream.

Hydrostructural maps of the Death Valley regional flow system, Nevada and California

USGS Publications Warehouse

Potter, C.J.; Sweetkind, D.S.; Dickerson, R.P.; Killgore, M.L.

2002-01-01

The locations of principal faults and structural zones that may influence ground-water flow were compiled in support of a three-dimensional ground-water model for the Death Valley regional flow system (DVRFS), which covers 80,000 square km in southwestern Nevada and southeastern California. Faults include Neogene extensional and strike-slip faults and pre-Tertiary thrust faults. Emphasis was given to characteristics of faults and deformed zones that may have a high potential for influencing hydraulic conductivity. These include: (1) faulting that results in the juxtaposition of stratigraphic units with contrasting hydrologic properties, which may cause ground-water discharge and other perturbations in the flow system; (2) special physical characteristics of the fault zones, such as brecciation and fracturing, that may cause specific parts of the zone to act either as conduits or as barriers to fluid flow; (3) the presence of a variety of lithologies whose physical and deformational characteristics may serve to impede or enhance flow in fault zones; (4) orientation of a fault with respect to the present-day stress field, possibly influencing hydraulic conductivity along the fault zone; and (5) faults that have been active in late Pleistocene or Holocene time and areas of contemporary seismicity, which may be associated with enhanced permeabilities. The faults shown on maps A and B are largely from Workman and others (in press), and fit one or more of the following criteria: (1) faults that are more than 10 km in map length; (2) faults with more than 500 m of displacement; and (3) faults in sets that define a significant structural fabric that characterizes a particular domain of the DVRFS. The following fault types are shown: Neogene normal, Neogene strike-slip, Neogene low-angle normal, pre-Tertiary thrust, and structural boundaries of Miocene calderas. We have highlighted faults that have late Pleistocene to Holocene displacement (Piety, 1996). Areas of thick Neogene basin-fill deposits (thicknesses 1-2 km, 2-3 km, and >3 km) are shown on map A, based on gravity anomalies and depth-to-basement modeling by Blakely and others (1999). We have interpreted the positions of faults in the subsurface, generally following the interpretations of Blakely and others (1999). Where geophysical constraints are not present, the faults beneath late Tertiary and Quaternary cover have been extended based on geologic reasoning. Nearly all of these concealed faults are shown with continuous solid lines on maps A and B, in order to provide continuous structures for incorporation into the hydrogeologic framework model (HFM). Map A also shows the potentiometric surface, regional springs (25-35 degrees Celsius, D'Agnese and others, 1997), and cold springs (Turner and others, 1996).

High-resolution aeromagnetic survey of the Mono Basin-Long Valley Caldera region, California

NASA Astrophysics Data System (ADS)

Ponce, D. A.; Mangan, M.; McPhee, D.

2013-12-01

A new high-resolution aeromagnetic survey of the Mono Basin-Long Valley Caldera region greatly enhances previous magnetic interpretations that were based on older, low-resolution, and regional aeromagnetic data sets and provides new insights into volcano-tectonic processes. The surveyed area covers a 8,750 km2 NNW-trending swath situated between the Sierra Nevada to the west and the Basin and Range Province to the east. The surveyed area includes the volcanic centers of Mono Lake, Mono-Inyo Craters, Mammoth Mountain, Devils Postpile, and Long Valley Caldera. The NW-trending eastern Sierra frontal fault zone crosses through the study area, including the active Mono Lake, Silver Lake, Hartley Springs, Laurel Creek, and Hilton Creek faults. Over 6,000 line-kilometers of aeromagnetic data were collected at a constant terrain clearance of 150 m, a flight-line spacing of 400 m, and a tie-line spacing of 4 km. Data were collected via helicopter with an attached stinger housing a magnetic sensor using a Scintrex CS-3 cesium magnetometer. In the northern part of the survey area, data improve the magnetic resolution of the individual domes and coulees along Mono Craters and a circular shaped magnetic anomaly that coincides with a poorly defined ring fracture mapped by Kistler (1966). Here, aeromagnetic data combined with other geophysical data suggests that Mono Craters may have preferentially followed a pre-existing plutonic basement feature that may have controlled the sickle shape of the volcanic chain. In the northeastern part of the survey, aeromagnetic data reveal a linear magnetic anomaly that correlates with and extends a mapped fault. In the southern part of the survey, in the Sierra Nevada block just south of Long Valley Caldera, aeromagnetic anomalies correlate with NNW-trending Sierran frontal faults rather than to linear NNE-trends observed in recent seismicity over the last 30 years. These data provide an important framework for the further analysis of the volcanic hazard and geothermal resource potential of the Mono-Inyo volcanic chain and Long Valley Caldera region.

The Death Throes of Ocean Core Complexes: Examples from the Mid-Cayman Spreading Centre

NASA Astrophysics Data System (ADS)

Cheadle, M. J.; John, B. E.; German, C. R.; Kusznir, N. J.

2012-12-01

The Mid-Cayman Spreading Centre (MCSC) is an ultraslow (full rate 15-17 mm/yr) mid-ocean ridge that is located within the Cayman Trough, at the boundary between the North American and Caribbean plates. It is 110km long, and at ~6km below sea level, is the deepest spreading centre in the world. In the Summer of 2011, during NOAA EX 1104, the RV Okeanos Explorer collected high resolution (50m) Simrad EM302 multibeam bathymetry, and high-resolution video using the ROV Little Hercules ,which together provide insight into the evolution (from birth to death) of oceanic core complexes (OCCs). The MCSC exhibits bathymetry typical of slow spreading, magmatically deficient, ridges with thick lithosphere. It has both well-developed OCCs with ~15km of detachment fault offset and smaller offset (6-7km) normal faults forming >40km long linear ridges. Mass wasting is conspicuous. The MCSC is flanked on both sides by three oceanic core complexes: i) the now inactive, Mount Emms to the northeast, ii) the near-recently active Mount Dent in the west centre of the axial valley, and iii) the decapitated Mount Hudson on the south east flank. Together these massifs show different stages of OCC termination. Mount Emms lies approximately 2Ma off axis, is the oldest of the OCCs, and is heavily dissected by faulting and mass wasting. Mount Hudson is terminated by a west dipping high angle normal fault, with 1.6km throw and was initially rifted apart ~0.5Ma. A recently active axial volcanic ridge (AVR) with ROV observed pahoehoe lava forms, and a line of conical volcanic edifices lie within the rifted remains at the toe of the OCC. In contrast, Mount Dent was the most recently active, but is now in the very initial stages of being rifted apart by the presently active AVR that currently intersects the OCC. Incipient high angle normal faults that lie along strike of the AVR cut the dome of Mount Dent, and host the active von Damm hydrothermal system. Mount Dent also shows excess (>1km) uplift beyond that expected by simple flexural uplift, in contrast to the ridges bounded by the smaller offset (6-7km) normal faults, which can be explained by flexural uplift. Together these three OCCs adjacent to the MCSC highlight two interacting processes that lead to OCC termination. Firstly asymmetric spreading associated with OCC development leads to the root of the bounding detachment fault migrating across the axial valley. Secondly, migration of the locus of magmatism can lead to the AVR intersecting the OCC. Both of these processes ultimately lead to rifting and hence termination of the OCC. We suggest that the anomalous uplift of Mount Dent might be an initial response to increased magmatic activity beneath the OCC, and that continued magmatic activity led to thermal weakening of the lithosphere, with development of normal faults and rifting within the dome of the OCC. Interestingly, one key outcome of this new interpretation of the Mt Dent OCC is that the Von Damm hydrothermal field becomes an on-axis vent system.

On-board fault diagnostics for fly-by-light flight control systems using neural network flight processors

NASA Astrophysics Data System (ADS)

Urnes, James M., Sr.; Cushing, John; Bond, William E.; Nunes, Steve

1996-10-01

Fly-by-Light control systems offer higher performance for fighter and transport aircraft, with efficient fiber optic data transmission, electric control surface actuation, and multi-channel high capacity centralized processing combining to provide maximum aircraft flight control system handling qualities and safety. The key to efficient support for these vehicles is timely and accurate fault diagnostics of all control system components. These diagnostic tests are best conducted during flight when all facts relating to the failure are present. The resulting data can be used by the ground crew for efficient repair and turnaround of the aircraft, saving time and money in support costs. These difficult to diagnose (Cannot Duplicate) fault indications average 40 - 50% of maintenance activities on today's fighter and transport aircraft, adding significantly to fleet support cost. Fiber optic data transmission can support a wealth of data for fault monitoring; the most efficient method of fault diagnostics is accurate modeling of the component response under normal and failed conditions for use in comparison with the actual component flight data. Neural Network hardware processors offer an efficient and cost-effective method to install fault diagnostics in flight systems, permitting on-board diagnostic modeling of very complex subsystems. Task 2C of the ARPA FLASH program is a design demonstration of this diagnostics approach, using the very high speed computation of the Adaptive Solutions Neural Network processor to monitor an advanced Electrohydrostatic control surface actuator linked through a AS-1773A fiber optic bus. This paper describes the design approach and projected performance of this on-line diagnostics system.

Deformation during terrane accretion in the Saint Elias orogen, Alaska

USGS Publications Warehouse

Bruhn, R.L.; Pavlis, T.L.; Plafker, G.; Serpa, L.

2004-01-01

The Saint Elias orogen of southern Alaska and adjacent Canada is a complex belt of mountains formed by collision and accretion of the Yakutat terrane into the transition zone from transform faulting to subduction in the northeast Pacific. The orogen is an active analog for tectonic processes that formed much of the North American Cordillera, and is also an important site to study (1) the relationships between climate and tectonics, and (2) structures that generate large- to great-magnitude earthquakes. The Yakutat terrane is a fragment of the North American plate margin that is partly subducted beneath and partly accreted to the continental margin of southern Alaska. Interaction between the Yakutat terrane and the North American and Pacific plates causes significant differences in the style of deformation within the terrane. Deformation in the eastern part of the terrane is caused by strike-slip faulting along the Fairweather transform fault and by reverse faulting beneath the coastal mountains, but there is little deformation immediately offshore. The central part of the orogen is marked by thrusting of the Yakutat terrane beneath the North American plate along the Chugach-Saint Elias fault and development of a wide, thin-skinned fold-and-thrust belt. Strike-slip faulting in this segment may he localized in the hanging wall of the Chugach-Saint Elias fault, or dissipated by thrust faulting beneath a north-northeast-trending belt of active deformation that cuts obliquely across the eastern end of the fold-and-thrust belt. Superimposed folds with complex shapes and plunging hinge lines accommodate horizontal shortening and extension in the western part of the orogen, where the sedimentary cover of the Yakutat terrane is accreted into the upper plate of the Aleutian subduction zone. These three structural segments are separated by transverse tectonic boundaries that cut across the Yakutat terrane and also coincide with the courses of piedmont glaciers that flow from the topographic backbone of the Saint Elias Mountains onto the coastal plain. The Malaspina fault-Pamplona structural zone separates the eastern and central parts of the orogen and is marked by reverse faulting and folding. Onshore, most of this boundary is buried beneath the western or "Agassiz" lobe of the Malaspina piedmont glacier. The boundary between the central fold-and-thrust belt and western zone of superimposed folding lies beneath the middle and lower course of the Bering piedmont glacier. ?? 2004 Geological Society of America.

Fault zone structure and inferences on past activities of the active Shanchiao Fault in the Taipei metropolis, northern Taiwan

NASA Astrophysics Data System (ADS)

Chen, C.; Lee, J.; Chan, Y.; Lu, C.

2010-12-01

The Taipei Metropolis, home to around 10 million people, is subject to seismic hazard originated from not only distant faults or sources scattered throughout the Taiwan region, but also active fault lain directly underneath. Northern Taiwan including the Taipei region is currently affected by post-orogenic (Penglai arc-continent collision) processes related to backarc extension of the Ryukyu subduction system. The Shanchiao Fault, an active normal fault outcropping along the western boundary of the Taipei Basin and dipping to the east, is investigated here for its subsurface structure and activities. Boreholes records in the central portion of the fault were analyzed to document the stacking of post- Last Glacial Maximum growth sediments, and a tulip flower structure is illuminated with averaged vertical slip rate of about 3 mm/yr. Similar fault zone architecture and post-LGM tectonic subsidence rate is also found in the northern portion of the fault. A correlation between geomorphology and structural geology in the Shanchiao Fault zone demonstrates an array of subtle geomorphic scarps corresponds to the branch fault while the surface trace of the main fault seems to be completely erased by erosion and sedimentation. Such constraints and knowledge are crucial in earthquake hazard evaluation and mitigation in the Taipei Metropolis, and in understanding the kinematics of transtensional tectonics in northern Taiwan. Schematic 3D diagram of the fault zone in the central portion of the Shanchiao Fault, displaying regional subsurface geology and its relation to topographic features.

Fault model of the 2017 Jiuzhaigou Mw 6.5 earthquake estimated from coseismic deformation observed using Global Positioning System and Interferometric Synthetic Aperture Radar data

NASA Astrophysics Data System (ADS)

Nie, Zhaosheng; Wang, Di-Jin; Jia, Zhige; Yu, Pengfei; Li, Liangfa

2018-04-01

On August 8, 2017, the Jiuzhaigou Mw 6.5 earthquake occurred in Sichuan province, southwestern China, along the eastern margin of the Tibetan Plateau. The epicenter is surrounded by the Minjiang, Huya, and Tazang Faults. As the seismic activity and tectonics are very complicated, there is controversy regarding the accurate location of the epicenter and the seismic fault of the Jiuzhaigou earthquake. To investigate these aspects, first, the coseismic deformation field was derived from Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) measurements. Second, the fault geometry, coseismic slip model, and Coulomb stress changes around the seismic region were calculated using a homogeneous elastic half-space model. The coseismic deformation field derived from InSAR measurements shows that this event was mainly dominated by a left-lateral strike-slip fault. The maximal and minimal displacements were approximately 0.15 m and - 0.21 m, respectively, along line-of-sight observation. The whole deformation field follows a northwest-trending direction and is mainly concentrated west of the fault. The coseismic slip is 28 km along the strike and 18 km along the dip. It is dominated by a left-lateral strike-slip fault. The average and maximal fault slip is 0.18 and 0.85 m, respectively. The rupture did not fully reach the ground surface. The focal mechanism derived from GPS and InSAR data is consistent with the kinematics and geometry of the Huya Fault. Therefore, we conclude that the northern section or the Shuzheng segment of the Huya Fault is the seismogenic fault. The maximal fault slip is located at 33.25°N and 103.82°E at a depth of 11 km, and the release moment is approximately 6.635 × 1018 Nm, corresponding to a magnitude of Mw 6.49, which is consistent with results reported by the US Geological Survey, Global Centroid Moment Tensor, and other researchers. The coseismic Coulomb stress changes enhanced the stress on the northwest and southeast edges of the northern extension of the Huya Fault. Seismic risks cannot be ignored in the future although aftershocks are fewer in number in these regions.[Figure not available: see fulltext.

Probing the mechanical properties of seismically active crust with space geodesy: Study of the coseismic deformation due to the 1992 Mw7.3 Landers (southern California) earthquake

NASA Astrophysics Data System (ADS)

Fialko, Yuri

2004-03-01

The coseismic deformation due to the 1992 Mw7.3 Landers earthquake, southern California, is investigated using synthetic aperture radar (SAR) and Global Positioning System (GPS) measurements. The ERS-1 satellite data from the ascending and descending orbits are used to generate contiguous maps of three orthogonal components (east, north, up) of the coseismic surface displacement field. The coseismic displacement field exhibits symmetries with respect to the rupture plane that are suggestive of a linear relationship between stress and strain in the crust. Interferometric synthetic aperture radar (InSAR) data show small-scale deformation on nearby faults of the Eastern California Shear Zone. Some of these faults (in particular, the Calico, Rodman, and Pinto Mountain faults) were also subsequently strained by the 1999 Mw7.1 Hector Mine earthquake. I test the hypothesis that the anomalous fault strain represents essentially an elastic response of kilometer-scale compliant fault zones to stressing by nearby earthquakes [, 2002]. The coseismic stress perturbations due to the Landers earthquake are computed using a slip model derived from inversions of the InSAR and GPS data. Calculations are performed for both homogeneous and transversely isotropic half-space models. The compliant zone model that best explains the deformation on the Calico and Pinto Mountain faults due to the Hector Mine earthquake successfully predicts the coseismic displacements on these faults induced by the Landers earthquake. Deformation on the Calico and Pinto Mountain faults implies about a factor of 2 reduction in the effective shear modulus within the ˜2 km wide fault zones. The depth extent of the low-rigidity zones is poorly constrained but is likely in excess of a few kilometers. The same type of structure is able to explain high gradients in the radar line of sight displacements observed on other faults adjacent to the Landers rupture. In particular, the Lenwood fault north of the Soggy Lake has likely experienced a few centimeters of left-lateral motion across <1-km-wide compliant fault zone having the rigidity reduction of more than a factor of 2. The inferred compliant fault zones are interpreted to be a result of extensive damage due to past earthquakes.

Space shuttle main engine fault detection using neural networks

NASA Technical Reports Server (NTRS)

Bishop, Thomas; Greenwood, Dan; Shew, Kenneth; Stevenson, Fareed

1991-01-01

A method for on-line Space Shuttle Main Engine (SSME) anomaly detection and fault typing using a feedback neural network is described. The method involves the computation of features representing time-variance of SSME sensor parameters, using historical test case data. The network is trained, using backpropagation, to recognize a set of fault cases. The network is then able to diagnose new fault cases correctly. An essential element of the training technique is the inclusion of randomly generated data along with the real data, in order to span the entire input space of potential non-nominal data.

Graph-based real-time fault diagnostics

NASA Technical Reports Server (NTRS)

Padalkar, S.; Karsai, G.; Sztipanovits, J.

1988-01-01

A real-time fault detection and diagnosis capability is absolutely crucial in the design of large-scale space systems. Some of the existing AI-based fault diagnostic techniques like expert systems and qualitative modelling are frequently ill-suited for this purpose. Expert systems are often inadequately structured, difficult to validate and suffer from knowledge acquisition bottlenecks. Qualitative modelling techniques sometimes generate a large number of failure source alternatives, thus hampering speedy diagnosis. In this paper we present a graph-based technique which is well suited for real-time fault diagnosis, structured knowledge representation and acquisition and testing and validation. A Hierarchical Fault Model of the system to be diagnosed is developed. At each level of hierarchy, there exist fault propagation digraphs denoting causal relations between failure modes of subsystems. The edges of such a digraph are weighted with fault propagation time intervals. Efficient and restartable graph algorithms are used for on-line speedy identification of failure source components.

Enhancement of the national strong-motion network in Turkey

USGS Publications Warehouse

Gulkan, Polat; Ceken, U.; Colakoglu, Z.; Ugras, T.; Kuru, T.; Apak, A.; Anderson, J.G.; Sucuoglu, H.; Celebi, M.; Akkar, D.S.; Yazgan, U.; Denizlioglu, A.Z.

2007-01-01

Two arrays comprising 20 strong-motion sensors were established in western Turkey. The 14 stations of BYTNet follow a N-S trending line about 65 km in length, normal to strands of the North Anatolian fault that runs between the cities of Bursa and Yalova. Here the dominant character of the potential fault movement is a right-lateral transform slip. The DATNet array, comprising a total of eight stations, is arranged along a 110-km-long E-W trending direction along the Menderes River valley between Denizli and Aydin. (Two stations in this array were incorporated from the existing Turkish national strong-motion network.) This is an extensional tectonic environment, and the network mornitors potential large normal-faulting earthquakes on the faults in the valley. The installation of the arrays was supported by the North Atlantic Treaty Organization (NATO) under its Science for Peace Program. Maintenance and calibration is performed by the General Directorate of Disaster Affairs (GDDA) according to a protocol between Middle East Technical University (METU) and GDDA. Many young engineers and scientists have been trained in network operation and evaluation during the course of the project, and an international workshop dealing with strong-motion instrumentation has been organized as part of the project activities.

Tectonic creep in the Hayward fault zone, California

USGS Publications Warehouse

Radbruch-Hall, Dorothy H.; Bonilla, M.G.

1966-01-01

Tectonic creep is slight apparently continuous movement along a fault. Evidence of creep has been noted at several places within the Hayward fault zone--a zone trending northwestward near the western front of the hills bordering the east side of San Francisco Bay. D. H. Radbruch of the Geological Survey and B. J. Lennert, consulting engineer, confirmed a reported cracking of a culvert under the University of California stadium. F. B. Blanchard and C. L. Laverty of the East Bay Municipal Utility District of Oakland studied cracks in the Claremont water tunnel in Berkeley. M. G. Bonilla of the Geological Survey noted deformation of railroad tracks in the Niles district of Fremont. Six sets of tracks have been bent and shifted. L. S. Cluff of Woodward-Clyde-Sherard and Associates and K. V. Steinbrugge of the Pacific Fire Rating Bureau noted that the concrete walls of a warehouse in the Irvington district of Fremont have been bent and broken, and the columns forced out of line. All the deformations noted have been right lateral and range from about 2 inches in the Claremont tunnel to about 8 inches on the railroad tracks. Tectonic creep almost certainly will continue to damage buildings, tunnels, and other structures that cross the narrow bands of active movement within the Hayward fault zone.

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

USGS Publications Warehouse

Stoffer, Philip W.

2008-01-01

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

Helicopter Electromagnetic and Magnetic Surveys of the Upper and Middle Zones of the Trinity Aquifer, Uvalde and Bexar Counties, Texas

NASA Astrophysics Data System (ADS)

Smith, D. V.; Blome, C. D.; Smith, B. D.; Clark, A. C.

2009-12-01

Detailed helicopter electromagnetic and magnetic surveys (HEM) were conducted in northern Uvalde and Bexar Counties, Texas, as part of a geologic mapping and hydrologic study being conducted by the U.S. Geological Survey (USGS). The aquifers of the Lower Cretaceous Trinity Group (collectively termed the Trinity aquifer) are an important regional water source in the Hill Country of south-central Texas. Rock units comprising the middle aquifer segment are represented by the lower member of the Glen Rose Formation and the Cow Creek Limestone and Hensel Sandstone members of the Pearsall Formation. The lower Trinity hydrologic segment is composed of the Hosston and Sligo Limestones and is confined by the overlying Hammet Shale. Karst features commonly occur in the Trinity Group because of the dissolution of gypsum- and anhydrite-rich beds. Faults and fractures have not been sufficiently analyzed to evaluate the effects these structures have on inter- and intra-formational groundwater flow. The survey in the north Seco Creek area covers the recharge zone of the Edwards aquifer and part of the catchment zone composed of the upper Trinity segment. These data augment the scant geologic mapping in the area by delineating faults, collapse features, and hydrostratigraphic units. The HEM survey in northern Bexar County covered the Camp Stanley Storage Activity, the Camp Bullis Training Site, parts of the recharge zone of the Edwards aquifer south of the military bases, and part of Cibolo Creek to the north. Basic line spacing was 200 meters using six frequencies. In-fill lines were flown with a spacing of 100 meters in the central part of the study area to better resolve geologic structures and karst features. The data processing took into account high EM interference and cultural noise. Apparent resistivity (ρa) maps are used in interpretation of geologic structures, trends, and in the identification of electrical properties of lithologic units. The ρa maps show the northwest trending faults of the Balcones fault zone as well as oblique trending cross faults. Though many of the major faults had been identified in previous geologic mapping, other possibly significant faults were not recognized from traditional techniques. High resistivities within the Glen Rose Limestone are indicative of more competent lithologies which have a greater limestone content. During the evolution of the groundwater system the limestone units are most likely to have developed secondary porosity conducive to establishing flow paths. In contrast, lower resistivities are associated with clay, marl, and mudstone units which have lower porosity and permeability. Resistivity depth sections along flight lines and 3D visualization of resistive zones define reefal structures in the middle Trinity segment. Detailed hydrogeologic mapping and HEM depth modeling illustrate the approach to be taken in future studies of the Trinity.

Observation of seafloor crustal movement using the seafloor acoustic ranging on Kumano-nada

NASA Astrophysics Data System (ADS)

Osada, Y.; Kido, M.; Fujimoto, H.

2010-12-01

Along the Nankai Trough, where the Philippine Sea plate subducts under southeastern Japan with a convergence rate of about 65 mm/yr, large interplate thrust earthquakes of magnitude 8 class have occurred repeatedly with recurrence intervals of 100-200 years. About 60 years have passed since the last earthquakes happened in 1944 and 1946. Therefore it is important to monitor the tectonic activities in the Nankai Trough. Since most of the source region of the earthquakes is located beneath the ocean, an observation system is necessary in the offshore source region. We developed a seafloor acoustic ranging system to continuously monitor the seafloor crustal movement. We aim to monitor the activity in the splay faults in the rupture area of the Tonankai earthquake in the Nankai subduction zone. Slips along the active splay faults may be an important mechanism that the elastic strain caused by relative plate motion. We carried out two experiments, a short-term (one day) and a long-term (four month) experiments, to estimate the repeatability of acoustic measurements of this system. We deployed four PXPs (precision acoustic transponders) with about 600 m (M2-S1 baseline) and 920 m (M2-S2 base line) spacing in the long-term experiment. The standard deviation in acoustic measurements was about 1 cm on each baseline. In September 2008 we carried out an observation to monitor an active splay faults on Kumano-Nada prism slope. We deployed three PXPs with about 925 m (M1-S2 baseline) and 725 m (M1-S2 base line) spacing at the depth of some 2880 m. We recovered them in August 2010 to get data of acoustic measurements for 6 month and pressure measurements for 18 month. The round trip travel time shows a variation with peak-to-peak amplitude of about 1msec. We preliminarily collected the time series of round trip travel times using sound speed, which was estimated from measured temperature and pressure, and attitude data. We discuss the result of a variation of distance.

A systematic overview of the coincidences of river sinuosity changes and tectonically active structures in the Pannonian Basin

NASA Astrophysics Data System (ADS)

Petrovszki, Judit; Székely, Balázs; Timár, Gábor

2012-12-01

As tectonic movements change the valley slope (low-gradient reaches of valleys, in sedimentary basins), the alluvial rivers, as sensitive indicators, respond to these changes, by varying their courses to accommodate this forcing. In our study sinuosity values, a commonly used characteristic parameter to detect river pattern changes, were studied for the major rivers in the Pannonian Basin in order to reveal neotectonic influence on their planform shape. Our study area comprises the entire Pannonian Basin (330,000 km2) located in eastern Central-Europe, bounded by the Alps, Carpathians and Dinarides. The studied rivers were mostly in their natural meandering state before the main river regulations of the 19th century. The last quasi-natural, non-regulated river planforms were surveyed somewhat earlier, during the Second Military Survey of the Habsburg Empire. Using the digitized river sections of that survey, the sinuosities of the rivers were calculated with different sample section sizes ranging from 5 km to 80 km. Depending on the bank-full discharge, also a 'most representative' section size is given, which can be connected to the neotectonic activity. In total, the meandering reaches of 28 rivers were studied; their combined length is 7406 km. The places where the river sinuosity changed were compared to the structural lines of the "Atlas of the present-day geodynamics of the Pannonian Basin" (Horváth et al., 2006). 36 junctions along 26 structural lines were identified where the fault lines of this neotectonic map crossed the rivers. Across these points the mean sinuosity changed. Depending on the direction of the relative vertical movements, the sinuosity values increased or decreased. There were some points, where the sinuosity changed in an opposite way. Along these sections, the rivers belong to the range of unorganized meandering or there are lithological margins. Assuming that the rivers indicate on-going faulting accurately, some places were found, where positioning of the faults of the neotectonic map could be improved according to the sinuosity jumps. However, some significant sinuosity changes cannot be correlated to known faults. In these cases other factors may play a role (e.g., hydrological changes, increase of sediment discharge also can modify sinuosity). In order to clarify the origin of these changes seismic sections and other geodynamical information should be analyzed to prove or disprove tectonic relationship if hydrological reasons can be excluded.

Structuring and evolution of Neogene transcurrent basins in the Tellian foreland domain, north-eastern Tunisia

NASA Astrophysics Data System (ADS)

Melki, Fetheddine; Zouaghi, Taher; Harrab, Salah; Sainz, Antonio Casas; Bédir, Mourad; Zargouni, Fouad

2011-07-01

The Neogene sedimentary basins (Serravallian to Quaternary) of the Tellian tectonic foreland in north-eastern Tunisia formed within the overall NE-SW sinistral strike-slip tectonic framework of the Ras El Korane-Thibar and El Alia-Teboursouk fault systems. From stratigraphic logs, structural cross sections and interpretation of 2D seismic lines and boreholes, the pre-Neogene basement can be interpreted to be structured according to Eocene (NW-SE) compressional and Oligocene extensional phases. This basement comprises structural highs (anticlines and horsts) and subsiding areas (synclines, half-grabens and grabens) formed during the Neogene. The subsiding areas are delineated by faults striking N030E, N-S and N140E, defining (i) narrow, strongly subsiding synclines, (ii) lozenge-shaped basins and (iii) trapezoidal basins. The architecture of their fill results from the sedimentary balance between tectonics and eustatism. Halokinesis and clay diapirism (driven by Triassic and Neogene evaporites and clays) also played an important role in basin evolution, contributing to the formation of domes and diapirs along active faults.

Passive Acoustic Thermometry Using Low-Frequency Deep Water Noise

DTIC Science & Technology

2015-09-30

where potential ice noise sources contributing to the coherent arrivals shown in C-D are located (18b). In the low-frequency band used in this...seismic activity (e.g. along major undersea fault lines) or ice -breaking noise in the Polar Regions (19-22). Ice - generated ambient noise near the...using geodesic paths to obtain a simple estimate of the geographical area from where ice -generated ambient noise is likely to emanate for each site

Structural superposition in fault systems bounding Santa Clara Valley, California

USGS Publications Warehouse

Graymer, Russell W.; Stanley, Richard G.; Ponce, David A.; Jachens, Robert C.; Simpson, Robert W.; Wentworth, Carl M.

2015-01-01

Santa Clara Valley is bounded on the southwest and northeast by active strike-slip and reverse-oblique faults of the San Andreas fault system. On both sides of the valley, these faults are superposed on older normal and/or right-lateral normal oblique faults. The older faults comprised early components of the San Andreas fault system as it formed in the wake of the northward passage of the Mendocino Triple Junction. On the east side of the valley, the great majority of fault displacement was accommodated by the older faults, which were almost entirely abandoned when the presently active faults became active after ca. 2.5 Ma. On the west side of the valley, the older faults were abandoned earlier, before ca. 8 Ma and probably accumulated only a small amount, if any, of the total right-lateral offset accommodated by the fault zone as a whole. Apparent contradictions in observations of fault offset and the relation of the gravity field to the distribution of dense rocks at the surface are explained by recognition of superposed structures in the Santa Clara Valley region.

Shallow seismic reflection profiles and geological structure in the Benton Hills, southeast Missouri

USGS Publications Warehouse

Palmer, J.R.; Hoffman, D.; Stephenson, W.J.; Odum, J.K.; Williams, R.A.

1997-01-01

During late May and early June of 1993, we conducted two shallow, high-resolution seismic reflection surveys (Mini-Sosie method) across the southern escarpment of the Benton Hills segment of Crowleys Ridge. The reflection profiles imaged numerous post-late Cretaceous faults and folds. We believe these faults may represent a significant earthquake source zone. The stratigraphy of the Benton Hills consists of a thin, less than about 130 m, sequence of mostly unconsolidated Cretaceous, Tertiary and Quaternary sediments which unconformably overlie a much thicker section of Paleozoic carbonate rocks. The survey did not resolve reflectors within the upper 75-100 ms of two-way travel time (about 60-100 m), which would include all of the Tertiary and Quaternary and most of the Cretaceous. However, the Paleozoic-Cretaceous unconformity (Pz) produced an excellent reflection, and, locally a shallower reflector within the Cretaceous (K) was resolved. No coherent reflections below about 200 ms of two-way travel time were identified. Numerous faults and folds, which clearly offset the Paleozoic-Cretaceous unconformity reflector, were imaged on both seismic reflection profiles. Many structures imaged by the reflection data are coincident with the surface mapped locations of faults within the Cretaceous and Tertiary succession. Two locations show important structures that are clearly complex fault zones. The English Hill fault zone, striking N30??-35??E, is present along Line 1 and is important because earlier workers indicated it has Pleistocene Loess faulted against Eocene sands. The Commerce fault zone striking N50??E, overlies a major regional basement geophysical lineament, and is present on both seismic lines at the southern margin of the escarpment. The fault zones imaged by these surveys are 30 km from the area of intense microseismicity in the New Madrid seismic zone (NMSZ). If these are northeast and north-northeast oriented fault zones like those at Thebes Gap they are favorably oriented in the modern stress field to be reactivated as right-lateral strike slip faults. Currently, earthquake hazards assessments are most dependent upon historical seismicity, and there are little geological data available to evaluate the earthquake potential of fault zones outside of the NMSZ. We anticipate that future studies will provide evidence that seismicity has migrated between fault zones well beyond the middle Mississippi Valley. The potential earthquake hazards represented by faults outside the NMSZ may be significant.

A case study on pseudo 3-D Chirp sub-bottom profiler (SBP) survey for the detection of a fault trace in shallow sedimentary layers at gas hydrate site in the Ulleung Basin, East Sea

NASA Astrophysics Data System (ADS)

Kim, Young-Jun; Koo, Nam-Hyung; Cheong, Snons; Kim, Jung-Ki; Chun, Jong-Hwa; Shin, Sung-Ryul; Riedel, Michael; Lee, Ho-Young

2016-10-01

A pseudo 3-D Chirp sub-bottom profiler (SBP) survey was conducted to define the extension of a fault that was previously identified on low-resolution 2-D seismic data with an emphasis on the shallow sedimentary layers and to determine if the fault extends to the seafloor. The geophysical survey was conducted as part of an environmental impact assessment for a proposed gas hydrate production test in the Ulleung Basin, East Sea. The Chirp SBP raw data were acquired over an area of 1 km × 1 km with an average line spacing of 20 m. To produce a 3-D Chirp SBP volume, we developed an optimal processing sequence that was divided into two steps. The first phase of 2-D data processing included a sweep signature estimation, correlation, deconvolution, swell effect correction, and migration. The second phase of 3-D data processing was composed of a bin design, bin gathering of the final processed 2-D data set, amplitude normalization, and residual statics correction. The 3-D Chirp SBP volume provides enhanced imaging especially due to the residual static processing using a moving average method and shows better continuity of the sedimentary layers and consistency of the reflection events than the individual 2-D lines. Deformation of the seafloor as a result of the fault was detected, and the fault offset increases in the deeper sedimentary layers. We also determined that the fault strikes northwest-southeast. However, the shallow sub-seafloor sediments have high porosities and therefore do not exhibit brittle fault-behavior but rather deform continuously due to fault movement.

A dense, intersecting array of normal faults on the outer shelf off Southern Costa Rica, associated with subducting Quepos ridge

NASA Astrophysics Data System (ADS)

Silver, E. A.; Kluesner, J. W.; Gibson, J. C.; Bangs, N. L.; McIntosh, K. D.; von Huene, R.; Orange, D.; Ranero, C. R.

2012-12-01

Use of narrow, fixed swath multibeam data with high sounding densities has allowed order of magnitude improvement in image resolution with EM122 multibeam and backscatter data, as part of a 3D seismic study west of the Osa Peninsula. On the outer shelf, along the projection of the subducting Quepos Ridge, we mapped a dense array of faults cutting an arcuate, well-layered set of outcropping beds in the backscatter imagery (mosaicked at 2 m), with roughly N-S and E-W trends. The N-S trends dominate, and show inconsistent offsets, implying that the faults are normal and not strike-slip. The faults also show normal displacement in the 3D seismic data, consistent with the surface interpretation. The outcropping beds (of late Pleistocene age, based on Expedition 334 drilling), may have been truncated during the late Pleistocene low sea-level stand. The outermost shelf (edged by arcuate bathymetric contours) does not show these folded beds, as it was below wave base and buried by a thin sediment layer. However, narrow lines of small pockmarks and mounds follow the fault trends exactly, indicating that fluid flow through the faults is expressed at the surface, including a gas plume that extends to the sea-surface. The almost unprecedented increase in resolution of the EM122 data allows us to infer that the N-S, E-W grid of faults overlying the NE-trending Quepos Ridge projection (and NE directed subduction) formed by extensional arching above the ridge, not by collisional slip lines at a rigid indenter (as proposed earlier based on sandbox models). The extensional fault pattern also facilitates fluid and gas flow through the sedimentary section.

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

NASA Astrophysics Data System (ADS)

Falcucci, E.; Gori, S.

2015-12-01

The 2009 L'Aquila earthquake (Mw 6.1), in central Italy, raised the issue of surface faulting hazard in Italy, since large urban areas were affected by surface displacement along the causative structure, the Paganica fault. Since then, guidelines for microzonation were drew up that take into consideration the problem of surface faulting in Italy, and laying the bases for future regulations about related hazard, similarly to other countries (e.g. USA). More specific guidelines on the management of areas affected by active and capable faults (i.e. able to produce surface faulting) are going to be released by National Department of Civil Protection; these would define zonation of areas affected by active and capable faults, with prescriptions for land use planning. As such, the guidelines arise the problem of the time interval and general operational criteria to asses fault capability for the Italian territory. As for the chronology, the review of the international literature and regulatory allowed Galadini et al. (2012) to propose different time intervals depending on the ongoing tectonic regime - compressive or extensional - which encompass the Quaternary. As for the operational criteria, the detailed analysis of the large amount of works dealing with active faulting in Italy shows that investigations exclusively based on surface morphological features (e.g. fault planes exposition) or on indirect investigations (geophysical data), are not sufficient or even unreliable to define the presence of an active and capable fault; instead, more accurate geological information on the Quaternary space-time evolution of the areas affected by such tectonic structures is needed. A test area for which active and capable faults can be first mapped based on such a classical but still effective methodological approach can be the central Apennines. Reference Galadini F., Falcucci E., Galli P., Giaccio B., Gori S., Messina P., Moro M., Saroli M., Scardia G., Sposato A. (2012). Time intervals to assess active and capable faults for engineering practices in Italy. Eng. Geol., 139/140, 50-65.

Imaging the Alpine Fault to depths of more than 2 km - Initial results from the 2011 WhataDUSIE seismic reflection profile, Whataroa Valley, New Zealand

NASA Astrophysics Data System (ADS)

Kovacs, A.; Gorman, A. R.; Buske, S.; Schmitt, D. R.; Eccles, J. D.; Toy, V. G.; Sutherland, R.; Townend, J.; Norris, R.; Pooley, B.; Cooper, J.; Bruce, C.; Smillie, M.; Bain, S.; Hellwig, O.; Hlousek, F.; Hellmich, J.; Riedel, M.; Schijns, H. M.

2011-12-01

The Alpine Fault is a major plate-bounding fault that is thought to fail in large earthquakes (Mw~7.9) every 200-400 years and to have last ruptured in AD 1717. It is the principal geological structure accommodating transpressional motion between the Australian and Pacific plates on the South Island, with a long-term horizontal motion over the last 1-2 million years of 21-27 mm/yr. Determining the Alpine Fault zone structure at depths of several kilometres beneath the Earth's surface is crucial for understanding not only what conditions govern earthquake rupture but also how ongoing faulting produces mountain ranges such as the Southern Alps. The valley of the Whataroa River, in the central sector of the Alpine Fault, provides rare access to the SE (hanging wall) side of the fault for the purpose of a seismic survey. During January and February 2011, a ~5-km-long seismic reflection line was collected that aimed to image the Alpine Fault at depth. The acquisition was undertaken with the use of 21 Geode seismographs and two Seistronix seismographs with a total capacity of 552 channels. Geophone spacing varied from 4 m in the north (close to the surface trace of the fault) to 8 m in the south (farther from the surface trace.) Sources were 400-g Pentex charges buried in 1.5-2.0 m deep holes of which ~100 were dug by an excavator and ~100 were dug by hand tools where heavy equipment could not access shot locations. Single shots had a nominal separation of 25 m at the north end of the line. At the south end of the line, shots were deployed in patterns of five with a nominal spacing of 125 m. Acquisition system requirements and surface morphology (meanders in the Whataroa River) required five separate acquisition systems. Timing of shots for these systems was accomplished with a radio-controlled firing system, GPS clocks linked to co-located Reftek seismographs, and overlapping traces between acquisition systems. Shot records have been merged and processed through to stacks using the GLOBE Claritas seismic processing package. Initial observations and interpretations of the data are presented. The hanging wall of the Alpine Fault beneath the Whataroa Valley contains at least two major units, a lower basement of Alpine Schist rocks overlain by a substantial layer of glacial sediments that are as much as 700 m thick in places. A sharp reflection marks the boundary between the two units. In places, the Alpine Fault is interpreted as a dipping reflection in the seismic data. The strength of the reflection varies, perhaps as a result of changes in the rocks of the footwall or changes in the geometry of the fault or fault zone.

The HayWired Earthquake Scenario—Earthquake Hazards

USGS Publications Warehouse

Detweiler, Shane T.; Wein, Anne M.

2017-04-24

The HayWired scenario is a hypothetical earthquake sequence that is being used to better understand hazards for the San Francisco Bay region during and after an earthquake of magnitude 7 on the Hayward Fault. The 2014 Working Group on California Earthquake Probabilities calculated that there is a 33-percent likelihood of a large (magnitude 6.7 or greater) earthquake occurring on the Hayward Fault within three decades. A large Hayward Fault earthquake will produce strong ground shaking, permanent displacement of the Earth’s surface, landslides, liquefaction (soils becoming liquid-like during shaking), and subsequent fault slip, known as afterslip, and earthquakes, known as aftershocks. The most recent large earthquake on the Hayward Fault occurred on October 21, 1868, and it ruptured the southern part of the fault. The 1868 magnitude-6.8 earthquake occurred when the San Francisco Bay region had far fewer people, buildings, and infrastructure (roads, communication lines, and utilities) than it does today, yet the strong ground shaking from the earthquake still caused significant building damage and loss of life. The next large Hayward Fault earthquake is anticipated to affect thousands of structures and disrupt the lives of millions of people. Earthquake risk in the San Francisco Bay region has been greatly reduced as a result of previous concerted efforts; for example, tens of billions of dollars of investment in strengthening infrastructure was motivated in large part by the 1989 magnitude 6.9 Loma Prieta earthquake. To build on efforts to reduce earthquake risk in the San Francisco Bay region, the HayWired earthquake scenario comprehensively examines the earthquake hazards to help provide the crucial scientific information that the San Francisco Bay region can use to prepare for the next large earthquake, The HayWired Earthquake Scenario—Earthquake Hazards volume describes the strong ground shaking modeled in the scenario and the hazardous movements of the Earth’s surface that the fault rupture and shaking will activate.

Levelling Profiles and a GPS Network to Monitor the Active Folding and Faulting Deformation in the Campo de Dalias (Betic Cordillera, Southeastern Spain)

PubMed Central

Marín-Lechado, Carlos; Galindo-Zaldívar, Jesús; Gil, Antonio José; Borque, María Jesús; de Lacy, María Clara; Pedrera, Antonio; López-Garrido, Angel Carlos; Alfaro, Pedro; García-Tortosa, Francisco; Ramos, Maria Isabel; Rodríguez-Caderot, Gracia; Rodríguez-Fernández, José; Ruiz-Constán, Ana; de Galdeano-Equiza, Carlos Sanz

2010-01-01

The Campo de Dalias is an area with relevant seismicity associated to the active tectonic deformations of the southern boundary of the Betic Cordillera. A non-permanent GPS network was installed to monitor, for the first time, the fault- and fold-related activity. In addition, two high precision levelling profiles were measured twice over a one-year period across the Balanegra Fault, one of the most active faults recognized in the area. The absence of significant movement of the main fault surface suggests seismogenic behaviour. The possible recurrence interval may be between 100 and 300 y. The repetitive GPS and high precision levelling monitoring of the fault surface during a long time period may help us to determine future fault behaviour with regard to the existence (or not) of a creep component, the accumulation of elastic deformation before faulting, and implications of the fold-fault relationship. PMID:22319309

Randomness fault detection system

NASA Technical Reports Server (NTRS)

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

1996-01-01

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

Study of hydrothermal channels based on near-bottom magnetic prospecting: Application to Longqi hydrothermal area

NASA Astrophysics Data System (ADS)

Tao, W.; Tao, C.; Li, H.; Zhaocai, W.; Jinhui, Z.; Qinzhu, C.; Shili, L.

2014-12-01

Mid-ocean ridges, largely present far from the continental plates, are characterized by complex geological structures and numerous hydrothermal systems with complex controlling factors. Exploring seafloor sulfide resources for industrial and scientific applications is a challenge. With the advent of geophysical surveys for seabed investigation, near-bottom magnetic prospecting, which yields shallow geological structure, is an efficient method for investigating active and inactive hydrothermal fields and for researching the structure of hydrothermal systems (Tivey et al., 1993, 1996；German et al., 2008). We collected near-bottom magnetic data in the Longqi hydrothermal area, located in the southwest Indian ridge (49.6° E; Zhu et al., 2010; Tao et al., 2014), using the autonomous benthic explorer, an autonomous underwater vehicle, during the second leg of the Chinese cruise DY115-19 on board R/V DaYangYiHao. Based on the results of the intensity of the spatial differential vector method (Seaman et al., 1993), we outline the hydrothermal alternation zone. By building models, we subsequently infer a fault along the discovered hydrothermal vents; this fault line may be connected to a detachment fault (Zhao et al., 2013). In addition, we discuss the channels of the hydrothermal circulation system (Figure 1), and presume that heat was conducted to the sea subsurface by the detachment fault; the aqueous fluid that infiltrated the fault is heated and conveyed to the seafloor, promoting the circulation of the hydrothermal system.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, Howard; Braun, James E.

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, Howard; Braun, James E.

2015-12-31

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

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

USGS Publications Warehouse

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

2005-01-01

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

Activation of preexisting transverse structures in an evolving magmatic rift in East Africa

NASA Astrophysics Data System (ADS)

Muirhead, J. D.; Kattenhorn, S. A.

2018-01-01

Inherited crustal weaknesses have long been recognized as important factors in strain localization and basin development in the East African Rift System (EARS). However, the timing and kinematics (e.g., sense of slip) of transverse (rift-oblique) faults that exploit these weaknesses are debated, and thus the roles of inherited weaknesses at different stages of rift basin evolution are often overlooked. The mechanics of transverse faulting were addressed through an analysis of the Kordjya fault of the Magadi basin (Kenya Rift). Fault kinematics were investigated from field and remote-sensing data collected on fault and joint systems. Our analysis indicates that the Kordjya fault consists of a complex system of predominantly NNE-striking, rift-parallel fault segments that collectively form a NNW-trending array of en echelon faults. The transverse Kordjya fault therefore reactivated existing rift-parallel faults in ∼1 Ma lavas as oblique-normal faults with a component of sinistral shear. In all, these fault motions accommodate dip-slip on an underlying transverse structure that exploits the Aswa basement shear zone. This study shows that transverse faults may be activated through a complex interplay among magma-assisted strain localization, preexisting structures, and local stress rotations. Rather than forming during rift initiation, transverse structures can develop after the establishment of pervasive rift-parallel fault systems, and may exhibit dip-slip kinematics when activated from local stress rotations. The Kordjya fault is shown here to form a kinematic linkage that transfers strain to a newly developing center of concentrated magmatism and normal faulting. It is concluded that recently activated transverse faults not only reveal the effects of inherited basement weaknesses on fault development, but also provide important clues regarding developing magmatic and tectonic systems as young continental rift basins evolve.

Interactions between Polygonal Normal Faults and Larger Normal Faults, Offshore Nova Scotia, Canada

NASA Astrophysics Data System (ADS)

Pham, T. Q. H.; Withjack, M. O.; Hanafi, B. R.

2017-12-01

Polygonal faults, small normal faults with polygonal arrangements that form in fine-grained sedimentary rocks, can influence ground-water flow and hydrocarbon migration. Using well and 3D seismic-reflection data, we have examined the interactions between polygonal faults and larger normal faults on the passive margin of offshore Nova Scotia, Canada. The larger normal faults strike approximately E-W to NE-SW. Growth strata indicate that the larger normal faults were active in the Late Cretaceous (i.e., during the deposition of the Wyandot Formation) and during the Cenozoic. The polygonal faults were also active during the Cenozoic because they affect the top of the Wyandot Formation, a fine-grained carbonate sedimentary rock, and the overlying Cenozoic strata. Thus, the larger normal faults and the polygonal faults were both active during the Cenozoic. The polygonal faults far from the larger normal faults have a wide range of orientations. Near the larger normal faults, however, most polygonal faults have preferred orientations, either striking parallel or perpendicular to the larger normal faults. Some polygonal faults nucleated at the tip of a larger normal fault, propagated outward, and linked with a second larger normal fault. The strike of these polygonal faults changed as they propagated outward, ranging from parallel to the strike of the original larger normal fault to orthogonal to the strike of the second larger normal fault. These polygonal faults hard-linked the larger normal faults at and above the level of the Wyandot Formation but not below it. We argue that the larger normal faults created stress-enhancement and stress-reorientation zones for the polygonal faults. Numerous small, polygonal faults formed in the stress-enhancement zones near the tips of larger normal faults. Stress-reorientation zones surrounded the larger normal faults far from their tips. Fewer polygonal faults are present in these zones, and, more importantly, most polygonal faults in these zones were either parallel or perpendicular to the larger faults.

The mechanism of post-rift fault activities in Baiyun sag, Pearl River Mouth basin

NASA Astrophysics Data System (ADS)

Sun, Zhen; Xu, Ziying; Sun, Longtao; Pang, Xiong; Yan, Chengzhi; Li, Yuanping; Zhao, Zhongxian; Wang, Zhangwen; Zhang, Cuimei

2014-08-01

Post-rift fault activities were often observed in deepwater basins, which have great contributions to oil and gas migration and accumulation. The main causes for post-rift fault activities include tectonic events, mud or salt diapirs, and gravitational collapse. In the South China Sea continental margin, post-rift fault activities are widely distributed, especially in Baiyun sag, one of the largest deepwater sag with its main body located beneath present continental slope. During the post-rift stage, large population of faults kept active for a long time from 32 Ma (T70) till 5.5 Ma (T10). Seismic interpretation, fault analysis and analogue modeling experiments indicate that the post-rift fault activities in Baiyun sag between 32 Ma (T70) and 13.8 Ma (T30) was mainly controlled by gravity pointing to the Main Baiyun sag, which caused the faults extensive on the side facing Main Baiyun sag and the back side compressive. Around 32 Ma (T70), the breakup of the continental margin and the spreading of the South China Sea shed a combined effect of weak compression toward Baiyun sag. The gravity during post-rift stage might be caused by discrepant subsidence and sedimentation between strongly thinned sag center and wing areas. This is supported by positive relationship between sedimentation rate and fault growth index. After 13.8 Ma (T30), fault activity shows negative relationship with sedimentation rate. Compressive uplift and erosion in seismic profiles as well as negative tectonic subsiding rates suggest that the fault activity from 13.8 Ma (T30) to 5.5 Ma (T10) might be controlled by the subductive compression from the Philippine plate in the east.

Fault Activity in the Terrebonne Trough, Southeastern Louisiana: A Continuation of Salt-Withdrawal Fault Activity from the Miocene into the late Quaternary and Implication for Subsidence Hot-Spots

NASA Astrophysics Data System (ADS)

Akintomide, A. O.; Dawers, N. H.

2017-12-01

The observed displacement along faults in southeastern Louisiana has raised questions about the kinematic history of faults during the Quaternary. The Terrebonne Trough, a Miocene salt withdrawal basin, is bounded by the Golden Meadow fault zone on its northern boundary; north dipping, so-called counter-regional faults, together with a subsurface salt ridge, define its southern boundary. To date, there are relatively few published studies on fault architecture and kinematics in the onshore area of southeastern Louisiana. The only publically accessible studies, based on 2d seismic reflection profiles, interpreted faults as mainly striking east-west. Our interpretation of a 3-D seismic reflection volume, located in the northwestern Terrebonne Trough, as well as industry well log correlations define a more complex and highly-segmented fault architecture. The northwest striking Lake Boudreaux fault bounds a marsh on the upthrown block from Lake Boudreaux on the downthrown block. To the east, east-west striking faults are located at the Montegut marsh break and north of Isle de Jean Charles. Portions of the Lake Boudreaux and Isle de Jean Charles faults serve as the northern boundary of the Madison Bay subsidence hot-spot. All three major faults extend to the top of the 3d seismic volume, which is inferred to image latest Pleistocene stratigraphy. Well log correlation using 11+ shallow markers across these faults and kinematic techniques such as stratigraphic expansion indices indicate that all three faults were active in the middle(?) and late Pleistocene. Based on expansion indices, both the Montegut and Isle de Jean Charles faults were active simultaneously at various times, but with different slip rates. There are also time intervals when the Lake Boudreaux fault was slipping at a faster rate compared to the east-west striking faults. Smaller faults near the margins of the 3d volume appear to relate to nearby salt stocks, Bully Camp and Lake Barre. Our work to date suggests both salt and fault activity continued at least into the latest Pleistocene.

Optical chaos and hybrid WDM/TDM based large capacity quasi-distributed sensing network with real-time fiber fault monitoring.

PubMed

Luo, Yiyang; Xia, Li; Xu, Zhilin; Yu, Can; Sun, Qizhen; Li, Wei; Huang, Di; Liu, Deming

2015-02-09

An optical chaos and hybrid wavelength division multiplexing/time division multiplexing (WDM/TDM) based large capacity quasi-distributed sensing network with real-time fiber fault monitoring is proposed. Chirped fiber Bragg grating (CFBG) intensity demodulation is adopted to improve the dynamic range of the measurements. Compared with the traditional sensing interrogation methods in time, radio frequency and optical wavelength domains, the measurand sensing and the precise locating of the proposed sensing network can be simultaneously interrogated by the relative amplitude change (RAC) and the time delay of the correlation peak in the cross-correlation spectrum. Assisted with the WDM/TDM technology, hundreds of sensing units could be potentially multiplexed in the multiple sensing fiber lines. Based on the proof-of-concept experiment for axial strain measurement with three sensing fiber lines, the strain sensitivity up to 0.14% RAC/με and the precise locating of the sensors are achieved. Significantly, real-time fiber fault monitoring in the three sensing fiber lines is also implemented with a spatial resolution of 2.8 cm.

Shear concentration in a collision zone: kinematics of the Chihshang Fault as revealed by outcrop-scale quantification of active faulting, Longitudinal Valley, eastern Taiwan

NASA Astrophysics Data System (ADS)

Angelier, J.; Chu, H.-T.; Lee, J.-C.

1997-06-01

Repeated measurements of active deformation were carried out at three sites along the active Chihshang Fault, a segment of the Longitudinal Valley Fault zone of eastern Taiwan (the present-day plate boundary between the Philippine Sea Plate and Eurasia). Reliable annual records of displacement along an active fault, were obtained based on detailed surveys of faulted concrete structures. Along the active Chihshang Fault striking N18°E, we determined average motion vectors trending N37°W with an average shortening of 2.2 cm/yr. Thus, the transverse component of motion related to westward thrusting is 1.8 cm/yr, whereas the left-lateral strike-slip component of motion is 1.3 cm/yr. The fault dips 39-45° to the east, so that the vertical displacement is 1.5-3 cm/yr and the actual oblique offset of the fault increases at a rate of 2.7-3.7 cm/yr. This is in good agreement with the results of regional geodetic and tectonic analyses in Taiwan, and consistent with the N54°W trend of convergence between the northernmost Luzon Arc and South China revealed by GPS studies. Our study provides an example of extreme shear concentration in an oblique collision zone. At Chihshang, the whole horizontal shortening of the Longitudinal Valley Fault, 2.2 cm/yr on average, occurs across a single, narrow fault zone, so that the whole reverse slip (about 2.7-3.7 cm/yr depending on fault dip) was entirely recorded by walls 20-200 m long where faults are tightly localized. This active faulting accounts for more than one fourth (27%) of the total shortening between the Luzon Arc and South China recorded through GPS analyses. Further surveys should indicate whether the decreasing shortening velocity across the fault is significant (revealing increasing earthquake risk due to stress accumulation) or not (revealing continuing fault creep and 'weak' behaviour of the Chihshang Fault).

The San Andreas Fault and a Strike-slip Fault on Europa

NASA Technical Reports Server (NTRS)

1998-01-01

The mosaic on the right of the south polar region of Jupiter's moon Europa shows the northern 290 kilometers (180 miles) of a strike-slip fault named Astypalaea Linea. The entire fault is about 810 kilometers (500 miles) long, the size of the California portion of the San Andreas fault on Earth which runs from the California-Mexico border north to the San Francisco Bay.

The left mosaic shows the portion of the San Andreas fault near California's san Francisco Bay that has been scaled to the same size and resolution as the Europa image. Each covers an area approximately 170 by 193 kilometers(105 by 120 miles). The red line marks the once active central crack of the Europan fault (right) and the line of the San Andreas fault (left).

A strike-slip fault is one in which two crustal blocks move horizontally past one another, similar to two opposing lanes of traffic. The overall motion along the Europan fault seems to have followed a continuous narrow crack along the entire length of the feature, with a path resembling stepson a staircase crossing zones which have been pulled apart. The images show that about 50 kilometers (30 miles) of displacement have taken place along the fault. Opposite sides of the fault can be reconstructed like a puzzle, matching the shape of the sides as well as older individual cracks and ridges that had been broken by its movements.

Bends in the Europan fault have allowed the surface to be pulled apart. This pulling-apart along the fault's bends created openings through which warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean, could reach the surface. This upwelling of material formed large areas of new ice within the boundaries of the original fault. A similar pulling apart phenomenon can be observed in the geological trough surrounding California's Salton Sea, and in Death Valley and the Dead Sea. In those cases, the pulled apart regions can include upwelled materials, but may be filled in mostly by sedimentary and erosional material deposited from above. Comparisons between faults on Europa and Earth may generate ideas useful in the study of terrestrial faulting.

One theory is that fault motion on Europa is induced by the pull of variable daily tides generated by Jupiter's gravitational tug on Europa. The tidal tension opens the fault; subsequent tidal stress causes it to move lengthwise in one direction. Then the tidal forces close the fault up again. This prevents the area from moving back to its original position. If it moves forward with the next daily tidal cycle, the result is a steady accumulation of these lengthwise offset motions.

Unlike Europa, here on Earth, large strike-slip faults such as the San Andreas are set in motion not by tidal pull, but by plate tectonic forces from the planet's mantle.

North is to the top of the picture. The Earth picture (left) shows a LandSat Thematic Mapper image acquired in the infrared (1.55 to 1.75 micrometers) by LandSat5 on Friday, October 20th 1989 at 10:21 am. The original resolution was 28.5 meters per picture element.

The Europa picture (right)is centered at 66 degrees south latitude and 195 degrees west longitude. The highest resolution frames, obtained at 40 meters per picture element with a spacecraft range of less than 4200 kilometers (2600 miles), are set in the context of lower resolution regional frames obtained at 200 meters per picture element and a range of 22,000 kilometers (13,600 miles). The images were taken on September 26, 1998 by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL HTTP://www.jpl.nasa.gov/galileo/sepo

Automatic recloser circuit breaker integrated with GSM technology for power system notification

NASA Astrophysics Data System (ADS)

Lada, M. Y.; Khiar, M. S. A.; Ghani, S. A.; Nawawi, M. R. M.; Rahim, N. H.; Sinar, L. O. M.

2015-05-01

Lightning is one type of transient faults that usually cause the circuit breaker in the distribution board trip due to overload current detection. The instant tripping condition in the circuit breakers clears the fault in the system. Unfortunately most circuit breakers system is manually operated. The power line will be effectively re-energized after the clearing fault process is finished. Auto-reclose circuit is used on the transmission line to carry out the duty of supplying quality electrical power to customers. In this project, an automatic reclose circuit breaker for low voltage usage is designed. The product description is the Auto Reclose Circuit Breaker (ARCB) will trip if the current sensor detects high current which exceeds the rated current for the miniature circuit breaker (MCB) used. Then the fault condition will be cleared automatically and return the power line to normal condition. The Global System for Mobile Communication (GSM) system will send SMS to the person in charge if the tripping occurs. If the over current occurs in three times, the system will fully trip (open circuit) and at the same time will send an SMS to the person in charge. In this project a 1 A is set as the rated current and any current exceeding a 1 A will cause the system to trip or interrupted. This system also provides an additional notification for user such as the emergency light and warning system.

Structural analysis of the Valence basin (SE France) based on kriging and borehole data: implications for hercynian fault zone behaviour in geothermic reservoirs.

NASA Astrophysics Data System (ADS)

Chabani, Arezki; Mehl, Caroline; Bruel, Dominique; Cojan, Isabelle

2017-04-01

The Valence basin is a 130 km-long and 60 km-wide Tertiary sub-basin situated north to the SE basin of France, in the central part of the European Cenozoic RIft System (ECRIS). That structural key position in a naturally fractured hostrock associated with a favorable thermal regime make that basin a good target for geothermal exploitation in France. The structure and kinematics of the Valence basin is controlled by a several kilometer-scale hercynian fault system that may have a strong influence on fluid flows and thermal anomalies within the basin. This study aimed to constrain the geometry of deposits and the way they fracture regards to the major faults, to determine their diagenetic evolution and to characterize the hydraulic behavior of the major faults. We thus performed a structural model of the basin and analyzed the Montoison borehole. Kriging on data pointed on 348 boreholes from BSS, synthetic boreholes calculated from two seismic lines and isohypses from existing models allowed modeling the geometry of basement and the ceno-mesozoic unconformity. Basement is structured by two pluri-kilometer long fault corridors striking N/S to NE/SW. The central extends laterally on around 1 kilometer and has been identified as a segment of the Cevennes fault. The maximum depth of the basement is around 6000 m and is situated between the two corridors. Interpretations on seismic lines highlight a westward migration of Cenozoic depocenters within time. A structural analysis of the Montoison borehole confirms it is affected by a major fault interpreted as the Cevennes fault. Fault zone cuts across the Keuper and is characterized by an heterometric breccia within marly layers. The entire sedimentary pile recorded 2 sets of fractures: perpendicular and parallel to the borehole axis. Both sets are recrystallized. Nature of recrystallization (quartz, calcite and dolomite) strongly depends on the hostrock. An important thread of barite is located under the fault zone, putting forward the potential role of drain of that fault in the fluid flows across the basin.

An overview of results from the CO2SINK 3D baseline seismic survey at Ketzin, Germany

NASA Astrophysics Data System (ADS)

Juhlin, C.; Giese, R.; Cosma, C.; Kazemeini, H.; Juhojuntti, N.; Lüth, S.; Norden, B.; Förster, A.; Yordkayhun, S.

2009-04-01

A 3D seismic survey was acquired at the CO2SINK project site over the Ketzin anticline in the fall of 2005. Main objectives of the survey were (1) to verify earlier geological interpretations of the structure based on vintage 2D seismic and borehole data, (2) to provide, if possible, an understanding of the structural geometry for flow pathways within the reservoir, (3) a baseline for later evaluation of the time evolution of rock properties as CO2 is injected into the reservoir, and (4) detailed sub-surface images near the injection borehole for planning of the drilling operations. Overlapping templates with 5 receiver lines containing 48 active channels in each template were used for the acquisition. In each template, 200 nominal source points were activated using an accelerated weight drop, giving a nominal fold of 25. Due to logistics, the number of actual source points in each template varied. In spite of the relatively low fold and the simple source used, data quality is generally good with the uppermost 1000 m being well imaged. Data processing results clearly show a fault system across the top of the Ketzin anticline that is termed the Central Graben Fault Zone (CGFZ). The fault zone consists of west-southwest-east-northeast- to east-west-trending normal faults bounding a 600-800 m wide graben. Within the Jurassic section, discrete faults are well developed, and the main graben-bounding faults have throws of up to 30 m. At shallower levels, the fault system appears to disappear in the Tertiary Rupelian clay. The main bounding faults of the CGFZ can be traced downwards to the top of the Weser Formation and possibly to the Stuttgart level, the target formation for CO2 injection. No faults were imaged near the injection site on the southern limb of the anticline. Remnant gas, cushion and residual gas from a previous natural gas storage facility at the site, is present near the top of the anticline in the depth interval of about 250-400 m and has a clear seismic signature. In addition to the standard processing and interpretation applied, attribute analysis, detailed shallow reflection seismic processing, tomographic inversion of first arrival times, and initial seismic modeling of the CO2 response have been performed. Attribute analysis of the target horizon using the continuous wavelet transform indicates that the injection site penetrates the target reservoir near the edge of a north-northwest-south-southeast striking channel.

[X-ray diffraction and infrared spectrum analysis of fault gouge in Wenchuan seismic belt].

PubMed

Wang, Zheng-Yang; Cao, Jian-Jin; Luo, Song-Ying; Liao, Yi-Peng

2014-05-01

Wenchuan earthquake produced a series of co-seismic surface ruptures in Leigu and Zhaojiagou, and we collected samples of co-seismic fault gouge in the surface ruptures as well as the old gouge in the fault of Nanba. Testing The new and old fault gouge was tested with X-ray diffraction and infrared absorption spectra, and its characteristics such as mineral compositions, clay mineral contents and combinations were comprehensively analyzed. The results display obvious differences between the new and old fault gouge, showing that the old fault gouge is mainly composed of wall rock debris or milled powders, while the main components of new fault gouge are clay minerals. The assemblage of clay minerals composition shows that the environment of the fault activity was mainly warm and humid, and the clay minerals were mainly transformed by low temperature and low pressure dynamic metamorphism. And this also partly indicates that the latest way of the fault activity in this area may be a creeping. However the previous researches on the fault gouge of Wenchuan earthquake fault zone are mainly focused on its mechanical properties as well as its texture and structure, the research in this paper is to determine the physical and chemical environment of fault activity through the mineral compositions and clay mineral contents in the fault gouge characteristics, and this research has important scientific significance to the researches on the evolution of the fault environment and the activity mechanism of the earthquake.

New constraints on slip-rates, recurrence intervals, and strain partitioning beneath Pyramid Lake, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eisses, Amy

A high-resolution CHIRP seismic survey of Pyramid Lake, Nevada, located within the northern Walker Lane Deformation Belt, was conducted in summer 2010. Seismic CHIRP data with submeter vertical accuracy, together with piston and gravity cores, were used to calculate Holocene vertical slip rates, relative earthquake timing, and produce the first complete fault map beneath the lake. More than 500 line-kilometers of CHIRP data imaged complex fault patterns throughout the basin. Fault architecture beneath Pyramid Lake highlights a polarity flip, where down-to-the west patterns of sedimentation near the dextral Pyramid Lake fault to the south give way to down-to-the-east geometries tomore » the north within a mostly normal (i.e., Lake Range fault) and transtensional environment. The Lake Range fault predominantly controls extensional deformation within the northern two-thirds of the basin and exhibits varying degrees of asymmetric tilting and divergence due to along-strike segmentation. This observation is likely a combination of fault segments splaying onshore moving the focus of extension away from the lake coupled with some true along-strike differences in slip-rate. The combination of normal and oblique-slip faults in the northern basin gives Pyramid Lake its distinctive “fanning open to the north” tectonic geometry. The dense network of oblique-slip faults in the northwestern region of the lake, in contrast to the well-defined Lake Range fault, are short and discontinuous in nature, and possible represent a nascent shear zone. Preliminary vertical slip-rates measured across the Lake Range and other faults provide new estimates on the extension across the Pyramid Lake basin. A minimum vertical slip rate of ~1.0 mm/yr is estimated along the Lake Range fault, which yields a potential earthquake magnitude range between M6.4 and M7.0. A rapid influx of sediment was deposited shortly after the end of the Tioga glaciation somewhere between 12.5 ka to 9.5 ka and provides a punctuated short-term record of little to no slip on the Lake Range fault. In contrast, for the past 9,500 years, the basin has experienced a decrease in sedimentation rate, but an escalation in earthquake activity on the Lake Range fault, with the potential of 3 or 4 major earthquakes assuming a characteristic offset of 2.5 m per event. Regionally, our CHIRP investigation helps to reveal how strain is partitioned along the boundary between the eastern edge of the Walker Lane Deformation Belt and the northwest Great Basin proper.« less

Crustal Structure of Northern Grenada Basin Call into Question the Origin of Arc Migration in the Lesser Antilles: Preliminary Results from GARANTI Cruise

NASA Astrophysics Data System (ADS)

Jean-Frederic, L.; Lallemand, S.; Marcaillou, B.; Klingelhoefer, F.; Agranier, A.; Arcay, D.; Audemard, F. A.; Bassetti, M. A.; Beslier, M. O.; Boucard, M.; Cornée, J. J.; Fabre, M.; Gay, A.; Graindorge, D.; Heuret, A.; Laigle, M.; Léticée, J. L.; Malengros, D.; Mercier de Lepinay, B.; Morena, P.; Münch, P.; Oliot, E.; Oregioni, D.; Padron, C.; Philippon, M. M.; Quillevere, F.; Ratzov, G.; Schenini, L.; Yates, B.; Zami, F.

2017-12-01

The Grenada Basin, a crescent-shape basin forming a back-arc relative to the Lesser Antilles arc, separate Aves Ridge, a remnant early paleogene arc, from Eocene-Oligocene and Late Miocene - actual Lesser Antilles arcs. In its northern part the shallowness and rough topography of the basin basement call into questioned the relevance of opening of a back arc basin for the northern Grenada Basin. During the GARANTI survey (May-June 2017 french R/V L'Atalante), we acquired two transversal (EW) and one basin parallel (NS), ca. 300km long, combined wide-angle seismic (WAS) and multichannel seismic reflection (MCS) lines, plus ca. 3500km of MCS together with multibeam bathymetric data and dredged 14 sites across Grenada basin. Part of these profiles are located in the northern Grenada Basin, north and south of Saba Bank carbonate plateform. South of Saba Bank, the existence of buried crustal faults extending across Aves Ridge and the basin suggest continuity of inherited structures between the two domains. Preliminary modeling of the WAS data along the northern line shows an about 35km thick crust across the Lesser Antilles arc and in the Grenada basin at that latitude, suggesting no or only little extension in the back arc. Along the western side of Saba Bank the north trending Aves Ridge is cut at low angle by steeply dipping reverse faults that vanish southward. North of Saba Bank our data merged with seismic profiles from the AntiTheSis project reveal transpressive deformation south of the Anegada passage, trending N40° to N110° extending toward the Lesser Antilles Eo-Oligocene outer-arc. Only few N90° trending faults extend toward the active arc. These faults trend at high angle with N140-160° intra-arc fault system observed further south. Dredge samples from transpressive ridges west of the outer arc provided mix arc volcanic rocks in foraminifers rich carbonate limestones of possibly mid-Cenozoic age. Our new data call into question the mechanisms that led to arc migration in the Lesser Antilles during mid Cenozoic.

Geophysical reassessment of the role of ancient crustal structures on the development of western Laurentia and Selwyn Basin, Yukon and Northwest Territories, Canada.

NASA Astrophysics Data System (ADS)

Hayward, N.

2017-12-01

The structure of the western margin of the North American craton (Laurentia) in the northern Canadian Cordillera and its role in the development of the Neoproterozoic-Early Paleozoic Selwyn Basin are reassessed through 3D inversion of a new compilation of aeromagnetic data and archival Bouguer gravity data. The region's tectonic history is obscured by partial burial beneath Selwyn Basin, and a tectonic overprint that includes terrane accretion, regional plutonism, and strike-slip faults with displacements of 100s and perhaps 1000s of kilometers. Despite the implied complexity, preliminary geological and geophysical based interpretations of the structure of the western margin of Laurentia, have been adopted with few refinements in over two decades. Regionally continuous, NE-trending, crustal lineaments, including the Fort Norman line and Leith Ridge fault, were interpreted as having had long-standing influence on the craton development, its western margin, and overlapping sedimentary basin. New results reveal limited evidence for the regional continuity of the NE-trending lineaments. Instead, models suggest that the structure of the Laurentian margin is characterised by segmentation on numerous shorter structures of varied strike. The western margin of the craton and its structures are bound by a NW-trending structure that connects with the Richardson Trough to the north and may have been active during rifting of the Misty Creek embayment. This boundary also marks the easternmost limit of both granitic intrusions in Selwyn Basin, which gravity models suggest are of greater extent than reflected on geological maps, and SEDEX occurrences. An ENE-trending structure beneath northern Selwyn Basin is interpreted as marking the southern edge of a previously unidentified cratonic promontory, akin to the Liard line that marks a transfer fault that bounds the promontory of the Macdonald Platform, south of Selwyn Basin. The ENE-trending structure is traced from the Tintina fault in the west to near to the Great Bear magmatic zone. The structure's regional continuity also limits the interpretation of a post-Cretaceous structure, inboard of the Tintina fault that could be responsible for 1000's km of dextral strike-slip ascribed to the Baja-BC terrane translation model.

Active Fault Near-Source Zones Within and Bordering the State of California for the 1997 Uniform Building Code

USGS Publications Warehouse

Petersen, M.D.; Toppozada, Tousson R.; Cao, T.; Cramer, C.H.; Reichle, M.S.; Bryant, W.A.

2000-01-01

The fault sources in the Project 97 probabilistic seismic hazard maps for the state of California were used to construct maps for defining near-source seismic coefficients, Na and Nv, incorporated in the 1997 Uniform Building Code (ICBO 1997). The near-source factors are based on the distance from a known active fault that is classified as either Type A or Type B. To determine the near-source factor, four pieces of geologic information are required: (1) recognizing a fault and determining whether or not the fault has been active during the Holocene, (2) identifying the location of the fault at or beneath the ground surface, (3) estimating the slip rate of the fault, and (4) estimating the maximum earthquake magnitude for each fault segment. This paper describes the information used to produce the fault classifications and distances.

Active fault databases: building a bridge between earthquake geologists and seismic hazard practitioners, the case of the QAFI v.3 database

NASA Astrophysics Data System (ADS)

García-Mayordomo, Julián; Martín-Banda, Raquel; Insua-Arévalo, Juan M.; Álvarez-Gómez, José A.; Martínez-Díaz, José J.; Cabral, João

2017-08-01

Active fault databases are a very powerful and useful tool in seismic hazard assessment, particularly when singular faults are considered seismogenic sources. Active fault databases are also a very relevant source of information for earth scientists, earthquake engineers and even teachers or journalists. Hence, active fault databases should be updated and thoroughly reviewed on a regular basis in order to keep a standard quality and uniformed criteria. Desirably, active fault databases should somehow indicate the quality of the geological data and, particularly, the reliability attributed to crucial fault-seismic parameters, such as maximum magnitude and recurrence interval. In this paper we explain how we tackled these issues during the process of updating and reviewing the Quaternary Active Fault Database of Iberia (QAFI) to its current version 3. We devote particular attention to describing the scheme devised for classifying the quality and representativeness of the geological evidence of Quaternary activity and the accuracy of the slip rate estimation in the database. Subsequently, we use this information as input for a straightforward rating of the level of reliability of maximum magnitude and recurrence interval fault seismic parameters. We conclude that QAFI v.3 is a much better database than version 2 either for proper use in seismic hazard applications or as an informative source for non-specialized users. However, we already envision new improvements for a future update.

Mechanical fault detection of electric motors by laser vibrometer and accelerometer measurements

NASA Astrophysics Data System (ADS)

Cristalli, C.; Paone, N.; Rodríguez, R. M.

2006-08-01

This paper presents a comparative study between accelerometer and laser vibrometer measurements aimed at on-line quality control carried out on the universal motors used in washing machines, which exhibit defects localised mainly in the bearings, including faults in the cage, in the rolling element and in the outer and inner ring. A set of no defective and defective motors were analysed by means of the acceleration signal provided by the accelerometer, and the displacement and velocity signals given by a single-point laser vibrometer. Advantages and disadvantages of both absolute and relative sensors and of contact and non-contact instrumentation are discussed taking into account the applicability to real on-line quality control measurements and bringing to light the related measurement problems due to the specific environmental conditions of assembly lines and sensor installation constraints. The performance of different signal-processing algorithms is discussed: RMS computation at steady-state proves effective for pass or fail diagnosis, while the amplitude of selected frequencies in the averaged spectra allows also for classification of a variety of special faults in bearings. Joint time-frequency analysis output data can be successfully used for pass or fail diagnosis during transients, thus achieving a remarkable reduction in testing time, which is important for on-line diagnostics.

3-D GPR data analysis for high-resolution imaging of shallow subsurface faults: the Mt Vettore case study (Central Apennines, Italy)

NASA Astrophysics Data System (ADS)

Ercoli, Maurizio; Pauselli, Cristina; Frigeri, Alessandro; Forte, Emanuele; Federico, Costanzo

2014-07-01

The activation of Late Quaternary faults in the Central Apennines (Italy) could generate earthquakes with magnitude of about 6.5, and the Monte Vettore fault system probably belongs to the same category of seismogenetic faults. Such structure has been defined `silent', because of its geological and geomorphological evidences of past activation, but the absence of historical records in the seismic catalogues to be associated with its activation. The `Piano di Castelluccio' intramountain basin, resulting from the Quaternary activity of normal faults, is characterized by a secondary fault strand highlighted by a NW-SE fault scarp: it has been already studied through palaeoseismological trenches, which highlighted evidences of Quaternary shallow faulting due to strong earthquakes, and through a 2-D ground penetrating radar (GPR) survey, showing the first geophysical signature of faulting for this site. Within the same place, a 3-D GPR volume over a 20 × 20 m area has been collected. The collection of radar echoes in three dimensions allows to map both the vertical and lateral continuity of shallow geometries of the fault zone (Fz), imaging features with high resolution, ranging from few metres to centimetres and therefore imaging also local variations at the microscale. Several geophysical markers of faulting, already highlighted on this site, have been taken as reference to plan the 3-D survey. In this paper, we provide the first 3-D subsurface imaging of an active shallow fault belonging to the Umbria-Marche Apennine highlighting the subsurface fault geometry and the stratigraphic sequence up to a depth of about 5 m. From our data, geophysical faulting signatures are clearly visible in three dimensions: diffraction hyperbolas, truncations of layers, local attenuated zones and varying dip of the layers have been detected within the Fz. The interpretation of the 3-D data set provided qualitative and quantitative geological information in addition to the fault location, like its geometry, boundaries and an estimation of the fault throw.

Up-dip partitioning of displacement components on the oblique-slip Clarence Fault, New Zealand

NASA Astrophysics Data System (ADS)

Nicol, Andrew; Van Dissen, Russell

2002-09-01

Active strike-slip faults in New Zealand occur within an obliquely-convergent plate boundary zone. Although the traces of these faults commonly delineate the base of mountain ranges, they do not always accommodate significant shortening at the free surface. Along the active trace of Clarence Fault in northeastern South Island, New Zealand, displaced landforms and slickenside striations indicate predominantly horizontal displacements at the ground surface, and a right-lateral slip rate of ca. 3.5-5 mm/year during the Holocene. The Inland Kaikoura mountain range occupies the hanging wall of the fault and rises steeply from the active trace to altitudes of ca. 3 km. The geomorphology of the range indicates active uplift and mountain building, which is interpreted to result, in part, from a vertical component of fault slip at depth. These data are consistent with the fault accommodating oblique-slip at depth aligned parallel to the plate-motion vector and compatible with regional geodetic data and earthquake focal-mechanisms. Oblique-slip on the Clarence Fault at depth is partitioned at the free surface into: (1) right-lateral displacement on the fault, and (2) hanging wall uplift produced by distributed displacement on small-scale faults parallel to the main fault. Decoupling of slip components reflects an up-dip transfer of fault throw to an off-fault zone of distributed uplift. Such zones are common in the hanging walls of thrusts and reverse faults, and support the idea that the dip of the oblique-slip Clarence Fault steepens towards the free surface.

Interpretation of shallow crustal structure of the Imperial Valley, California, from seismic reflection profiles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Severson, L.K.

1987-05-01

Eight seismic reflection profiles (285 km total length) from the Imperial Valley, California, were provided to CALCRUST for reprocessing and interpretation. Two profiles were located along the western margin of the valley, five profiles were situated along the eastern margin and one traversed the deepest portion of the basin. These data reveal that the central basin contains a wedge of highly faulted sediments that thins to the east. Most of the faulting is strike-slip but there is evidence for block rotations on the scale of 5 to 10 kilometers within the Brawley Seismic Zone. These lines provide insight into themore » nature of the east and west edges of the Imperial Valley. The basement at the northwestern margin of the valley, to the north of the Superstition Hills, has been normal-faulted and blocks of basement material have ''calved'' into the trough. A blanket of sediments has been deposited on this margin. To the south of the Superstition Hills and Superstition Mountain, the top of the basement is a detachment surface that dips gently into the basin. This margin is also covered by a thick sequence sediments. The basement of the eastern margin consists of metamorphic rocks of the upper plate of the Chocolate Mountain Thrust system underlain by the Orocopia Schist. These rocks dip to the southeast and extend westward to the Sand Hills Fault but do not appear to cross it. Thus, the Sand Hills Fault is interpreted to be the southern extension of the San Andreas Fault. North of the Sand Hills Fault the East Highline Canal seismicity lineament is associated with a strike-slip fault and is probably linked to the Sand Hills Fault. Six geothermal areas crossed by these lines, in agreement with previous studies of geothermal reservoirs, are associated with ''faded'' zones, Bouguer gravity and heat flow maxima, and with higher seismic velocities than surrounding terranes.« less

Ground-Penatrating Radar Investigations Across the Sawmill Branch Fault Near Charleston, South Carolina

NASA Astrophysics Data System (ADS)

Dura-Gomez, I.; Addison, A.; Knapp, C. C.; Talwani, P.; Chapman, A.

2005-12-01

During the 1886 Charleston earthquake, two parallel tabby walls of Fort Dorchester broke left-laterally, and a strike of ~N25°W was inferred for the causative Sawmill Branch fault. To better define this fault, which does not have any surface expression, we planned to cut trenches across it. However, as Fort Dorchester is a protected archeological site, we were required to locate the fault accurately away from the fort, before permission could be obtained to cut short trenches. The present GPR investigations were planned as a preliminary step to determine locations for trenching. A pulseEKKO 100 GPR was used to collect data along eight profiles (varying in length from 10 m to 30 m) that were run across the projected strike of the fault, and one 50 m long profile that was run parallel to it. The locations of the profiles were obtained using a total station. To capture the signature of the fault, sixteen common-offset (COS) lines were acquired by using different antennas (50, 100 and 200 MHz) and stacking 64 times to increase the signal-to-noise ratio. The location of trees and stumps were recorded. In addition, two common-midpoint (CMP) tests were carried out, and gave an average velocity of about 0.097 m/ns. Processing included the subtraction of the low frequency "wow" on the trace (dewow), automatic gain control (AGC) and the application of bandpass filters. The signals using the 50 MHz, 100 MHz and 200 MHz antennas were found to penetrate up to about 30 meters, 20 meters and 12 meters respectively. Vertically offset reflectors and disruptions of the electrical signal were used to infer the location of the fault(s). Comparisons of the locations of these disruptions on various lines were used to infer the presence of a N30°W fault zone We plan to confirm these locations by cutting shallow trenches.

InSAR and GPS derived coseismic deformation and fault model of the 2017 Ms7.0 Jiuzhaigou earthquake in the Northeast Bayanhar block

NASA Astrophysics Data System (ADS)

Zhao, Dezheng; Qu, Chunyan; Shan, Xinjian; Gong, Wenyu; Zhang, Yingfeng; Zhang, Guohong

2018-02-01

On 8 August 2017, a Ms7.0 earthquake stroke the city of Jiuzhaigou, Sichuan, China. The Jiuzhaigou earthquake occurred on a buried fault in the vicinity of three well-known active faults and this event offers a unique opportunity to study tectonic structures in the epicentral region and stress transferring. Here we present coseismic displacement field maps for this earthquake using descending and ascending Sentinel-1A Interferometric Synthetic Aperture Radar (InSAR) data. Deformation covered an area of approximately 50 × 50 km, with a maximum line-of-sight (LOS) displacement of 22 cm in ascending and 14 cm in descending observations on the west side of the source fault. Based on InSAR and Global Positioning System (GPS) measurements, both separately and jointly, we constructed a one-segment model to invert the coseismic slip distribution and dip angle of this event. Our final fault slip model suggests that slip was concentrated at an upper depth of 15 km; there was a maximum slip of 1.3 m and the rupture was dominated by a left-lateral strike-slip motion. The inverted geodetic moment was approximately 6.75 × 1018 Nm, corresponding to a moment magnitude of Mw6.5, consistent with seismological results. The calculated static Coulomb stress changes indicate that most aftershocks occurred in stress increasing zones caused by the mainshock rupture; the Jiuzhaigou earthquake has brought the western part of the Tazang fault 0.1-0.4 MPa closer to failure, indicating an increasing seismic hazard in this region. The Coulomb stress changes caused by the 2008 Mw7.8 Wenchuan earthquake suggest that stress loading from this event acted as a trigger for the Jiuzhaigou earthquake.

Volcanoes, Central Java, Indonesia

NASA Technical Reports Server (NTRS)

1992-01-01

The island of Java (8.0S, 112.0E), perhaps better than any other, illustrates the volcanic origin of Pacific Island groups. Seen in this single view are at least a dozen once active volcano craters. Alignment of the craters even defines the linear fault line of Java as well as the other some 1500 islands of the Indonesian Archipelago. Deep blue water of the Indian Ocean to the south contrasts to the sediment laden waters of the Java Sea to the north.

Volcanoes, Central Java, Indonesia

NASA Image and Video Library

1992-08-08

The island of Java (8.0S, 112.0E), perhaps better than any other, illustrates the volcanic origin of Pacific Island groups. Seen in this single view are at least a dozen once active volcano craters. Alignment of the craters even defines the linear fault line of Java as well as the other some 1500 islands of the Indonesian Archipelago. Deep blue water of the Indian Ocean to the south contrasts to the sediment laden waters of the Java Sea to the north.

Preservation of amorphous ultrafine material: A proposed proxy for slip during recent earthquakes on active faults

NASA Astrophysics Data System (ADS)

Hirono, Tetsuro; Asayama, Satoru; Kaneki, Shunya; Ito, Akihiro

2016-11-01

The criteria for designating an “Active Fault” not only are important for understanding regional tectonics, but also are a paramount issue for assessing the earthquake risk of faults that are near important structures such as nuclear power plants. Here we propose a proxy, based on the preservation of amorphous ultrafine particles, to assess fault activity within the last millennium. X-ray diffraction data and electron microscope observations of samples from an active fault demonstrated the preservation of large amounts of amorphous ultrafine particles in two slip zones that last ruptured in 1596 and 1999, respectively. A chemical kinetic evaluation of the dissolution process indicated that such particles could survive for centuries, which is consistent with the observations. Thus, preservation of amorphous ultrafine particles in a fault may be valuable for assessing the fault’s latest activity, aiding efforts to evaluate faults that may damage critical facilities in tectonically active zones.

Along-strike variations of geometry and kinematics on the border fault of Nanpu sag, Bohai Bay Basin

NASA Astrophysics Data System (ADS)

Zhang, C.; Ren, J.; Liu, X.; Sun, Z.; Su, M.

2010-12-01

Nanpu sag is located in the north-eastern portion of the Huanghua depression, covering an area of approximately 1900km2, and comprises one of the most important petroliferous basins of the Bohai Bay Basin. The Nanpu sag is bordered by two master faults with long-term activity: the Xi’nanzhuang (XNZ) and Bogezhuang (BGZ) fault. By analysis of horizontal slices, gravity anomaly map and seismic reflection sections, we found there is no cutting relationship, and thus considered the XNZ and BGZ fault as a same one. However it showed striking differences between the XNZ and BGZ segment in fault occurrence, fault throw and residual formation thickness and so on. The BGZ fault was NW trending fault with a steep inclination. Taken section across the northern region in Nanpu sag for example, its controlling depocenter is located in eastern subsag (Fig.1); the XNZ fault was a NE fault and displayed a Shovel-shaped to plate-like geometry, with its controlling depocenter located in western subsag. We qualitify the fault throw, showing that the XNZ fault strongly acted during the sedimentary period of Es3-Es2, while the BGZ fault presented weak activity, and especially during Es31 submember-Es2 member, the XNZ fault acted so strongly that the hanging wall of BGZ fault was tilt-lifted and suffered erosion (Fig.1), which created Es1 uncomformity; The BGZ fault acted strongly during the sedimentary period of Es1-Ed, which led the hanging wall of XNZ fault to be tilt-lifted. Controlled by such segmented activity of the whole border fault, which we suggested a "seesaw" model for its evolution, the northern part in the Nanpu sag experienced an alternative variation between a deposition center and an erosion region after tilt-lifting. Combination of the sediment stacking patterns, we further classified the history of "seesaw" activities into four stages: 1) Early double-break stage (Es35-Es31), both of the XNZ and BGZ fault acted; 2) Middle the XNZ segment throw and the BGZ tilting (Es2); 3) Late the XNZ segment tilting and BGZ throw (Es1-Ed3); 4) End weak double-break stage (Ed2-Present), the whole fault acted weakly and were superposed by neotectonic movement. Fig.1 Seesaw activity of the whole border fault

Deformation from the 1989 Loma Prieta earthquake near the southwest margin of the Santa Clara Valley, California

USGS Publications Warehouse

Schmidt, Kevin M.; Ellen, Stephen D.; Peterson, David M.

2014-01-01

To gain additional measurement of any permanent ground deformation that accompanied this damage, we compiled and conducted post-earthquake surveys along two 5-km lines of horizontal control and a 15-km level line. Measurements of horizontal distortion indicate approximately 0.1 m shortening in a NE-SW direction across the valley margin, similar to the amount measured in the channel lining. Evaluation of precise leveling by the National Geodetic Survey showed a downwarp, with an amplitude of >0.1 m over a span of >12 km, that resembled regional geodetic models of coseismic deformation. Although the leveling indicates broad, regional warping, abrupt discontinuities characteristic of faulting characterize both the broad-scale distribution of damage and the local deformation of the channel lining. Reverse movement largely along preexisting faults and probably enhanced significantly by warping combined with enhanced ground shaking, produced the documented coseismic ground deformation.

Gently dipping normal faults identified with Space Shuttle radar topography data in central Sulawesi, Indonesia, and some implications for fault mechanics

USGS Publications Warehouse

Spencer, J.E.

2011-01-01

Space-shuttle radar topography data from central Sulawesi, Indonesia, reveal two corrugated, domal landforms, covering hundreds to thousands of square kilometers, that are bounded to the north by an abrupt transition to typical hilly to mountainous topography. These domal landforms are readily interpreted as metamorphic core complexes, an interpretation consistent with a single previous field study, and the abrupt northward transition in topographic style is interpreted as marking the trace of two extensional detachment faults that are active or were recently active. Fault dip, as determined by the slope of exhumed fault footwalls, ranges from 4?? to 18??. Application of critical-taper theory to fault dip and hanging-wall surface slope, and to similar data from several other active or recently active core complexes, suggests a theoretical limit of three degrees for detachment-fault dip. This result appears to conflict with the dearth of seismological evidence for slip on faults dipping less than ~. 30??. The convex-upward form of the gently dipping fault footwalls, however, allows for greater fault dip at depths of earthquake initiation and dominant energy release. Thus, there may be no conflict between seismological and mapping studies for this class of faults. ?? 2011 Elsevier B.V.

Geology Report: Area 3 Radioactive Waste Management Site DOE/Nevada Test Site, Nye County, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

NSTec Environmental Management

2006-07-01

Surficial geologic studies near the Area 3 Radioactive Waste Management Site (RWMS) were conducted as part of a site characterization program. Studies included evaluation of the potential for future volcanism and Area 3 fault activity that could impact waste disposal operations at the Area 3 RWMS. Future volcanic activity could lead to disruption of the Area 3 RWMS. Local and regional studies of volcanic risk indicate that major changes in regional volcanic activity within the next 1,000 years are not likely. Mapped basalts of Paiute Ridge, Nye Canyon, and nearby Scarp Canyon are Miocene in age. There is a lackmore » of evidence for post-Miocene volcanism in the subsurface of Yucca Flat, and the hazard of basaltic volcanism at the Area 3 RWMS, within the 1,000-year regulatory period, is very low and not a forseeable future event. Studies included a literature review and data analysis to evaluate unclassified published and unpublished information regarding the Area 3 and East Branch Area 3 faults mapped in Area 3 and southern Area 7. Two trenches were excavated along the Area 3 fault to search for evidence of near-surface movement prior to nuclear testing. Allostratigraphic units and fractures were mapped in Trenches ST02 and ST03. The Area 3 fault is a plane of weakness that has undergone strain resulting from stress imposed by natural events and underground nuclear testing. No major vertical displacement on the Area 3 fault since the Early Holocene, and probably since the Middle Pleistocene, can be demonstrated. The lack of major displacement within this time frame and minimal vertical extent of minor fractures suggest that waste disposal operations at the Area 3 RWMS will not be impacted substantially by the Area 3 fault, within the regulatory compliance period. A geomorphic surface map of Yucca Flat utilizes the recent geomorphology and soil characterization work done in adjacent northern Frenchman Flat. The approach taken was to adopt the map unit boundaries (line work) of Swadley and Hoover (1990) and re-label these with map unit designations like those in northern Frenchman Flat (Huckins-Gang et al, 1995a,b,c; Snyder et al, 1995a,b,c,d).« less

Earthquake disaster mitigation of Lembang Fault West Java with electromagnetic method

NASA Astrophysics Data System (ADS)

Widodo

2015-04-01

The Lembang fault is located around eight kilometers from Bandung City, West Java, Indonesia. The existence of this fault runs through densely populated settlement and tourism area. It is an active fault structure with increasing seismic activity where the 28 August 2011 earthquake occurred. The seismic response at the site is strongly influenced by local geological conditions. The ambient noise measurements from the western part of this fault give strong implication for a complex 3-D tectonic setting. Hence, near surface Electromagnetic (EM) measurements are carried out to understand the location of the local active fault of the research area. Hence, near surface EM measurements are carried out to understand the location of the local active fault and the top of the basement structure of the research area. The Transientelectromagnetic (TEM) measurements are carried out along three profiles, which include 35 TEM soundings. The results indicate that TEM data give detailed conductivity distribution of fault structure in the study area.

Earthquake disaster mitigation of Lembang Fault West Java with electromagnetic method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Widodo, E-mail: widodo@gf.itb.ac.id

The Lembang fault is located around eight kilometers from Bandung City, West Java, Indonesia. The existence of this fault runs through densely populated settlement and tourism area. It is an active fault structure with increasing seismic activity where the 28 August 2011 earthquake occurred. The seismic response at the site is strongly influenced by local geological conditions. The ambient noise measurements from the western part of this fault give strong implication for a complex 3-D tectonic setting. Hence, near surface Electromagnetic (EM) measurements are carried out to understand the location of the local active fault of the research area. Hence,more » near surface EM measurements are carried out to understand the location of the local active fault and the top of the basement structure of the research area. The Transientelectromagnetic (TEM) measurements are carried out along three profiles, which include 35 TEM soundings. The results indicate that TEM data give detailed conductivity distribution of fault structure in the study area.« less

Gravity and Magnetic Surveys Over the Santa Rita Fault System, Southeastern Arizona

USGS Publications Warehouse

Hegmann, Mary

2001-01-01

Gravity and magnetic surveys were performed in the northeast portion of the Santa Rita Experimental Range, in southeastern Arizona, to identify faults and gain a better understanding of the subsurface geology. A total of 234 gravity stations were established, and numerous magnetic data were collected with portable and truck-mounted proton precession magnetometers. In addition, one line of very low frequency electromagnetic data was collected together with magnetic data. Gravity anomalies are used to identify two normal faults that project northward toward a previously identified fault. The gravity data also confirm the location of a second previously interpreted normal fault. Interpretation of magnetic anomaly data indicates the presence of a higher-susceptibility sedimentary unit located beneath lowersusceptibility surficial sediments. Magnetic anomaly data identify a 1-km-wide negative anomaly east of these faults caused by an unknown source and reveal the high variability of susceptibility in the Tertiary intrusive rocks in the area.

Geometry and kinematics of the Triassic rift basin in Jameson Land (East Greenland)

NASA Astrophysics Data System (ADS)

Guarnieri, Pierpaolo; Brethes, Anaïs.; Rasmussen, Thorkild M.

2017-04-01

The Triassic rift basin along the east Greenland margin described in this paper is represented by NE-SW trending basins and highs segmented by NW-SE trending transfer zones. Coarse-grained sediments along the eastern side of Jameson Land are shown to be hosted in half-graben structures belonging to the Carlsberg Fjord Basin that is bounded by NW dipping normal faults mapped and described after fieldwork in the Klitdal area in Liverpool Land. New aeromagnetic and electromagnetic data together with new drill cores allow the reinterpretation of available seismic lines showing the continuation of the Triassic rift basin toward the SW where it is buried under the Upper Triassic postrift sediments and the Jurassic successions of the Jameson Land Basin. The N-S trending Liverpool Land, interpreted as the boundary block of the Triassic basin, is shown to represent a structural high inherited from the Late Carboniferous tectonics and faulted during the Triassic rifting. The Carlsberg Fjord Basin and the Klitdal Fault System described in this paper should be seen as analogues to the Helgeland Basin in the Norwegian offshore that is bounded by the Ylvingen Fault Zone and to the Papa and West of Shetlands Basins that are bounded by the Spine Fault. The Triassic rift zone and transfer faults on both conjugate margins show a straightforward correlation with the trends of the initial spreading line and fracture zones of the northeast Atlantic indicating a possible inheritance of the Triassic rifting.

Initiation and development of the southern California uplift along its northern margin

USGS Publications Warehouse

Stein, R.S.; Thatcher, W.; Castle, R.O.

1979-01-01

Analysis of three first-order leveling lines that traverse the White Wolf fault (site of the 1952 M = 7.7 earthquake), each resurveyed nine times between 1926 and 1974, reveals probable preseismic tilting, major coseismic movements, and a spatial association between these movements and the subsequently recognized southern California uplift. In examining the vertical control record, we have both searched for evidence of systematic errors and excluded from consideration portions of the lines contaminated by subsurface fluid and gas extraction. Movements have been referred to an invariant datum based on the 1926 position of tidal BM 8 in San Pedro, corrected for subsequent eustatic sea-level change. An 8 ??rad up-to-the-north preseismic tilt (6 cm/7.5 km) was apparently recorded on two adjacent line segments within 10 km of the 1952 epicenter between 1942 and 1947. It is possible, however, that this tilt was in part caused by extraction-induced subsidence at one of the six releveled benchmarks. Data also show evidence of episodic tilts that are not earthquake related. At the junction of the Garlock and San Andreas faults, for example, an ???5 ??rad up-to-the-north tilt (7.2 cm/???16 km) took place between Lebec and Grapevine within three months during 1964. Comparison of the 1947 and 1953 surveys, which includes the coseismic interval, shows that the SW-fault end (nearest the epicenter) and the central fault reach sustained four times the uplift recorded at the NE end of the fault (+72 cm SW, +53 cm Central, +16 cm NE). A regional postseismic uplift of 4 cm extended ???25 km to either side of the fault after the main event, from 1953 to 1956. An interval of relative quiescence followed at least through 1959, in which the elevation change did not exceed ??3 cm. The detailed pattern of aseismic uplift demonstrates that movement proceeded in space-time pulses: one half of the uplift at the SW-fault end and extending southward occurred between 1959 and 1961, one half of the uplift at the NE-fault end and extending eastward occurred between 1961 and 1965, while the central fault reach sustained successive pulses of subsidence, uplift, and collapse (-4 cm, 1953-1960; +7 cm, 1960-1965; -2 cm, 1965-1970). In addition, the number of aftershocks concentrated near the fault ends increased in the NE relative to the SW from 1952 to 1974. These observations suggest that the aseismic uplift may have migrated northeastward from 1959 to 1965 at an approximate rate of 7-16 km/yr. Evidence for a mechanical coupling between the earthquake and the subsequent aseismic uplift is equivocal. At both fault ends, the major NWbounding flexure or tilted front of the southern California uplift is spatially coincident with the coseismic flexure that preceded it. In addition, the postulated migration of vertical deformation is similar to the 1952 seismic event in which the rupture initiated at the SW end of the fault and then propagated to the NE-fault end. However, the spatial distribution of aseismic uplift, nearly identical at both fault ends and to the south and east, and near zero in the central fault reach, is distinctly different from the nonuniform and localized coseismic deformation. ?? 1979.

Stacking fault density and bond orientational order of fcc ruthenium nanoparticles

NASA Astrophysics Data System (ADS)

Seo, Okkyun; Sakata, Osami; Kim, Jae Myung; Hiroi, Satoshi; Song, Chulho; Kumara, Loku Singgappulige Rosantha; Ohara, Koji; Dekura, Shun; Kusada, Kohei; Kobayashi, Hirokazu; Kitagawa, Hiroshi

2017-12-01

We investigated crystal structure deviations of catalytic nanoparticles (NPs) using synchrotron powder X-ray diffraction. The samples were fcc ruthenium (Ru) NPs with diameters of 2.4, 3.5, 3.9, and 5.4 nm. We analyzed average crystal structures by applying the line profile method to a stacking fault model and local crystal structures using bond orientational order (BOO) parameters. The reflection peaks shifted depending on rules that apply to each stacking fault. We evaluated the quantitative stacking faults densities for fcc Ru NPs, and the stacking fault per number of layers was 2-4, which is quite large. Our analysis shows that the fcc Ru 2.4 nm-diameter NPs have a considerably high stacking fault density. The B factor tends to increase with the increasing stacking fault density. A structural parameter that we define from the BOO parameters exhibits a significant difference from the ideal value of the fcc structure. This indicates that the fcc Ru NPs are highly disordered.

Preliminary interpretation of industry two-dimensional seismic data from Susitna Basin, south-central Alaska

USGS Publications Warehouse

Lewis, Kristen A.; Potter, Christopher J.; Shah, Anjana K.; Stanley, Richard G.; Haeussler, Peter J.; Saltus, Richard W.

2015-07-30

The eastern seismic lines show evidence of numerous short-wavelength antiforms that appear to correspond to a series of northeast-trending lineations observed in aeromagnetic data, which have been interpreted as being due to folding of Paleogene volcanic strata. The eastern side of the basin is also cut by a number of reverse faults and thrust faults, the majority of which strike north-south. The western side of the Susitna Basin is cut by a series of regional reverse faults and is characterized by synformal structures in two fault blocks between the Kahiltna River and Skwentna faults. These synforms are progressively deeper to the west in the footwalls of the east-vergent Skwentna and northeast-vergent Beluga Mountain reverse faults. Although the seismic data are limited to the south, we interpret a potential regional south-southeast-directed reverse fault striking east-northeast on the east side of the basin that may cross the entire southern portion of the basin.

Radon measurements in an area of tectonic zone: A case study in Central Slovakia.

PubMed

Mojzeš, Andrej; Marko, František; Porubčanová, Barbara; Bartošová, Andrea

2017-01-01

General overviews of the spatial distribution of radon and other natural radionuclides in the geological basement as commonly presented on regional or country maps tend to offer a low density of information, insufficient for gaining relevant knowledge of the environmental impact, especially in the areas of tectonic zones often assumed to be radon prone and therefore dangerous for the human population. An additional survey, employing radon measurements in soil and indoor air, was carried out seeking to provide a more detailed characterization of the expressive fault zone of the Malá Magura in the Horná Nitra region of Central Slovakia. Eventually, the results of soil 222 Rn volume activity measurements along two short profiles crossing the assumed fault line did not reveal any indication of active nature of local tectonics, but merely pointed to an existence of a zone of contact between different types of rocks. The results of indoor radon measurements in dwellings of two villages lying on the studied fault showed values that were lower than those commonly observed on the Slovak territory, ruling out any negative health impact on population. Nevertheless, in order to add new findings to an already well established study of geological structure of the region, the indoor radon data collected through a previous survey require a further analysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

E-W strike slip shearing of Kinwat granitoid at South East Deccan Volcanic Province, Kinwat, Maharashtra, India

NASA Astrophysics Data System (ADS)

Kaplay, R. D.; Kumar, T. Vijay; Mukherjee, Soumyajit; Wesanekar, P. R.; Babar, Md; Chavan, Sumeet

2017-07-01

We study the margin of South East Deccan Volcanic Province around Kinwat lineament, Maharashtra, India, which is NW extension of the Kaddam Fault. Structural field studies document ˜ E-W strike-slip mostly brittle faults from the basement granite. We designate this as `Western boundary East Dharwar Craton Strike-slip Zone' (WBEDCSZ). At local level, the deformation regime from Kinwat, Kaddam Fault, micro-seismically active Nanded and seismically active Killari corroborate with the nearby lineaments. Morphometric analyses suggest that the region is moderately tectonically active. The region of intense strike-slip deformation lies between seismically active fault along Tapi in NW and Bhadrachalam in the SE part of the Kaddam Fault/lineament. The WBEDCSZ with the surface evidences of faulting, presence of a major lineaments and intersection of faults could be a zone of intraplate earthquake.

Imaging the complexity of an active normal fault system: The 1997 Colfiorito (central Italy) case study

USGS Publications Warehouse

Chiaraluce, L.; Ellsworth, W.L.; Chiarabba, C.; Cocco, M.

2003-01-01

Six moderate magnitude earthquakes (5 < Mw < 6) ruptured normal fault segments of the southern sector of the North Apennine belt (central Italy) in the 1997 Colfiorito earthquake sequence. We study the progressive activation of adjacent and nearby parallel faults of this complex normal fault system using ???1650 earthquake locations obtained by applying a double-difference location method, using travel time picks and waveform cross-correlation measurements. The lateral extent of the fault segments range from 5 to 10 km and make up a broad, ???45 km long, NW trending fault system. The geometry of each segment is quite simple and consists of planar faults gently dipping toward SW with an average dip of 40??-45??. The fault planes are not listric but maintain a constant dip through the entire seismogenic volume, down to 8 km depth. We observe the activation of faults on the hanging wall and the absence of seismicity in the footwall of the structure. The observed fault segmentation appears to be due to the lateral heterogeneity of the upper crust: preexisting thrusts inherited from Neogene's compressional tectonic intersect the active normal faults and control their maximum length. The stress tensor obtained by inverting the six main shock focal mechanisms of the sequence is in agreement with the tectonic stress active in the inner chain of the Apennine, revealing a clear NE trending extension direction. Aftershock focal mechanisms show a consistent extensional kinematics, 70% of which are mechanically consistent with the main shock stress field.

Fracture zone drilling through Atotsugawa fault in central Japan - geological and geophysical structure -

NASA Astrophysics Data System (ADS)

Omura, K.; Yamashita, F.; Yamada, R.; Matsuda, T.; Fukuyama, E.; Kubo, A.; Takai, K.; Ikeda, R.; Mizuochi, Y.

2004-12-01

Drilling is an effective method to investigate the structure and physical state in and around the active fault zone, such as, stress and strength distribution, geological structure and materials properties. In particular, the structure in the fault zone is important to understand where and how the stress accumulates during the earthquake cycle. In previous studies, we did integrate investigation on active faults in central Japan by drilling and geophysical prospecting. Those faults are estimated to be at different stage in the earthquake cycle, i.e., Nojima fault which appeared on the surface by the 1995 Great Kobe earthquake (M=7.2), the Neodani fault which appeared by the 1891 Nobi earth-quake (M=8.0), the Atera fault, of which some parts have seemed to be dislocated by the 1586 Tensyo earthquake (M=7.9), and Gofukuji Fault that is considered to have activated about 1200 years ago. Each faults showed characteristic features of fracture zone structure according to their geological and geophysical situations. In a present study, we did core recovery and down hole measurements at the Atotsugawa fault, central Japan, that is considered to have activated at 1858 Hida earthquake (M=7.0). The Atotsugawa fault is characterized by active seismicity along the fault. But, at the same time, the shallow region in the central segment of the fault seems to have low seismicity. The high seismicity segment and low seismicity segments may have different mechanical, physical and material properties. A 350m depth borehole was drilled vertically beside the surface trace of the fault in the low seismicity segment. Recovered cores were overall heavily fractured and altered rocks. In the cores, we observed many shear planes holding fault gouge. Logging data showed that the apparent resistance was about 100 - 600 ohm-m, density was about 2.0 - 2.5g/cm3, P wave velocity was approximately 3.0 - 4.0 km/sec, neutron porosity was 20 - 40 %. Results of physical logging show features of fault fracture zone that were the same as the fault fracture zones of other active faults that we have drilled previously. By the BHTV logging, we detected many fractures of which the strikes are not only parallel to the fault trace bur also oblique to the fault trace. The observations of cores and logging data indicate that the borehole passed in the fracture zone down to the bottom, and that the fracture zone has complicate internal structure including foliation not parallel to the fault trace. The core samples are significant for further investigation on material properties in the fracture zone. And we need data of geophysical prospecting to infer the deeper structure of the fracture zone.

Protection Relaying Scheme Based on Fault Reactance Operation Type

NASA Astrophysics Data System (ADS)

Tsuji, Kouichi

The theories of operation of existing relays are roughly divided into two types: one is the current differential types based on Kirchhoff's first law and the other is impedance types based on second law. We can apply the Kirchhoff's laws to strictly formulate fault phenomena, so the circuit equations are represented non linear simultaneous equations with variables fault point k and fault resistance Rf. This method has next two defect. 1) heavy computational burden for the iterative calculation on N-R method, 2) relay operator can not easily understand principle of numerical matrix operation. The new protection relay principles we proposed this paper focuses on the fact that the reactance component on fault point is almost zero. Two reactance Xf(S), Xf(R) on branch both ends are calculated by operation of solving linear equations. If signs of Xf(S) and Xf(R) are not same, it can be judged that the fault point exist in the branch. This reactance Xf corresponds to difference of branch reactance between actual fault point and imaginaly fault point. And so relay engineer can to understand fault location by concept of “distance". The simulation results using this new method indicates the highly precise estimation of fault locations compared with the inspected fault locations on operating transmission lines.

Radon concentration distributions in shallow and deep groundwater around the Tachikawa fault zone.

PubMed

Tsunomori, Fumiaki; Shimodate, Tomoya; Ide, Tomoki; Tanaka, Hidemi

2017-06-01

Groundwater radon concentrations around the Tachikawa fault zone were surveyed. The radon concentrations in shallow groundwater samples around the Tachikawa fault segment are comparable to previous studies. The characteristics of the radon concentrations on both sides of the segment are considered to have changed in response to the decrease in groundwater recharge caused by urbanization on the eastern side of the segment. The radon concentrations in deep groundwater samples collected around the Naguri and the Tachikawa fault segments are the same as those of shallow groundwater samples. However, the radon concentrations in deep groundwater samples collected from the bedrock beside the Naguri and Tachikawa fault segments are markedly higher than the radon concentrations expected from the geology on the Kanto plane. This disparity can be explained by the development of fracture zones spreading on both sides of the two segments. The radon concentration distribution for deep groundwater samples from the Naguri and the Tachikawa fault segments suggests that a fault exists even at the southern part of the Tachikawa fault line. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fluid-rock interaction during a large earthquake recorded in fault gouge: A case study of the Nojima fault, Japan

NASA Astrophysics Data System (ADS)

Bian, D.; Lin, A.

2016-12-01

Distinguishing the seismic ruptures during the earthquake from a lot of fractures in borehole core is very important to understand rupture processes and seismic efficiency. In particular, a great earthquake like the 1995 Mw 7.2 Kobe earthquake, but again, evidence has been limited to the grain size analysis and the color of fault gouge. In the past two decades, increasing geological evidence has emerged that seismic faults and shear zones within the middle to upper crust play a crucial role in controlling the architectures of crustal fluid migration. Rock-fluid interactions along seismogenic faults give us a chance to find the seismic ruptures from the same event. Recently, a new project of "Drilling into Fault Damage Zone" has being conducted by Kyoto University on the Nojima Fault again after 20 years of the 1995 Kobe earthquake for an integrated multidisciplinary study on the assessment of activity of active faults involving active tectonics, geochemistry and geochronology of active fault zones. In this work, we report on the signature of slip plane inside the Nojima Fault associated with individual earthquakes on the basis of trace element and isotope analyses. Trace element concentrations and 87Sr/86Sr ratios of fault gouge and host rocks were determined by an inductively coupled plasma mass spectrometer (ICP-MS) and thermal ionization mass spectrometry (TIMS). Samples were collected from two trenches and an outcrop of Nojima Fault which. Based on the geochemical result, we interpret these geochemical results in terms of fluid-rock interactions recorded in fault friction during earthquake. The trace-element enrichment pattern of the slip plane can be explained by fluid-rock interactions at high temperature. It also can help us find the main coseismic fault slipping plane inside the thick fault gouge zone.

On-line diagnosis of sequential systems

NASA Technical Reports Server (NTRS)

Sundstrom, R. J.

1973-01-01

A model for on-line diagnosis was investigated for discrete-time systems, and resettable sequential systems. Generalized notions of a realization are discussed along with fault tolerance and errors. Further investigation into the theory of on-line diagnosis is recommended for three levels: binary state-assigned level, logical circuit level, and the subsystem-network level.

Identifying buried segments of active faults in the northern Rio Grande Rift using aeromagnetic, LiDAR,and gravity data, south-central Colorado, USA

USGS Publications Warehouse

Grauch, V.J.S.; Ruleman, Chester A.

2013-01-01

Combined interpretation of aeromagnetic and LiDAR data builds on the strength of the aeromagnetic method to locate normal faults with significant offset under cover and the strength of LiDAR interpretation to identify the age and sense of motion of faults. Each data set helps resolve ambiguities in interpreting the other. In addition, gravity data can be used to infer the sense of motion for totally buried faults inferred solely from aeromagnetic data. Combined interpretation to identify active faults at the northern end of the San Luis Basin of the northern Rio Grande rift has confirmed general aspects of previous geologic mapping but has also provided significant improvements. The interpretation revises and extends mapped fault traces, confirms tectonic versus fluvial origins of steep stream banks, and gains additional information on the nature of active and potentially active partially and totally buried faults. Detailed morphology of surfaces mapped from the LiDAR data helps constrain ages of the faults that displace the deposits. The aeromagnetic data provide additional information about their extents in between discontinuous scarps and suggest that several totally buried, potentially active faults are present on both sides of the valley.

INNOVATIVE METHODOLOGY FOR DETECTION OF FRACTURE-CONTROLLED SWEET SPOTS IN THE NORTHERN APPALACHIAN BASIN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robert Jacobi; John Fountain

2002-01-30

In the structure task, we completed reducing the data we had collected from a N-S transect on the east of Seneca Lake. We have calculated the fracture frequency for all the fracture sets at each site, and constructed modified rose diagrams that summarize the fracture attributes at each site. These data indicate a N-striking fault near the southeastern shore of Seneca Lake, and also indicate NE and ENE-trending FIDs and faults north of Valois. The orientation and existence of the ENE-striking FIDs and faults are thought to be guided by faults in the Precambrian basement; these basement faults apparently weremore » sufficiently reactivated to cause faulting in the Paleozoic section. Other faults are thrust ramps above the Silurian salt section that were controlled by a far-field Alleghanian stress field. Structure contour maps and isopach maps have been revised based on additional well log analyses. Except for the Glodes Corners Field, the well spacing generally is insufficient to definitively identify faults. However, relatively sharp elevational changes east of Keuka Lake support the contention that faults occur along the east side of Keuka Lake. Outcrop stratigraphy along the east side of Seneca Lake indicates that faults and gentle folds can be inferred from the some exposures along Seneca Lake, but the lensing nature of the individual sandstones can preclude long-distance definitive correlations and structure identification. Soil gas data collected during the 2000 field season was reduced and displayed in the previous semiannual report. The seismic data that Quest licensed has been reprocessed. Several grabens observed in the Trenton reflector are consistent with surface structure, soil gas, and aeromagnetic anomalies. In this report we display an interpreted seismic line that crosses the Glodes Corners and Muck Farm fields. The final report from the subcontractor concerning the completed aeromagnetic survey is included. Prominent magnetic anomalies suggest that faults in the Precambrian basement are located beneath regions where grabens in the Trenton are located. The trend and location of these faults based on aeromagnetics agrees with the location based on FIDs. These data indicate that integration of aeromagnetic and topographic lineaments, surface structure, soil gas with seismic and well logs allows us to extrapolate Trenton-Black River trends away from confirmatory seismic lines.« less

Using UAVSAR to Estimate Creep Along the Superstition Hills Fault, Southern California

NASA Astrophysics Data System (ADS)

Donnellan, A.; Parker, J. W.; Pierce, M.; Wang, J.

2012-12-01

UAVSAR data were first acquired over the Salton Trough region, just north of the Mexican border in October 2009. Second passes of data were acquired on 12 and 13 April 2010, about one week following the 5 April 2010 M 7.2 El Mayor - Cucapah earthquake. The earthquake resulted in creep on several faults north of the main rupture, including the Yuha, Imperial, and Superstition Hills faults. The UAVSAR platform acquires data about every six meters in swaths about 15 km wide. Tropospheric effects and residual aircraft motion contribute to error in the estimation of surface deformation in the Repeat Pass Interferometry products. The Superstition Hills fault shows clearly in the associated radar interferogram; however, error in the data product makes it difficult to infer deformation from long profiles that cross the fault. Using the QuakeSim InSAR Profile tool we extracted line of site profiles on either side of the fault delineated in the interferogram. We were able to remove much of the correlated error by differencing profiles 250 m on either side of the fault. The result shows right-lateral creep of 1.5±.4 mm along the northern 7 km of the fault in the interferogram. The amount of creep abruptly changes to 8.4±.4 mm of right lateral creep along at least 9 km of the fault covered in the image to the south. The transition occurs within less than 100 m along the fault. We also extracted 2 km long line of site profiles perpendicular to this section of the fault. Averaging these profiles shows a step across the fault of 14.9±.3 mm with greater creep on the order of 20 mm on the northern two profiles and lower creep of about 10 mm on the southern two profiles. Nearby GPS stations P503 and P493 are consistent with this result. They also confirm that the creep event occurred at the time of the El Mayor - Cucapah earthquake. By removing regional deformation resulting from the main rupture we were able to invert for the depth of creep from the surface. Results indicate that the slip occurred from the surface to 10-20 km, not shallowly, as previously suggested.

Combined 2-D Electrical Resistivity and Self Potential Survey to Investigate the Pattern of the Watukosek Fault System Around the Lusi Eruption Site, Indonesia.

NASA Astrophysics Data System (ADS)

Mazzini, A.; Husein, A.; Mauri, G.; Lupi, M.; Hadi, S.; Kemna, A.

2015-12-01

The Lusi mud eruption is located in the Sidoarjo area, Indonesia and is continuously erupting hot mud since its birth in May 2006. A comprehensive combined electrical resistivity and self-potential (SP) survey was performed in the 7 km2 area inside the Lusi embankment that had been built to contain the erupted mud and to prevent flooding of the surrounding roads and settlements. The goal of the geophysical survey is to map the near-surface occurrence of the Watukosek fault system, upon which LUSI resides, delineate its spatial pattern and monitor its development. We completed six lines of measurements combining resistivity measurement using Wenner configuration and SP measurements using roll-along technique. Three subparallel lines were located either to the north and to the south of the main crater. Each line was approximately W-E oriented extending for ~1.26 km. The surveyed regions consist of dried mud breccia (containing clayey-silty-sandy admixture with clast up to ~ 10 cm in size). The thickness of the dry walkable mud is approximately 2-3 m and the deeper layer consist of water saturated mud that could be vulnerable to a liquefaction scenario in case of significant seismic activity in the region. The resistivity data were inverted into 2-D resistivity images with a maximum exploration depth of almost 200 m. The resistivity images consistently reveal a region of about 300 m in width (between 30-90 m depth) characterized by anomalous resistivities, which are lower than the value observed in the surounding area. The position of these anomalies is also supported by the SP data, which suggests that their origin is related to fluid flow path in the subsurface. Thus the combined resistivity and SP results allow inference of an improved model of the Watukosek fault system.

Millennial strain partitioning revealed by 36Cl cosmogenic data on active bedrock fault scarps from Abruzzo, Italy

NASA Astrophysics Data System (ADS)

Gregory, Laura; Roberts, Gerald; Cowie, Patience; Wedmore, Luke; McCaffrey, Ken; Shanks, Richard; Zijerveld, Leo; Phillips, Richard

2017-04-01

In zones of distributed continental faulting, it is critical to understand how slip is partitioned onto brittle structures over both long-term millennial time scales and shorter-term individual earthquake cycles. Measuring earthquake slip histories on different timescales is challenging due to earthquake repeat-times being longer or similar to historical earthquake records, and a paucity of data on fault activity covering millennial to Quaternary scales in detail. Cosmogenic isotope analyses from bedrock fault scarps have the potential to bridge the gap, as these datasets track the exposure of fault planes due to earthquakes with millennial resolution. In this presentation, we present new 36Cl data combined with historical earthquake records to document orogen-wide changes in the distribution of seismicity on millennial timescales in Abruzzo, central Italy. Seismic activity due to extensional faulting was concentrated on the northwest side of the mountain range during the historical period, or since approximately the 14th century. Seismicity is more limited on the southwest side of Abruzzo during historical times. This pattern has led some to suggest that faults on the southwest side of Abruzzo are not active, however clear fault scarps cutting Holocene-aged slopes are well preserved across the whole of the orogen. These scarps preserve an excellent record of Late Pleistocene to Holocene earthquake activity, which can be quantified using cosmogenic isotopes that track the exposure of the bedrock fault scarps. 36Cl accumulates in the fault scarps as the plane is progressively exhumed by earthquakes and the concentration of 36Cl measured up the fault plane reflects the rate and patterns of slip. We utilise Bayesian modelling techniques to estimate slip histories based on the cosmogenic data. Each sampling site is carefully characterised using LiDAR and GPR to ensure that fault plane exposure is due to slip during earthquakes and not sediment transport processes. In this presentation we will focus on new data from faults located across-strike in Abruzzo. Many faults in Abruzzo demonstrate slip rate variability on millennial timescales, with relatively fast slip interspersed between quiescent periods. We show that heightened activity is co-located and spatially migrates across Abruzzo over time. We highlight the importance of understanding this dynamic fault behaviour of migrating seismic activity, and in particular how our research is relevant to the 2016 Amatrice-Vettore seismic sequence in central Italy.

Seismic Images of the Non-Volcanic Tremor Region around Cholame, California, USA

NASA Astrophysics Data System (ADS)

Gutjahr, S.; Buske, S.

2012-04-01

We reprocessed the industry seismic reflection profile "WSJ-6" which is so far the only seismic profile crossing the San Andreas fault at the non-volcanic tremor region around Cholame. The profile "WSJ-6" runs from Morro Bay eastward to the foothills of the Sierra Nevada and crosses several prominent fault systems, e.g.the Rinconada fault as well as the San Juan fault and the San Andreas fault respectively. By applying the so-called Fresnel Volume migration to the data we produced seismic images of the lower crust and the upper mantle down to depths of approximately 40 km. A 3D tomographic velocity model derived from local earthquake data analysis (Thurber et al., 2006, Lin et al., 2010) was used for slowness analyses and traveltime calculations. The imaging technique was implemented in 3D taking into account the true shot and receiver locations on the crooked profile line. The imaged subsurface volume itself was divided into three separate parts to correctly account for the significant kink in the profile line near the San Andreas fault. The most prominent features in the resulting images are areas of high reflectivity down to 30 km depth in particular in the central western part of the profile corresponding to the Salinian Block between the Rinconada fault and the San Andreas fault. Southwest of the San Andreas fault surface trace a broad zone of high reflectivity is located at depths between 20 km to 35 km. In this region non-volcanic tremor has been located below the seismogenic zone down to 30 km depth. Tremor locations correlate with zones of high reflectivity. This correlation may be an indicator for high pore pressures and fluid content in that region as it is assumed by several authors. The images of the eastern part of the profile show slightly west dipping sedimentary layers in the area of the San Joaquin Valley that are folded and faulted below the Kettleman Hills. Our imaging results will be compared to existing interpretations of the same data.

Advanced microprocessor based power protection system using artificial neural network techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Z.; Kalam, A.; Zayegh, A.

This paper describes an intelligent embedded microprocessor based system for fault classification in power system protection system using advanced 32-bit microprocessor technology. The paper demonstrates the development of protective relay to provide overcurrent protection schemes for fault detection. It also describes a method for power fault classification in three-phase system based on the use of neural network technology. The proposed design is implemented and tested on a single line three phase power system in power laboratory. Both the hardware and software development are described in detail.

Enigmatic rift-parallel, strike-slip faults around Eyjafjörður, Northern Iceland

NASA Astrophysics Data System (ADS)

Proett, J. A.; Karson, J. A.

2014-12-01

Strike-slip faults along mid-ocean ridge spreading centers are generally thought to be restricted to transform boundaries connecting rift segments. Faults that are parallel to spreading centers are generally assumed to be normal faults associated with tectonic extension. However, clear evidence of north-south (rift-parallel), strike-slip displacements occur widely around the southern portion of Eyjafjörður, northern Iceland about 50 km west of the Northern Rift Zone. The area is south of the southernmost strand (Dalvík Lineament) of the NW-SE-trending, dextral-slip, Tjӧrnes Fracture Zone (where N-S, sinistral, strike-slip "bookshelf" faulting occurs). Faults in the Eyjafjörður area cut 8.5-10 m.y. basaltic crust and are parallel to spreading-related dikes and are commonly concentrated along dike margins. Fault rocks range from fault breccia to gouge. Riedel shears and other kinematic indicators provide unambiguous evidence of shear sense. Most faults show evidence of sinistral, strike-slip movement but smaller proportions of normal and oblique-slip faults also are present. Cross cutting relations among the different types of faults are inconsistent and appear to be related to a single deformation event. Fault slip-line kinematic analysis yields solutions indicating sinistral-normal oblique-slip overall. These results may be interpreted in terms of either previously unrecognized transform-fault bookshelf faulting or slip accommodating block rotation associated with northward propagation of the Northern Rift Zone.

On-line diagnosis of inter-turn short circuit fault for DC brushed motor.

PubMed

Zhang, Jiayuan; Zhan, Wei; Ehsani, Mehrdad

2018-06-01

Extensive research effort has been made in fault diagnosis of motors and related components such as winding and ball bearing. In this paper, a new concept of inter-turn short circuit fault for DC brushed motors is proposed to include the short circuit ratio and short circuit resistance. A first-principle model is derived for motors with inter-turn short circuit fault. A statistical model based on Hidden Markov Model is developed for fault diagnosis purpose. This new method not only allows detection of motor winding short circuit fault, it can also provide estimation of the fault severity, as indicated by estimation of the short circuit ratio and the short circuit resistance. The estimated fault severity can be used for making appropriate decisions in response to the fault condition. The feasibility of the proposed methodology is studied for inter-turn short circuit of DC brushed motors using simulation in MATLAB/Simulink environment. In addition, it is shown that the proposed methodology is reliable with the presence of small random noise in the system parameters and measurement. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

FAULT PROPAGATION AND EFFECTS ANALYSIS FOR DESIGNING AN ONLINE MONITORING SYSTEM FOR THE SECONDARY LOOP OF A NUCLEAR POWER PLANT PART OF A HYBRID ENERGY SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Huijuan; Diao, Xiaoxu; Li, Boyuan

This paper studies the propagation and effects of faults of critical components that pertain to the secondary loop of a nuclear power plant found in Nuclear Hybrid Energy Systems (NHES). This information is used to design an on-line monitoring (OLM) system which is capable of detecting and forecasting faults that are likely to occur during NHES operation. In this research, the causes, features, and effects of possible faults are investigated by simulating the propagation of faults in the secondary loop. The simulation is accomplished by using the Integrated System Failure Analysis (ISFA). ISFA is used for analyzing hardware and softwaremore » faults during the conceptual design phase. In this paper, the models of system components required by ISFA are initially constructed. Then, the fault propagation analysis is implemented, which is conducted under the bounds set by acceptance criteria derived from the design of an OLM system. The result of the fault simulation is utilized to build a database for fault detection and diagnosis, provide preventive measures, and propose an optimization plan for the OLM system.« less

GUI Type Fault Diagnostic Program for a Turboshaft Engine Using Fuzzy and Neural Networks

NASA Astrophysics Data System (ADS)

Kong, Changduk; Koo, Youngju

2011-04-01

The helicopter to be operated in a severe flight environmental condition must have a very reliable propulsion system. On-line condition monitoring and fault detection of the engine can promote reliability and availability of the helicopter propulsion system. A hybrid health monitoring program using Fuzzy Logic and Neural Network Algorithms can be proposed. In this hybrid method, the Fuzzy Logic identifies easily the faulted components from engine measuring parameter changes, and the Neural Networks can quantify accurately its identified faults. In order to use effectively the fault diagnostic system, a GUI (Graphical User Interface) type program is newly proposed. This program is composed of the real time monitoring part, the engine condition monitoring part and the fault diagnostic part. The real time monitoring part can display measuring parameters of the study turboshaft engine such as power turbine inlet temperature, exhaust gas temperature, fuel flow, torque and gas generator speed. The engine condition monitoring part can evaluate the engine condition through comparison between monitoring performance parameters the base performance parameters analyzed by the base performance analysis program using look-up tables. The fault diagnostic part can identify and quantify the single faults the multiple faults from the monitoring parameters using hybrid method.

Identification of active fault using analysis of derivatives with vertical second based on gravity anomaly data (Case study: Seulimeum fault in Sumatera fault system)

NASA Astrophysics Data System (ADS)

Hududillah, Teuku Hafid; Simanjuntak, Andrean V. H.; Husni, Muhammad

2017-07-01

Gravity is a non-destructive geophysical technique that has numerous application in engineering and environmental field like locating a fault zone. The purpose of this study is to spot the Seulimeum fault system in Iejue, Aceh Besar (Indonesia) by using a gravity technique and correlate the result with geologic map and conjointly to grasp a trend pattern of fault system. An estimation of subsurface geological structure of Seulimeum fault has been done by using gravity field anomaly data. Gravity anomaly data which used in this study is from Topex that is processed up to Free Air Correction. The step in the Next data processing is applying Bouger correction and Terrin Correction to obtain complete Bouger anomaly that is topographically dependent. Subsurface modeling is done using the Gav2DC for windows software. The result showed a low residual gravity value at a north half compared to south a part of study space that indicated a pattern of fault zone. Gravity residual was successfully correlate with the geologic map that show the existence of the Seulimeum fault in this study space. The study of earthquake records can be used for differentiating the active and non active fault elements, this gives an indication that the delineated fault elements are active.

Ground Motion Simulation for a Large Active Fault System using Empirical Green's Function Method and the Strong Motion Prediction Recipe - a Case Study of the Noubi Fault Zone -

NASA Astrophysics Data System (ADS)

Kuriyama, M.; Kumamoto, T.; Fujita, M.

2005-12-01

The 1995 Hyogo-ken Nambu Earthquake (1995) near Kobe, Japan, spurred research on strong motion prediction. To mitigate damage caused by large earthquakes, a highly precise method of predicting future strong motion waveforms is required. In this study, we applied empirical Green's function method to forward modeling in order to simulate strong ground motion in the Noubi Fault zone and examine issues related to strong motion prediction for large faults. Source models for the scenario earthquakes were constructed using the recipe of strong motion prediction (Irikura and Miyake, 2001; Irikura et al., 2003). To calculate the asperity area ratio of a large fault zone, the results of a scaling model, a scaling model with 22% asperity by area, and a cascade model were compared, and several rupture points and segmentation parameters were examined for certain cases. A small earthquake (Mw: 4.6) that occurred in northern Fukui Prefecture in 2004 were examined as empirical Green's function, and the source spectrum of this small event was found to agree with the omega-square scaling law. The Nukumi, Neodani, and Umehara segments of the 1891 Noubi Earthquake were targeted in the present study. The positions of the asperity area and rupture starting points were based on the horizontal displacement distributions reported by Matsuda (1974) and the fault branching pattern and rupture direction model proposed by Nakata and Goto (1998). Asymmetry in the damage maps for the Noubi Earthquake was then examined. We compared the maximum horizontal velocities for each case that had a different rupture starting point. In the case, rupture started at the center of the Nukumi Fault, while in another case, rupture started on the southeastern edge of the Umehara Fault; the scaling model showed an approximately 2.1-fold difference between these cases at observation point FKI005 of K-Net. This difference is considered to relate to the directivity effect associated with the direction of rupture propagation. Moreover, it was clarified that the horizontal velocities by assuming the cascade model was underestimated more than one standard deviation of empirical relation by Si and Midorikawa (1999). The scaling and cascade models showed an approximately 6.4-fold difference for the case, in which the rupture started along the southeastern edge of the Umehara Fault at observation point GIF020. This difference is significantly large in comparison with the effect of different rupture starting points, and shows that it is important to base scenario earthquake assumptions on active fault datasets before establishing the source characterization model. The distribution map of seismic intensity for the 1891 Noubi Earthquake also suggests that the synthetic waveforms in the southeastern Noubi Fault zone may be underestimated. Our results indicate that outer fault parameters (e.g., earthquake moment) related to the construction of scenario earthquakes influence strong motion prediction, rather than inner fault parameters such as the rupture starting point. Based on these methods, we will predict strong motion for approximately 140 to 150 km of the Itoigawa-Shizuoka Tectonic Line.

A New Kinematic Model for Polymodal Faulting: Implications for Fault Connectivity

NASA Astrophysics Data System (ADS)

Healy, D.; Rizzo, R. E.

2015-12-01

Conjugate, or bimodal, fault patterns dominate the geological literature on shear failure. Based on Anderson's (1905) application of the Mohr-Coulomb failure criterion, these patterns have been interpreted from all tectonic regimes, including normal, strike-slip and thrust (reverse) faulting. However, a fundamental limitation of the Mohr-Coulomb failure criterion - and others that assume faults form parallel to the intermediate principal stress - is that only plane strain can result from slip on the conjugate faults. However, deformation in the Earth is widely accepted as being three-dimensional, with truly triaxial stresses and strains. Polymodal faulting, with three or more sets of faults forming and slipping simultaneously, can generate three-dimensional strains from truly triaxial stresses. Laboratory experiments and outcrop studies have verified the occurrence of the polymodal fault patterns in nature. The connectivity of polymodal fault networks differs significantly from conjugate fault networks, and this presents challenges to our understanding of faulting and an opportunity to improve our understanding of seismic hazards and fluid flow. Polymodal fault patterns will, in general, have more connected nodes in 2D (and more branch lines in 3D) than comparable conjugate (bimodal) patterns. The anisotropy of permeability is therefore expected to be very different in rocks with polymodal fault patterns in comparison to conjugate fault patterns, and this has implications for the development of hydrocarbon reservoirs, the genesis of ore deposits and the management of aquifers. In this contribution, I assess the published evidence and models for polymodal faulting before presenting a novel kinematic model for general triaxial strain in the brittle field.

Database and Map of Quaternary Faults and Folds in Peru and its Offshore Region

USGS Publications Warehouse

Machare, Jose; Fenton, Clark H.; Machette, Michael N.; Lavenu, Alain; Costa, Carlos; Dart, Richard L.

2003-01-01

This publication consists of a main map of Quaternary faults and fiolds of Peru, a table of Quaternary fault data, a region inset map showing relative plate motion, and a second inset map of an enlarged area of interest in southern Peru. These maps and data compilation show evidence for activity of Quaternary faults and folds in Peru and its offshore regions of the Pacific Ocean. The maps show the locations, ages, and activity rates of major earthquake-related features such as faults and fault-related folds. These data are accompanied by text databases that describe these features and document current information on their activity in the Quaternary.

Fault Zone Imaging from Correlations of Aftershock Waveforms

NASA Astrophysics Data System (ADS)

Hillers, Gregor; Campillo, Michel

2018-03-01

We image an active fault zone environment using cross correlations of 154 15 s long 1992 Landers earthquake aftershock seismograms recorded along a line array. A group velocity and phase velocity dispersion analysis of the reconstructed Rayleigh waves and Love waves yields shear wave velocity images of the top 100 m along the 800 m long array that consists of 22 three component stations. Estimates of the position, width, and seismic velocity of a low-velocity zone are in good agreement with the findings of previous fault zone trapped waves studies. Our preferred solution indicates the zone is offset from the surface break to the east, 100-200 m wide, and characterized by a 30% velocity reduction. Imaging in the 2-6 Hz range resolves further a high-velocity body of similar width to the west of the fault break. Symmetry and shape of zero-lag correlation fields or focal spots indicate a frequency and position dependent wavefield composition. At frequencies greater than 4 Hz surface wave propagation dominates, whereas at lower frequencies the correlation field also exhibits signatures of body waves that likely interact with the high-velocity zone. The polarization and late arrival times of coherent wavefronts observed above the low-velocity zone indicate reflections associated with velocity contrasts in the fault zone environment. Our study highlights the utility of the high-frequency correlation wavefield obtained from records of local and regional seismicity. The approach does not depend on knowledge of earthquake source parameters, which suggests the method can return images quickly during aftershock campaigns to guide network updates for optimal coverage of interesting geological features.

Active tectonic deformation of the western Indian plate boundary: A case study from the Chaman Fault System

NASA Astrophysics Data System (ADS)

Crupa, Wanda E.; Khan, Shuhab D.; Huang, Jingqiu; Khan, Abdul S.; Kasi, Aimal

2017-10-01

Collision of the Eurasian and Indian plates has resulted in two spatially offset subduction zones, the Makran subduction zone to the south and the Himalayan convergent margin to the north. These zones are linked by a system of left-lateral strike-slip faults known as the Chaman Fault System, ∼1200 km, which spans along western Pakistan. Although this is one of the greatest strike-slip faults, yet temporal and spatial variation in displacement has not been adequately defined along this fault system. This study conducted geomorphic and geodetic investigations along the Chaman Fault in a search for evidence of spatial variations in motion. Four study areas were selected over the span of the Chaman Fault: (1) Tarnak-Rud area over the Tarnak-Rud valley, (2) Spinatizha area over the Spinatizha Mountain Range, (3) Nushki area over the Nushki basin, and (4) Kharan area over the northern tip of the Central Makran Mountains. Remote sensing data allowed for in depth mapping of different components and faults within the Kohjak group. Wind and water gap pairs along with offset rivers were identified using high-resolution imagery and digital-elevation models to show displacement for the four study areas. The mountain-front-sinuosity ratio, valley height-to-width-ratio, and the stream-length-gradient index were calculated and used to determine the relative tectonic activity of each area. These geomorphic indices suggest that the Kharan area is the most active and the Tarnak-Rud area is the least active. GPS data were processed into a stable Indian plate reference frame and analyzed. Fault parallel velocity versus fault normal distance yielded a ∼8-10 mm/yr displacement rate along the Chaman Fault just north of the Spinatizha area. InSAR data were also integrated to assess displacement rates along the fault system. Geodetic data support that ultra-slow earthquakes similar to those that strike along other major strike-slip faults, such as the San Andreas Fault System, are possible along the northern segments of the Chaman Fault zone. Geomorphic data suggest that the Chaman Fault along southern part is not very active now but may have gone through high tectonic activity in the past.

Towards a Fault-based SHA in the Southern Upper Rhine Graben

NASA Astrophysics Data System (ADS)

Baize, Stéphane; Reicherter, Klaus; Thomas, Jessica; Chartier, Thomas; Cushing, Edward Marc

2016-04-01

A brief overview at a seismic map of the Upper Rhine Graben area (say between Strasbourg and Basel) reveals that the region is seismically active. The area has been hit recently by shallow and moderate quakes but, historically, strong quakes damaged and devastated populated zones. Several authors previously suggested, through preliminary geomorphological and geophysical studies, that active faults could be traced along the eastern margin of the graben. Thus, fault-based PSHA (probabilistic seismic hazard assessment) studies should be developed. Nevertheless, most of the input data in fault-based PSHA models are highly uncertain, based upon sparse or hypothetical data. Geophysical and geological data document the presence of post-Tertiary westward dipping faults in the area. However, our first investigations suggest that the available surface fault map do not provide a reliable document of Quaternary fault traces. Slip rate values that can be currently used in fault-PSHA models are based on regional stratigraphic data, but these include neither detailed datings nor clear base surface contours. Several hints on fault activity do exist and we have now relevant tools and techniques to figure out the activity of the faults of concern. Our preliminary analyses suggest that the LiDAR topography can adequately image the fault segments and, thanks to detailed geomorphological analysis, these data allow tracking cumulative fault offsets. Because the fault models can therefore be considered highly uncertain, our coming project for the next 3 years is to acquire and analyze these accurate topographical data, to trace the active faults and to determine slip rates through relevant features dating. Eventually, we plan to find a key site to perform a paleoseismological trench because this approach has been proved to be worth in the Graben, both to the North (Wörms and Strasbourg) and to the South (Basel). This would be done in order to definitely prove whether the faults ruptured the ground surface during the Quaternary, and in order to determine key fault parameters such as magnitude and age of large events.

Airborne Gravity Measurements using a Helicopter with Special Emphases on Delineating Local Gravity Anomalies Mainly for Detecting Active Seismic Faults (Invited)

NASA Astrophysics Data System (ADS)

Segawa, J.

2010-12-01

The first aerial gravity measurement in Japan started in 1998 using a Japanese airborne gravimeter ‘ Segawa-TKeiki airborne gravimeter Model FGA-1’. We lay emphasis on the measurement of detailed gravity structures at the land-to-sea border areas and mountainous areas. This is the reason why we use a helicopter and make surveys at low altitude and low speed. We have so far made measurement at twelve sites and the total flight amounts to 20,000km. The accuracy of measurement is 1.5 mgal and half-wavelength resolution is 1.5 km. The Japanese type gravimeter consists of a servo-accelerometer type gravity sensor, a horizontal platform controlled by an optical fiber gyro, GPS positioning system, and a data processing system. Helicopter movement has to be precisely monitored three-dimensionally to calculate the vehicle’s acceleration noises. The necessary accuracy of positioning of the vehicle must be better than 10 cm in positioning error. Our helicopter gravity measurement has a special target in Japan to investigate active seismic faults located across land-to-sea borderlines. In Japan, it is generally thought that gravity over most of the country has already been measured by the governmental surveys, leaving the land-sea border lines and mountainous zones unsurveyed as difficult-to-access areas. In addition the use of airplane or helicopter in Japan appeared disadvantageous because of the narrowness of the Japanese Islands. Under such situations the author thought there still remained a particular as well as unique need for aerial gravity measurement in Japan, i.e. the need for detailed and seamless knowledge of gravity structures across land-to-sea border lines to elucidate complicated crustal structures of the Japanese Islands as well as distribution of active seismic faults for disaster prevention. The results of gravity measurements we have conducted so far include those of 12 sites. In the following the brief logs of our measurements are listed. 1)April 2000. Saitama-Tsukuba-Kashima-Nada. Flight Length 1,300km. Discovery of inconsistency between land and marine gravity nearby. 2)July 2000. Suruga Bay. Flight Length 1,500km. Gravity was contoured in the Suruga Bay. 3)November 2000. Enshu-Nada Sea. Flight Length 1,700km. First measurement of land-sea border line of the Tokai area. 4)October 2001. Enshu-Nada Sea. Flight Length 1,500km. Revisit to Enshu Nada sea. 5)December 2001. Kohdu-shima and Miyake Jima. Flight Length 1,800km. Measurement of gravity over the basin between Miyake and Kohdu. 6)June 2002. Enshu-Nada Sea. Flight Length 2,200km. Measurement of gravity across the Tenryu-River active fault. 7)November 2004. Iyonada and Sata Peninsula. (Commercial works). 8)March 2006. Middle Noto Peninsula. (Commercial works). 9)November 2006. Wakasa Bay. (Commercial works). 10)October 2008. North Noto Peninsula. (Commercial works). 11)November 2008. West Seto Inland Sea. (Commercial works). 12)November 2009. Shimokita Peninsula and Seto Inland Sea.

Formation of an active thrust triangle zone associated with structural inversion in a subduction setting, eastern New Zealand

NASA Astrophysics Data System (ADS)

Barnes, Philip M.; Nicol, Andrew

2004-02-01

We analyze a thrust triangle zone, which underlies the continental shelf of Hawke Bay, eastern New Zealand, within the Hikurangi subduction margin. This triangle zone differs from many other examples in that it is active, 90 km from the leading edge of the overriding plate, and formed due to polyphase deformation involving opposed dipping thrust duplex and backthrust, with the later structure forming in response to inversion of an extensional graben. The component structures of the zone mainly developed sequentially rather than synchronously. High-quality marine seismic reflection lines, tied to well and seabed samples, reveal the three-dimensional structure of the zone, together with its 25 Myr evolution and late Quaternary activity. The triangle zone occurs in the lateral overlap between a stack of NW dipping blind thrusts, and a principal backthrust, the Kidnappers fault. The NW dipping thrusts initiated in the early-middle Miocene during the early stages of subduction, with subsequent thrust duplex formation producing major uplift and erosion in the late Miocene-early Pliocene. The active backthrust formed during the late Miocene to early Pliocene as a thin-skinned listric extensional fault confined to the cover sequence. Structural inversion of the extensional fault commenced in the early-middle Pliocene, produced the backthrust and marks the formation of the thrust triangle zone. The thrust duplex and backthrust accrued strain following inversion; however, the later structure accommodated most of the surface deformation in the Quaternary. Section balancing of the triangle zone together with a detailed analysis of reverse displacements along the backthrust reveal spatial and temporal variations of strain accumulation on the two principal components of the zone. Although the formation of the triangle zone is strongly influenced by regional tectonics of the subduction system, these variations may also, in part, reflect local fault interaction. For example, high Quaternary displacement rates on the backthrust accounts for ˜70% of the displacement loss that occurs on the southern segments of the overlapping, Lachlan fault. Understanding the tectonic evolution of such complex, polyphase thrust triangle zones requires the preservation of growth strata that record sequential deformation history. In the absence of such data, synchroneity of opposed dipping thrusts in triangle zones cannot be assumed.

Seismicity and Seismotectonic Properties of The Sultandağı Fault Zone (Afyonkarahisar-Konya): Western Anatolia,Turkey

NASA Astrophysics Data System (ADS)

Kalafat, D.; Gunes, Y.; Kekovali, K.; Kara, M.; Gorgun, E.

2017-12-01

n this study we investigated seismicity and source characteristics of the Sultandağı Fault Zone (SFZ). As known Western Anatolia is one of the most important seismically active region in Turkey. The relative movement of the African-Arabian plates, it causes the Anatolian Plate to movement to the west-Southwest direction 2.5 cm per year and this result provides N-S direction with extensional regime in the recent tectonic. In this study, especially with the assessment of seismic activity occurring in Afyon and around between 200-2002 years, we have been evaluated to date with seismic activity as well as fault mechanism solution. We analyzed recent seismicity and distribution of earthquakes in this region. In the last century, 3 important earthquakes occurred in the Sultandağı Fault zone (Afyon-Akşehir Graben), this result shown it was seismic active and broken fault segments caused stress balance in the region and it caused to occur with short intervals of earthquakes in 2000 and 2002, triggering each other. The scope of this tudy, we installed new BB stations in the region and we have been done of the fault plane solutions for important earthquakes. The focal mechanisms clearly exhibit the activation of a NE-SW trending normal faulting system along the SFZ region. The results of stress analysis showed that the effective current tectonic evolution of normal faulting in this region. This study is supported by Bogazici University Research Projects Commission under SRP/BAP project No. 12280. Key Words: Sultandağı fault zone, normal faulting, seismicity, fault mechanism

Preservation of amorphous ultrafine material: A proposed proxy for slip during recent earthquakes on active faults

PubMed Central

Hirono, Tetsuro; Asayama, Satoru; Kaneki, Shunya; Ito, Akihiro

2016-01-01

The criteria for designating an “Active Fault” not only are important for understanding regional tectonics, but also are a paramount issue for assessing the earthquake risk of faults that are near important structures such as nuclear power plants. Here we propose a proxy, based on the preservation of amorphous ultrafine particles, to assess fault activity within the last millennium. X-ray diffraction data and electron microscope observations of samples from an active fault demonstrated the preservation of large amounts of amorphous ultrafine particles in two slip zones that last ruptured in 1596 and 1999, respectively. A chemical kinetic evaluation of the dissolution process indicated that such particles could survive for centuries, which is consistent with the observations. Thus, preservation of amorphous ultrafine particles in a fault may be valuable for assessing the fault’s latest activity, aiding efforts to evaluate faults that may damage critical facilities in tectonically active zones. PMID:27827413

Preliminary atlas of active shallow tectonic deformation in the Puget Lowland, Washington

USGS Publications Warehouse

Barnett, Elizabeth A.; Haugerud, Ralph A.; Sherrod, Brian L.; Weaver, Craig S.; Pratt, Thomas L.; Blakely, Richard J.

2010-01-01

This atlas presents an up-to-date map compilation of the geological and geophysical observations that underpin interpretations of active, surface-deforming faults in the Puget Lowland, Washington. Shallow lowland faults are mapped where observations of deformation from paleoseismic, seismic-reflection, and potential-field investigations converge. Together, results from these studies strengthen the identification and characterization of regional faults and show that as many as a dozen shallow faults have been active during the Holocene. The suite of maps presented in our atlas identifies sites that have evidence of deformation attributed to these shallow faults. For example, the paleoseismic-investigations map shows where coseismic surface rupture and deformation produced geomorphic scarps and deformed shorelines. Other maps compile results of seismic-reflection and potential-field studies that demonstrate evidence of deformation along suspected fault structures in the subsurface. Summary maps show the fault traces derived from, and draped over, the datasets presented in the preceding maps. Overall, the atlas provides map users with a visual overview of the observations and interpretations that support the existence of active, shallow faults beneath the densely populated Puget Lowland.

Eight Years of Surface Deformation in the Asal-Ghoubbet Rift (Afar Depression) Observed With SAR Data

NASA Astrophysics Data System (ADS)

Doubre, C.; Peltzer, G.; Manighetti, I.; Jacques, E.

2005-12-01

The volcano-tectonic Asal-Ghoubbet rift (Djibouti) is the youngest spreading segment of the Aden oceanic ridge propagating inland into the Afar Depression. The deformation in the rift is characterized by magmatic inflation and dilatation (dyking), distributed extension, fissure opening, and normal faulting, contributing to a far field opening velocity of ~1.5 cm/yr. We use radar interferometry data acquired by the Canadian satellite Radarsat on 24-day repeat, descending passes to measure the surface deformation in a 100 km wide region centered on the rift. The data set defines 87 epochs of acquisitions distributed between 1997 and 2005. We combined the SAR data into 354 full-resolution interferograms and solved for incremental displacements between epochs using a least-square approach [Berardino et al., 2002]. The resulting line of sight displacement map time series shows the following features: - A 40 km-wide zone centered on the rift is uplifted as a dome at a steady rate. - The central rift is subsiding with respect to the north and south shoulders. The velocity field shows a marked asymmetry with faster rates occurring along the northern edge of the rift. The mean velocity of the relative movement of the subsiding inner floor with respect to the northern up-lifting shoulder reaches 7 mm/yr. - Subsidence is faster in the north half of the inner floor of the rift and is associated with episodic creep events on normal faults. These includes a slip of 16 mm on the north-dipping δ fault in 2003 and an episode of accelerated creep of 10 mm occurring in 2000 on the γ fault, which is creeping at a steady rate of 3.5 mm/yr. A northern-dipping normal fault is slipping with a mean rate of 1.4 mm/yr and accommodates also the subsidence of the northern part of the inner floor. Unlike other active faults, this one does not coincide with a topographic scarp but shows evidence of surface creep in the velocity field. - The southeastern part of F fault system is the only fault clearly active on the south side of the rift axis and shows a creep event of 9 mm in 2002. We investigate the spatial and temporal relationship between deformation events observed in the SAR data and the catalog of seismicity collected by the Djibouti Observatory and during field campaign in the winter 2000/2001. We observe that creep events are generally associated with bursts of micro-seismicity distributed in the vicinity of the fault, or with swarms of small events concentrated below the fault. These observations suggest that while the overall region is deforming in response to the steady inflation of a magmatic chamber below the central rift, the faults and dykes that accommodate the deformation at the surface are sensitive and respond rapidly to small stress changes occurring episodically within the rift.

A set of alternative explanations to account for the deformation field at Montserrat, West Indies

NASA Astrophysics Data System (ADS)

Collinson, Amy; Neuberg, Jurgen; Pascal, Karen

2015-04-01

For almost 20 years, Soufrière Hills Volcano, Monsterrat, has been in a state of volcanic unrest. Intermittent periods of dome building have been punctuated by explosive eruptions and dome collapse events, endangering the lives of the inhabitants of the island. To date, there have been numerous phases to the activity, with the current activity designated Pause 5. There has not been any active magma extrusion since February 2010, and the last significant explosive (ash-venting) event occurred in March 2012. However, the volcano continues to emit an average of 374t/d SO2 and shows signs of deformation. Current observations indicate a line lengthening between several pairs of GPS stations across the island, suggesting an overall inflation of Montserrat. Through the use of three-dimensional numerical modelling using a finite element method, we explore the potential sources of this deformation, ranging from an inflating magma chamber or dyke - suggesting ongoing volcanic activity, to the existence of an active left-lateral strike-slip fault - which may indicate cessation of volcanic activity. We show the effect of different dyke sources (shapes, characters and depths) on the surface displacement. Furthermore, through the inclusion of topographic data, we investigate how the topography may affect the displacement pattern at the surface. Alternatively, we determine how much fault slip would be required in order to derive the deformation observed.

A remote sensing study of active folding and faulting in southern Kerman province, S.E. Iran

NASA Astrophysics Data System (ADS)

Walker, Richard Thomas

2006-04-01

Geomorphological observations reveal a major oblique fold-and-thrust belt in Kerman province, S.E. Iran. The active faults appear to link the Sabzevaran right-lateral strike-slip fault in southeast Iran to other strike-slip faults within the interior of the country and may provide the means of distributing right-lateral shear between the Zagros and Makran mountains over a wider region of central Iran. The Rafsanjan fault is manifest at the Earth's surface as right-lateral strike-slip fault scarps and folding in alluvial sediments. Height changes across the anticlines, and widespread incision of rivers, are likely to result from hanging-wall uplift above thrust faults at depth. Scarps in recent alluvium along the northern margins of the folds suggest that the thrusts reach the surface and are active at the present-day. The observations from Rafsanjan are used to identify similar late Quaternary faulting elsewhere in Kerman province near the towns of Mahan and Rayen. No instrumentally recorded destructive earthquakes have occurred in the study region and only one historical earthquake (Lalehzar, 1923) is recorded. In addition GPS studies show that present-day rates of deformation are low. However, fault structures in southern Kerman province do appear to be active in the late Quaternary and may be capable of producing destructive earthquakes in the future. This study shows how widely available remote sensing data can be used to provide information on the distribution of active faulting across large areas of deformation.

Differential Fault Analysis on CLEFIA

NASA Astrophysics Data System (ADS)

Chen, Hua; Wu, Wenling; Feng, Dengguo

CLEFIA is a new 128-bit block cipher proposed by SONY corporation recently. The fundamental structure of CLEFIA is a generalized Feistel structure consisting of 4 data lines. In this paper, the strength of CLEFIA against the differential fault attack is explored. Our attack adopts the byte-oriented model of random faults. Through inducing randomly one byte fault in one round, four bytes of faults can be simultaneously obtained in the next round, which can efficiently reduce the total induce times in the attack. After attacking the last several rounds' encryptions, the original secret key can be recovered based on some analysis of the key schedule. The data complexity analysis and experiments show that only about 18 faulty ciphertexts are needed to recover the entire 128-bit secret key and about 54 faulty ciphertexts for 192/256-bit keys.

Seismic Hazard Analysis on a Complex, Interconnected Fault Network

NASA Astrophysics Data System (ADS)

Page, M. T.; Field, E. H.; Milner, K. R.

2017-12-01

In California, seismic hazard models have evolved from simple, segmented prescriptive models to much more complex representations of multi-fault and multi-segment earthquakes on an interconnected fault network. During the development of the 3rd Uniform California Earthquake Rupture Forecast (UCERF3), the prevalence of multi-fault ruptures in the modeling was controversial. Yet recent earthquakes, for example, the Kaikora earthquake - as well as new research on the potential of multi-fault ruptures (e.g., Nissen et al., 2016; Sahakian et al. 2017) - have validated this approach. For large crustal earthquakes, multi-fault ruptures may be the norm rather than the exception. As datasets improve and we can view the rupture process at a finer scale, the interconnected, fractal nature of faults is revealed even by individual earthquakes. What is the proper way to model earthquakes on a fractal fault network? We show multiple lines of evidence that connectivity even in modern models such as UCERF3 may be underestimated, although clustering in UCERF3 mitigates some modeling simplifications. We need a methodology that can be applied equally well where the fault network is well-mapped and where it is not - an extendable methodology that allows us to "fill in" gaps in the fault network and in our knowledge.

Active Neotectonic Structures in Glacial and Postglacial Sediment in Lake Timiskaming, Timiskaming Graben, Ontario/Quebec Canada

NASA Astrophysics Data System (ADS)

Doughty, M.; Eyles, N.; Eyles, C.

2009-05-01

The Timiskaming Graben (TG) is a northwest-trending arm of the Ottawa-Bonnechere Graben and the St. Lawrence Rift System (SLRS) in eastern Canada. Together they form a 600 km long failed rift in the Canadian Shield, extending southward along the border of Ontario and Quebec to the St.Lawrence River Valley onto the Hudson Valley and Lake Champlain in the USA. The Timiskaming Graben preserves faulted outliers of Early Paleozoic limestones and has been reactivated several time during the Phanerozoic most recently during the breakup of Pangea. The 110 kilometre-long, ~100 m deep Lake Timiskaming fills the inner part of the Timiskaming Graben along the border of Ontario and Quebec. It is the postglacial successor to glacial Lake Barlow ponded against the northward-retreating Laurentide Ice Sheet some 9,000 years BP. The sedimentary record of Lake Timiskaming was established by collecting more than 1000 line kilometres of high-resolution 'chirp' seismic profiles, side scan and multibeam survey data between 2003 and 2007. These show that bathymetric relief is the product of ongoing tectonic subsidence where lateglacial Barlow glaciolacustrine and postglacial sediments are extensively deformed by closely-spaced horst and grabens. The greatest subsidence has occurred within a narrow (< 3 km) and deep (up to 209 m) central graben basin. We are able to infer the presence of hitherto unrecognized bounding and relay faults within the graben, and a 20 km long 8 m high fault scarp and sand blows produced by large postglacial earthquakes. The region is one of the most seismically active areas in eastern North America (Western Quebec Seismic Zone) with frequent moderate to large magnitude (> M5) intracratonic earthquakes. Structural activity is ongoing along the Timiskaming Graben and its lateglacial and postglacial sediment record provides the clearest evidence to date of modern intracratonic faulting anywhere in eastern North America.

Novel elastic protection against DDF failures in an enhanced software-defined SIEPON

NASA Astrophysics Data System (ADS)

Pakpahan, Andrew Fernando; Hwang, I.-Shyan; Yu, Yu-Ming; Hsu, Wu-Hsiao; Liem, Andrew Tanny; Nikoukar, AliAkbar

2017-07-01

Ever-increasing bandwidth demands on passive optical networks (PONs) are pushing the utilization of every fiber strand to its limit. This is mandating comprehensive protection until the end of the distribution drop fiber (DDF). Hence, it is important to provide refined protection with an advanced fault-protection architecture and recovery mechanism that is able to cope with various DDF failures. We propose a novel elastic protection against DDF failures that incorporates a software-defined networking (SDN) capability and a bus protection line to enhance the resiliency of the existing Service Interoperability in Ethernet Passive Optical Networks (SIEPON) system. We propose the addition of an integrated SDN controller and flow tables to the optical line terminal and optical network units (ONUs) in order to deliver various DDF protection scenarios. The proposed architecture enables flexible assignment of backup ONU(s) in pre/post-fault conditions depending on the PON traffic load. A transient backup ONU and multiple backup ONUs can be deployed in the pre-fault and post-fault scenarios, respectively. Our extensively discussed simulation results show that our proposed architecture provides better overall throughput and drop probability compared to the architecture with a fixed DDF protection mechanism. It does so while still maintaining overall QoS performance in terms of packet delay, mean jitter, packet loss, and throughput under various fault conditions.

A modified NARMAX model-based self-tuner with fault tolerance for unknown nonlinear stochastic hybrid systems with an input-output direct feed-through term.

PubMed

Tsai, Jason S-H; Hsu, Wen-Teng; Lin, Long-Guei; Guo, Shu-Mei; Tann, Joseph W

2014-01-01

A modified nonlinear autoregressive moving average with exogenous inputs (NARMAX) model-based state-space self-tuner with fault tolerance is proposed in this paper for the unknown nonlinear stochastic hybrid system with a direct transmission matrix from input to output. Through the off-line observer/Kalman filter identification method, one has a good initial guess of modified NARMAX model to reduce the on-line system identification process time. Then, based on the modified NARMAX-based system identification, a corresponding adaptive digital control scheme is presented for the unknown continuous-time nonlinear system, with an input-output direct transmission term, which also has measurement and system noises and inaccessible system states. Besides, an effective state space self-turner with fault tolerance scheme is presented for the unknown multivariable stochastic system. A quantitative criterion is suggested by comparing the innovation process error estimated by the Kalman filter estimation algorithm, so that a weighting matrix resetting technique by adjusting and resetting the covariance matrices of parameter estimate obtained by the Kalman filter estimation algorithm is utilized to achieve the parameter estimation for faulty system recovery. Consequently, the proposed method can effectively cope with partially abrupt and/or gradual system faults and input failures by the fault detection. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

Predictive fault-tolerant control of an all-thruster satellite in 6-DOF motion via neural network model updating

NASA Astrophysics Data System (ADS)

Tavakoli, M. M.; Assadian, N.

2018-03-01

The problem of controlling an all-thruster spacecraft in the coupled translational-rotational motion in presence of actuators fault and/or failure is investigated in this paper. The nonlinear model predictive control approach is used because of its ability to predict the future behavior of the system. The fault/failure of the thrusters changes the mapping between the commanded forces to the thrusters and actual force/torque generated by the thruster system. Thus, the basic six degree-of-freedom kinetic equations are separated from this mapping and a set of neural networks are trained off-line to learn the kinetic equations. Then, two neural networks are attached to these trained networks in order to learn the thruster commands to force/torque mappings on-line. Different off-nominal conditions are modeled so that neural networks can detect any failure and fault, including scale factor and misalignment of thrusters. A simple model of the spacecraft relative motion is used in MPC to decrease the computational burden. However, a precise model by the means of orbit propagation including different types of perturbation is utilized to evaluate the usefulness of the proposed approach in actual conditions. The numerical simulation shows that this method can successfully control the all-thruster spacecraft with ON-OFF thrusters in different combinations of thruster fault and/or failure.

Response of deformation patterns to reorganizations of the southern San Andreas fault system since ca. 1.5 Ma

NASA Astrophysics Data System (ADS)

Cooke, M. L.; Fattaruso, L.; Dorsey, R. J.; Housen, B. A.

2015-12-01

Between ~1.5 and 1.1 Ma, the southern San Andreas fault system underwent a major reorganization that included initiation of the San Jacinto fault and termination of slip on the extensional West Salton detachment fault. The southern San Andreas fault itself has also evolved since this time, with several shifts in activity among fault strands within San Gorgonio Pass. We use three-dimensional mechanical Boundary Element Method models to investigate the impact of these changes to the fault network on deformation patterns. A series of snapshot models of the succession of active fault geometries explore the role of fault interaction and tectonic loading in abandonment of the West Salton detachment fault, initiation of the San Jacinto fault, and shifts in activity of the San Andreas fault. Interpreted changes to uplift patterns are well matched by model results. These results support the idea that growth of the San Jacinto fault led to increased uplift rates in the San Gabriel Mountains and decreased uplift rates in the San Bernardino Mountains. Comparison of model results for vertical axis rotation to data from paleomagnetic studies reveals a good match to local rotation patterns in the Mecca Hills and Borrego Badlands. We explore the mechanical efficiency at each step in the evolution, and find an overall trend toward increased efficiency through time. Strain energy density patterns are used to identify regions of off-fault deformation and potential incipient faulting. These patterns support the notion of north-to-south propagation of the San Jacinto fault during its initiation. The results of the present-day model are compared with microseismicity focal mechanisms to provide additional insight into the patterns of off-fault deformation within the southern San Andreas fault system.

Upper crustal structures beneath Yogyakarta imaged by ambient seismic noise tomography

NASA Astrophysics Data System (ADS)

Zulfakriza, Saygin, E.; Cummins, P.; Widiyantoro, S.; Nugraha, Andri Dian

2013-09-01

Delineating the upper crustal structures beneath Yogyakarta is necessary for understanding its tectonic setting. The presence of Mt. Merapi, fault line and the alluvial deposits contributes to the complex geology of Yogyakarta. Recently, ambient seismic noise tomography can be used to image the subsurface structure. The cross correlations of ambient seismic noise of pair stations were applied to extract the Green's function. The total of 27 stations from 134 seismic stations available in MERapi Amphibious EXperiment (MERAMEX) covering Yogyakarta region were selected to conduct cross correlation. More than 500 Rayleigh waves of Green's functions could be extracted by cross-correlating available the station pairs of short-period and broad-band seismometers. The group velocities were obtained by filtering the extracted Green's function between 0.5 and 20 s. 2-D inversion was applied to the retrieved travel times. Features in the derived tomographic images correlate with the surface geology of Yogyakarta. The Merapi active volcanoes and alluvial deposit in Yogyakarta are clearly described by lower group velocities. The high velocity anomaly contrasts which are visible in the images obtained from the period range between 1 and 5 s, correspond to subsurface imprints of fault that could be the Opak Fault.

GeoBioScience: Red Wood Ants as Bioindicators for Active Tectonic Fault Systems in the West Eifel (Germany)

PubMed Central

Berberich, Gabriele; Schreiber, Ulrich

2013-01-01

Simple Summary In a 1.140 km² study area of the volcanic West Eifel, approx. 3,000 Red Wood Ant (RWA; Formica rufa-group) mounds had been identified and correlated with tectonically active gas-permeable faults, mostly strike-slip faults. Linear alignment of RWA mounds and soil gas anomalies distinctly indicate the course of these faults, while clusters of mounds indicate crosscut zones of fault systems, which can be correlated with voids caused by crustal block rotation. This demonstrates that RWA are bioindicators for identifying active fault systems and useful where information on the active regime is incomplete or the resolution by technical means is insufficient. Abstract In a 1.140 km² study area of the volcanic West Eifel, a comprehensive investigation established the correlation between red wood ant mound (RWA; Formica rufa-group) sites and active tectonic faults. The current stress field with a NW-SE-trending main stress direction opens pathways for geogenic gases and potential magmas following the same orientation. At the same time, Variscan and Mesozoic fault zones are reactivated. The results showed linear alignments and clusters of approx. 3,000 RWA mounds. While linear mound distribution correlate with strike-slip fault systems documented by quartz and ore veins and fault planes with slickensides, the clusters represent crosscut zones of dominant fault systems. Latter can be correlated with voids caused by crustal block rotation. Gas analyses from soil air, mineral springs and mofettes (CO2, Helium, Radon and H2S) reveal limiting concentrations for the spatial distribution of mounds and colonization. Striking is further the almost complete absence of RWA mounds in the core area of the Quaternary volcanic field. A possible cause can be found in occasionally occurring H2S in the fault systems, which is toxic at miniscule concentrations to the ants. Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel. PMID:26487413

Structural control on the CO2 release west of Mt. Epomeo resurgent block (Ischia, Italy)

NASA Astrophysics Data System (ADS)

de Vita, S.; Marotta, E.; Ventura, G.; Chiodini, G.

2003-04-01

Volcanism at Ischia started more than 150 ka B.P. and continued until the last eruption occurred in 1302 A.D. Ischia is dominated by the caldera forming eruption of Mt. Epomeo Green Tuff (55 ka), which was followed by block resurgence inside the caldera from 33 ka B.P. Resurgence influenced the volcanic activity determining the conditions for magma ascent mainly along the eastern edge of the resurgent block. The resurgent area has a poligonal shape resulting from reactivation of regional faults and by activation of faults related to volcanotectonism. The western sector is bordered by inward dipping, high angle strike-slip/reverse faults testifying a compressional stress regime in this area. These features are cut by late outward dipping normal faults due to gravitational stress. The activity of the volcanic system is testified by seismicity and thermal manifestations. Fumarolic activity concentrates along the faults that borders westward the Mt. Epomeo resurgent block, where the Green Tuff overlies fractured lavas. The structural data show that, outside the most active degassing zone, fractures show a NNW-SSE strike and dip toward Mt. Epomeo. These fractures delimit the northern sector of Mt. Epomeo and show strike and dip consistent with the inward dipping reverse faults. Inside the degassing area fractures show a NW-SE strike and dip outward Mt. Epomeo. These gravity-related faults cut the lavas where the hydrothermal circulation is active. The dip direction of the NW-SE striking fractures within the degassing zone is not consistent with that of the strike-slip/reverse faults (i.e. towards NE) but agrees well with that of the gravity-induced faults (dip direction towards SW). Inside the degassing zone, NW-SE striking faults with lengths not exceeding the hydrothermalized extension occur. This arrangement indicate that the syn-resurgence faults act as permeability barriers, whereas the youngest faults act as the main fluid pathway.

Deep heterogeneous structure of active faults in the Kinki region, southwest Japan: Inversion analysis of coda envelopes

NASA Astrophysics Data System (ADS)

Nishigami, K.

2006-12-01

It is essential to estimate the deep structure of active faults related to the earthquake rupture process as well as the crustal structure related to the propagation of seismic waves, in order to improve the accuracy of estimating strong ground motion caused by future large inland earthquakes. In the Kinki region, southwest Japan, there are several active fault zones near large cities such as Osaka and Kyoto, and the evaluation of realistic strong ground motion is an important subject. We have been carrying out the Special Project for Earthquake Disaster Mitigation in Urban Areas, in the Kinki region for these purposes. In this presentation we will show the result of estimating the fault structure model of the Biwako-seigan, Hanaore, and Arima- Takatsuki fault zones. We estimated a 3-D distribution of relative scattering coefficients in the Kinki region, also in the vicinity of each active fault zone, by inversion of coda envelopes from local earthquakes. We analyzed 758 seismograms from 52 events which occurred in 2003, recorded at 50 stations of Kyoto Univ., Hi- net, and JMA. The preliminary result shows that active fault zones can be imaged as higher scattering than the surroundings. Based on previous studies of scattering properties in the crust, we consider that the relatively weaker scattering (namely more homogeneous) part on the fault plane may act as an asperity during future large earthquakes, and also that the part with relatively stronger scattering (namely more heterogeneous part) may become an initiation point of rupture. We are also studying the detailed distribution of microearthquakes, b-values, and velocity anomalies along these active fault zones. Combining these results, we will construct a possible fault model for each of the active fault zones. This study is sponsored by the Special Project for Earthquake Disaster Mitigation in Urban Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan.

Height changes along selected lines through the Death Valley region, California and Nevada, 1905-1984

USGS Publications Warehouse

Castle, Robert O.; Gilmore, Thomas D.; Walker, James P.; Castle, Susan A.

2005-01-01

Comparisons among repeated levelings along selected lines through the Death Valley region of California and adjacent parts of Nevada have disclosed surprisingly large vertical displacements. The vertical control data in this lightly populated area is sparse; moreover, as much as a third of the recovered data is so thoroughly contaminated by systematic error and survey blunders that no attempt was made to correct these data and they were simply discarded. In spite of these limitations, generally episodic, commonly large vertical displacements are disclosed along a number of lines. Displacements in excess of 0.4 m, with respect to our selected control point at Beatty, Nevada, and differential displacements of about 0.7 m apparently occurred during the earlier years of the 20th century and continued episodically through at least 1943. While this area contains abundant evidence of continuing tectonic activity through latest Quaternary time, it is virtually devoid of historic seismicity. We have detected no clear connection between the described vertical displacements and fault zones reportedly active during Holocene time, although we sense some association with several more broadly defined tectonic features.

Tectonics earthquake distribution pattern analysis based focal mechanisms (Case study Sulawesi Island, 1993–2012)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ismullah M, Muh. Fawzy, E-mail: mallaniung@gmail.com; Lantu,; Aswad, Sabrianto

Indonesia is the meeting zone between three world main plates: Eurasian Plate, Pacific Plate, and Indo – Australia Plate. Therefore, Indonesia has a high seismicity degree. Sulawesi is one of whose high seismicity level. The earthquake centre lies in fault zone so the earthquake data gives tectonic visualization in a certain place. This research purpose is to identify Sulawesi tectonic model by using earthquake data from 1993 to 2012. Data used in this research is the earthquake data which consist of: the origin time, the epicenter coordinate, the depth, the magnitude and the fault parameter (strike, dip and slip). Themore » result of research shows that there are a lot of active structures as a reason of the earthquake in Sulawesi. The active structures are Walannae Fault, Lawanopo Fault, Matano Fault, Palu – Koro Fault, Batui Fault and Moluccas Sea Double Subduction. The focal mechanism also shows that Walannae Fault, Batui Fault and Moluccas Sea Double Subduction are kind of reverse fault. While Lawanopo Fault, Matano Fault and Palu – Koro Fault are kind of strike slip fault.« less

High-Resolution Regional Phase Attenuation Models of the Iranian Plateau and Surrounding Regions

DTIC Science & Technology

2014-03-03

1 2.2. Tectonic and Geophysical Setting ..........................................................................2 2.3...superimposed with the major tectonic features across the Middle East. The major faults are depicted with black solid lines. The main continental boundary fault...zones and tectonic settings are abbreviated on the map and described here. The red triangles present the location of quaternary volcanoes. The dashed

Response of deformation patterns to reorganization of the southern San Andreas fault system since ca. 1.5 Ma

NASA Astrophysics Data System (ADS)

Fattaruso, Laura A.; Cooke, Michele L.; Dorsey, Rebecca J.; Housen, Bernard A.

2016-12-01

Between 1.5 and 1.1 Ma, the southern San Andreas fault system underwent a major reorganization that included initiation of the San Jacinto fault zone and termination of slip on the extensional West Salton detachment fault. The southern San Andreas fault itself has also evolved since this time, with several shifts in activity among fault strands within San Gorgonio Pass. We use three-dimensional mechanical Boundary Element Method models to investigate the impact of these changes to the fault network on deformation patterns. A series of snapshot models of the succession of active fault geometries explore the role of fault interaction and tectonic loading in abandonment of the West Salton detachment fault, initiation of the San Jacinto fault zone, and shifts in activity of the San Andreas fault. Interpreted changes to uplift patterns are well matched by model results. These results support the idea that initiation and growth of the San Jacinto fault zone led to increased uplift rates in the San Gabriel Mountains and decreased uplift rates in the San Bernardino Mountains. Comparison of model results for vertical-axis rotation to data from paleomagnetic studies reveals a good match to local rotation patterns in the Mecca Hills and Borrego Badlands. We explore the mechanical efficiency at each step in the modeled fault evolution, and find an overall trend toward increased efficiency through time. Strain energy density patterns are used to identify regions of incipient faulting, and support the notion of north-to-south propagation of the San Jacinto fault during its initiation.

Autonomous power expert fault diagnostic system for Space Station Freedom electrical power system testbed

NASA Technical Reports Server (NTRS)

Truong, Long V.; Walters, Jerry L.; Roth, Mary Ellen; Quinn, Todd M.; Krawczonek, Walter M.

1990-01-01

The goal of the Autonomous Power System (APS) program is to develop and apply intelligent problem solving and control to the Space Station Freedom Electrical Power System (SSF/EPS) testbed being developed and demonstrated at NASA Lewis Research Center. The objectives of the program are to establish artificial intelligence technology paths, to craft knowledge-based tools with advanced human-operator interfaces for power systems, and to interface and integrate knowledge-based systems with conventional controllers. The Autonomous Power EXpert (APEX) portion of the APS program will integrate a knowledge-based fault diagnostic system and a power resource planner-scheduler. Then APEX will interface on-line with the SSF/EPS testbed and its Power Management Controller (PMC). The key tasks include establishing knowledge bases for system diagnostics, fault detection and isolation analysis, on-line information accessing through PMC, enhanced data management, and multiple-level, object-oriented operator displays. The first prototype of the diagnostic expert system for fault detection and isolation has been developed. The knowledge bases and the rule-based model that were developed for the Power Distribution Control Unit subsystem of the SSF/EPS testbed are described. A corresponding troubleshooting technique is also described.

Fracture overprinting history using Markov chain analysis: Windsor-Kennetcook subbasin, Maritimes Basin, Canada

NASA Astrophysics Data System (ADS)

Snyder, Morgan E.; Waldron, John W. F.

2018-03-01

The deformation history of the Upper Paleozoic Maritimes Basin, Atlantic Canada, can be partially unraveled by examining fractures (joints, veins, and faults) that are well exposed on the shorelines of the macrotidal Bay of Fundy, in subsurface core, and on image logs. Data were collected from coastal outcrops and well core across the Windsor-Kennetcook subbasin, a subbasin in the Maritimes Basin, using the circular scan-line and vertical scan-line methods in outcrop, and FMI Image log analysis of core. We use cross-cutting and abutting relationships between fractures to understand relative timing of fracturing, followed by a statistical test (Markov chain analysis) to separate groups of fractures. This analysis, previously used in sedimentology, was modified to statistically test the randomness of fracture timing relationships. The results of the Markov chain analysis suggest that fracture initiation can be attributed to movement along the Minas Fault Zone, an E-W fault system that bounds the Windsor-Kennetcook subbasin to the north. Four sets of fractures are related to dextral strike slip along the Minas Fault Zone in the late Paleozoic, and four sets are related to sinistral reactivation of the same boundary in the Mesozoic.

Investigation of the fluid flow dynamic parameters for Newtonian and non-Newtonian materials: an approach to understanding the fluid flow-like structures within fault zones

NASA Astrophysics Data System (ADS)

Tanaka, H.; Shiomi, Y.; Ma, K.-F.

2017-11-01

To understand the fault zone fluid flow-like structure, namely the ductile deformation structure, often observed in the geological field (e.g., Ramsay and Huber The techniques of modern structure geology, vol. 1: strain analysis, Academia Press, London, 1983; Hobbs and Ord Structure geology: the mechanics of deforming metamorphic rocks, Vol. I: principles, Elsevier, Amsterdam, 2015), we applied a theoretical approach to estimate the rate of deformation, the shear stress and the time to form a streak-line pattern in the boundary layer of viscous fluids. We model the dynamics of streak lines in laminar boundary layers for Newtonian and pseudoplastic fluids and compare the results to those obtained via laboratory experiments. The structure of deformed streak lines obtained using our model is consistent with experimental observations, indicating that our model is appropriate for understanding the shear rate, flow time and shear stress based on the profile of deformed streak lines in the boundary layer in Newtonian and pseudoplastic viscous materials. This study improves our understanding of the transportation processes in fluids and of the transformation processes in fluid-like materials. Further application of this model could facilitate understanding the shear stress and time history of the fluid flow-like structure of fault zones observed in the field.[Figure not available: see fulltext.

Active faulting in apparently stable peninsular India: Rift inversion and a Holocene-age great earthquake on the Tapti Fault

NASA Astrophysics Data System (ADS)

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

2014-08-01

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.

Discovery of previously unrecognised local faults in London, UK, using detailed 3D geological modelling

NASA Astrophysics Data System (ADS)

Aldiss, Don; Haslam, Richard

2013-04-01

In parts of London, faulting introduces lateral heterogeneity to the local ground conditions, especially where construction works intercept the Palaeogene Lambeth Group. This brings difficulties to the compilation of a ground model that is fully consistent with the ground investigation data, and so to the design and construction of engineering works. However, because bedrock in the London area is rather uniform at outcrop, and is widely covered by Quaternary deposits, few faults are shown on the geological maps of the area. This paper discusses a successful resolution of this problem at a site in east central London, where tunnels for a new underground railway station are planned. A 3D geological model was used to provide an understanding of the local geological structure, in faulted Lambeth Group strata, that had not been possible by other commonly-used methods. This model includes seven previously unrecognised faults, with downthrows ranging from about 1 m to about 12 m. The model was constructed in the GSI3D geological modelling software using about 145 borehole records, including many legacy records, in an area of 850 m by 500 m. The basis of a GSI3D 3D geological model is a network of 2D cross-sections drawn by a geologist, generally connecting borehole positions (where the borehole records define the level of the geological units that are present), and outcrop and subcrop lines for those units (where shown by a geological map). When the lines tracing the base of each geological unit within the intersecting cross-sections are complete and mutually consistent, the software is used to generate TIN surfaces between those lines, so creating a 3D geological model. Even where a geological model is constructed as if no faults were present, changes in apparent dip between two data points within a single cross-section can indicate that a fault is present in that segment of the cross-section. If displacements of similar size with the same polarity are found in a series of adjacent cross-sections, the presence of a fault can be substantiated. If it is assumed that the fault is planar and vertical, then the pairs of constraining data points in each cross-section form a two-dimensional envelope within which the surface trace of the fault must lie. Generally, the broader the area of the model, the longer the envelope defined by the pairs of boreholes is, resulting in better constraint of the fault zone width and azimuth. Repetition or omission of the local stratigraphy in the constraining boreholes can demonstrate reverse or normal dip-slip motion. Even if this is not possible, borehole intercepts at the base of the youngest bedrock unit or at the top of the oldest bedrock unit can constrain the minimum angle of dip of the fault plane. Assessment of the maximum angle of dip requires intrusive investigation. This work is distributed under the Creative Commons Attribution 3.0 Unported License together with an NERC copyright. This license does not conflict with the regulations of the Crown Copyright.

Development of Hydrologic Characterization Technology of Fault Zones -- Phase I, 2nd Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karasaki, Kenzi; Onishi, Tiemi; Black, Bill

2009-03-31

This is the year-end report of the 2nd year of the NUMO-LBNL collaborative project: Development of Hydrologic Characterization Technology of Fault Zones under NUMO-DOE/LBNL collaboration agreement, the task description of which can be found in the Appendix 3. Literature survey of published information on the relationship between geologic and hydrologic characteristics of faults was conducted. The survey concluded that it may be possible to classify faults by indicators based on various geometric and geologic attributes that may indirectly relate to the hydrologic property of faults. Analysis of existing information on the Wildcat Fault and its surrounding geology was performed. Themore » Wildcat Fault is thought to be a strike-slip fault with a thrust component that runs along the eastern boundary of the Lawrence Berkeley National Laboratory. It is believed to be part of the Hayward Fault system but is considered inactive. Three trenches were excavated at carefully selected locations mainly based on the information from the past investigative work inside the LBNL property. At least one fault was encountered in all three trenches. Detailed trench mapping was conducted by CRIEPI (Central Research Institute for Electric Power Industries) and LBNL scientists. Some intriguing and puzzling discoveries were made that may contradict with the published work in the past. Predictions are made regarding the hydrologic property of the Wildcat Fault based on the analysis of fault structure. Preliminary conceptual models of the Wildcat Fault were proposed. The Wildcat Fault appears to have multiple splays and some low angled faults may be part of the flower structure. In parallel, surface geophysical investigations were conducted using electrical resistivity survey and seismic reflection profiling along three lines on the north and south of the LBNL site. Because of the steep terrain, it was difficult to find optimum locations for survey lines as it is desirable for them to be as straight as possible. One interpretation suggests that the Wildcat Fault is westerly dipping. This could imply that the Wildcat Fault may merge with the Hayward Fault at depth. However, due to the complex geology of the Berkeley Hills, multiple interpretations of the geophysical surveys are possible. iv An effort to construct a 3D GIS model is under way. The model will be used not so much for visualization of the existing data because only surface data are available thus far, but to conduct investigation of possible abutment relations of the buried formations offset by the fault. A 3D model would be useful to conduct 'what if' scenario testing to aid the selection of borehole drilling locations and configurations. Based on the information available thus far, a preliminary plan for borehole drilling is outlined. The basic strategy is to first drill boreholes on both sides of the fault without penetrating it. Borehole tests will be conducted in these boreholes to estimate the property of the fault. Possibly a slanted borehole will be drilled later to intersect the fault to confirm the findings from the boreholes that do not intersect the fault. Finally, the lessons learned from conducting the trenching and geophysical surveys are listed. It is believed that these lessons will be invaluable information for NUMO when it conducts preliminary investigations at yet-to-be selected candidate sites in Japan.« less

The study of active tectonic based on hyperspectral remote sensing

NASA Astrophysics Data System (ADS)

Cui, J.; Zhang, S.; Zhang, J.; Shen, X.; Ding, R.; Xu, S.

2017-12-01

As of the latest technical methods, hyperspectral remote sensing technology has been widely used in each brach of the geosciences. However, it is still a blank for using the hyperspectral remote sensing to study the active structrure. Hyperspectral remote sensing, with high spectral resolution, continuous spectrum, continuous spatial data, low cost, etc, has great potentialities in the areas of stratum division and fault identification. Blind fault identification in plains and invisible fault discrimination in loess strata are the two hot problems in the current active fault research. Thus, the study of active fault based on the hyperspectral technology has great theoretical significance and practical value. Magnetic susceptibility (MS) records could reflect the rhythm alteration of the formation. Previous study shown that MS has correlation with spectral feature. In this study, the Emaokou section, located to the northwest of the town of Huairen, in Shanxi Province, has been chosen for invisible fault study. We collected data from the Emaokou section, including spectral data, hyperspectral image, MS data. MS models based on spectral features were established and applied to the UHD185 image for MS mapping. The results shown that MS map corresponded well to the loess sequences. It can recognize the stratum which can not identity by naked eyes. Invisible fault has been found in this section, which is useful for paleoearthquake analysis. The faults act as the conduit for migration of terrestrial gases, the fault zones, especially the structurally weak zones such as inrtersections or bends of fault, may has different material composition. We take Xiadian fault for study. Several samples cross-fault were collected and these samples were measured by ASD Field Spec 3 spectrometer. Spectral classification method has been used for spectral analysis, we found that the spectrum of the fault zone have four special spectral region(550-580nm, 600-700nm, 700-800nm and 800-900nm), which different with the spectrum of the none-fault zone. It could help us welly located the fault zone. The located result correspond well to the physical prospecting method result. The above study shown that Hypersepctral remote sensing technology provide a new method for active study.

Modes of active deformation in Eastern Hispaniola

NASA Astrophysics Data System (ADS)

García-Senz, J.; Pérez-Estaún, A.

2012-04-01

Eastern Hispaniola and the Puerto Rico Island are the emerged part of a doubly vergent thrust wedge formed by oblique arc-continent collision with subduction and underthrusting of the North America Plate in the Puerto Rico trench and underthrusting of the Caribbean crust in The Muertos trough (Dolan et al. 1998, Mann et al., 2002, ten Brink et al. 2010). In the relatively small area of Eastern Hispaniola several types of active crustal deformation have been recognized: 1) At the prowedge of the orogene, the rear of the accretionary prism is cut by the strike-slip Septentrional Fault, bounding a sliver plate (Mann et al, 2002). Recent detailed mapping and aeromagnetic surveys in the onshore part of the prism (Samaná Peninsula and Septentrional Cordillera, Sysmin Team) revealed that the internal structure of the sliver is made of parallel bands of sigmoidal, left-lateral, NW-SE thrust splays, bounded by steep strike-slip faults. We interpreted these structures as transpressional strike-slip duplex. It is worth to note the similarity between the strike and dip of the thrust splays and the 303, 62, 74 focal mechanism calculated by Russo and Villaseñor (1995) for the thrust event of the August 4, 1946 Hispaniola earthquake. 2) The uplifted core of the orogen extends between the accretionary prism and the beginning of the Muertos retrowedge. Half of this area is occupied by the Oriental Cordillera, a recent uplift of cretaceous island-arc rocks arching the Late Neogene reef. The rest of the territory is the Caribbean Coastal Plain modelled on the Late Neogene reef. The Oriental Cordillera is made of two en echelon left-stepping uplifts: the domal-shaped Haitises and the rhombohedral-shaped Seibo (García-Senz et al, 2007); the latter share structural similarities and scaling relations with the 90° neutral stepover model of McClay and Bonora (2001). Therefore we interpret it as a restraining stepover developed over a blind splay of the Septentrional Fault, and the main active fault at surface, the Yabón fault, as a trans pop-up strike-slip fault. 3) The contractive faults and folds that form the Oriental Cordillera disappear to the east replaced by a field of NW-SE to WNW-ESE trending normal faults with fresh scarps up to 75 m high depressing the Late Neogene reef (Punta Cana extended area). In plan form, the faults show multiple relays and transverse ramps at the overlaps. A NE-SW section coast to coast across the Punta Cana area show the Late Neogene reef gently arched and cut by normal faults bounding half-grabens, with the main throw directed to the NE. The amount of extension exceeds 3 km (5% of stretching). A very similar system of normal faults has been documented in seismic lines across the Mona Passage (eg. van Gestel et al., 1998, Mondziel, 2007, Chaytor and ten Brink, 2010) and onshore western Puerto Rico (Hippolyte et al., 2005), which are interpreted by a pinning extension model (Dolan et al., 1998, Mann et al., 2002) or by oblique extension (Chaytor and ten Brink, 2010). Whatever the tectonic model may be, our data places an onshore boundary between transpressional and extensional domains. 4) The retrowedge at the southern margin of Hispaniola form an imbricate of E-W segmented thrusts overriding the Muertos trough (ten Brink et al., 2010). These authors suggest that the transport direction within the Muertos thrust system is southward perpendicular to the regional trend of the belt.

Geometry and active tectonics of the Los Osos-Hosgri Fault Intersection in Estero Bay, CA: Reconciling seismicity patterns with near-surface geology

NASA Astrophysics Data System (ADS)

Watt, J. T.; Hardebeck, J.; Johnson, S. Y.; Kluesner, J.

2016-12-01

Characterizing active structures within structurally complex fault intersections is essential for unraveling the deformational history and for assessing the importance of fault intersections in regional earthquake hazard assessments. We employ an integrative, multi-scale geophysical approach to describe the 3D geometry and active tectonics of the offshore Los Osos fault (LOF) in Estero Bay, California. The shallow structure of the LOF, as imaged with multibeam and high-resolution seismic-reflection data, reveals a complex west-diverging zone of active faulting that bends into and joins the Hosgri fault. The down-dip geometry of the LOF as revealed by gravity, magnetic, and industry multi-channel seismic data, is vertical to steeply-dipping and varies along strike. As the LOF extends offshore, it is characterized by SW-side-up motion on a series of W-NW trending, steeply SW-dipping reverse faults. The LOF bends to the north ( 23°) as it approaches the Hosgri fault and dips steeply to the NE along a magnetic basement block. Inversion of earthquake focal mechanisms within Estero Bay yields maximum compressive stress axes that are near-horizontal and trend approximately N15E. This trend is consistent with dextral strike-slip faulting along NW-SE trending structures such as the Hosgri fault and northern LOF, and oblique dip-slip motion along the W-NW trending section of the LOF. Notably, NW-SE trending structures illuminated by seismicity in Estero Bay coincide with, but also appear to cross-cut, LOF structures imaged in the near-surface. We suggest this apparent disconnect reflects ongoing fault reorganization at a dynamic and inherently unstable fault intersection, in which the seismicity reflects active deformation at depth that is not clearly expressed in the near-surface geology. Direct connectivity between the Hosgri and Los Osos faults suggests a combined earthquake rupture is possible; however, the geometrical complexity along the offshore LOF may limit the extent of rupture.

Characterization of Seismogenic Faults of Central Japan by Geophysical Survey and Drilling

NASA Astrophysics Data System (ADS)

Ikeda, R.; Omura, K.; Matsuda, T.

2004-12-01

Integrated investigations on seismogenic faults by geophysical survey and drilling are indispensable to better understand deep structure and physical properties of a fault fracture zone. In central Japan, three large active faults, Neodani, Atotsugawa and Atera faults, exist and are remarkable for research because of the potentiality of a scale of magnitude 7 to 8 class earthquake and the different characteristics of the seismogenic activities in these faults. Each individual fault shows its own characteristic features, which may reflect different stages in an earthquake cycle. High seismicity is concentrated with a clear lineation on and around the Atotsugawa fault, which is recognized as aftershocks from the latest event of the 1858 Hida earthquake (M=7.0). On the other hand, extremely low seismicity is found around the Atera fault, of which some parts seemed to be dislocated by the 1586 Tensyo earthquake (M=7.9). As an example of the results of study at the Atera fault, we obtained a wide variety of fault structures, composed materials, states of crustal stress and strengths of the fault from the geophysical survey (resistivity and gravity) and in-situ borehole experiments. Our findings are as follows: (1) The fracture zone around the Atera fault shows a very wide and complex fracture structure, from approximately 1 km to 4 km wide. (2) The average slip rate was estimated to be 5.3 m /1000 yr by the distribution of basalt in the age of 1.5 Ma as determined by radioactive dating. We inferred that the Atera fault has been repeatedly active in recent geologic time; however, it is in a very weak state at present. (3) Stress magnitude decreases in the area closer to the center of the fracture zone. These are important results to evaluate fault activity. Recent in-situ downhole measurements and coring through active faults have provided us with new insights into the physical properties of fault zones. In the vicinity of the epicenter of the 1995 Hyogo-ken Nanbu (Kobe) earthquake, we have conducted an integrated study by using 1,000 m to 1,800 m deep drilling wells. In particular, the Nojima-Hirabayashi borehole was drilled to a depth of 1,838 m and directly intersected the Nojima fault. Three possible fault strands were detected at depths of 1,140 m, 1,313 m and 1,800 m. Major results obtained from this study include the following: (1) Shear stress around the fault zone is very small, and the orientation of the maximum horizontal compression is perpendicular to the surface trace of faults. (2) From the results of a heat flow study, the lower cut-off depth of the aftershocks was estimated to be roughly 300 _E#8249;C. (3) Cores were classified into several types of fault rocks, and an asymmetric distribution pattern of these fault rocks in the fracture zones was identified. (4) Country rock is characterized by very low permeability and high strength. (5) Resistivity structure can be explained by a model of a fault extending to greater depths but with low resistivity. The integrated study by geophysical survey, drilling and core analyses, downhole measurements and long-term monitoring directly within these fault zones, provide us with characteristic features and dynamics of active faults.

Geometry and slip rates of active blind thrusts in a reactivated back-arc rift using shallow seismic imaging: Toyama basin, central Japan

NASA Astrophysics Data System (ADS)

Ishiyama, Tatsuya; Kato, Naoko; Sato, Hiroshi; Koshiya, Shin; Toda, Shigeru; Kobayashi, Kenta

2017-10-01

Active blind thrust faults, which can be a major seismic hazard in urbanized areas, are commonly difficult to image with seismic reflection surveys. To address these challenges in coastal plains, we collected about 8 km-long onshore high-resolution two-dimensional (2D) seismic reflection data using a dense array of 800 geophones across compressionally reactivated normal faults within a failed rift system located along the southwestern extension of the Toyama trough in the Sea of Japan. The processing of the seismic reflection data illuminated their detailed subsurface structures to depths of about 3 km. The interpreted depth-converted section, correlated with nearby Neogene stratigraphy, indicated the presence of and along-strike variation of previously unrecognized complex thrust-related structures composed of active fault-bend folds coupled with pairs of flexural slip faults within the forelimb and newly identified frontal active blind thrusts beneath the alluvial plain. In addition, growth strata and fold scarps that deform lower to upper Pleistocene units record the recent history of their structural growth and fault activity. This case shows that shallow seismic reflection imaging with densely spaced seismic recorders is a useful tool in defining locations, recent fault activity, and complex geometry of otherwise inaccessible active blind thrust faults.

Current state of active-fault monitoring in Taiwan

NASA Astrophysics Data System (ADS)

Hou, C.; Lin, C.; Chen, Y.; Liu, H.; Chen, C.; Lin, Y.; Chen, C.

2008-12-01

The earthquake is one of the major hazard sources in Taiwan where an arc-continent collision is on-going. For the purpose of seismic hazard mitigation, to understand current situation of each already-known active fault is urgently needed. After the 1999 Chi-chi earthquake shocked Taiwan, the Central Geological Survey (CGS) of Taiwan aggressively promoted the tasks on studying the activities of active faults. One of them is the deployment of miscellaneous monitoring networks to cover all the target areas, where the earthquake occurrence potentials on active faults are eager to be answered. Up to the end of 2007, CGS has already deployed over 1000 GPS campaign sites, 44 GPS stations in continuous mode, and 42 leveling transects across the major active faults with a total ground distance of 974 km. The campaign sites and leveling tasks have to be measured once a year. The resulted crustal deformation will be relied on to derive the fault slip model. The time series analysis on continuous mode of GPS can further help understand the details of the fault behavior. In addition, 12 down-hole strain meters, five stations for liquid flux and geochemical proxies, and two for water table monitoring have been also installed to seek possible anomalies related to the earthquake activities. It may help discover reliable earthquake precursors.

Zn-dopant dependent defect evolution in GaN nanowires

NASA Astrophysics Data System (ADS)

Yang, Bing; Liu, Baodan; Wang, Yujia; Zhuang, Hao; Liu, Qingyun; Yuan, Fang; Jiang, Xin

2015-10-01

Zn doped GaN nanowires with different doping levels (0, <1 at%, and 3-5 at%) have been synthesized through a chemical vapor deposition (CVD) process. The effect of Zn doping on the defect evolution, including stacking fault, dislocation, twin boundary and phase boundary, has been systematically investigated by transmission electron microscopy and first-principles calculations. Undoped GaN nanowires show a hexagonal wurtzite (WZ) structure with good crystallinity. Several kinds of twin boundaries, including (101&cmb.macr;3), (101&cmb.macr;1) and (202&cmb.macr;1), as well as Type I stacking faults (...ABABC&cmb.b.line;BCB...), are observed in the nanowires. The increasing Zn doping level (<1 at%) induces the formation of screw dislocations featuring a predominant screw component along the radial direction of the GaN nanowires. At high Zn doping level (3-5 at%), meta-stable cubic zinc blende (ZB) domains are generated in the WZ GaN nanowires. The WZ/ZB phase boundary (...ABABAC&cmb.b.line;BA...) can be identified as Type II stacking faults. The density of stacking faults (both Type I and Type II) increases with increasing the Zn doping levels, which in turn leads to a rough-surface morphology in the GaN nanowires. First-principles calculations reveal that Zn doping will reduce the formation energy of both Type I and Type II stacking faults, favoring their nucleation in GaN nanowires. An understanding of the effect of Zn doping on the defect evolution provides an important method to control the microstructure and the electrical properties of p-type GaN nanowires.Zn doped GaN nanowires with different doping levels (0, <1 at%, and 3-5 at%) have been synthesized through a chemical vapor deposition (CVD) process. The effect of Zn doping on the defect evolution, including stacking fault, dislocation, twin boundary and phase boundary, has been systematically investigated by transmission electron microscopy and first-principles calculations. Undoped GaN nanowires show a hexagonal wurtzite (WZ) structure with good crystallinity. Several kinds of twin boundaries, including (101&cmb.macr;3), (101&cmb.macr;1) and (202&cmb.macr;1), as well as Type I stacking faults (...ABABC&cmb.b.line;BCB...), are observed in the nanowires. The increasing Zn doping level (<1 at%) induces the formation of screw dislocations featuring a predominant screw component along the radial direction of the GaN nanowires. At high Zn doping level (3-5 at%), meta-stable cubic zinc blende (ZB) domains are generated in the WZ GaN nanowires. The WZ/ZB phase boundary (...ABABAC&cmb.b.line;BA...) can be identified as Type II stacking faults. The density of stacking faults (both Type I and Type II) increases with increasing the Zn doping levels, which in turn leads to a rough-surface morphology in the GaN nanowires. First-principles calculations reveal that Zn doping will reduce the formation energy of both Type I and Type II stacking faults, favoring their nucleation in GaN nanowires. An understanding of the effect of Zn doping on the defect evolution provides an important method to control the microstructure and the electrical properties of p-type GaN nanowires. Electronic supplementary information (ESI) available: HRTEM image of undoped GaN nanowires and first-principles calculations of Zn doped WZ-GaN. See DOI: 10.1039/c5nr04771d

The reflection of evolving bearing faults in the stator current's extended park vector approach for induction machines

NASA Astrophysics Data System (ADS)

Corne, Bram; Vervisch, Bram; Derammelaere, Stijn; Knockaert, Jos; Desmet, Jan

2018-07-01

Stator current analysis has the potential of becoming the most cost-effective condition monitoring technology regarding electric rotating machinery. Since both electrical and mechanical faults are detected by inexpensive and robust current-sensors, measuring current is advantageous on other techniques such as vibration, acoustic or temperature analysis. However, this technology is struggling to breach into the market of condition monitoring as the electrical interpretation of mechanical machine-problems is highly complicated. Recently, the authors built a test-rig which facilitates the emulation of several representative mechanical faults on an 11 kW induction machine with high accuracy and reproducibility. Operating this test-rig, the stator current of the induction machine under test can be analyzed while mechanical faults are emulated. Furthermore, while emulating, the fault-severity can be manipulated adaptively under controllable environmental conditions. This creates the opportunity of examining the relation between the magnitude of the well-known current fault components and the corresponding fault-severity. This paper presents the emulation of evolving bearing faults and their reflection in the Extended Park Vector Approach for the 11 kW induction machine under test. The results confirm the strong relation between the bearing faults and the stator current fault components in both identification and fault-severity. Conclusively, stator current analysis increases reliability in the application as a complete, robust, on-line condition monitoring technology.

Neotectonics and geomorphic evolution of the northwestern arm of the Yellowstone Tectonic Parabola: Controls on intra-cratonic extensional regimes, southwest Montana

USGS Publications Warehouse

Ruleman, Chester A.; Larsen, Mort; Stickney, Michael C.

2014-01-01

The catastrophic Hebgen Lake earthquake of 18 August 1959 (MW 7.3) led many geoscientists to develop new methods to better understand active tectonics in extensional tectonic regimes that address seismic hazards. The Madison Range fault system and adjacent Hebgen Lake–Red Canyon fault system provide an intermountain active tectonic analog for regional analyses of extensional crustal deformation. The Madison Range fault system comprises fault zones (~100 km in length) that have multiple salients and embayments marked by preexisting structures exposed in the footwall. Quaternary tectonic activity rates differ along the length of the fault system, with less displacement to the north. Within the Hebgen Lake basin, the 1959 earthquake is the latest slip event in the Hebgen Lake–Red Canyon fault system and southern Madison Range fault system. Geomorphic and paleoseismic investigations indicate previous faulting events on both fault systems. Surficial geologic mapping and historic seismicity support a coseismic structural linkage between the Madison Range and Hebgen Lake–Red Canyon fault systems. On this trip, we will look at Quaternary surface ruptures that characterize prehistoric earthquake magnitudes. The one-day field trip begins and ends in Bozeman, and includes an overview of the active tectonics within the Madison Valley and Hebgen Lake basin, southwestern Montana. We will also review geologic evidence, which includes new geologic maps and geomorphic analyses that demonstrate preexisting structural controls on surface rupture patterns along the Madison Range and Hebgen Lake–Red Canyon fault systems.

New insights on the recent and current deformation in Central-Eastern Iran, derived from a combined tectonic and GPS analysis

NASA Astrophysics Data System (ADS)

Walpersdorf, A.; Manighetti, I.; Tavakoli, F.; Mousavi, Z.; Vergnolle, M.; Jadidi, A.; Hatzfeld, D.; Aghamohammadi, A.; Djamour, Y.; Nankali, H.; Sedighi, M.; Lutz, L.

2012-04-01

We have studied the recent to current deformation in Iran and especially Central-Eastern Iran by tightly combining tectonic and GPS analyses. Based on morphotectonic analyses of satellite images, we have identified and mapped the major active faults that dissect the entire ≈ 4500 km x 2500 km2 region that extends from Eastern Turkey to Western Afghanistan/Pakistan and hence encompasses Iran, emphasizing their large-scale organization and kinematic relationships. Doing so, we have identified the major fault systems that control the tectonics of Iran, especially in its central-eastern part. We have also analyzed the 11 years GPS record on the 92 stations deployed in central-eastern Iran in the framework of the Iranian-French collaboration. The GPS analysis reveals that all major faults identified as seismogenic in central-eastern Iran are indeed currently active and slipping at fast rates. The northerly-trending East Lut, West Lut, Kuhbanan, Anar and Deshir faults have a current right-lateral slip rate of 5.7 ± 0.9, 4.7 ± 1.7, 2.3 ± 1.9, 2.7 ± 1.3 and 0.5 ± 0.2 mm/yr, respectively, while the ≈ EW-trending Doruneh and Sedeh faults have a left-lateral current slip rate of 3.1 ± 1.8 and 1.7 ± 0.2 mm/yr, respectively. The large regions bounded by the northerly-striking faults behave as fairly rigid blocks that are all found to move towards both the N13°E ARA-EUR convergence direction and the WNW, at fast rates, in the range 6.5-12.5 and 1-5 mm/yr, respectively. Combined with the available data on the studied faults, our tectonic and geodetic results suggest that a bookshelf faulting strain transfer mechanism has been and is still operating in central-eastern Iran. The coeval dextral motion of the two major, overlapping, North Anatolian-Main Recent and Caucasus-Kopeh Dagh-Herat fault lines that embrace central-eastern Iran, induces a large-scale regional sinistral shear on either side of the region, which forces the northerly-trending right-lateral faults and the blocks they bound to rotate counterclockwise in the horizontal plane. The faults and blocks have been rotating over the last ≈12 Ma, at rates reaching 1.8 °/Ma, and are still currently rotating at about these rates. We estimate the sinistral shear imposed at both edges of the central-eastern rotating zone to be in the range 2.2 - 7.2 mm/yr. The Doruneh fault likely formed more recently than the other central-eastern Iranian faults, as the imposed sinistral shear was evolving from diffuse to more localized. As a consequence, the western half of the Doruneh fault currently accommodates a significant part of the imposed regional sinistral shear. Our study thus shows that the recent to current tectonics of central-eastern Iran is not only controlled by the ARA-EUR convergence, but also by the large-scale kinematics of the adjacent plates. We finally discuss the implications of the novel strain model that we propose on the seismicity that occurs in Central-Eastern Iran.

Active tectonics of the Binalud Mountains, a key puzzle segment to describe Quaternary deformations at the northeastern boundary of the Arabia-Eurasia collision

NASA Astrophysics Data System (ADS)

Shabanian, Esmaeil; Bellier, Olivier; Siame, Lionel L.; Abbassi, Mohammad R.; Leanni, Laetitia; Braucher, Régis; Farbod, Yassaman; Bourlès, Didier L.

2010-05-01

In northeast Iran, the Binalud Mountains accommodate part of active convergence between the Arabian and Eurasian plates. This fault-bounded mountain range has been considered a key region to describe Quaternary deformations at the northeastern boundary of the Arabia-Eurasia collision. But, the lack of knowledge on active faulting hampered evaluating the geological reliability of tectonic models describing the kinematics of deformation in northeast Iran. Morphotectonic investigations along both sides of the Binalud Mountains allowed us to characterize the structural and active faulting patterns along the Neyshabur and Mashhad fault systems on the southwest and northeast sides of the mountain range, respectively. We applied combined approaches of morphotectonic analyses based on satellite imageries (SPOT5 and Landsat ETM+), STRM and site-scale digital topographic data, and field surveys complemented with in situ-produced 10Be exposure dating to determine the kinematics and rate of active faulting. Three regional episodes of alluvial surface abandonments were dated at 5.3±1.1 kyr (Q1), 94±5 kyr (Q3), and 200±14 kyr (S3). The geomorphic reconstruction of both vertical and right-lateral fault offsets postdating these surface abandonment episodes yielded Quaternary fault slip rates on both sides of the Binalud Mountains. On the Neyshabur Fault System, thanks to geomorphic reconstructions of cumulative offsets recorded by Q3 fan surfaces, slip rates of 2.7±0.8 mm/yr and 2.4±0.2 mm/yr are estimated for right-lateral and reverse components of active faulting, respectively. Those indicate a total slip rate of 3.6±1.2 mm/yr for the late Quaternary deformation on the southwest flank of the Binalud Mountains. Reconstructing the cumulative right-lateral offset recorded by S3 surfaces, a middle-late Quaternary slip rate of 1.6±0.1 mm/yr is determined for the Mashhad Fault System. Altogether, our geomorphic observations reveal that, on both sides of the Binalud Mountains, the relative motion between central Iran and Eurasia is partly taken-up by dextral-reverse oblique-slip faulting along the Neyshabur and Mashhad fault systems. This faulting mechanism implies a long-term rate of ~4 mm/yr for the range-parallel strike-slip faulting, and an uplift rate of ~2.4 mm/yr due to the range-normal shortening during late Quaternary. Our data provide the first geological constraints on the rate of active faulting on both sides of the Binalud Mountains, and allow us to examine the geological reliability of preexisting tectonic models proposed to describe the kinematics of active deformation at the northeastern boundary of the Arabia-Eurasia collision. Our results favor the northward translation of central Iran with respect to Eurasia through strike-slip faulting localized along distinct crustal scale fault systems rather than systematic block rotations around vertical axes.

Crustal architecture of an inverted back arc rift basin, Niigata, central Japan

NASA Astrophysics Data System (ADS)

Sato, H.; Abe, S.; Kawai, N.; Saito, H.; Kato, N.; Ishiyama, T.; Iwasaki, T.; Kurashimo, E.; Inaba, M.; Van Horne, A.

2012-04-01

A back arc rift basin, formed during the Miocene opening of the Japan Sea, now uplifted and exposed in Niigata, central Japan, provides an exceptional opportunity to study a back arc rift formed on a short time scale and in a still active setting for the present day shortening deformation. Due to stress build up before the 2011 Tohoku earthquake (M9), two damaging earthquakes (M6.8) occurred in 2004 and 2007 in this inverted rift basin. Deep seismic profiling was performed along four seismic lines between 2008 and 2011. We used onshore-offshore deep seismic reflection profiling to examine the crustal architecture of the back arc basin, in particular the geometry of the source faults. We further applied refraction tomography analysis to distinguish between previously undifferentiated syn-rift volcanics and pre-rift Mesozoic rock based on P-wave velocity. Our findings indicate that the Miocene rift structure created during the extensional phase regulates the style of deformation and the geometry of the source faults in the current compressional regime. Syn-rift volcanics with a maximum thickness of 6 km filled the fault controlled basins as rifting proceeded. The volcanism was bimodal, comprising a reflective unit of mafic rocks around the rift axis and a non-reflective unit of felsic rocks near the margins of the basins. Once rifting ended, thermal subsidence, and subsequently, mechanical subsidence related to the onset of the compressional regime, allowed deposition of up to 5 km of post-rift, deep marine to fluvial sedimentation, including the Teradomari Formation, an over-pressured mudstone in the middle of the section that later became an important shallow detachment layer. Continued compression has caused fault-related fold and wedge thrusting in the post-rift sedimentary strata which are highly deformed by thin-skin style deformation. Since the Pliocene, normal faults created during the rift phase have been reactivated as reverse faults, including a shallow detachment in the Teradomari Formation which forms a complicated shortened deformation structure. Quaternary geomorphology suggests ongoing shortening. Transform faults inherited from the rift stage control the extent of present day reverse source faults and more importantly, earthquake magnitude.

Near-shore Evaluation of Holocene Faulting and Earthquake Hazard in the New York City Metropolitan Region

NASA Astrophysics Data System (ADS)

Cormier, M. H.; King, J. W.; Seeber, L.; Heil, C. W., Jr.; Caccioppoli, B.

2016-12-01

During its relatively short historic period, the Atlantic Seaboard of North America has experienced a few M6+ earthquakes. These events raise the specter of a similar earthquake occurring anywhere along the eastern seaboard, including in the greater New York City (NYC) metropolitan area. Indeed, the NYC Seismic Zone is one of several concentrations of earthquake activity that stand out in the field of epicenters over eastern North America. Various lines of evidence point to a maximum magnitude in the M7 range for metropolitan NYC - a dramatic scenario that is counterbalanced by the low probability of such an event. Several faults mapped near NYC strike NW, sub-normal to the NE-striking structural trends of the Appalachians, and all earthquake sequences with well-established fault sources in the NYC seismic zone originate from NW-striking faults. With funding from the USGS Earthquake Hazard Program, we recently (July 2016) collected 85 km of high-resolution sub-bottom (CHIRP) profiles along the north shore of western Long Island Sound, immediately adjacent to metropolitan NYC. This survey area is characterized by a smooth, 15.5 kyr-old erosional surface and overlying strata with small original relief. CHIRP sonar profiles of these reflectors are expected to resolve fault or fold-related vertical relief (if present) greater than 50 cm. They would also resolve horizontal fault displacements with similar resolution, as may be expressed by offsets of either sedimentary or geomorphic features. No sedimentary cover on the land portion of the metro area offers such ideal reference surfaces, which are continuous in both time and space. Seismic profiles have a spacing of 200 m and have been acquired mostly perpendicular to the NW-striking faults mapped on land. These new data will be analyzed systematically for all resolvable features and then interpreted, distinguishing sedimentary, geomorphic, and tectonic features. The absence of evidence of post-glacial tectonic deformation would be a reliable negative result with implications regarding the lateral dimensions and southeastward continuity of the brittle faults mapped on land, and their potential for generation of large earthquakes with surface ruptures.

InSAR Analysis of Post-Seismic Deformation Following the 2013 Mw 7.7 Balochistan, Pakistan Earthquake

NASA Astrophysics Data System (ADS)

Peterson, K.; Barnhart, W. D.

2017-12-01

On September 24th, 2013, a Mw 7.7 earthquake ruptured a 200 km portion of the Hoshab fault, a reverse fault in the Makran accretionary prism of southern Pakistan. This earthquake is notable because it ruptured a reverse fault with a predominantly strike-slip sense of displacement, and it ruptured a mechanically weak accretionary prism. Here, we present initial analysis of ongoing post-seismic deformation imaged with the Sentinel-1 interferometric synthetic aperture radar (InSAR) mission with the goals of a) determining the dominant post-seismic deformation processes active, b) characterizing the rigidity and rheological structure of a flat-slab subduction zone, and c) elucidating whether post-seismic deformation may account for or exacerbate the 4-6 m fault convergence deficit left by the 2013 earthquake. We first present InSAR time series analysis of the post-seismic transient derived from ongoing Sentinel-1 SAR acquisitions, including a comparison of atmosphere-corrected and uncorrected time series. Interferograms spanning December 2014 to the present reveal an ongoing post-seismic deformation transient in the region surrounding the Hoshab fault. Additionally, fault creep signals on and adjacent to the Hoshab fault are present. Second, we present a suite of forward models that explore the potential contributions of viscoelastic relaxation and frictional afterslip to the recorded displacement signal. These models, conducted using the semi-analytical solutions of RELAX and compared to InSAR line-of-sight time series displacements, explore a range of candidate rheological descriptions of the Makran subduction zone that are designed to probe the rheological structure of a region where current knowledge of the subsurface geology is highly limited. Our preliminary results suggest that post-seismic displacements arise from a combination of viscoelastic deformation and frictional afterslip, as opposed to one single mechanism. Additionally, our preliminary results suggest surface displacements are characterized by dominantly fault- parallel displacements, indicating that post-seismic deformation in the observed time period following the 2013 earthquake likely cannot account for the 4-6 m convergence deficit left by that earthquake.

Hydrogeochemistry Characteristics and Daily Variation of Geothermal Water in the Moxi Fault,Southwest of China

NASA Astrophysics Data System (ADS)

Qi, Jihong; Xu, Mo; An, Chenjiao; Zhang, Yunhui; Zhang, Qiang

2017-04-01

The Xianshuihe Fault with frequent earthquakes activities is the regional deep fault in China. The Moxi Fault is the southern part of the Xianshuihe Fault, where the strong activities of geothermal water could bring abundant information of deep crust. In this article, some typical geothermal springs were collected along the Moxi fault from Kangding to Shimian. Using the the Na-K-Mg equilibrium diagram, it explains the state of water-rock equilibrium, and estimates the reservoir temperature basing appropriate geothermometers. Basing on the relationship between the enthalpy and chlorine concentration of geothermal water, it analyze the mixing progress of thermal water with shallow groundwater. Moreover, the responses of variation of geothermal water to the solid tides are considered to study the hydrothermal activities of this fault. The Guanding in Kangding are considered as the center of the geothermal system, and the hydrothermal activities decrease southward extending. Geothermal water maybe is heated by the deep heat source of the Himalayan granites, while the springs in the south area perform the mixture with thermal water in the sub-reservoir of the Permian crystalline limestone. It improves the research of hydrothermal activities in the Moxi Fault, meanwhile using the variation of geothermal water maybe become a important method to study the environment of deep earth in the future.

The Devils Mountain Fault zone: An active Cascadia upper plate zone of deformation, Pacific Northwest of North America

NASA Astrophysics Data System (ADS)

Barrie, J. Vaughn; Greene, H. Gary

2018-02-01

The Devils Mountain Fault Zone (DMFZ) extends east to west from Washington State to just south of Victoria, British Columbia, in the northern Strait of Juan de Fuca of Canada and the USA. Recently collected geophysical data were used to map this fault zone in detail, which show the main fault trace, and associated primary and secondary (conjugate) strands, and extensive northeast-southwest oriented folding that occurs within a 6 km wide deformation zone. The fault zone has been active in the Holocene as seen in the offset and disrupted upper Quaternary strata, seafloor displacement, and deformation within sediment cores taken close to the seafloor expression of the faults. Data suggest that the present DMFZ and the re-activated Leech River Fault may be part of the same fault system. Based on the length and previously estimated slip rates of the fault zone in Washington State, the DMFZ appears to have the potential of producing a strong earthquake, perhaps as large as magnitude 7.5 or greater, within 2 km of the city of Victoria.

Basement depth and sedimentary infill from deep seismic reflection data at the western tip of the offshore Corinth Rift

NASA Astrophysics Data System (ADS)

Beckers, Arnaud; Tripsanas, Efthymios; Hubert-Ferrari, Aurélia; Beck, Christian; Sakellariou, Dimitris

2015-04-01

The Corinth rift is a young continental rift located in central Greece. The active part of the rift forms an E-W striking depression - the Gulf of Corinth - that is the deepest in its central part. Extensive seismic surveys have imaged the basin's basement and allowed to estimate the total extension across most of the Gulf except its western tip. Extension is high in the central part and decreases westward and eastward, as reflected in the present-day bathymetry. Two decades of GPS measurements have shown that the extension rate increases westwards from ~5 to 10-15 mm yr-1, but this is not consistent with the long term pattern. However, no data allowed so far to estimate the basement depth at the western tip of the Gulf, where the geodetic extension rate is the largest. Such data would allow to check the apparent inconsistency between the present rate and the long-term estimates of crustal extension. We present here an unpublished multichannel seismic line dating from 1979 and crossing the western tip of the Gulf of Corinth. The line is 22 km long and strikes WNW-ESE, from the Mornos delta to the West-Channel fault. A Maxipulse source has been used, allowing to image the basement below the synrift sedimentary infill. To the east, a ~1.6 km deep basin is imaged between the southern margin of the Gulf and an inactive south-dipping fault located between the Aigion and the Trizonia faults. The sedimentary infill consists in an alternation between basin-focused bodies made of incoherent reflections and more extensive high-amplitude reflectors. Attributing this alternation to eustatic variations give an age of 300-350 ka to the oldest well imaged deposits. Northwest of the Trizonia fault, the basement is imaged at shallower depth, i.e. ~450 m. The western tip of the seismic line reaches the Mornos delta, close to the northern shoreline. There, the depth to the basement is larger, reaching ~1.2 km. The infill is made of 3 units : on the basement lies a thin unit of incoherent reflections that may corresponds to coarse-grained fluvial deposits. A second unit of parallel, high-amplitude, low-frequency reflections could represent deeper-water deposits. The last seismic unit represents the Mornos delta coarse-grained deposits, from 0 to ~0.7 km deep. The depth of the basement deduced from this seismic line at the western tip of the Gulf of Corinth (1.2-1.6 km) is shallower than the one in the central part of the Gulf (2.5-3 km). This reinforce the inconsistency between long-term and short-term rates of extension in the Corinth Rift, which may be explained by assuming that the Western Corinth Rift initiated much later than the Central Rift. These data also allow to constrain the total displacement on the N-dipping Psathopyrgos fault, one of the major, normal, basin-bounding faults at the western tip of the Rift. The total offset would reach 2.1-2.3 km and the uplift/subsidence ratio would be ~1:1.7, implying a slip rate of 2.2-2.5 mm yr-1 based on footwall uplift rate data.

Modelling of hydrothermal fluid flow and structural architecture in an extensional basin, Ngakuru Graben, Taupo Rift, New Zealand

NASA Astrophysics Data System (ADS)

Kissling, W. M.; Villamor, P.; Ellis, S. M.; Rae, A.

2018-05-01

Present-day geothermal activity on the margins of the Ngakuru graben and evidence of fossil hydrothermal activity in the central graben suggest that a graben-wide system of permeable intersecting faults acts as the principal conduit for fluid flow to the surface. We have developed numerical models of fluid and heat flow in a regional-scale 2-D cross-section of the Ngakuru Graben. The models incorporate simplified representations of two 'end-member' fault architectures (one symmetric at depth, the other highly asymmetric) which are consistent with the surface locations and dips of the Ngakuru graben faults. The models are used to explore controls on buoyancy-driven convective fluid flow which could explain the differences between the past and present hydrothermal systems associated with these faults. The models show that the surface flows from the faults are strongly controlled by the fault permeability, the fault system architecture and the location of the heat source with respect to the faults in the graben. In particular, fault intersections at depth allow exchange of fluid between faults, and the location of the heat source on the footwall of normal faults can facilitate upflow along those faults. These controls give rise to two distinct fluid flow regimes in the fault network. The first, a regular flow regime, is characterised by a nearly unchanging pattern of fluid flow vectors within the fault network as the fault permeability evolves. In the second, complex flow regime, the surface flows depend strongly on fault permeability, and can fluctuate in an erratic manner. The direction of flow within faults can reverse in both regimes as fault permeability changes. Both flow regimes provide insights into the differences between the present-day and fossil geothermal systems in the Ngakuru graben. Hydrothermal upflow along the Paeroa fault seems to have occurred, possibly continuously, for tens of thousands of years, while upflow in other faults in the graben has switched on and off during the same period. An asymmetric graben architecture with the Paeroa being the major boundary fault will facilitate the predominant upflow along this fault. Upflow on the axial faults is more difficult to explain with this modelling. It occurs most easily with an asymmetric graben architecture and heat sources close to the graben axis (which could be associated with remnant heat from recent eruptions from Okataina Volcanic Centre). Temporal changes in upflow can also be associated with acceleration and deceleration of fault activity if this is considered a proxy for fault permeability. Other explanations for temporal variations in hydrothermal activity not explored here are different permeability on different faults, and different permeability along fault strike.

Fault tectonics and earthquake hazards in parts of southern California. [penninsular ranges, Garlock fault, Salton Trough area, and western Mojave Desert

NASA Technical Reports Server (NTRS)

Merifield, P. M. (Principal Investigator); Lamar, D. L.; Gazley, C., Jr.; Lamar, J. V.; Stratton, R. H.

1976-01-01

The author has identified the following significant results. Four previously unknown faults were discovered in basement terrane of the Peninsular Ranges. These have been named the San Ysidro Creek fault, Thing Valley fault, Canyon City fault, and Warren Canyon fault. In addition fault gouge and breccia were recognized along the San Diego River fault. Study of features on Skylab imagery and review of geologic and seismic data suggest that the risk of a damaging earthquake is greater along the northwestern portion of the Elsinore fault than along the southeastern portion. Physiographic indicators of active faulting along the Garlock fault identifiable in Skylab imagery include scarps, linear ridges, shutter ridges, faceted ridges, linear valleys, undrained depressions and offset drainage. The following previously unrecognized fault segments are postulated for the Salton Trough Area: (1) An extension of a previously known fault in the San Andreas fault set located southeast of the Salton Sea; (2) An extension of the active San Jacinto fault zone along a tonal change in cultivated fields across Mexicali Valley ( the tonal change may represent different soil conditions along opposite sides of a fault). For the Skylab and LANDSAT images studied, pseudocolor transformations offer no advantages over the original images in the recognition of faults in Skylab and LANDSAT images. Alluvial deposits of different ages, a marble unit and iron oxide gossans of the Mojave Mining District are more readily differentiated on images prepared from ratios of individual bands of the S-192 multispectral scanner data. The San Andreas fault was also made more distinct in the 8/2 and 9/2 band ratios by enhancement of vegetation differences on opposite sides of the fault. Preliminary analysis indicates a significant earth resources potential for the discrimination of soil and rock types, including mineral alteration zones. This application should be actively pursued.

Temporal evolution of fault systems in the Upper Jurassic of the Central German Molasse Basin: case study Unterhaching

NASA Astrophysics Data System (ADS)

Budach, Ingmar; Moeck, Inga; Lüschen, Ewald; Wolfgramm, Markus

2018-03-01

The structural evolution of faults in foreland basins is linked to a complex basin history ranging from extension to contraction and inversion tectonics. Faults in the Upper Jurassic of the German Molasse Basin, a Cenozoic Alpine foreland basin, play a significant role for geothermal exploration and are therefore imaged, interpreted and studied by 3D seismic reflection data. Beyond this applied aspect, the analysis of these seismic data help to better understand the temporal evolution of faults and respective stress fields. In 2009, a 27 km2 3D seismic reflection survey was conducted around the Unterhaching Gt 2 well, south of Munich. The main focus of this study is an in-depth analysis of a prominent v-shaped fault block structure located at the center of the 3D seismic survey. Two methods were used to study the periodic fault activity and its relative age of the detected faults: (1) horizon flattening and (2) analysis of incremental fault throws. Slip and dilation tendency analyses were conducted afterwards to determine the stresses resolved on the faults in the current stress field. Two possible kinematic models explain the structural evolution: One model assumes a left-lateral strike slip fault in a transpressional regime resulting in a positive flower structure. The other model incorporates crossing conjugate normal faults within a transtensional regime. The interpreted successive fault formation prefers the latter model. The episodic fault activity may enhance fault zone permeability hence reservoir productivity implying that the analysis of periodically active faults represents an important part in successfully targeting geothermal wells.

Sliding mode based fault detection, reconstruction and fault tolerant control scheme for motor systems.

PubMed

Mekki, Hemza; Benzineb, Omar; Boukhetala, Djamel; Tadjine, Mohamed; Benbouzid, Mohamed

2015-07-01

The fault-tolerant control problem belongs to the domain of complex control systems in which inter-control-disciplinary information and expertise are required. This paper proposes an improved faults detection, reconstruction and fault-tolerant control (FTC) scheme for motor systems (MS) with typical faults. For this purpose, a sliding mode controller (SMC) with an integral sliding surface is adopted. This controller can make the output of system to track the desired position reference signal in finite-time and obtain a better dynamic response and anti-disturbance performance. But this controller cannot deal directly with total system failures. However an appropriate combination of the adopted SMC and sliding mode observer (SMO), later it is designed to on-line detect and reconstruct the faults and also to give a sensorless control strategy which can achieve tolerance to a wide class of total additive failures. The closed-loop stability is proved, using the Lyapunov stability theory. Simulation results in healthy and faulty conditions confirm the reliability of the suggested framework. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Identification and interpretation of tectonic features from Skylab imagery. [California to Arizona

NASA Technical Reports Server (NTRS)

Abdel-Gawad, M. (Principal Investigator)

1974-01-01

The author has identified the following significant results. S190-B imagery confirmed previous conclusions from S190-A that the Garlock fault does not extend eastward beyond its known termination near the southern end of Death Valley. In the Avawatz Mountains, California, two faults related to the Garlock fault zone (Mule Spring fault and Leach Spring fault) show evidence of recent activity. There is evidence that faulting related to Death Valley fault zone extends southeastward across the Old Dad Mountains. There, the Old Dad fault shows evidence of recent activity. A significant fault lineament has been identified from McCullough Range, California southeastward to Eagle Tail Mountains in southwestern Arizona. The lineament appears to control tertiary and possible cretaceous intrusives. Considerable right lateral shear is suspected to have taken place along parts of this lineament.

Fault detection of helicopter gearboxes using the multi-valued influence matrix method

NASA Technical Reports Server (NTRS)

Chin, Hsinyung; Danai, Kourosh; Lewicki, David G.

1993-01-01

In this paper we investigate the effectiveness of a pattern classifying fault detection system that is designed to cope with the variability of fault signatures inherent in helicopter gearboxes. For detection, the measurements are monitored on-line and flagged upon the detection of abnormalities, so that they can be attributed to a faulty or normal case. As such, the detection system is composed of two components, a quantization matrix to flag the measurements, and a multi-valued influence matrix (MVIM) that represents the behavior of measurements during normal operation and at fault instances. Both the quantization matrix and influence matrix are tuned during a training session so as to minimize the error in detection. To demonstrate the effectiveness of this detection system, it was applied to vibration measurements collected from a helicopter gearbox during normal operation and at various fault instances. The results indicate that the MVIM method provides excellent results when the full range of faults effects on the measurements are included in the training set.

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

NASA Astrophysics Data System (ADS)

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

2007-12-01

As a result of continued distributed deformation in the Gulf Extensional Province along an oblique-divergent plate margin, active normal faulting is well manifest in southeastern Baja California. By characterizing normal-fault related deformation along the San Juan de los Planes fault zone (SJPFZ) southwest of La Paz, Baja California Sur we contribute to understanding the patterns and rates of faulting along the southwest gulf-margin fault system. The geometry, history, and rate of faulting provide constraints on the relative significance of gulf-margin deformation as compared to axial system deformation. The SJPFZ is a major north-trending structure in the southern Baja margin along which we focused our field efforts. These investigations included: a detailed strip map of the active fault zone, including delineation of active scarp traces and geomorphic surfaces on the hanging wall and footwall; fault scarp profiles; analysis of bedrock structures to better understand how the pattern and rate of strain varied during the development of this fault zone; and a gravity survey across the San Juan de los Planes basin to determine basin geometry and fault behavior. The map covers a N-S swath from the Gulf of California in the north to San Antonio in the south, an area ~45km long and ~1-4km wide. Bedrock along the SJPFZ varies from Cretaceous Las Cruces Granite in the north to Cretaceous Buena Mujer Tonalite in the south and is scarred by shear zones and brittle faults. The active scarp-forming fault juxtaposes bedrock in the footwall against Late Quaternary sandstone-conglomerate. This ~20m wide zone is highly fractured bedrock infused with carbonate. The northern ~12km of the SJPFZ, trending 200°, preserves discontinuous scarps 1-2km long and 1-3m high in Quaternary units. The scarps are separated by stretches of bedrock embayed by hundreds of meters-wide tongues of Quaternary sandstone-conglomerate, implying low Quaternary slip rate. Further south, ~2 km north of the Los Planes highway, the fault steps to the right 2km with no overlap. The fault is inactive until ~3km south of the Los Planes highway where scarp heights in the Quaternary sediments rise to ~3-11m for ~11km with an average trend of 160°, implying increasing slip rate. The fault then steps left 2km with no overlap, trending 145°. Scarp heights range from 3-6m in the step. The southernmost 9km of the fault zone, trending 200°, is marked by discontinuous scarps and embayed bedrock, reflecting diminished fault activity. The footwall landscape in this area is characterized by a broad, gently-sloping, low-relief pediment surface with thin Quaternary cover, disrupted by inselberg-like hills. The young scarp-forming fault appears to have reactivated older faults to rupture this pediment, reflecting the episodic nature of slip along this fault zone. Preliminary OSL ages of the youngest faulted deposit imply a Late Pleistocene-Holocene slip rate of 0.1-1mm/yr. The SJPFZ is thus characterized by reactivation of pre-existing faults to rupture a pre-existing low relief erosional landscape. Whereas the entire region might have experienced the quiescent period that allowed for development of the low- relief, stable surface along the SJPFZ, we speculate that while the SJPFZ was dormant, other faults within the gulf-margin system were actively accommodating strain.

Multifaulting in a tectonic syntaxis revealed by InSAR: The case of the Ziarat earthquake sequence (Pakistan)

NASA Astrophysics Data System (ADS)

Pinel-Puysségur, B.; Grandin, R.; Bollinger, L.; Baudry, C.

2014-07-01

On 28-29 October 2008, within 12 h, two similar Mw = 6.4 strike-slip earthquakes struck Baluchistan (Pakistan), as part of a complex seismic sequence. Interferometric Synthetic Aperture Radar (InSAR) data reveal that the peak of surface displacement is near the Ziarat anticline, a large active fold affected by Quaternary strike-slip faulting. All coseismic interferograms integrate the deformation due to both earthquakes. As their causative faults ruptured close to each other, the individual signals cannot be separated. According to their focal mechanisms, each earthquake may have activated a NE-SW sinistral or a NW-SE dextral fault segment, which leads to four possible scenarios of fault orientations. A nonlinear inversion of the InSAR data set allows rejecting two scenarios. The best slip distributions on the two fault segments for the two remaining scenarios are determined by linear inversion. Stress-change modeling favors a scenario involving two abutting conjugate strike-slip faults. Two other fault segments accommodated left-lateral strike slip during the seismic sequence. The activated fault system includes multiple fault segments with different orientations and little surface expression. This may highlight, at a smaller scale, the distributed, possibly transient character of deformation within a broader right-lateral shear zone. It suggests that the activated faults delineate a small tectonic block extruding and subtly rotating within the shear zone. It occurs in the vicinity of the local tectonic syntaxis where orogenic structures sharply turn around a vertical axis. These mechanisms could participate in the long-term migration of active tectonic structures within this kinematically unstable tectonic syntaxis.

A reconnaissance space sensing investigation of crustal structure for a strip from the eastern Sierra Nevada to the Colorado Plateau

NASA Technical Reports Server (NTRS)

Bechtold, I. C. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Analysis of ERTS-1 MSS imagery over the sourthern Basin-Range Province of California, Nevada, and Arizona has led to recognition of regional tectonic control of volcanism, plutonism, mineralization, and fault patterns. This conclusion is the result of geologic reconnaissance of anomalies observed in ERTS-1 and Apollo-9 data, guided by intermediate scale U-2 photography, SLAR, and relevant geologic literature. In addition to regional tectonic studies, the ERTS-1 imagery provides a basis for detailed research of relatively small geologic features. Interpretation of ERTS-1 and Apollo-9 space imagery and intermediate scale X-15 and U-2 photography indicates the presence of a major fault zone along the California-Nevada state line, here named the Pahrump fault zone. Field mapping confirms previously unreported evidence of fault breaks in bedrock, along range fronts and in Quaternary alluvium and lake sediments. Regional gravity lows and fault traces within the Pahrump fault zone from a general left stepping en echelon pattern. The trend and postulated diplacement for this fault are similar to other major strike slip fault zones in the southern Basin-Range Province.

Faults Diagnostics of Railway Axle Bearings Based on IMF’s Confidence Index Algorithm for Ensemble EMD

PubMed Central

Yi, Cai; Lin, Jianhui; Zhang, Weihua; Ding, Jianming

2015-01-01

As train loads and travel speeds have increased over time, railway axle bearings have become critical elements which require more efficient non-destructive inspection and fault diagnostics methods. This paper presents a novel and adaptive procedure based on ensemble empirical mode decomposition (EEMD) and Hilbert marginal spectrum for multi-fault diagnostics of axle bearings. EEMD overcomes the limitations that often hypothesize about data and computational efforts that restrict the application of signal processing techniques. The outputs of this adaptive approach are the intrinsic mode functions that are treated with the Hilbert transform in order to obtain the Hilbert instantaneous frequency spectrum and marginal spectrum. Anyhow, not all the IMFs obtained by the decomposition should be considered into Hilbert marginal spectrum. The IMFs’ confidence index arithmetic proposed in this paper is fully autonomous, overcoming the major limit of selection by user with experience, and allows the development of on-line tools. The effectiveness of the improvement is proven by the successful diagnosis of an axle bearing with a single fault or multiple composite faults, e.g., outer ring fault, cage fault and pin roller fault. PMID:25970256

Sidescan Sonar Imagery of the Escanaba Trough, Southern Gorda Ridge, Offshore Northern California

USGS Publications Warehouse

Ross, Stephanie L.; Zierenberg, Robert A.

2009-01-01

This map features sidescan imagery of the northern Escanaba (NESCA) site at the Escanaba Trough, southern Gorda Ridge, offshore northern California. The Escanaba Trough, a largely sediment-covered seafloor spreading center, contains at least six large massive sulfide deposits. It is a slow spreading center (2.5 cm/yr) with axial depths locally exceeding 3,300 m. Discrete igneous centers occur at 5- to 10-km intervals along this slow-spreading ridge. Basaltic magma intrudes the sediment fill of the axial valley, creating uplifted sediment hills, and, in some areas, erupts onto the sea floor. Large massive sulfide deposits occur along the margins of the uplifted sediment hills. The only active hydrothermal system is located on Central Hill where 220 deg C fluids construct anhydrite chimneys on pyrrhotite-rich massive sulfide mounds (Campbell and others, 1994). Central Hill is bounded by both ridge-parallel basement faults and a concentric set of faults that rim the top of the hill and may be associated with sill intrusion. Central Hill was one of the primary drill sites for Ocean Drilling Program (ODP) Leg 169. The sidescan sonar data (mosaics A, B, C, D) were collected aboard the National Oceanic and Atmospheric Administration (NOAA) research vessel Discoverer in the summer of 1996 with a 60-kHz system towed 100 to 200 m above the sea floor. Major faults and contacts are interpreted from the sidescan mosaics and 4.5-kHz seismic profiles collected simultaneously, as well as from previously conducted camera transects and submersible dives. The seismic profiles (lines 9, 11, 13) provide high-resolution subbottom structure and stratigraphy to a depth of about 50 m. In the sidescan images (mosaics A, B, C, D), bright areas denote high-energy returns from hard reflectors such as volcanic flows, sulfide deposits, or seafloor scarps. Dark areas denote low-energy returns and generally signify relatively undisturbed surface sediment. The grid lines mark one-minute intervals of latitude and longitude. The large sidescan sonar image (mosaic A) is centered on the NESCA igneous center. The spreading axis is flanked on either side by uplifted, sediment-covered terraces that show relatively continuous and undisturbed turbiditic sediment. These terraces bound the 4- to 5-km-wide neotectonic zone that is characterized by more closely spaced, small offset (<20 m) faults, volcanic flows (brightest area of backscatter), and areas where the seismic layering of the turbidites has been partially to completely disrupted by the intrusion of basaltic sills. The most prominent bathymetric features are the three uplifted sediment hills: Central Hill, Southwest Hill, and an unnamed uplifted hill to the north. These features are interpreted to be uplifted above large-volume basaltic intrusions emplaced near the basalt/sediment interface. Southwest Hill is adjacent to the zone of most recent faulting. This hill no longer retains the circular shape of the other hills due to slumps (lines 9, 11), which may have failed along faults related to the most recent spreading. Central Hill is interpreted to be the most recently uplifted sediment hill based on the morphology of the hill and the presence of an active hydrothermal system. The generally continuous area of volcanic basalt flow east of Central Hill appears as a distinct, bright sonar reflector stretching for approximately 6 km along axis (red contact on mosaic A). This flow may be related to the intrusion that is presumed to have uplifted Central Hill. Submersible observations indicate that lava flowed around the sediment hills and ponded against the eastern up-faulted turbidite-covered sediment terrace. Previously collected, deep-penetration seismic data indicate that the lavas overlie about 450 m of sediment (Morton and Fox, 1994). Late-stage emplacement of magma in the shallow subsurface beneath the exposed lava flow is interpreted to have domed the lava flow, forming the east-west-

Seismicity and Tectonics of the West Kaibab Fault Zone, AZ

NASA Astrophysics Data System (ADS)

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

2014-12-01

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 <1.6 Ma. Slip rates are estimated to be less than 0.2 mm/yr. No historic fault slip has been documented. The WKFZ is 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.

Subsurface Resistivity Structures in and Around Strike-Slip Faults - Electromagnetic Surveys and Drillings Across Active Faults in Central Japan -

NASA Astrophysics Data System (ADS)

Omura, K.; Ikeda, R.; Iio, Y.; Matsuda, T.

2005-12-01

Electrical resistivity is important property to investigate the structure of active faults. Pore fluid affect seriously the electrical properties of rocks, subsurface electrical resistivity can be an indicator of the existence of fluid and distribution of pores. Fracture zone of fault is expected to have low resistivity due to high porosity and small gain size. Especially, strike-slip type fault has nearly vertical fracture zone and the fracture zone would be detected by an electrical survey across the fault. We performed electromagnetic survey across the strike-slip active faults in central Japan. At the same faults, we also drilled borehole into the fault and did downhole logging in the borehole. We applied MT or CSAMT methods onto 5 faults: Nojima fault which appeared on the surface by the 1995 Great Kobe earthquake (M=7.2), western Nagano Ohtaki area(1984 Nagano-ken seibu earthquake (M=6.8), the fault did not appeared on the surface), Neodani fault which appeared by the 1891 Nobi earthquake (M=8.0), Atera fault which seemed to be dislocated by the 1586 Tensyo earthquake (M=7.9), Gofukuji fault that is considered to have activated about 1200 years ago. The sampling frequencies of electrical and magnetic field were 2 - 1024Hz (10 frequencies) for CSAMT survey and 0.00055 - 384Hz (40 frequencies) for MT survey. The electromagnetic data were processed by standard method and inverted to 2-D resistivity structure along transects of the faults. Results of the survey were compared with downhole electrical logging data and observational descriptions of drilled cores. Fault plane of each fault were recognized as low resistivity region or boundary between relatively low and high resistivity region, except for Gofukuji fault. As for Gofukuji fault, fault was located in relatively high resistivity region. During very long elapsed time from the last earthquake, the properties of fracture zone of Gofukuji fault might changed from low resistivity properties as observed for other faults. Downhole electrical logging data were consistent to values of resistivity estimated by electromagnetic survey for each fault. The existence of relatively low and high resistivity regions in 2-D structure from electromagnetic survey was observed again by downhole logging at the correspondent portion in the borehole. Cores recovered from depthes where the electrical logging showed low resistivity were hardly fractured and altered from host rock which showed high resistivity. Results of electromagnetic survey, downhole electrical logging and observation of drilled cores were consistent to each other. In present case, electromagnetic survey is useful to explore the properties of fault fracture zone. In the further investigations, it is important to explore relationships among features of resistivity structure and geological and geophysical situations of the faults.

2D resistivity imaging and magnetic survey for characterization of thermal springs: A case study of Gergedi thermal springs in the northwest of Wonji, Main Ethiopian Rift, Ethiopia

NASA Astrophysics Data System (ADS)

Abdulkadir, Yahya Ali; Eritro, Tigistu Haile

2017-09-01

Electrical resistivity imaging and magnetic surveys were carried out at Gergedi thermal springs, located in the Main Ethiopian Rift, to characterize the geothermal condition of the area. The area is geologically characterized by alluvial and lacustrine deposits, basaltic lava, ignimbrites, and rhyolites. The prominent structural feature in this part of the Main Ethiopian Rift, the SW -NE trending structures of the Wonji Fault Belt System, crosse over the study area. Three lines of imaging data and numerous magnetic data, encompassing the active thermal springs, were collected. Analysis of the geophysical data shows that the area is covered by low resistivity response regions at shallow depths which resulted from saline moisturized soil subsurface horizon. Relatively medium and high resistivity responses resulting from the weathered basalt, rhyolites, and ignimbrites are also mapped. Qualitative interpretation of the magnetic data shows the presence of structures that could act as pathways for heat and fluids manifesting as springs and also characterize the degree of thermal alteration of the area. Results from the investigations suggest that the Gergedi thermal springs area is controlled by fault systems oriented parallel and sub-parallel to the main tectonic lines of the Main Ethiopian Rift.

Do mesoscale faults near the tip of an active strike-slip fault indicate regional or local stress?

NASA Astrophysics Data System (ADS)

Yamaji, Atsushi

2017-04-01

Fault-slip analysis is used in Japan after the Great Tohoku Earthquake (2011) to judge the stability of fractures in the foundations of nuclear power plants. In case a fault-slip datum from a fracture surface is explained by the present stress condition, the fracture is thought to have a risk to be activated as a fault. So, it is important to understand the relative significance of regional and local stresses. To answer the question whether mesoscale faults indicate regional or local stress, fault-slip data were collected from the walls of a trenching site of the Nojima Fault in central Japan—an active, dextral, strike-slip fault. The fault gave rise to the 1995 Kobe earthquake, which killed more than 6000 people. The trench was placed near the fault tip, which produced compressional and extensional local stress conditions on the sides of the fault near the tip. A segment of the fault, which ruptured the surface in 1995, bounded Cretaceous granite and latest Pliocene sediments in the trench. As a result, the stress inversion of the data from the mesoscale faults observed in the trench showed both the local stresses. The present WNW-ESE regional compression was found from the compressive side, but was not in the extensional side, probably because local extension surpassed the regional compression. Instead, the regional N-S compression of the Early Pleistocene was found from the extensional side. From this project, we got the lesson that fault-slip analysis reveals regional and local stresses, and that local stress sometimes masks regional one. This work was supported by a science project of "Drilling into Fault Damage Zone" (awarded to A. Lin) of the Secretariat of Nuclear Regulation Authority (Japan).

Boundary integral solutions for faults in flowing rock

NASA Astrophysics Data System (ADS)

Wei, Wei

We develop new boundary-integral solutions for faulting in viscous rock and implement solutions numerically with a boundary-element computer program, called Faux_Pas. In the solutions, large permanent rock deformations near faults are treated with velocity discontinuities within linear, incompressible, creeping, viscous flows. The faults may have zero strength or a finite strength that can be a constant or varying with deformation. Large deformations are achieved by integrating step by step with the fourth-order Runge-Kutta method. With this method, the boundaries and passive markers are updated dynamically. Faux_Pas has been applied to straight and curved elementary faults, and to listric and dish compound faults, composed of two or more elementary faults, such as listric faults and dish faults, all subjected to simple shear, shortening and lengthening. It reproduces the essential geometric elements seen in seismic profiles of fault-related folds associated with listric thrust faults in the Bighorn Basin of Wyoming, with dish faults in the Appalachians in Pennsylvania, Parry Islands of Canada and San Fernando Valley, California, and with listric normal faults in the Gulf of Mexico. Faux_Pas also predicts that some of these fault-related structures will include fascinating minor folds, especially in the footwall of the fault, that have been recognized earlier but have not been known to be related to the faulting. Some of these minor folds are potential structural traps. Faux_Pas is superior in several respects to current geometric techniques of balancing profiles, such as the "fault-bend fold" construction. With Faux_Pas, both the hanging wall and footwall are deformable, the faults are mechanical features, the cross sections are automatically balanced and, most important, the solutions are based on the first principles of mechanics. With the geometric techniques, folds are drawn only in the hanging wall, the faults are simply lines, the cross sections are arbitrarily balanced and, most important, the drawings are based on unsubstantiated rules of thumb. Faux_Pas provides the first rational tool for the study of fault-related folds.

Mantle fault zone beneath Kilauea Volcano, Hawaii.

PubMed

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

2003-04-18

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

Mantle fault zone beneath Kilauea Volcano, Hawaii

USGS Publications Warehouse

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

2003-01-01

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

Frictional and hydraulic behaviour of carbonate fault gouge during fault reactivation - An experimental study

NASA Astrophysics Data System (ADS)

Delle Piane, Claudio; Giwelli, Ausama; Clennell, M. Ben; Esteban, Lionel; Nogueira Kiewiet, Melissa Cristina D.; Kiewiet, Leigh; Kager, Shane; Raimon, John

2016-10-01

We present a novel experimental approach devised to test the hydro-mechanical behaviour of different structural elements of carbonate fault rocks during experimental re-activation. Experimentally faulted core plugs were subject to triaxial tests under water saturated conditions simulating depletion processes in reservoirs. Different fault zone structural elements were created by shearing initially intact travertine blocks (nominal size: 240 × 110 × 150 mm) to a maximum displacement of 20 and 120 mm under different normal stresses. Meso-and microstructural features of these sample and the thickness to displacement ratio characteristics of their deformation zones allowed to classify them as experimentally created damage zones (displacement of 20 mm) and fault cores (displacement of 120 mm). Following direct shear testing, cylindrical plugs with diameter of 38 mm were drilled across the slip surface to be re-activated in a conventional triaxial configuration monitoring the permeability and frictional behaviour of the samples as a function of applied stress. All re-activation experiments on faulted plugs showed consistent frictional response consisting of an initial fast hardening followed by apparent yield up to a friction coefficient of approximately 0.6 attained at around 2 mm of displacement. Permeability in the re-activation experiments shows exponential decay with increasing mean effective stress. The rate of permeability decline with mean effective stress is higher in the fault core plugs than in the simulated damage zone ones. It can be concluded that the presence of gouge in un-cemented carbonate faults results in their sealing character and that leakage cannot be achieved by renewed movement on the fault plane alone, at least not within the range of slip measureable with our apparatus (i.e. approximately 7 mm of cumulative displacement). Additionally, it is shown that under sub seismic slip rates re-activated carbonate faults remain strong and no frictional weakening was observed during re-activation.

Role of the offshore Pedro Banks left-lateral strike-slip fault zone in the plate tectonic evolution of the northern Caribbean

NASA Astrophysics Data System (ADS)

Ott, B.; Mann, P.; Saunders, M.

2013-12-01

Previous workers, mainly mapping onland active faults on Caribbean islands, defined the northern Caribbean plate boundary zone as a 200-km-wide bounded by two active and parallel strike-slip faults: the Oriente fault along the northern edge of the Cayman trough with a GPS rate of 14 mm/yr, and and the Enriquillo-Plaintain Garden fault zone (EPGFZ) with a rate of 5-7 mm/yr. In this study we use 5,000 km of industry and academic data from the Nicaraguan Rise south and southwest of the EPGFZ in the maritime areas of Jamaica, Honduras, and Colombia to define an offshore, 700-km-long, active, left-lateral strike-slip fault in what has previously been considered the stable interior of the Caribbean plate as determined from plate-wide GPS studies. The fault was named by previous workers as the Pedro Banks fault zone because a 100-km-long segment of the fault forms an escarpment along the Pedro carbonate bank of the Nicaraguan Rise. Two fault segments of the PBFZ are defined: the 400-km-long eastern segment that exhibits large negative flower structures 10-50 km in width, with faults segments rupturing the sea floor as defined by high resolution 2D seismic data, and a 300-km-long western segment that is defined by a narrow zone of anomalous seismicity first observed by previous workers. The western end of the PBFZ terminates on a Quaternary rift structure, the San Andres rift, associated with Plio-Pleistocene volcanism and thickening trends indicating initial rifting in the Late Miocene. The southern end of the San Andreas rift terminates on the western Hess fault which also exhibits active strands consistent with left-lateral, strike-slip faults. The total length of the PBFZ-San Andres rift-Southern Hess escarpment fault is 1,200 km and traverses the entire western end of the Caribbean plate. Our interpretation is similar to previous models that have proposed the "stable" western Caribbean plate is broken by this fault whose rate of displacement is less than the threshold recognizable from the current GPS network (~3 mm/yr). The Late Miocene age of the fault indicates it may have activated during the Late Miocene to recent Hispaniola-Bahamas oblique collision event.

2D Seismic Reflection Data across Central Illinois

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Valerie; Leetaru, Hannes

In a continuing collaboration with the Midwest Geologic Sequestration Consortium (MGSC) on the Evaluation of the Carbon Sequestration Potential of the Cambro-Ordovician Strata of the Illinois and Michigan Basins project, Schlumberger Carbon Services and WesternGeco acquired two-dimensional (2D) seismic data in the Illinois Basin. This work included the design, acquisition and processing of approximately 125 miles of (2D) seismic reflection surveys running west to east in the central Illinois Basin. Schlumberger Carbon Services and WesternGeco oversaw the management of the field operations (including a pre-shoot planning, mobilization, acquisition and de-mobilization of the field personnel and equipment), procurement of the necessarymore » permits to conduct the survey, post-shoot closure, processing of the raw data, and provided expert consultation as needed in the interpretation of the delivered product. Three 2D seismic lines were acquired across central Illinois during November and December 2010 and January 2011. Traversing the Illinois Basin, this 2D seismic survey was designed to image the stratigraphy of the Cambro-Ordovician sections and also to discern the basement topography. Prior to this survey, there were no regionally extensive 2D seismic data spanning this section of the Illinois Basin. Between the NW side of Morgan County and northwestern border of Douglas County, these seismic lines ran through very rural portions of the state. Starting in Morgan County, Line 101 was the longest at 93 miles in length and ended NE of Decatur, Illinois. Line 501 ran W-E from the Illinois Basin – Decatur Project (IBDP) site to northwestern Douglas County and was 25 miles in length. Line 601 was the shortest and ran N-S past the IBDP site and connected lines 101 and 501. All three lines are correlated to well logs at the IBDP site. Originally processed in 2011, the 2D seismic profiles exhibited a degradation of signal quality below ~400 millisecond (ms) which made interpretation of the Mt. Simon and Knox sections difficult. The data quality also gradually decreased moving westward across the state. To meet evolving project objectives, in 2012 the seismic data was re-processed using different techniques to enhance the signal quality thereby rendering a more coherent seismic profile for interpreters. It is believed that the seismic degradation could be caused by shallow natural gas deposits and Quaternary sediments (which include abandoned river and stream channels, former ponds, and swamps with peat deposits) that may have complicated or changed the seismic wavelet. Where previously limited by seismic coverage, the seismic profiles have provided valuable subsurface information across central Illinois. Some of the interpretations based on this survey included, but are not limited to: - Stratigraphy generally gently dips to the east from Morgan to Douglas County. - The Knox Supergroup roughly maintains its thickness. There is little evidence for faulting in the Knox. However, at least one resolvable fault penetrates the entire Knox section. - The Eau Claire Formation, the primary seal for the Mt. Simon Sandstone, appears to be continuous across the entire seismic profile. - The Mt. Simon Sandstone thins towards the western edge of the basin. As a result, the highly porous lowermost Mt. Simon section is absent in the western part of the state. - Overall basement dip is from west to east. - Basement topography shows evidence of basement highs with on-lapping patterns by Mt. Simon sediments. - There is evidence of faults within the lower Mt. Simon Sandstone and basement rock that are contemporaneous with Mt. Simon Sandstone deposition. These faults are not active and do not penetrate the Eau Claire Shale. It is believed that these faults are associated with a possible failed rifting event 750 to 560 million years ago during the breakup of the supercontinent Rodinia.« less

Fault zone structure from topography: signatures of en echelon fault slip at Mustang Ridge on the San Andreas Fault, Monterey County, California

USGS Publications Warehouse

DeLong, Stephen B.; Hilley, George E.; Rymer, Michael J.; Prentice, Carol

2010-01-01

We used high-resolution topography to quantify the spatial distribution of scarps, linear valleys, topographic sinks, and oversteepened stream channels formed along an extensional step over on the San Andreas Fault (SAF) at Mustang Ridge, California. This location provides detail of both creeping fault landform development and complex fault zone kinematics. Here, the SAF creeps 10–14 mm/yr slower than at locations ∼20 km along the fault in either direction. This spatial change in creep rate is coincident with a series of en echelon oblique-normal faults that strike obliquely to the SAF and may accommodate the missing deformation. This study presents a suite of analyses that are helpful for proper mapping of faults in locations where high-resolution topographic data are available. Furthermore, our analyses indicate that two large subsidiary faults near the center of the step over zone appear to carry significant distributed deformation based on their large apparent vertical offsets, the presence of associated sag ponds and fluvial knickpoints, and the observation that they are rotating a segment of the main SAF. Several subsidiary faults in the southeastern portion of Mustang Ridge are likely less active; they have few associated sag ponds and have older scarp morphologic ages and subdued channel knickpoints. Several faults in the northwestern part of Mustang Ridge, though relatively small, are likely also actively accommodating active fault slip based on their young morphologic ages and the presence of associated sag ponds.

The relationship of near-surface active faulting to megathrust splay fault geometry in Prince William Sound, Alaska

NASA Astrophysics Data System (ADS)

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

2010-12-01

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.

On-line early fault detection and diagnosis of municipal solid waste incinerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao Jinsong; Huang Jianchao; Sun Wei

A fault detection and diagnosis framework is proposed in this paper for early fault detection and diagnosis (FDD) of municipal solid waste incinerators (MSWIs) in order to improve the safety and continuity of production. In this framework, principal component analysis (PCA), one of the multivariate statistical technologies, is used for detecting abnormal events, while rule-based reasoning performs the fault diagnosis and consequence prediction, and also generates recommendations for fault mitigation once an abnormal event is detected. A software package, SWIFT, is developed based on the proposed framework, and has been applied in an actual industrial MSWI. The application shows thatmore » automated real-time abnormal situation management (ASM) of the MSWI can be achieved by using SWIFT, resulting in an industrially acceptable low rate of wrong diagnosis, which has resulted in improved process continuity and environmental performance of the MSWI.« less

A fault tolerant gait for a hexapod robot over uneven terrain.

PubMed

Yang, J M; Kim, J H

2000-01-01

The fault tolerant gait of legged robots in static walking is a gait which maintains its stability against a fault event preventing a leg from having the support state. In this paper, a fault tolerant quadruped gait is proposed for a hexapod traversing uneven terrain with forbidden regions, which do not offer viable footholds but can be stepped over. By comparing performance of straight-line motion and crab walking over even terrain, it is shown that the proposed gait has better mobility and terrain adaptability than previously developed gaits. Based on the proposed gait, we present a method for the generation of the fault tolerant locomotion of a hexapod over uneven terrain with forbidden regions. The proposed method minimizes the number of legs on the ground during walking, and foot adjustment algorithm is used for avoiding steps on forbidden regions. The effectiveness of the proposed strategy over uneven terrain is demonstrated with a computer simulation.

Sensor Fault Detection and Diagnosis Simulation of a Helicopter Engine in an Intelligent Control Framework

NASA Technical Reports Server (NTRS)

Litt, Jonathan; Kurtkaya, Mehmet; Duyar, Ahmet

1994-01-01

This paper presents an application of a fault detection and diagnosis scheme for the sensor faults of a helicopter engine. The scheme utilizes a model-based approach with real time identification and hypothesis testing which can provide early detection, isolation, and diagnosis of failures. It is an integral part of a proposed intelligent control system with health monitoring capabilities. The intelligent control system will allow for accommodation of faults, reduce maintenance cost, and increase system availability. The scheme compares the measured outputs of the engine with the expected outputs of an engine whose sensor suite is functioning normally. If the differences between the real and expected outputs exceed threshold values, a fault is detected. The isolation of sensor failures is accomplished through a fault parameter isolation technique where parameters which model the faulty process are calculated on-line with a real-time multivariable parameter estimation algorithm. The fault parameters and their patterns can then be analyzed for diagnostic and accommodation purposes. The scheme is applied to the detection and diagnosis of sensor faults of a T700 turboshaft engine. Sensor failures are induced in a T700 nonlinear performance simulation and data obtained are used with the scheme to detect, isolate, and estimate the magnitude of the faults.

Active faults system and related potential seismic events near Ulaanbaatar, capital of Mongolia.

NASA Astrophysics Data System (ADS)

Schlupp, Antoine; Ferry, Matthieu; Munkhuu, Ulziibat; Sodnomsambuu, Demberel; Al-Ashkar, Abeer

2013-04-01

The region of Ulaanbaatar lies several hundred kilometers from large known active faults that produced magnitude 6 to 8+ earthquakes during the last century. Beside the Hustai fault, which displays a clear morphological expression, no active fault was previously described less than 100 km from the city. In addition, no large historical (i.e. more recent than the 16th c.) earthquakes are known in this region. However, since 2005 a very dense seismic activity has developed over the Emeelt Township area, a mere 10 km from Ulaanbaatar. The activity is characterized by numerous low magnitude events (M<2.8), which are distributed linearly along several tens of kilometers where no active fault has been identified. This raises several questions: Is this seismicity associated to a -yet- unknown active fault? If so, are there other unknown active faults near Ulaanbaatar? Hence, we deployed a multi-disciplinary approach including morpho-tectonic, near-surface geophysical and paleoseismological investigations. We describe four large active faults west and south of Ulaanbaatar, three of them are newly discovered (Emeelt, Sharai, Avdar), one was previously known (Hustai) but without precise study on its seismic potential. The Emeelt seismicity can be mapped over 35 km along N150 and corresponds in the field to a smoothed, but clear, active fault morphology that can be mapped along a 10-km-long section. The fault dips at ~30° NE (GPR and surface morphology observations) and uplifts the eastern block. The age of the last surface rupture observed in trenches is about 10 ka (preliminary OSL dating). Considering a rupture length of 35 km, a full segment rupture would be comparable to the 1967 Mogod earthquake with a magnitude as large as Mw 7. It has to be considered today as a possible scenario for the seismic risk of Ulaanbaatar. The 90-km-long Hustai Range Fault System, oriented WSW-ENE and located about 10 km west of Ulaanbaatar, displays continuous microseismicity with five light to moderate (M 4 - 5.4) earthquakes over the last 40 years. The last surface-rupturing earthquake occurred about 1000 years ago (OSL dating). Alluvial fans affected by the fault suggest the rate of deformation (left lateral with normal component) along the main segment ranges from 0.3 to 0.4 mm/year for the last 120 000 years. Hence, the average recurrence interval for a full-segment M 7-7.5 is likely in the order of 10 ky. However, if the Hustai fault also releases strain during partial ruptures along its strongly segmented trace, a Mw 6.5 event may be expected anytime. However, only the main central fault segment has been investigated in terms of paleoseismicity. The Sharai and Avdar faults, oriented NNE-SSW, were mapped along ~50-km-long sections. Each of these faults was the site of earthquakes of magnitude 6 and more in the past as suggested by morphology and trench observations. Full-segment-ruptures could produce events as large as M 7.2. The precise relationship and interactions between these faults as well as associated earthquakes have to be clarified by collecting more data. They are the key of the seismic hazard and risk of Ulaanbaatar.

FTAPE: A fault injection tool to measure fault tolerance

NASA Technical Reports Server (NTRS)

Tsai, Timothy K.; Iyer, Ravishankar K.

1995-01-01

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

Troubleshooting of signal power supply system for Shanghai metro line 7

NASA Astrophysics Data System (ADS)

Lu, Kaixia; Xiao, Jie

2018-03-01

With the rapid development of Urban Rail Transit Signal Technology, the demand of signal power supply system for signal equipment is higher and higher. The signal intelligent power supply panel is the main component of the urban rail traffic signal power supply system. Whether the intelligent power supply panel working or not is directly related to traffic safety. The maintenance of intelligent signal power supply panel is particularly important. Line 7 of Shanghai Metro adopts PMZG Signal Intelligent Power Supply Panel, which is produced by Beijing Jinyujiaxin Polytron Technologies Inc. Maintenance of power supply system mainly includes routine maintenance and troubleshooting. This article will make clear the routine maintenance contents of PMZG Signal Intelligent Power Supply Panel, and put forward the common fault information and troubleshooting methods of PMZG Signal Intelligent Power Supply Panel. In accordance with the steps of fault handling, the faults can be eliminated in the shortest possible time, and PMZG Signal Intelligent Power Supply Panel can be quickly restored to normal working state.

Aircraft engine sensor fault diagnostics using an on-line OBEM update method.

PubMed

Liu, Xiaofeng; Xue, Naiyu; Yuan, Ye

2017-01-01

This paper proposed a method to update the on-line health reference baseline of the On-Board Engine Model (OBEM) to maintain the effectiveness of an in-flight aircraft sensor Fault Detection and Isolation (FDI) system, in which a Hybrid Kalman Filter (HKF) was incorporated. Generated from a rapid in-flight engine degradation, a large health condition mismatch between the engine and the OBEM can corrupt the performance of the FDI. Therefore, it is necessary to update the OBEM online when a rapid degradation occurs, but the FDI system will lose estimation accuracy if the estimation and update are running simultaneously. To solve this problem, the health reference baseline for a nonlinear OBEM was updated using the proposed channel controller method. Simulations based on the turbojet engine Linear-Parameter Varying (LPV) model demonstrated the effectiveness of the proposed FDI system in the presence of substantial degradation, and the channel controller can ensure that the update process finishes without interference from a single sensor fault.

Aircraft engine sensor fault diagnostics using an on-line OBEM update method

PubMed Central

Liu, Xiaofeng; Xue, Naiyu; Yuan, Ye

2017-01-01

This paper proposed a method to update the on-line health reference baseline of the On-Board Engine Model (OBEM) to maintain the effectiveness of an in-flight aircraft sensor Fault Detection and Isolation (FDI) system, in which a Hybrid Kalman Filter (HKF) was incorporated. Generated from a rapid in-flight engine degradation, a large health condition mismatch between the engine and the OBEM can corrupt the performance of the FDI. Therefore, it is necessary to update the OBEM online when a rapid degradation occurs, but the FDI system will lose estimation accuracy if the estimation and update are running simultaneously. To solve this problem, the health reference baseline for a nonlinear OBEM was updated using the proposed channel controller method. Simulations based on the turbojet engine Linear-Parameter Varying (LPV) model demonstrated the effectiveness of the proposed FDI system in the presence of substantial degradation, and the channel controller can ensure that the update process finishes without interference from a single sensor fault. PMID:28182692

Latest Rate, Extent, and Temporal Evolution of Growth Faulting over Greater Houston Region Revealed by Multi- Band InSAR Time-Series Analysis

NASA Astrophysics Data System (ADS)

Qu, F.; Lu, Z.; Kim, J. W.

2017-12-01

Growth faults are common and continue to evolve throughout the unconsolidated sediments of Greater Houston (GH) region in Texas. Presence of faults can induce localized surface displacements, aggravate localized subsidence, and discontinue the integrity of ground water flow. Property damages due to fault creep have become more evident during the past few years over the GH area, portraying the necessity of further study of these faults. Interferometric synthetic aperture radar (InSAR) has been proven to be effective in mapping creep along and/or across faults. However, extracting a short wavelength, as well as small amplitude of the creep signal (about 10-20 mm/year) from long time span interferograms is extremely difficult, especially in agricultural or vegetated areas. This paper aims to map and monitor the latest rate, extent, and temporal evolution of faulting at a highest spatial density over GH region using an improved Multi-temporal InSAR (MTI) technique. The method, with maximized usable signal and correlation, has the ability to identify and monitor the active faults to provide an accurate and elaborate image of the faults. In this study, two neighboring ALOS tracks and Sentinel-1A datasets are used. Many zones of steep phase gradients and/or discontinuities have been recognized from the long term velocity maps by both ALOS (2007-2011) and Sentinei-1A (2015-2017) imagery. Not only those previously known faults position but also the new fault traces that have not been mapped by other techniques are imaged by our MTI technique. Fault damage and visible cracking of ground were evident at most locations through our field survey. The discovery of new fault activation, or faults moved from earlier locations is a part of the Big Barn Fault and Conroe fault system, trending from southwest to northeast between Hockley and Conroe. The location of area of subsidence over GH is also shrinking and migrating toward the northeast (Montgomery County) after 2000. The continuous mining of ground water from the Jasper aquifer formed a new water-level decline cones over Montgomery County, exactly reflects the intensity of new fault activity. The discovery of new fault activation, or faults moved from earlier locations appear to be related to excessive water exploitation from Montgomery County aquifers.

Geomorphic Proxies to Test Strain Accommodation in Southwestern Puerto Rico from Digital Elevation Models

NASA Astrophysics Data System (ADS)

Barrios Galindez, I. M.; Xue, L.; Laó-Dávila, D. A.

2017-12-01

The Puerto Rico and the Virgin Island microplate is located in at the northeastern corner of the Caribbean plate boundary with North America is placed within an oblique subduction zone in which strain patterns remain unresolved. Seismic hazard is a major concern in the region as seen from the seismic history of the Caribbean-North America plate boundary zone. Most of the tectonic models of the microplate show the accommodation of strain occurring offshore, despite evidence from seismic activity, trench studies, and geodetic studies suggesting the existence of strain accomodation in southwest Puerto Rico. These studies also suggest active faulting specially in the western part of the island, but limited work has been done regarding their mechanism. Therefore, this work aims to define and map these active faults in western Puerto Rico by integrating data from analysis of fluvial terrains, and detailed mapping using digital elevation model (DEM) extracted from Shuttle Radar Topography Mission (SRTM) and LIDAR data. The goal is to (1) identify structural features such as surface lineaments and fault scarps for the Cerro Goden fault, South Lajas fault, and other active faults in the western of Puerto Rico, (2) correlate these information with the distribution pattern and values of the geomorphic proxies, including Chi integral (χ), normalized steepness (ksn) and Asymmetric factor (AF). Our preliminary results from geomorphic proxies and Lidar data provide some insight of the displacement and stage of activities of these faults (e.g. Boqueron-Punta Malva Fault and Cerro Goden fault). Also, the anomaly of the geomorphic proxies generally correlate with the locations of the landslides in the southwestern Puerto Rico. The geomorphic model of this work include new information of active faulting fundamental to produce better seismic hazards maps. Additionally, active tectonics studies are vital to issue and adjust construction buildings codes and zonification codes.

Investigation of the line arrangement of 2D resistivity surveys for 3D inversion*

NASA Astrophysics Data System (ADS)

Inoue, Keisuke; Nakazato, Hiroomi; Takeuchi, Mutsuo; Sugimoto, Yoshihiro; Kim, Hee Joon; Yoshisako, Hiroshi; Konno, Michiaki; Shoda, Daisuke

2018-03-01

We have conducted numerical and field experiments to investigate the applicability of electrode configurations and line layouts commonly used for two-dimensional (2D) resistivity surveys to 3D inversion. We examined three kinds of electrode configurations and two types of line arrangements, for 16 resistivity models of a conductive body in a homogeneous half-space. The results of the numerical experiment revealed that the parallel-line arrangement was effective in identifying the approximate location of the conductive body. The orthogonal-line arrangement was optimal for identifying a target body near the line intersection. As a result, we propose that parallel lines are useful to highlight areas of particular interest where further detailed work with an intersecting line could be carried out. In the field experiment, 2D resistivity data were measured on a loam layer with a backfilled pit. The reconstructed resistivity image derived from parallel-line data showed a low-resistivity portion near the backfilled pit. When an orthogonal line was added to the parallel lines, the newly estimated location of the backfilled pit coincided well with the actual location. In a further field application, we collected several 2D resistivity datasets in the Nojima Fault area in Awaji Island. The 3D inversion of these datasets provided a resistivity distribution corresponding to the geological structure. In particular, the Nojima Fault was imaged as the western boundary of a low-resistivity belt, from only two orthogonal lines.

Integration of high-resolution seismic and aeromagnetic data for earthquake hazards evaluations: An example from the Willamette Valley, Oregon

USGS Publications Warehouse

Liberty, L.M.; Trehu, A.M.; Blakely, R.J.; Dougherty, M.E.

1999-01-01

Aeromagnetic and high-resolution seismic reflection data were integrated to place constraints on the history of seismic activity and to determine the continuity of the possibly active, yet largely concealed Mount Angel fault in the Willamette Valley, Oregon. Recent seismic activity possibly related to the 20-km-long fault includes a swarm of small earthquakes near Woodburn in 1990 and the magnitude 5.6 Scotts Mills earthquake in 1993. Newly acquired aeromagnetic data show several large northwest-trending anomalies, including one associated with the Mount Angel fault. The magnetic signature indicates that the fault may actually extend 70 km across the Willamette Valley to join the Newberg and Gales Creek faults in the Oregon Coast Range. We collected 24-fold high-resolution seismic reflection data along two transects near Woodburn, Oregon, to image the offset of the Miocene-age Columbia River Basalts (CRB) and overlying sediments at and northwest of the known mapped extent of the Mount Angel fault. The seismic data show a 100-200-m offset in the CRB reflector at depths from 300 to 700 m. Folded or offset sediments appear above the CRB with decreasing amplitude to depths as shallow as were imaged (approximately 40 m). Modeling experiments based on the magnetic data indicate, however, that the anomaly associated with the Mount Angel fault is not caused solely by an offset of the CRB and overlying sediments. Underlying magnetic sources, which we presume to be volcanic rocks of the Siletz terrane, must have vertical offsets of at least 500 m to fit the observed data. We conclude that the Mount Angel fault appears to have been active since Eocene age and that the Gales Creek, Newberg, and Mount Angel faults should be considered a single potentially active fault system. This fault, as well as other parallel northwest-trending faults in the Willamette Valley, should be considered as risks for future potentially damaging earthquakes.

Near-Surface Geophysical Character of a Holocene Fault Carrying Geothermal Flow Near Pyramid Lake, Nevada

NASA Astrophysics Data System (ADS)

Dudley, C.; Dorsey, A.; Louie, J. N.; Schwering, P. C.; Pullammanappallil, S.

2012-12-01

Lines of calcium carbonate tufa columns mark recent faults that cut 11 ka Lake Lahontan sediments at Astor Pass, north of Pyramid Lake, Nevada. Throughout the Great Basin, faults appear to control the location of geothermal resources, providing pathways for fluid migration. Reservoir-depth (greater than 1 km) seismic imaging at Astor Pass shows a fault that projects to one of the lines of tufa columns at the surface. The presence of the tufa deposits suggests this fault carried warm geothermal waters through the lakebed clay sediments in recent time. The warm fluids deposited the tufa when they hit cold Lake Lahontan water at the lakebed. Lake Lahontan covered this location to a depth of at least 60 m at 11 ka. In collaboration with the Pyramid Lake Paiute Tribe, an Applied Geophysics class at UNR investigated the near-surface geophysical characteristics of this fault. The survey comprises near-surface seismic reflection and refraction, nine near-surface refraction microtremor (SeisOpt® ReMi™) arrays, nine near-surface direct-current resistivity soundings, magnetic surveys, and gravity surveys at and near the tufa columns. The refraction microtremor results show shear velocities near tufa and faults to be marginally lower, compared to Vs away from the faults. Overall, the 30-m depth-averaged shear velocities are low, less than 300 m/s, consistent with the lakebed clay deposits. These results show no indication of any fast (> 500 m/s) tufa below the surface at or near the tufa columns. Vs30 averages were 274 ± 13 m/s on the fault, 287 ± 2 m/s at 150 m east of the fault, and 290 ± 15 m/s at 150 m west of the fault. The P-velocity refraction optimization results also show no indication of high-velocity tufa buried below the surface in the Lahontan sediments, reinforcing the idea that all tufa was deposited above the lakebed surface. The seismic results provide a negative test of the hypothesis that deposition of the lakebeds in the Quaternary buried and preserved older tufa columns within the section. Near-surface Wenner arrays with a-spacings up to 30 m show a higher resistivity near the faults, and tufa, than away from the faults. Resistivity averages were 33 ± 17 ohm-m on the fault, 13 ± 3 ohm-m east of the fault, and 9 ± 3 ohm-m west of the fault. It is possible the geothermal waters are fresher than waters held in the lakebed clays. Water samples from more than 1 km depth in exploration wells had almost drinking-water quality. This higher resistivity of the waters carried by the fault zone, with perhaps a higher porosity and permeability along the fault, could explain the higher resistivity near the fault. Our work shows that there is no high-velocity, high-resistivity tufa along the faults below the surface, so we are unable to use buried tufa to locate faults with geothermal upwellings in this area. We can further hypothesize that as sedimentation buried the tufa during the Quaternary, warm geothermal waters re-dissolved it, and re-precipitated it only in the cold lake-bottom water.

Role of tectonic inheritance in the instauration of Tunisian Atlassic fold-and-thrust belt: Case of Bouhedma - Boudouaou structures

NASA Astrophysics Data System (ADS)

Ghanmi, Mohamed Abdelhamid; Ghanmi, Mohamed; Aridhi, Sabri; Ben Salem, Mohamed Sadok; Zargouni, Fouad

2016-07-01

Tectonic inversion in the Bouhedma-Boudouaou Mountains was investigated through recent field work and seismic lines interpretation calibrated with petroleum well data. Located to the Central-Southern Atlas of Tunisia, this area signed shortened intra-continental fold-and-thrust belts. Two dissymmetric anticlines characterize Bouhedma - Boudouaou major fold. These structures show a strong virgation respectively from E-W to NNE-SSW as a response to the interference between both tectonic inversion and tectonic inheritance. This complex geometry is driven by Mesozoic rifting, which marked an extensional inherited regime. A set of late Triassic-Early Jurassic E-W and NW-SE normal faults dipping respectively to the North and to the East seems to widely affect the overall geodynamic evolution of this domain. They result in major thickness changes across the hanging wall and the footwall blocks in response with the rifting activity. Tectonic inversion is inferred from convergence between African and European plates since late Cretaceous. During Serravalian - Tortonian event, NW-SE trending paroxysm led to: 1) folding of pre-inversion and syn-inversion strata, 2) reactivation of pre-existing normal faults to reverse ones and 3) orogeny of the main structures with NE-SW and E-W trending. The compressional feature still remains active during Quaternary event (Post-Villafranchian) with N-S trending compression. Contraction during inversion generates folding and internal deformation as well as Fault-Propagation-Fold and folding related strike.

Location of deeply buried, offshore Mesozoic transform fault along the western margin of the Gulf of Mexico inferred from gravity and magnetic data

NASA Astrophysics Data System (ADS)

Nguyen, L. C.; Mann, P.; Bird, D. E.

2013-12-01

Several workers have proposed that a Jurassic age, 500-km-long, right-lateral transform fault along the western margin of the Gulf of Mexico, possibly extending southward and onshore for another 500 km onto the isthmus area of southern Mexico, was formed as the ocean basin opened. This proposed transform fault plays a critical role in the most widely accepted tectonic model for the Mesozoic opening of the Gulf of Mexico by a ~40 degree, CCW rotation of the Yucatan block about a pole near southern Florida. Previously proposed names for the fault include the Tamaulipas-Chiapas transform fault and the Western Main transform fault for the offshore fault and the Orizaba transform fault for the southern, onland continuation of the fault into southern Mexico. There are few direct geologic or geophysical observations on the location or characteristics of the proposed offshore transform because it is buried beneath an over 10-km-thick sedimentary wedge along the continental margin of eastern Mexico. To better define this offshore fault, we identify a 500-km-long, 40-km-wide gravity anomaly, concentric with, and located about 60-70 km off the eastern coast of Mexico. Two east-west 200/1200-km-long gravity models constructed to cross the anomaly at right angles are parallel to existing multi-channel seismic lines with age-correlated stratigraphy. Both gravity models reveal an abrupt crustal thickness change beneath the gravity anomaly: from 27 km to 12 km over a distance of 65 km in the southern profile, and from 23 km to 16 km over a distance of 30 km in northern profile. The linearity of the anomaly in map view combined with the abrupt change in thickness inferred from gravity modeling is consistent with the tectonic origin of a right-lateral transform fault separating continental rocks of Mexico from Mesozoic seafloor produced by the opening of the Gulf of Mexico. Magnetic profiles were analyzed using a Werner depth-to-magnetic source technique, coincident with the gravity models, estimate the depth to top of crystalline basement for the northern (9 km) and southern (11 km) transects. Subsidence analysis along both transects shows that sedimentation rates sharply peaked during the Laramide orogeny in the latest Cretaceous-Eocene, but otherwise conform to steady thermal subsidence of oceanic crust in the deep Gulf of Mexico that formed during the Jurassic CCW rotation of the Yucatan block. The more precisely defined offshore fault aligns well with the onland right-lateral Orizaba transform fault of southern Mexico that is thought to have been active in Mesozoic time.

Implications of river morphology response to Dien Bien Phu fault in NW Vietnam

NASA Astrophysics Data System (ADS)

Lai, K.; Chen, Y.; Lam, D.

2007-12-01

In northern Vietnam, most rivers are flowing southeastward sub- or parallel to the valley of Red River and characterized by long but narrow catchments. The Dien Bien Phu fault is associated with the most seismically active zone in Vietnam and situated in the potential eastern boundary of the rotating southeastern Tibetan block. It cuts the Da River, the largest tributary of Red River in northwest Vietnam and has distorted the drainage basin resulting in complex river patterns. To assess the river morphology response to active Dien Bien Phu fault, we use 1/50,000 topographic data and ASTER images to map the precise river courses and digital elevation model data of SRTM to retrieve and analyze the river profiles. From the mapping results, the N-S striking fault results in three conspicuous north-trending river valleys coincided with the different fault segments to facilitate the measurement and reconstruction of the offsets along the fault. Further combining the longitudinal profile analysis we obtain ca. 10 km offsets by deflected river as the largest left-lateral displacement recorded along the active fault. The restored results show the downstream paleochannel of the Da River had been abandoned and becomes two small tributaries in opposite flow directions at present due to differential crustal uplift. Also the present crisscross valley at the junction of the Da River and the fault is resulted from the capture by another river which has been also deflected by the neotectonics. Based on our observations on river response, the Dien Bien Phu fault is a sinistral dominant fault with an uplift occurring in its eastern block. Furthermore the active Dien Bien Phu fault does not cut through the Red River northward indicating the western block of the fault can not be regarded as a single rigid block. There should be possible to find NW-SE trending faults paralleling to Red River to accommodate the deformation of the western block of the fault.

Implications of river morphology response to Dien Bien Phu fault in NW Vietnam

NASA Astrophysics Data System (ADS)

Lai, K.; Chen, Y.; Lam, D.

2004-12-01

In northern Vietnam, most rivers are flowing southeastward sub- or parallel to the valley of Red River and characterized by long but narrow catchments. The Dien Bien Phu fault is associated with the most seismically active zone in Vietnam and situated in the potential eastern boundary of the rotating southeastern Tibetan block. It cuts the Da River, the largest tributary of Red River in northwest Vietnam and has distorted the drainage basin resulting in complex river patterns. To assess the river morphology response to active Dien Bien Phu fault, we use 1/50,000 topographic data and ASTER images to map the precise river courses and digital elevation model data of SRTM to retrieve and analyze the river profiles. From the mapping results, the N-S striking fault results in three conspicuous north-trending river valleys coincided with the different fault segments to facilitate the measurement and reconstruction of the offsets along the fault. Further combining the longitudinal profile analysis we obtain ca. 10 km offsets by deflected river as the largest left-lateral displacement recorded along the active fault. The restored results show the downstream paleochannel of the Da River had been abandoned and becomes two small tributaries in opposite flow directions at present due to differential crustal uplift. Also the present crisscross valley at the junction of the Da River and the fault is resulted from the capture by another river which has been also deflected by the neotectonics. Based on our observations on river response, the Dien Bien Phu fault is a sinistral dominant fault with an uplift occurring in its eastern block. Furthermore the active Dien Bien Phu fault does not cut through the Red River northward indicating the western block of the fault can not be regarded as a single rigid block. There should be possible to find NW-SE trending faults paralleling to Red River to accommodate the deformation of the western block of the fault.

Cold seeps and splay faults on Nankai margin

NASA Astrophysics Data System (ADS)

Henry, P.; Ashi, J.; Tsunogai, U.; Toki, T.; Kuramoto, S.; Kinoshita, M.; Lallemant, S. J.

2003-04-01

Cold seeps (bacterial mats, specific fauna, authigenic carbonates) are common on the Nankai margin and considered as evidence for seepage of methane bearing fluids. Camera and submersible surveys performed over the years have shown that cold seeps are generally associated with active faults. One question is whether part of the fluids expelled originate from the seismogenic zone and migrate along splay faults to the seafloor. The localisation of most cold seeps on the hanging wall of major thrusts may, however, be interpreted in various ways: (a) footwall compaction and diffuse flow (b) fluid channelling along the fault zone at depths and diffuse flow near the seafloor (c) erosion and channelling along permeable strata. In 2002, new observations and sampling were performed with submersible and ROV (1) on major thrusts along the boundary between the Kumano forearc basin domain and the accretionary wedge domain, (2) on a fault affecting the forearc (Kodaiba fault), (3) on mud volcanoes in the Kumano basin. In area (1) tsunami and seismic inversions indicate that the targeted thrusts are in the slip zone of the To-Nankai 1944 earthquakes. In this area, the largest seep zone, continuous over at least 2 km, coincides with the termination of a thrust trace, indicating local fluid channelling along the edge of the fault zone. Kodaiba fault is part of another splay fault system, which has both thrusting and strike-slip components and terminates westward into an en-echelon fold system. Strong seepage activity with abundant carbonates was found on a fold at the fault termination. One mud volcano, rooted in one of the en-echelon fold, has exceptionally high seepage activity compared with the others and thick carbonate crusts. These observations suggest that fluid expulsion along fault zones is most active at fault terminations and may be enhanced during fault initiation. Preliminary geochemical results indicate signatures differ between seep sites and suggests that the two fault systems tap in different sources.

An automatic procedure for high-resolution earthquake locations: a case study from the TABOO near fault observatory (Northern Apennines, Italy)

NASA Astrophysics Data System (ADS)

Valoroso, Luisa; Chiaraluce, Lauro; Di Stefano, Raffaele; Latorre, Diana; Piccinini, Davide

2014-05-01

The characterization of the geometry, kinematics and rheology of fault zones by seismological data depends on our capability of accurately locate the largest number of low-magnitude seismic events. To this aim, we have been working for the past three years to develop an advanced modular earthquake location procedure able to automatically retrieve high-resolution earthquakes catalogues directly from continuous waveforms data. We use seismograms recorded at about 60 seismic stations located both at surface and at depth. The network covers an area of about 80x60 km with a mean inter-station distance of 6 km. These stations are part of a Near fault Observatory (TABOO; http://taboo.rm.ingv.it/), consisting of multi-sensor stations (seismic, geodetic, geochemical and electromagnetic). This permanent scientific infrastructure managed by the INGV is devoted to studying the earthquakes preparatory phase and the fast/slow (i.e., seismic/aseismic) deformation process active along the Alto Tiberina fault (ATF) located in the northern Apennines (Italy). The ATF is potentially one of the rare worldwide examples of active low-angle (< 15°) normal fault accommodating crustal extension and characterized by a regular occurrence of micro-earthquakes. The modular procedure combines: i) a sensitive detection algorithm optimized to declare low-magnitude events; ii) an accurate picking procedure that provides consistently weighted P- and S-wave arrival times, P-wave first motion polarities and the maximum waveform amplitude for local magnitude calculation; iii) both linearized iterative and non-linear global-search earthquake location algorithms to compute accurate absolute locations of single-events in a 3D geological model (see Latorre et al. same session); iv) cross-correlation and double-difference location methods to compute high-resolution relative event locations. This procedure is now running off-line with a delay of 1 week to the real-time. We are now implementing this procedure to obtain high-resolution double-difference earthquake locations in real-time (DDRT). We show locations of ~30k low-magnitude earthquakes recorded during the past 4 years (2010-2013) of network operation, reaching a completeness magnitude of the catalogue of 0.2. The spatiotemporal seismicity distribution has an almost constant and high rate of r = 24.30e-04 eqks/day*km2, interrupted by low to moderate magnitude seismic sequences such as the 2010 Pietralunga sequence (M L 3.8) and the still ongoing 2013 Gubbio sequence (M L 4.0 on 22nd December 2013). Low-magnitude seismicity images the fine scale geometry of the ATF: an E-dipping plane at low angle (15°) from 4 km down to ~15 km of depth. While in the ATF hanging-wall we observe the activation of high-angle minor synthetic and antithetic normal faults (4-5 km long) confined at depth by the detachment. Both seismic sequences activated up to now only these high-angle fault segments.

Active faults and minor plates in NE Asia

NASA Astrophysics Data System (ADS)

Kozhurin, Andrey I.; Zelenin, Egor A.

2014-05-01

Stated nearly 40 yr ago the uncertainty with plate boundaries location in NE Asia (Chapman, Solomon, 1976) still remains unresolved. Based on the prepositions that a plate boundary must, first, reveal itself in linear sets of active structures, and, second, be continuous and closed, we have undertaken interpretation of medium-resolution KH-9 Hexagon satellite imageries, mostly in stereoscopic regime, for nearly the entire region of NE Asia. Main findings are as follows. There are two major active fault zones in the region north of the Bering Sea. One of them, the Khatyrka-Vyvenka zone, stretches NE to ENE skirting the Bering Sea from the Kamchatka isthmus to the Navarin Cape. Judging by the kinematics of the Olyutorsky 2006 earthquake fault, the fault zones move both right-laterally and reversely. The second active fault zone, the Lankovaya-Omolon zone, starts close to the NE margin of the Okhotsk Sea and extends NE up to nearly the margin of the Chukcha Sea. The fault zone is mostly right-lateral, with topographically expressed cumulative horizontal offsets amounting to 2.5-2.6 km. There may be a third NE-SW zone between the major two coinciding with the Penzhina Range as several active faults found in the southern termination of the Range indicate. The two active fault zones divide the NE Asia area into two large domains, which both could be parts of the Bering Sea plate internally broken and with uncertain western limit. Another variant implies the Khatyrka-Vyvenka zone as the Bering Sea plate northern limit, and the Lankovaya-Omolon zone as separating an additional minor plate from the North-American plate. The choice is actually not crucial, and more important is that both variants leave the question of where the Bering Sea plate boundary is in Alaska. The Lankovaya-Omolon zone stretches just across the proposed northern boundary of the Okhorsk Sea plate. NW of the zone, there is a prominent left-lateral Ulakhan fault, which is commonly interpreted to be a portion of the plate northern boundary. With this, we have discovered no active faults or fault zones of the Ulakhan fault strike, which could be the portion of the boundary between the Lankovaya-Omolon zone and either the western margin of the Komandor basin or the westernmost Aleutians. We conclude that there is a certain disagreement between active faulting pattern and plate models for NE Asia, relating to the extent of the plates and missing portions of the plate boundaries. The research was supported by grant # 110500136-a from the Russian Foundation for Basic Research.

Quantitative Assessment of Potentially Active Faults in Oklahoma Utilizing Detailed Information on In Situ Stress Orientation and Relative Magnitude

NASA Astrophysics Data System (ADS)

Walsh, R.; Zoback, M. D.

2015-12-01

Over the past six years, the earthquake rate in the central and eastern U.S. has increased markedly, and is related to fluid injection. Nowhere has seismicity increased more than in Oklahoma, where large volumes of saline pore water are co-produced with oil and gas, then injected into deeper sedimentary formations. These deeper formations appear to be in hydraulic communication with potentially active faults in crystalline basement, where nearly all the earthquakes are occurring. Although the majority of the recent earthquakes have posed little danger to the public, the possibility of triggering damaging earthquakes on potentially active basement faults cannot be discounted. To understand probability of slip on a given fault, we invert for stresses from the hundreds of M4+ events in Oklahoma for which moment tensors have been made. We then resolve these stresses, while incorporating uncertainties, on the faults from the preliminary Oklahoma fault map. The result is a probabilistic understanding of which faults are most likely active and best avoided.

Earth Observations taken by Expedition 30 crewmember

NASA Image and Video Library

2012-01-14

ISS030-E-035487 (14 Jan. 2012) --- The East African Rift Valley in Kenya is featured in this image photographed by an Expedition 30 crew member on the International Space Station. This photograph highlights classical geological structures associated with a tectonic rift valley, in this case the Eastern Branch of the East African Rift near Kenya’s southern border with Tanzania and just south of the Equator. The East African Rift is one of the great tectonic features of Africa, caused by fracturing of Earth’s crust. The Nubian (or African) plate includes the older continental crust of Africa to the west, while the Somalian plate that is moving away includes the Horn of Africa to the northeast; the tectonic boundary stretches from the southern Red Sea to central Mozambique. Landscapes in the rift valley can appear confusing. The most striking features in this view are the numerous, nearly parallel, linear fault lines that occupy the floor of the valley (most of the image). Shadows cast by the late afternoon sun make the fault scarps (steps in the landscape caused by slip motion along individual faults) more prominent. The faults are aligned with the north-south axis of the valley (lower left to top right). A secondary trend of less linear faults cuts the main fault trend at an acute angle, the fault steps throwing large shadows. The Eastern Branch of the East African Rift is arid (compared with the Western Branch which lies on the border of the Congolese rainforest). Evidence of this can be seen in the red, salt-loving algae of the shallow and salty Lake Magadi (center). A neighboring small lake to the north has deeper water and appears dark in the image. The white salt deposits of the dry part of the Lake Magadi floor (center) host a few small commercial salt pans. The lakes appear to be located where the main and secondary fault trends intersect. The East African rift system is marked by substantial volcanic activity, including lavas erupted from fissures along the rift in the region. Much of the faulting observed in this image cuts through such lavas. Elsewhere along the rift system individual volcanoes form. Some of those volcanoes are very large, including Mt. Kilimanjaro and Mt. Kenya. In this image, rising 400 meters above the valley floor, a volcano appears to be superimposed on the faults—indicating that the volcano is younger than the faults it covers. Deeply eroded slopes also suggest that the volcano has not been active for a long time. The largest vegetated area (lower left)—in an desert zone with no vegetation visible to the naked eye from space—is the green floor of a valley which drains an area large enough for water to exist near the surface so that plants can thrive. For a sense of scale, the vegetated valley floor is 17 kilometers long (10.5 miles).

Evidence of post-Pleistocene faults on New Jersey Atlantic outer continental shelf

USGS Publications Warehouse

Sheridan, R.E.; Knebel, H.J.

1976-01-01

Recently obtained high-resolution seismic profiles (400-4,000-Hz band) show evidence of faults in shallow sedimentary strata near the edge of the Atlantic continental shelf off New Jersey. Apparent normal faults having a throw of about 1.5 m displace sediments to within 7 m of the sea floor. The faults appear to be overlain by undeformed horizontal beds of relatively recent age. Several faults 1 to 2 km apart strike approximately N70°E and dip northwest. The data suggest that the faults are upthrown on the southeast.Projection of the faults on the high-resolution profiles to a nearby multichannel seismic-reflection profile indicates that these shallow faults might be the near-surface expression of a more fundamental deep-seated fault. Several prominent reflectors in the multichannel records are offset by a high-angle normal fault reaching depths of 4.0 to 5.0 sec (6.0 to 6.5 km). The deep fault on the multichannel line also is upthrown on the southeast. Throws of as much as 90 m are apparent at depth, but offsets of as much as 10 m could be present in the shallower parts of the section that may not be resolved in the multichannel data.The position and strike of these faults coincide with and parallel the East Coast magnetic anomaly interpreted as the fundamental seaward basement boundary of the Baltimore Canyon trough. Recurring movements along such boundary faults are expected theoretically if the marginal basins are subsiding in response to the plate rotation of North America and seafloor spreading in the Atlantic.

Late Quaternary strike-slip along the Taohuala Shan-Ayouqi fault zone and its tectonic implications in the Hexi Corridor and the southern Gobi Alashan, China

NASA Astrophysics Data System (ADS)

Yu, Jing-xing; Zheng, Wen-jun; Zhang, Pei-zhen; Lei, Qi-yun; Wang, Xu-long; Wang, Wei-tao; Li, Xin-nan; Zhang, Ning

2017-11-01

The Hexi Corridor and the southern Gobi Alashan are composed of discontinuous a set of active faults with various strikes and slip motions that are located to the north of the northern Tibetan Plateau. Despite growing understanding of the geometry and kinematics of these active faults, the late Quaternary deformation pattern in the Hexi Corridor and the southern Gobi Alashan remains controversial. The active E-W trending Taohuala Shan-Ayouqi fault zone is located in the southern Gobi Alashan. Study of the geometry and nature of slip along this fault zone holds crucial value for better understanding the regional deformation pattern. Field investigations combined with high-resolution imagery show that the Taohuala Shan fault and the E-W trending faults within the Ayouqi fault zone (F2 and F5) are left-lateral strike-slip faults, whereas the NW or WNW-trending faults within the Ayouqi fault zone (F1 and F3) are reverse faults. We collected Optically Stimulated Luminescence (OSL) and cosmogenic exposure age dating samples from offset alluvial fan surfaces, and estimated a vertical slip rate of 0.1-0.3 mm/yr, and a strike-slip rate of 0.14-0.93 mm/yr for the Taohuala Shan fault. Strata revealed in a trench excavated across the major fault (F5) in the Ayouqi fault zone and OSL dating results indicate that the most recent earthquake occurred between ca. 11.05 ± 0.52 ka and ca. 4.06 ± 0.29 ka. The geometry and kinematics of the Taohuala Shan-Ayouqi fault zone enable us to build a deformation pattern for the entire Hexi Corridor and the southern Gobi Alashan, which suggest that this region experiences northeastward oblique extrusion of the northern Tibetan Plateau. These left-lateral strike-slip faults in the region are driven by oblique compression but not associated with the northeastward extension of the Altyn Tagh fault.

Calculation and use of an environment's characteristic software metric set

NASA Technical Reports Server (NTRS)

Basili, Victor R.; Selby, Richard W., Jr.

1985-01-01

Since both cost/quality and production environments differ, this study presents an approach for customizing a characteristic set of software metrics to an environment. The approach is applied in the Software Engineering Laboratory (SEL), a NASA Goddard production environment, to 49 candidate process and product metrics of 652 modules from six (51,000 to 112,000 lines) projects. For this particular environment, the method yielded the characteristic metric set (source lines, fault correction effort per executable statement, design effort, code effort, number of I/O parameters, number of versions). The uses examined for a characteristic metric set include forecasting the effort for development, modification, and fault correction of modules based on historical data.

Identification and interpretation of tectonic features from ERTS-1 imagery: Southwestern North America and the Red Sea area

NASA Technical Reports Server (NTRS)

Abdel-Gawad, M. (Principal Investigator); Tubbesing, L.

1975-01-01

The author has identified the following significant results. The ERTS-1 imagery was utilized to study major fault and tectonic lines and their intersections in southwestern North America. A system of transverse shear faults was recognized in the California Coast Ranges, the Sierra Nevada, the Great Basin, and Mexico. They are interpreted as expressions of a major left-lateral shear which predated the San Andreas system, the opening of the Gulf of California and Basin and Range rift development. Tectonic models for Basin and Range, Coast Ranges, and Texas-Parras shears were developed. Geological structures and Precambrian metamorphic trend lines of schistosity were studied across the Red Sea rift.

Project DAFNE - Drilling Active Faults in Northern Europe

NASA Astrophysics Data System (ADS)

Kukkonen, I. T.; Ask, M. S. V.; Olesen, O.

2012-04-01

We are currently developing a new ICDP project 'Drillling Active Faults in Northern Europe' (DAFNE) which aims at investigating, via scientific drilling, the tectonic and structural characteristics of postglacial (PG) faults in northern Fennoscandia, including their hydrogeology and associated deep biosphere [1, 2]. During the last stages of the Weichselian glaciation (ca. 9,000 - 15,000 years B.P.), reduced ice load and glacially affected stress field resulted in active faulting in Fennoscandia with fault scarps up to 160 km long and 30 m high. These postglacial (PG) faults are usually SE dipping, SW-NE oriented thrusts, and represent reactivated, pre-existing crustal discontinuities. Postglacial faulting indicates that the glacio-isostatic compensation is not only a gradual viscoelastic phenomenon, but includes also unexpected violent earthquakes, suggestively larger than other known earthquakes in stable continental regions. The research is anticipated to advance science in neotectonics, hydrogeology and deep biosphere studies, and provide important information for nuclear waste and CO2 disposal, petroleum exploration on the Norwegian continental shelf and studies of mineral resources in PG fault areas. We expect that multidisciplinary research applying shallow and deep drilling of postglacial faults would provide significant scientific results through generating new data and models, namely: (1) Understanding PG fault genesis and controls of their locations; (2) Deep structure and depth extent of PG faults; (3) Textural, mineralogical and physical alteration of rocks in the PG faults; (4) State of stress and estimates of paleostress of PG faults; (5) Hydrogeology, hydrochemistry and hydraulic properties of PG faults; (6) Dating of tectonic reactivation(s) and temporal evolution of tectonic systems hosting PG faults; (7) Existence/non-existence of deep biosphere in PG faults; (8) Data useful for planning radioactive waste disposal in crystalline bedrock; (9) Data on rock stress changes in the periphery of the inland ice; (10) Stress pattern along the Norwegian continental margin in relation to the bending spreading ridge and Plio-Pleistocene erosion, uplift and sedimentation with implications for fluid migration and sealing properties of petroleum reservoirs. (11) Data useful in predicting future seismic activity in areas of current deglaciation due to ongoing climatic warming.

The Quaternary thrust system of the northern Alaska Range

USGS Publications Warehouse

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

2012-01-01

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.

Geometry and kinematics of adhesive wear in brittle strike-slip fault zones

NASA Astrophysics Data System (ADS)

Swanson, Mark T.

2005-05-01

Detailed outcrop surface mapping in Late Paleozoic cataclastic strike-slip faults of coastal Maine shows that asymmetric sidewall ripouts, 0.1-200 m in length, are a significant component of many mapped faults and an important wall rock deformation mechanism during faulting. The geometry of these structures ranges from simple lenses to elongate slabs cut out of the sidewalls of strike-slip faults by a lateral jump of the active zone of slip during adhesion along a section of the main fault. The new irregular trace of the active fault after this jump creates an indenting asperity that is forced to plow through the adjoining wall rock during continued adhesion or be cut off by renewed motion along the main section of the fault. Ripout translation during adhesion sets up the structural asymmetry with trailing extensional and leading contractional ends to the ripout block. The inactive section of the main fault trace at the trailing end can develop a 'sag' or 'half-graben' type geometry due to block movement along the scallop-shaped connecting ramp to the flanking ripout fault. Leading contractional ramps can develop 'thrust' type imbrication and forces the 'humpback' geometry to the ripout slab due to distortion of the inactive main fault surface by ripout translation. Similar asymmetric ripout geometries are recognized in many other major crustal scale strike-slip fault zones worldwide. Ripout structures in the 5-500 km length range can be found on the Atacama fault system of northern Chile, the Qujiang and Xiaojiang fault zones in western China, the Yalakom-Hozameen fault zone in British Columbia and the San Andreas fault system in southern California. For active crustal-scale faults the surface expression of ripout translation includes a coupled system of extensional trailing ramps as normal oblique-slip faults with pull-apart basin sedimentation and contractional leading ramps as oblique thrust or high angle reverse faults with associated uplift and erosion. The sidewall ripout model, as a mechanism for adhesive wear during fault zone deformation, can be useful in studies of fault zone geometry, kinematics and evolution from outcrop- to crustal-scales.

Geodynamic model for the development of the Cameroon Hot Line (Equatorial Africa)

NASA Astrophysics Data System (ADS)

Nkono, Collin; Féménias, Olivier; Demaiffe, Daniel

2014-12-01

This work proposes a new geodynamic model for the development of the Cameroon Hot Line (CHL) in Equatorial Africa. It is based on the analysis of the distribution of lineaments and of magmatic bodies (Paleogene anorogenic ring-complexes and Neogene volcanic centres). Two successive geodynamic models are proposed to explain the distribution of the Cainozoic to recent magmatic activity. They are both sinistral. The first one, during the Paleogene, developed around the N ∼ 70°E direction while the second one (Neogene) is oriented around the N ∼ 130°E direction. The two periods are separated by a short transition. The emplacement follows the local reactivation of pre-existing (Pan-African) faults in relation to the collision between the Afro-Arabian and Eurasian plates, during the Alpine history.

Active transfer fault zone linking a segmented extensional system (Betics, southern Spain): Insight into heterogeneous extension driven by edge delamination

NASA Astrophysics Data System (ADS)

Martínez-Martínez, José Miguel; Booth-Rea, Guillermo; Azañón, José Miguel; Torcal, Federico

2006-08-01

Pliocene and Quaternary tectonic structures mainly consisting of segmented northwest-southeast normal faults, and associated seismicity in the central Betics do not agree with the transpressive tectonic nature of the Africa-Eurasia plate boundary in the Ibero-Maghrebian region. Active extensional deformation here is heterogeneous, individual segmented normal faults being linked by relay ramps and transfer faults, including oblique-slip and both dextral and sinistral strike-slip faults. Normal faults extend the hanging wall of an extensional detachment that is the active segment of a complex system of successive WSW-directed extensional detachments which have thinned the Betic upper crust since middle Miocene. Two areas, which are connected by an active 40-km long dextral strike-slip transfer fault zone, concentrate present-day extension. Both the seismicity distribution and focal mechanisms agree with the position and regime of the observed faults. The activity of the transfer zone during middle Miocene to present implies a mode of extension which must have remained substantially the same over the entire period. Thus, the mechanisms driving extension should still be operating. Both the westward migration of the extensional loci and the high asymmetry of the extensional systems can be related to edge delamination below the south Iberian margin coupled with roll-back under the Alborán Sea; involving the asymmetric westward inflow of asthenospheric material under the margins.

Transpressional Tectonics across the N. American-Caribbean Plate Boundary: Preliminary Results of a Multichannel Seismic Survey of Lake Azuei, Haiti.

NASA Astrophysics Data System (ADS)

Hearn, C. K.; Cormier, M. H.; Sloan, H.; Wattrus, N. J.; Boisson, D.; Brown, B.; Guerrier, K.; King, J. W.; Knotts, P.; Momplaisir, R.; Sorlien, C. C.; Stempel, R.; Symithe, S. J.; Ulysse, S. M. J.

2017-12-01

On January 12, 2010, a Mw 7.0 earthquake struck Haiti, killing over 200,000 people and devastating the Capital city of Port-au-Prince and the surrounding regions. It ruptured a previously unknown blind-thrust fault that abuts the Enriquillo Plantain Garden Fault (EPGF), one of two transform faults that define the North American-Caribbean plate boundary. That earthquake highlighted how transpression across this complex boundary is accommodated by slip partitioning into strike-slip and compressional structures. Because the seismic hazard is higher for a rupture on a reverse or oblique-slip fault than on a vertical strike-slip fault, the need to characterize the geometry of that fault system is clear. Lake Azuei overlies this plate boundary 60 km east of the 2010 epicenter. The lake's 23 km long axis trends NW-SE, parallel to the Haitian fold-and-thrust belt and oblique to the EPGF. This tectonic context makes it an ideal target for investigating the partitioning of plate motion between strike-slip and compressional structures. In January 2017, we acquired 222 km of multichannel seismic (MCS) profiles in the lake, largely concurrent with subbottom seismic (CHIRP) profiles. The MCS data were acquired using a high-frequency BubbleGun source and a 75 m-long, 24-channel streamer, achieving a 24 seismic fold with a penetration of 200 m below lakebed. With the goal of resolving tectonic structures in 3-D, survey lines were laid out in a grid with profiles spaced 1.2 km apart. Additional profiles were acquired at the SE end of the lake where most of the tectonic activity is presumably occurring. The co-located CHIRP and MCS profiles document the continuity of tectonic deformation between the surficial sediments and the deeper strata. Preliminary processing suggests that a SW-dipping blind thrust fault, expressed updip as a large monocline fold, may control the western edge of the lake. Gentle, young folds that protrude from the flat lakebed are also imaged with the CHIRP data. No obvious strike-slip faults are revealed in the MCS or CHIRP imagery. This result is consistent with a published analysis of GPS measurements that suggests oblique convergence on a south-dipping reverse fault along the southern shore of the lake.

Criteria for Seismic Splay Fault Activation During Subduction Earthquakes

NASA Astrophysics Data System (ADS)

Dedontney, N.; Templeton, E.; Bhat, H.; Dmowska, R.; Rice, J. R.

2008-12-01

As sediment is added to the accretionary prism or removed from the forearc, the material overlying the plate interface must deform to maintain a wedge structure. One of the ways this internal deformation is achieved is by slip on splay faults branching from the main detachment, which are possibly activated as part of a major seismic event. As a rupture propagates updip along the plate interface, it will reach a series of junctions between the shallowly dipping detachment and more steeply dipping splay faults. The amount and distribution of slip on these splay faults and the detachment determines the seafloor deformation and the tsunami waveform. Numerical studies by Kame et al. [JGR, 2003] of fault branching during dynamic slip-weakening rupture in 2D plane strain showed that branch activation depends on the initial stress state, rupture velocity at the branching junction, and branch angle. They found that for a constant initial stress state, with the maximum principal stress at shallow angles to the main fault, branch activation is favored on the compressional side of the fault for a range of branch angles. By extending the part of their work on modeling the branching behavior in the context of subduction zones, where critical taper wedge concepts suggest the angle that the principal stress makes with the main fault is shallow, but not horizontal, we hope to better understand the conditions for splay fault activation and the criteria for significant moment release on the splay. Our aim is to determine the range of initial stresses and relative frictional strengths of the detachment and splay fault that would result in seismic splay fault activation. In aid of that, we conduct similar dynamic rupture analyses to those of Kame et al., but use explicit finite element methods, and take fuller account of overall structure of the zone (rather than focusing just on the branching junction). Critical taper theory requires that the basal fault be weaker than the overlying material, so we build on previous work by incorporating the effect of strength contrasts between the basal and splay faults. The relative weakness of the basal fault is often attributed to high pore pressures, which lowers the effective normal stress and brings the basal fault closer to failure. We vary the initial stress state, while maintaining a constant principal stress orientation, to see how the closeness to failure affects the branching behavior for a variety of branch step-up angles.

Using LiDAR to quantify uplift of shoreline angles during late Holocene earthquakes in northwest Washington

NASA Astrophysics Data System (ADS)

Sherrod, B. L.

2014-12-01

Three reverse faults in northwestern Washington - the Seattle, Tacoma, and Birch Bay faults - experienced late Holocene earthquakes. Warped intertidal platforms in the hanging wall of each fault formed broad anticlines as a result of deformation during these three earthquakes. Estimates of past deformation rely on differencing raised shoreline features and corresponding modern features. I utilized profiles of LiDAR digital elevation models to calculate prehistoric (647 profiles) and modern shoreline angles (507 profiles) and used these angles to quantify the shape and amount of deformation of each anticline. I calculated shoreline angle elevations by visually fitting lines to modern and uplifted intertidal surfaces and adjacent shoreline cliffs. The intersection of the two fitted lines is the shoreline angle. Mean elevations of modern shoreline angles for 6 shoreline areas in northern Puget Sound and the Strait of Georgia (n=507) lie within 2-46 cm of mean tide level. Three additional shoreline areas in southern Puget Sound have modern shoreline angles closer to mean higher high water (within 22-88 cm) and lie in areas with less fetch and greater tidal range than sites in northern Puget Sound and the Straits of Georgia. A M>7 earthquake ~1.1 ka on the Seattle fault lifted a broad platform cut on sedimentary rocks out of the intertidal zone. Profiles of the platform at three locations along the western end of the Seattle fault zone define an anticline 8-10 km wide (orthogonal to the fault) with a maximum uplift during the earthquake of ~5-8 m. Another large earthquake ~1.1 ka uplifted an intertidal platform along the western part of the Tacoma fault. The raised platform formed an anticline ~10 km wide (orthogonal to the fault) with a maximum uplift of ~5 m. An earthquake ~1.2 ka raised shorelines in the hanging wall of the Birch Bay fault above an anticline observed on seismic reflection profiles near Bellingham, WA. Only part of the anticline is expressed in raised shorelines because shoreline angles are not preserved in the northern limb of the anticline. Estimated width of the anticline is ~8 km with a maximum uplift of 2.5 m. Ongoing elastic half-space modeling is intended to match profiles of each raised shoreline in order to estimate fault geometries and earthquake magnitudes required to produce the observed uplift profiles.

Miocene−Pleistocene deformation of the Saddle Mountains: Implications for seismic hazard in central Washington, USA

USGS Publications Warehouse

Staisch, Lydia; Kelsey, Harvey; Sherrod, Brian; Möller, Andreas; Paces, James B.; Blakely, Richard J.; Styron, Richard

2017-01-01

The Yakima fold province, located in the backarc of the Cascadia subduction zone, is a region of active strain accumulation and deformation distributed across a series of fault-cored folds. The geodetic network in central Washington has been used to interpret large-scale N-S shortening and westward-increasing strain; however, geodetic data are unable to resolve shortening rates across individual structures in this low-strain-rate environment. Resolving fault geometries, slip rates, and timing of faulting in the Yakima fold province is critically important to seismic hazard assessment for nearby infrastructure and population centers.The Saddle Mountains anticline is one of the most prominent Yakima folds. It is unique within the Yakima fold province in that the syntectonic strata of the Ringold Formation are preserved and provide a record of deformation and drainage reorganization. Here, we present new stratigraphic columns, U-Pb zircon tephra ages, U-series caliche ages, and geophysical modeling that constrain two line-balanced and retrodeformed cross sections. These new constraints indicate that the Saddle Mountains anticline has accommodated 1.0−1.3 km of N-S shortening since 10 Ma, that shortening increases westward along the anticline, and that the average slip rate has increased 6-fold since 6.8 Ma. Provenance analysis suggests that the source terrane for the Ringold Formation was similar to that of the modern Snake River Plain. Using new slip rates and structural constraints, we calculate the strain accumulation time, interpretable as a recurrence interval, for earthquakes on the Saddle Mountains fault and find that large-magnitude earthquakes could rupture along the Saddle Mountains fault every 2−11 k.y.

Faults on Skylab imagery of the Salton Trough area, Southern California

NASA Technical Reports Server (NTRS)

Merifield, P. M.; Lamar, D. L. (Principal Investigator)

1975-01-01

The author has identified the following significant results. Large segments of the major high angle faults in the Salton Trough area are readily identifiable in Skylab images. Along active faults, distinctive topographic features such as scarps and offset drainage, and vegetation differences due to ground water blockage in alluvium are visible. Other fault-controlled features along inactive as well as active faults visible in Skylab photography include straight mountain fronts, linear valleys, and lithologic differences producing contrasting tone, color or texture. A northwestern extension of a fault in the San Andreas set, is postulated by the regional alignment of possible fault-controlled features. The suspected fault is covered by Holocene deposits, principally windblown sand. A northwest trending tonal change in cultivated fields across Mexicali Valley is visible on Skylab photos. Surface evidence for faulting was not observed; however, the linear may be caused by differences in soil conditions along an extension of a segment of the San Jacinto fault zone. No evidence of faulting could be found along linears which appear as possible extensions of the Substation and Victory Pass faults, demonstrating that the interpretation of linears as faults in small scale photography must be corroborated by field investigations.

Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults

PubMed Central

Cowie, P. A.; Phillips, R. J.; Roberts, G. P.; McCaffrey, K.; Zijerveld, L. J. J.; Gregory, L. C.; Faure Walker, J.; Wedmore, L. N. J.; Dunai, T. J.; Binnie, S. A.; Freeman, S. P. H. T.; Wilcken, K.; Shanks, R. P.; Huismans, R. S.; Papanikolaou, I.; Michetti, A. M.; Wilkinson, M.

2017-01-01

Many areas of the Earth’s crust deform by distributed extensional faulting and complex fault interactions are often observed. Geodetic data generally indicate a simpler picture of continuum deformation over decades but relating this behaviour to earthquake occurrence over centuries, given numerous potentially active faults, remains a global problem in hazard assessment. We address this challenge for an array of seismogenic faults in the central Italian Apennines, where crustal extension and devastating earthquakes occur in response to regional surface uplift. We constrain fault slip-rates since ~18 ka using variations in cosmogenic 36Cl measured on bedrock scarps, mapped using LiDAR and ground penetrating radar, and compare these rates to those inferred from geodesy. The 36Cl data reveal that individual faults typically accumulate meters of displacement relatively rapidly over several thousand years, separated by similar length time intervals when slip-rates are much lower, and activity shifts between faults across strike. Our rates agree with continuum deformation rates when averaged over long spatial or temporal scales (104 yr; 102 km) but over shorter timescales most of the deformation may be accommodated by <30% of the across-strike fault array. We attribute the shifts in activity to temporal variations in the mechanical work of faulting. PMID:28322311

Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults.

PubMed

Cowie, P A; Phillips, R J; Roberts, G P; McCaffrey, K; Zijerveld, L J J; Gregory, L C; Faure Walker, J; Wedmore, L N J; Dunai, T J; Binnie, S A; Freeman, S P H T; Wilcken, K; Shanks, R P; Huismans, R S; Papanikolaou, I; Michetti, A M; Wilkinson, M

2017-03-21

Many areas of the Earth's crust deform by distributed extensional faulting and complex fault interactions are often observed. Geodetic data generally indicate a simpler picture of continuum deformation over decades but relating this behaviour to earthquake occurrence over centuries, given numerous potentially active faults, remains a global problem in hazard assessment. We address this challenge for an array of seismogenic faults in the central Italian Apennines, where crustal extension and devastating earthquakes occur in response to regional surface uplift. We constrain fault slip-rates since ~18 ka using variations in cosmogenic 36 Cl measured on bedrock scarps, mapped using LiDAR and ground penetrating radar, and compare these rates to those inferred from geodesy. The 36 Cl data reveal that individual faults typically accumulate meters of displacement relatively rapidly over several thousand years, separated by similar length time intervals when slip-rates are much lower, and activity shifts between faults across strike. Our rates agree with continuum deformation rates when averaged over long spatial or temporal scales (10 4  yr; 10 2  km) but over shorter timescales most of the deformation may be accommodated by <30% of the across-strike fault array. We attribute the shifts in activity to temporal variations in the mechanical work of faulting.

Assessing active faulting by hydrogeological modeling and superconducting gravimetry: A case study for Hsinchu Fault, Taiwan

NASA Astrophysics Data System (ADS)

Lien, Tzuyi; Cheng, Ching-Chung; Hwang, Cheinway; Crossley, David

2014-09-01

We develop a new hydrology and gravimetry-based method to assess whether or not a local fault may be active. We take advantage of an existing superconducting gravimeter (SG) station and a comprehensive groundwater network in Hsinchu to apply the method to the Hsinchu Fault (HF) across the Hsinchu Science Park, whose industrial output accounts for 10% of Taiwan's gross domestic product. The HF is suspected to pose seismic hazards to the park, but its existence and structure are not clear. The a priori geometry of the HF is translated into boundary conditions imposed in the hydrodynamic model. By varying the fault's location, depth, and including a secondary wrench fault, we construct five hydrodynamic models to estimate groundwater variations, which are evaluated by comparing groundwater levels and SG observations. The results reveal that the HF contains a low hydraulic conductivity core and significantly impacts groundwater flows in the aquifers. Imposing the fault boundary conditions leads to about 63-77% reduction in the differences between modeled and observed values (both water level and gravity). The test with fault depth shows that the HF's most recent slip occurred in the beginning of Holocene, supplying a necessary (but not sufficient) condition that the HF is currently active. A portable SG can act as a virtual borehole well for model assessment at critical locations of a suspected active fault.

Possible Non-volcanic Tremor Discovered in the Reelfoot Fault Zone, Northern Tennessee

NASA Astrophysics Data System (ADS)

Langston, C. A.; Williams, R. A.; Magnani, M.; Rieger, D. M.

2007-12-01

A swarm of ~80 microearthquakes was fortuitously detected in 20, 14 second-duration long-offset vibroseis shotgathers collected for a seismic reflection experiment near Mooring, TN, directly over the Reelfoot fault zone on the afternoon of 16 November 2006. These natural events show up in the shotgathers as near-vertically incident P waves with a dominant frequency of 10-15 Hz. The reflection line was 715m in length consisting of 144 channels with a sensor spacing of 5m, 8Hz vertical geophones, and recording using a Geometrics 24bit Geode seismograph. Small variations in event moveout across the linear array indicate that the seismicity was not confined to the same hypocenter and probably occurred at depths of approximately 10 km. The largest events in the series are estimated to have local magnitudes of ~-1 if at 10 km distance from the array. This is about 2.5 magnitude units lower than the threshold for local events detected and located by the CERI cooperative network in the area. The seismicity rate was ~1000 events per hour based on the total time duration of the shotgathers. The expected number of earthquakes of ML greater than or equal to -1 for the entire central United States is only 1 per hour. This detection of microseismic swarms in the Reelfoot fault zone indicates active physical processes that may be similar to non-volcanic tremor seen in the Cascadia and San Andreas fault zones and merits long-term monitoring to understand its source.

Spatial Distribution of the Coefficient of Variation and Bayesian Forecast for the Paleo-Earthquakes in Japan

NASA Astrophysics Data System (ADS)

Nomura, Shunichi; Ogata, Yosihiko

2016-04-01

We propose a Bayesian method of probability forecasting for recurrent earthquakes of inland active faults in Japan. Renewal processes with the Brownian Passage Time (BPT) distribution are applied for over a half of active faults in Japan by the Headquarters for Earthquake Research Promotion (HERP) of Japan. Long-term forecast with the BPT distribution needs two parameters; the mean and coefficient of variation (COV) for recurrence intervals. The HERP applies a common COV parameter for all of these faults because most of them have very few specified paleoseismic events, which is not enough to estimate reliable COV values for respective faults. However, different COV estimates are proposed for the same paleoseismic catalog by some related works. It can make critical difference in forecast to apply different COV estimates and so COV should be carefully selected for individual faults. Recurrence intervals on a fault are, on the average, determined by the long-term slip rate caused by the tectonic motion but fluctuated by nearby seismicities which influence surrounding stress field. The COVs of recurrence intervals depend on such stress perturbation and so have spatial trends due to the heterogeneity of tectonic motion and seismicity. Thus we introduce a spatial structure on its COV parameter by Bayesian modeling with a Gaussian process prior. The COVs on active faults are correlated and take similar values for closely located faults. It is found that the spatial trends in the estimated COV values coincide with the density of active faults in Japan. We also show Bayesian forecasts by the proposed model using Markov chain Monte Carlo method. Our forecasts are different from HERP's forecast especially on the active faults where HERP's forecasts are very high or low.

Hydrocarbon Reservoir Identification in Volcanic Zone by using Magnetotelluric and Geochemistry Information

NASA Astrophysics Data System (ADS)

Firda, S. I.; Permadi, A. N.; Supriyanto; Suwardi, B. N.

2018-03-01

The resistivity of Magnetotelluric (MT) data show the resistivity mapping in the volcanic reservoir zone and the geochemistry information for confirm the reservoir and source rock formation. In this research, we used 132 data points divided with two line at exploration area. We used several steps to make the resistivity mapping. There are time series correction, crosspower correction, then inversion of Magnetotelluric (MT) data. Line-2 and line-3 show anomaly geological condition with Gabon fault. The geology structure from the resistivity mapping show the fault and the geological formation with the geological rock data mapping distribution. The geochemistry information show the maturity of source rock formation. According to core sample analysis information, we get the visual porosity for reservoir rock formation in several geological structure. Based on that, we make the geological modelling where the potential reservoir and the source rock around our interest area.

Growth stratal records of instantaneous and progressive limb rotation in the Precordillera thrust belt and Bermejo basin, Argentina

NASA Astrophysics Data System (ADS)

Zapata, TomáS. R.; Allmendinger, Richard W.

1996-10-01

Analysis of synorogenic deposits preserved near the thrust front zone of the Precordillera fold and thrust belt and in the Bermejo foreland basin in central Argentina documents the evolution of deformation during the last 5 Myr as well as the thrust system kinematics. Seismic lines across the area display examples of progressive and instantaneous limb rotations. The easternmost thrust plate of the Central Precordillera, the Niquivil thrust, experienced episodic motion in two main stages: a first thrust movement as a fault-propagation fold and a second movement as a high-angle anticlinal breakthrough fault after a period of quiescence. Growth strata deposited in the La Pareja intermontane basin and the Las Salinas and Bermejo anticline recorded continuous growth of Eastern Precordilleran structures beginning at ˜2.7 Ma, with uplift rates of ˜0.3 mm/yr for the Niquivil anticline, 1.08 mm/yr for the Las Salinas anticline, and between ˜0.6 and 0.38 mm/yr during the last ˜2 Myr for the Bermejo anticline. Once the Eastern Precordillera began to grow, the propagation of the Niquivil thrust stopped, restricting the deformation to the young Vallecito out-of sequence thrust. The complex geometry of growth strata deposited on the back limb of the Las Salinas anticline can be explained by using a model of a two-step fault propagation fold with constant layer thickness. The Bermejo anticline of the Eastern Precordillera is formed by the simultaneous propagation of a shallow fault, responsible for the fold shape, and a deep fault that produced vertical uplift. A growth triangle that documents instantaneous forelimb rotation for a fault-propagation fold is recorded for the first time in a published seismic line.

Can a Red Wood-Ant Nest Be Associated with Fault-Related CH4 Micro-Seepage? A Case Study from Continuous Short-Term In-Situ Sampling

PubMed Central

Grumpe, Arne; Becker, Adrian; Wöhler, Christian

2018-01-01

Simple Summary Methane (CH4) is common on Earth but its natural sources are not well-characterized. We investigated concentrations of CH4 and its stable carbon isotope (δ13C-CH4) within a red wood-ant (RWA; Formica polyctena) nest in the Neuwied Basin, a part of the East Eifel Volcanic Field (EEVF), and tested for associations between methane concentration and RWA activity patterns, earthquakes, and earth tides. Methane degassing was not synchronized with earth tides, nor was it influenced by a micro-earthquake or RWA activity. Elevated CH4 concentrations in nest gas appear to result from a combination of microbial activity and fault-related emissions. The latter could result from micro-seepage of methane derived from low-temperature gas-water-rock reactions that subsequently moves via fault networks through the RWA nest or from overlapping micro-seepage of magmatic CH4 from the Eifel plume. Given the abundance of RWA nests on the landscape, their role as sources of microbial CH4 and biological indicators for abiotically-derived CH4 should be included in estimations of methane emissions that are contributing to climatic change. Abstract We measured methane (CH4) and stable carbon isotope of methane (δ13C-CH4) concentrations in ambient air and within a red wood-ant (RWA; Formica polyctena) nest in the Neuwied Basin (Germany) using high-resolution in-situ sampling to detect microbial, thermogenic, and abiotic fault-related micro-seepage of CH4. Methane degassing from RWA nests was not synchronized with earth tides, nor was it influenced by micro-earthquake degassing or concomitantly measured RWA activity. Two δ13C-CH4 signatures were identified in nest gas: −69‰ and −37‰. The lower peak was attributed to microbial decomposition of organic matter within the RWA nest, in line with previous observations that RWA nests are hot-spots of microbial CH4. The higher peak has not been reported in previous studies. We attribute this peak to fault-related CH4 emissions moving via fault networks into the RWA nest, which could originate either from thermogenic or abiotic CH4 formation. Sources of these micro-seepages could be Devonian schists, iron-bearing “Klerf Schichten”, or overlapping micro-seepage of magmatic CH4 from the Eifel plume. Given the abundance of RWA nests on the landscape, their role as sources of microbial CH4 and biological indicators for abiotically-derived CH4 should be included in estimation of methane emissions that are contributing to climatic change. PMID:29597318