Spatial and temporal variation of seismic velocity during earthquakes and volcanic eruptions in western Japan: Insight into mechanism for seismic velocity variation

NASA Astrophysics Data System (ADS)

Tsuji, T.; Ikeda, T.; Nimiya, H.

2017-12-01

We report spatio-temporal variations of seismic velocity around the seismogenic faults in western Japan. We mainly focus on the seismic velocity variation during (1) the 2016 Off-Mie earthquake in the Nankai subduction zone (Mw5.8) and (2) the 2016 Kumamoto earthquake in Kyushu Island (Mw7.0). We applied seismic interferometry and surface wave analysis to the ambient noise data recorded by Hi-net and DONET seismometers of National Research Institute for Earth Science and Disaster Resilience (NIED). Seismic velocity near the rupture faults and volcano decreased during the earthquake. For example, we observed velocity reduction around the seismogenic Futagawa-Hinagu fault system and Mt Aso in the 2016 Kumamoto earthquake. We also identified velocity increase after the eruptions of Mt Aso. During the 2016 Off-Mie earthquake, we observed seismic velocity variation in the Nankai accretionary prism. After the earthquakes, the seismic velocity gradually returned to the pre-earthquake value. The velocity recovering process (healing process) is caused by several mechanisms, such as pore pressure reduction, strain change, and crack sealing. By showing the velocity variations obtained at different geologic settings (volcano, seismogenic fault, unconsolidated sediment), we discuss the mechanism of seismic velocity variation as well as the post-seismic fault healing process.

Geologic setting, sedimentary architecture, and paragenesis of the Mesoproterozoic sediment-hosted Sheep Creek Cu-Co-Ag deposit, Helena embayment, Montana

USGS Publications Warehouse

Graham, Garth; Hitzman, Murray W.; Zieg, Jerry

2012-01-01

The northern margin of the Helena Embayment contains extensive syngenetic to diagenetic massive pyrite horizons that extend over 25 km along the Volcano Valley-Buttress fault zone and extend up to 8 km basinward (south) within the Mesoproterozoic Newland Formation. The Sheep Creek Cu-Co deposit occurs within a structural block along a bend in the fault system, where replacement-style chalcopyrite mineralization is spatially associated mostly with the two stratigraphically lowest massive pyrite zones. These mineralized pyritic horizons are intercalated with debris flows derived from synsedimentary movement along the Volcano Valley-Buttress fault zone. Cominco American Inc. delineated a geologic resource of 4.5 Mt at 2.5% Cu and 0.1% Co in the upper sulfide zone and 4 Mt at 4% Cu within the lower sulfide zone. More recently, Tintina Resources Inc. has delineated an inferred resource of 8.48 Mt at 2.96% Cu, 0.12% Co, and 16.4 g/t Ag in the upper sulfide zone. The more intact upper sulfide zone displays significant thickness variations along strike thought to represent formation in at least three separate subbasins. The largest accumulation of mineralized sulfide in the upper zone occurs as an N-S–trending body that thickens southward from the generally E trending Volcano Valley Fault and probably occupies a paleograben controlled by normal faults in the hanging wall of the Volcano Valley Fault. Early microcrystalline to framboidal pyrite was accompanied by abundant and local barite deposition in the upper and lower sulfide zones, respectively. The sulfide bodies underwent intense (lower sulfide zone) to localized (upper sulfide zone) recrystallization and overprinting by coarser-grained pyrite and minor marcasite that is intergrown with and replaces dolomite. Silicification and paragenetically late chalcopyrite, along with minor tennantite in the upper sulfide zone, replaces fine-grained pyrite, barite, and carbonate. The restriction of chalcopyrite to inferred synsedimentary E- and northerly trending faults and absence of definitive zonation with respect to the Laramide Volcano Valley Fault in the lower sulfide zone suggest a diagenetic age related to basin development for the Sheep Creek Cu-Co-Ag deposit.

Continuation, south of Oaxaca City (southern Mexico) of the Oaxaca-Juarez terrane boundary and of the Oaxaca Fault. Based in MT, gravity and magnetic studies

NASA Astrophysics Data System (ADS)

Campos-Enriquez, J. O.; Corbo, F.; Arzate-Flores, J.; Belmonte-Jimenez, S.; Arango-Galván, C.

2010-12-01

The Oaxaca Fault represents Tertiary extensional reactivation of the Juarez shear zone constituting the boundary-suture between the Oaxaca and Juarez terranes (southern Mexico). South of Oaxaca City, the fault trace disappears and there are not clear evidences for its southward continuation at depth. The crust in southern México has been studied through seismic refraction, and seismological and magnetotelluric (MT) studies. The refraction studies did not image the Oaxaca Fault. However, previous regional MT studies suggest that the Oaxaca-Juarez terrane boundary lies to the east of the Zaachila and Mitla sub-basins, which implies sinistral displacement along the Donaji Fault. Campos-Enriquez et al. (2009) established the shallow structure of the Oaxaca-Juarez terrane boundary based in detailed gravity and magnetic studies. This study enabled: 1) to establish the shallow structure of the composite depression comprising three N-S sub-basins: the northern Etla and southern Zaachila sub-basins separated by the Atzompa sub-basin. According to the Oaxaca-Juarez terrane boundary is displaced sinistrally ca. 20 km along the E-W Donají Fault, which defines the northern boundary of the Zaachila sub-basin. At the same time,, the Oaxaca Fault may either continue unbroken southwards along the western margin of a horst in the Zaachila sub-basin or be offset along with the terrane boundary. This model implies that originally the suture was continuous south of the Donaji Fault. A constraint for the accreation of the Oaxaca and Juarez terranes. Thirty MT soundings were done in the area of the Central Valleys, Oaxaca City (southern Mexico). In particular we wanted to image the possible southward continuation of the Oaxaca Fault. 22 Mt sounding are located along two NE-SW profiles to the northern and to the south of the City of Oaxaca. To the north of Oaxaca City, the electrical resistivity distribution obtained show a clear discontinuity across the superficial trace of the Oaxaca Fault that can be associated to the contact between the Oaxaca and Juarez terranes. The most conspicuous conductive feature is associated with the Juarez terrane, while the resistivity high observed to the SW of the northern profile is associated with the Oaxaca terrane. South of Oaxaca City (on the southern profile), the Oaxaca Fault is still observed but here it does not reach deep crustal levels. But contrastingly, a conspicuous resistivity low is observed dipping to the east and affecting crust at deep levels, that is being interpreted as the suture of the above mentioned terranes. Also the suture between the Oaxaca and Acatlan complexes (i.e., between the Oaxaca and Mixteco terranes) are also observed on the MT images. As a main result we have that the Oaxacan Complex continues eastward across the Oaxaca-Juarez terrane boundary

Investigating Crustal Scale Fault Systems Controlling Volcanic and Hydrothermal Fluid Processes in the South-Central Andes, First Results from a Magnetotelluric Survey

NASA Astrophysics Data System (ADS)

Pearce, R.; Mitchell, T. M.; Moorkamp, M.; Araya, J.; Cembrano, J. M.; Yanez, G. A.; Hammond, J. O. S.

2017-12-01

At convergent plate boundaries, volcanic orogeny is largely controlled by major thrust fault systems that act as magmatic and hydrothermal fluid conduits through the crust. In the south-central Andes, the volcanically and seismically active Tinguiririca and Planchon-Peteroa volcanoes are considered to be tectonically related to the major El Fierro thrust fault system. These large scale reverse faults are characterized by 500 - 1000m wide hydrothermally altered fault cores, which possess a distinct conductive signature relative to surrounding lithology. In order to establish the subsurface architecture of these fault systems, such conductivity contrasts can be detected using the magnetotelluric method. In this study, LEMI fluxgate-magnetometer long-period and Metronix broadband MT data were collected at 21 sites in a 40km2 survey grid that surrounds this fault system and associated volcanic complexes. Multi-remote referencing techniques is used together with robust processing to obtain reliable impedance estimates between 100 Hz and 1,000s. Our preliminary inversion results provide evidence of structures within the 10 - 20 km depth range that are attributed to this fault system. Further inversions will be conducted to determine the approximate depth extent of these features, and ultimately provide constraints for future geophysical studies aimed to deduce the role of these faults in volcanic orogeny and hydrothermal fluid migration processes in this region of the Andes.

The Surface faulting produced by the 30 October 2016 Mw 6.5 Central Italy earthquake: the Open EMERGEO Working Group experience

NASA Astrophysics Data System (ADS)

Pantosti, Daniela

2017-04-01

The October 30, 2016 (06:40 UTC) Mw 6.5 earthquake occurred about 28 km NW of Amatrice village as the result of upper crust normal faulting on a nearly 30 km-long, NW-SE oriented, SW dipping fault system in the Central Apennines. This earthquake is the strongest Italian seismic event since the 1980 Mw 6.9 Irpinia earthquake. The Mw 6.5 event was the largest shock of a seismic sequence, which began on August 24 with a Mw 6.0 earthquake and also included a Mw 5.9 earthquake on October 26, about 9 and 35 km NW of Amatrice village, respectively. Field surveys of coseismic geological effects at the surface started within hours of the mainshock and were carried out by several national and international teams of earth scientists (about 120 people) from different research institutions and universities coordinated by the EMERGEO Working Group of the Istituto Nazionale di Geofisica e Vulcanologia. This collaborative effort was focused on the detailed recognition and mapping of: 1) the total extent of the October 30 coseismic surface ruptures, 2) their geometric and kinematic characteristics, 3) the coseismic displacement distribution along the activated fault system, including subsidiary and antithetic ruptures. The huge amount of collected data (more than 8000 observation points of several types of coseismic effects at the surface) were stored, managed and shared using a specifically designed spreadsheet to populate a georeferenced database. More comprehensive mapping of the details and extent of surface rupture was facilitated by Structure-from-Motion photogrammetry surveys by means of several helicopter flights. An almost continuous alignment of ruptures about 30 km long, N150/160 striking, mainly SW side down was observed along the already known active Mt. Vettore - Mt. Bove fault system. The mapped ruptures occasionally overlapped those of the August 24 Mw 6.0 and October 26 Mw 5.9 shocks. The coincidence between the observed surface ruptures and the trace of active normal faults mapped in the available geological literature is noteworthy. The field data collected suggest a complex coseismic surface faulting pattern along closely-spaced, parallel or subparallel, overlapping or step-like synthetic and antithetic fault splays. The cumulative surface faulting length has been estimated in about 40 km. The maximum vertical offset is significant, locally exceeding 2 meters along the Mt. Vettore Fault, measured both along bedrock fault planes and free-faces affecting unconsolidated deposits. This enormous collaborative experience has a twofold relevance, on the one side allowed to document in high detail the earthquake ruptures before Winter would destroy them, on the other represent the first large European experience for coseismic effects survey that we should use a leading case to establish a coseismic effects European team to get ready to respond to future seismic crises at the European level.

Near-field fault slip of the 2016 Vettore Mw 6.6 earthquake (Central Italy) measured using low-cost GNSS.

PubMed

Wilkinson, Maxwell W; McCaffrey, Ken J W; Jones, Richard R; Roberts, Gerald P; Holdsworth, Robert E; Gregory, Laura C; Walters, Richard J; Wedmore, Luke; Goodall, Huw; Iezzi, Francesco

2017-07-04

The temporal evolution of slip on surface ruptures during an earthquake is important for assessing fault displacement, defining seismic hazard and for predicting ground motion. However, measurements of near-field surface displacement at high temporal resolution are elusive. We present a novel record of near-field co-seismic displacement, measured with 1-second temporal resolution during the 30 th October 2016 M w 6.6 Vettore earthquake (Central Italy), using low-cost Global Navigation Satellite System (GNSS) receivers located in the footwall and hangingwall of the Mt. Vettore - Mt. Bove fault system, close to new surface ruptures. We observe a clear temporal and spatial link between our near-field record and InSAR, far-field GPS data, regional measurements from the Italian Strong Motion and National Seismic networks, and field measurements of surface ruptures. Comparison of these datasets illustrates that the observed surface ruptures are the propagation of slip from depth on a surface rupturing (i.e. capable) fault array, as a direct and immediate response to the 30 th October earthquake. Large near-field displacement ceased within 6-8 seconds of the origin time, implying that shaking induced gravitational processes were not the primary driving mechanism. We demonstrate that low-cost GNSS is an accurate monitoring tool when installed as custom-made, short-baseline networks.

Preliminary study of Songa-Wayaua geothermal prospect area using volcanostratigraphy and remote sensing analysis

NASA Astrophysics Data System (ADS)

Asokawaty, Ribka; Nugroho, Indra; Satriana, Joshua; Hafidz, Muhamad; Suryantini

2017-12-01

Songa-Wayaua geothermal prospect area is located on Bacan Island, Northern Molluca Province. Geothermal systems in this area associated with three Quartenary volcanoes, such as Mt. Pele-pele, Mt. Lansa, and Mt. Bibinoi. Based on literature study, five surface manifestations such as hot springs and alteration occurred within this area. The active manifestations indicate that Songa-Wayaua area has potential geothermal resource. This study objective is to evaluate Songa-Wayaua geothermal system on preliminary study stage by using volcanostratigraphy and remote sensing analysis to delineate the boundary of geothermal system area. The result of this study showed that Songa-Wayaua prospect area has four heat sources potential (e.g. Pele-pele Hummock, Lansa Hummock, Songa Hummock, and Bibinoi Hummock), controlled by geological structure presented by Pele-pele Normal Fault, and had three places as the recharge and discharge area which are very fulfilling as a geothermal system.

Geophysical data reveal the crustal structure of the Alaska Range orogen within the aftershock zone of the Mw 7.9 Denali fault earthquake

USGS Publications Warehouse

Fisher, M.A.; Ratchkovski, N.A.; Nokleberg, W.J.; Pellerin, L.; Glen, J.M.G.

2004-01-01

Geophysical information, including deep-crustal seismic reflection, magnetotelluric (MT), gravity, and magnetic data, cross the aftershock zone of the 3 November 2002 Mw 7.9 Denali fault earthquake. These data and aftershock seismicity, jointly interpreted, reveal the crustal structure of the right-lateral-slip Denali fault and the eastern Alaska Range orogen, as well as the relationship between this structure and seismicity. North of the Denali fault, strong seismic reflections from within the Alaska Range orogen show features that dip as steeply as 25?? north and extend downward to depths between 20 and 25 km. These reflections reveal crustal structures, probably ductile shear zones, that most likely formed during the Late Cretaceous, but these structures appear to be inactive, having produced little seismicity during the past 20 years. Furthermore, seismic reflections mainly dip north, whereas alignments in aftershock hypocenters dip south. The Denali fault is nonreflective, but modeling of MT, gravity, and magnetic data suggests that the Denali fault dips steeply to vertically. However, in an alternative structural model, the Denali fault is defined by one of the reflection bands that dips to the north and flattens into the middle crust of the Alaska Range orogen. Modeling of MT data indicates a rock body, having low electrical resistivity (>10 ??-m), that lies mainly at depths greater than 10 km, directly beneath aftershocks of the Denali fault earthquake. The maximum depth of aftershocks along the Denali fault is 10 km. This shallow depth may arise from a higher-than-normal geothermal gradient. Alternatively, the low electrical resistivity of deep rocks along the Denali fault may be associated with fluids that have weakened the lower crust and helped determine the depth extent of the after-shock zone.

The Big Mountain oil field, Ventura, California

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

Hall, E.A.

1967-06-02

The Big Mt. oil field is believed to be primarily a fault trap accumulation. All faults are hidden beneath the unconformity at the base of the Vaqueros Formation, or die out before reaching the surface. The Sespe Formation is divided into an upper sandy unit, a middle alternating sand and shale unit, and a lower sandy unit in the Big Mt. area. The producing zone is in the upper portion of the lower sandy unit. The sands are soft and friable, medium to coarse, and the reservoir characteristics are relatively good. The geology is similar to that observed in manymore » Sespe fields, such as the Oxnard and Montalvo oil fields, and the SE. portion of the South Mt. oil field. These fields are broken into many fault blocks and different production characteristics in each block. Good wells and poor ones are interspersed, with good wells downdip from poor ones and visa versa. The Big Mt. field is shallow, drilling and production costs are relatively inexpensive, and there is no royalty burden on the oil.« less

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

Malin, Peter E.; Shalev, Eylon; Onacha, Stepthen A.

In this final report, we discuss both theoretical and applied research resulting from our DOE project, ICEKAP 2004: A Collaborative Joint Geophysical Imaging Project at Krafla and IDDP. The abstract below begins with a general discussion of the problem we addressed: the location and characterization of “blind” geothermal resources using microearthquake and magnetotelluric measurements. The abstract then describes the scientific results and their application to the Krafla geothermal area in Iceland. The text following this abstract presents the full discussion of this work, in the form of the PhD thesis of Stephen A. Onacha. The work presented here was awardedmore » the “Best Geophysics Paper” at the 2005 Geothermal Resources Council meeting, Reno. This study presents the modeling of buried fault zones using microearthquake and electrical resistivity data based on the assumptions that fluid-filled fractures cause electrical and seismic anisotropy and polarization. In this study, joint imaging of electrical and seismic data is used to characterize the fracture porosity of the fracture zones. P-wave velocity models are generated from resistivity data and used in locating microearthquakes. Fracture porosity controls fluid circulation in the hydrothermal systems and the intersections of fracture zones close to the heat source form important upwelling zones for hydrothermal fluids. High fracture porosity sites occur along fault terminations, fault-intersection areas and fault traces. Hydrothermal fault zone imaging using resistivity and microearthquake data combines high-resolution multi-station seismic and electromagnetic data to locate rock fractures and the likely presence fluids in high temperature hydrothermal systems. The depths and locations of structural features and fracture porosity common in both the MT and MEQ data is incorporated into a joint imaging scheme to constrain resistivity, seismic velocities, and locations of fracture systems. The imaging of the fault zones is constrained by geological, drilling, and geothermal production data. The objective is to determine interpretation techniques for evaluating structural controls of fluid circulation in hydrothermal systems. The conclusions are: • directions of MT polarization and anisotropy and MEQ S-splitting correlate. Polarization and anisotropy are caused by fluid filled fractures at the base of the clay cap. •Microearthquakes occur mainly on the boundary of low resistivity within the fracture zone and high resistivity in the host rock. Resistivity is lowest within the core of the fracture zone and increases towards the margins of the fracture zone. The heat source and the clay cap for the hydrothermal have very low resistivity of less than 5Ωm. •Fracture porosity imaged by resistivity indicates that it varies between 45-5% with most between 10-20%, comparable to values from core samples in volcanic areas in Kenya and Iceland. For resistivity values above 60Ωm, the porosity reduces drastically and therefore this might be used as the upper limit for modeling fracture porosity from resistivity. When resistivity is lower than 5Ωm, the modeled fracture porosity increases drastically indicating that this is the low resistivity limit. This is because at very low resistivity in the heat source and the clay cap, the resistivity is dominated by ionic conduction rather than fracture porosity. •Microearthquakes occur mainly above the heat source which is defined by low resistivity at a depth of 3-4.5 km at the Krafla hydrothermal system and 4-7 km in the Longonot hydrothermal system. •Conversions of S to P waves occur for microearthquakes located above the heat source within the hydrothermal system. Shallow microearthquakes occur mainly in areas that show both MT and S-wave anisotropy. •S-wave splitting and MT anisotropy occurs at the base of the clay cap and therefore reflects the variations in fracture porosity on top of the hydrothermal system. •In the Krafla hydrothermal system in Iceland, both MT polarization and MEQ splitting directions align with zones that have high fracture porosity below the clay cap. These zones coincide with fault zones trending in the NNE-SSW and NW-SE directions in otherwise uniform volcanic rocks and laterally continuous geology. The NW-SE orientation is parallel to the regional shear fractures while the NNE-SSW trending polarizations align parallel to rift zone fracture swarms. This suggest that correlations between MT polarizations and MEQ splitting may be related to fluid filled fractures. •In areas of high resistivity (60Ωm), the P-wave velocity approaches that of the rock matrix. •S-wave splitting polarization is determined from measurements of angles of rotation to get the optimum direction of polarization. •The use of MEQ and resistivity for imaging fractures requires that the MEQ data acquisition system be located close to the fracture zone.« less

Fault kinematics and active tectonics of the Sabah margin: Insights from the 2015, Mw 6.0, Mt. Kinabalu earthquake

NASA Astrophysics Data System (ADS)

Wang, Y.; Wei, S.; Tapponnier, P.; WANG, X.; Lindsey, E.; Sieh, K.

2016-12-01

A gravity-driven "Mega-Landslide" model has been evoked to explain the shortening seen offshore Sabah and Brunei in oil-company seismic data. Although this model is considered to account simultaneously for recent folding at the edge of the submarine NW Sabah trough and normal faulting on the Sabah shelf, such a gravity-driven model is not consistent with geodetic data or critical examination of extant structural restorations. The rupture that produced the 2015 Mw6.0 Mt. Kinabalu earthquake is also inconsistent with the gravity-driven model. Our teleseismic analysis shows that the centroid depth of that earthquake's mainshock was 13 to 14 km, and its favored fault-plane solution is a 60° NW-dipping normal fault. Our finite-rupture model exhibits major fault slip between 5 and 15 km depth, in keeping with our InSAR analysis, which shows no appreciable surface deformation. Both the hypocentral depth and the depth of principal slip are far too deep to be explained by gravity-driven failure, as such a model would predict a listric normal fault connecting at a much shallower depth with a very gentle detachment. Our regional mapping of tectonic landforms also suggests the recent rupture is part of a 200-km long system of narrowly distributed active extension in northern Sabah. Taken together, the nature of the 2015 rupture, the belt of active normal faults, and structural consideration indicate that active tectonic shortening plays the leading role in controlling the overall deformation of northern Sabah and that deep-seated, onland normal faulting likely results from an abrupt change in the dip-angle of the collision interface beneath the Sabah accretionary prism.

Joint Inversion of 3d Mt/gravity/magnetic at Pisagua Fault.

NASA Astrophysics Data System (ADS)

Bascur, J.; Saez, P.; Tapia, R.; Humpire, M.

2017-12-01

This work shows the results of a joint inversion at Pisagua Fault using 3D Magnetotellurics (MT), gravity and regional magnetic data. The MT survey has a poor coverage of study area with only 21 stations; however, it allows to detect a low resistivity zone aligned with the Pisagua Fault trace that it is interpreted as a damage zone. The integration of gravity and magnetic data, which have more dense sampling and coverage, adds more detail and resolution to the detected low resistivity structure and helps to improve the structure interpretation using the resulted models (density, magnetic-susceptibility and electrical resistivity). The joint inversion process minimizes a multiple target function which includes the data misfit, model roughness and coupling norms (crossgradient and direct relations) for all geophysical methods considered (MT, gravity and magnetic). This process is solved iteratively using the Gauss-Newton method which updates the model of each geophysical method improving its individual data misfit, model roughness and the coupling with the other geophysical models. For solving the model updates of magnetic and gravity methods were developed dedicated 3D inversion software codes which include the coupling norms with additionals geophysical parameters. The model update of the 3D MT is calculated using an iterative method which sequentially filters the priority model and the output model of a single 3D MT inversion process for obtaining the resistivity model coupled solution with the gravity and magnetic methods.

Paleoseismology of the Mt. Narryer Fault Zone, West Central Western Australia: a Multi-Segment Intraplate Fault System

NASA Astrophysics Data System (ADS)

Whitney, B. B.; Clark, D.; Hengesh, J.

2014-12-01

The Western Australia shear zone (WASZ) is a 2000 km long fault system within the intraplate region of Australia. A paleoseismological study of faults and fault-related folds comprising the Mount Narryer fault zone (MNfz) in the southern WASZ reveals a late Quaternary history of repeated morphogenic earthquake occurrence that has profoundly influenced the planform and course of the Murchison, Roderick, and Sanford Rivers. Folding in the near surface sediments is the predominant style of surface expression of reactivated basement faults which is consistent with other neotectonic structures throughout the Western Australia shear zone. CRN and OSL estimates of exposure and burial ages of fault-related folds and fold derived colluvium provide constraint on Late Quaternary slip rates on the underlying faults of ~0.05 - 0.1 mm/a. In the case of the Roderick River fault scarp, 2-3m high tectonic risers separating inset terraces where the Murchison River crosses the scarp are consistent with multiple late Quaternary seismic events on the order of magnitude Mw 7.1-7.3. Mid-Pleistocene ages of tectonically deformed strata in the MNfz are consistent with the timing of collision between the Australian extended margin and Savu-Rote ridge 0.2-1.8 Ma.

What electrical measurements can say about changes in fault systems.

PubMed Central

Madden, T R; Mackie, R L

1996-01-01

Earthquake zones in the upper crust are usually more conductive than the surrounding rocks, and electrical geophysical measurements can be used to map these zones. Magnetotelluric (MT) measurements across fault zones that are parallel to the coast and not too far away can also give some important information about the lower crustal zone. This is because the long-period electric currents coming from the ocean gradually leak into the mantle, but the lower crust is usually very resistive and very little leakage takes place. If a lower crustal zone is less resistive it will be a leakage zone, and this can be seen because the MT phase will change as the ocean currents leave the upper crust. The San Andreas Fault is parallel to the ocean boundary and close enough to have a lot of extra ocean currents crossing the zone. The Loma Prieta zone, after the earthquake, showed a lot of ocean electric current leakage, suggesting that the lower crust under the fault zone was much more conductive than normal. It is hard to believe that water, which is responsible for the conductivity, had time to get into the lower crustal zone, so it was probably always there, but not well connected. If this is true, then the poorly connected water would be at a pressure close to the rock pressure, and it may play a role in modifying the fluid pressure in the upper crust fault zone. We also have telluric measurements across the San Andreas Fault near Palmdale from 1979 to 1990, and beginning in 1985 we saw changes in the telluric signals on the fault zone and east of the fault zone compared with the signals west of the fault zone. These measurements were probably seeing a better connection of the lower crust fluids taking place, and this may result in a fluid flow from the lower crust to the upper crust. This could be a factor in changing the strength of the upper crust fault zone. PMID:11607664

Some aspects of active tectonism in Alaska as seen on ERTS-1

NASA Technical Reports Server (NTRS)

Gedney, L. D.; Vanwormer, J. D.

1973-01-01

ERTS-1 imagery is proving to be exceptionally useful in delineating structural features in Alaska which have never been recognized on the ground. Previously unmapped features such as seismically active faults and major structural lineaments are especially evident. Among the more significant results of this investigation is the discovery of an active strand of the Denali fault. The new fault has a history of scattered seismicity and was the scene of a magnitude 4.8 earthquake on October 1, 1972. Perhaps of greater significance is the disclosure of a large scale conjugate fracture system north of the Alaska Range. This fracture system appears to result from compressive stress radiating outward from around the outside of the great bend of the Alaska Range at Mt. McKinley.

Major Crustal Fault Zone Trends and Their Relation to Mineral Belts in the North-Central Great Basin, Nevada

USGS Publications Warehouse

Rodriguez, Brian D.; Sampson, Jay A.; Williams, Jackie M.

2007-01-01

The Great Basin physiographic province covers a large part of the western United States and contains one of the world's leading gold-producing areas, the Carlin Trend. In the Great Basin, many sedimentary-rock-hosted disseminated gold deposits occur along such linear mineral-occurrence trends. The distribution and genesis of these deposits is not fully understood, but most models indicate that regional tectonic structures play an important role in their spatial distribution. Over 100 magnetotelluric (MT) soundings were acquired between 1994 and 2001 by the U.S. Geological Survey to investigate crustal structures that may underlie the linear trends in north-central Nevada. MT sounding data were used to map changes in electrical resistivity as a function of depth that are related to subsurface lithologic and structural variations. Two-dimensional (2-D) resistivity modeling of the MT data reveals primarily northerly and northeasterly trending narrow 2-D conductors (1 to 30 ohm-m) extending to mid-crustal depths (5-20 km) that are interpreted to be major crustal fault zones. There are also a few westerly and northwesterly trending 2-D conductors. However, the great majority of the inferred crustal fault zones mapped using MT are perpendicular or oblique to the generally accepted trends. The correlation of strike of three crustal fault zones with the strike of the Carlin and Getchell trends and the Alligator Ridge district suggests they may have been the root fluid flow pathways that fed faults and fracture networks at shallower levels where gold precipitated in favorable host rocks. The abundant northeasterly crustal structures that do not correlate with the major trends may be structures that are open to fluid flow at the present time.

Crustal structure of the alaska range orogen and denali fault along the richardson highway

USGS Publications Warehouse

Fisher, M.A.; Pellerin, L.; Nokleberg, W.J.; Ratchkovski, N.A.; Glen, J.M.G.

2007-01-01

A suite of geophysical data obtained along the Richardson Highway crosses the eastern Alaska Range and Denali fault and reveals the crustal structure of the orogen. Strong seismic reflections from within the orogen north of the Denali fault dip as steeply as 25?? north and extend downward to depths between 20 and 25 km. These reflections reveal what is probably a shear zone that transects most of the crust and is part of a crustal-scale duplex structure that probably formed during the Late Cretaceous. These structures, however, appear to be relict because over the past 20 years, they have produced little or no seismicity despite the nearby Mw = 7.9 Denali fault earthquake that struck in 2002. The Denali fault is nonreflective, but we interpret modeled magnetotelluric (MT), gravity, and magnetic data to propose that the fault dips steeply to vertically. Modeling of MT data shows that aftershocks of the 2002 Denali fault earthquake occurred above a rock body that has low electrical resistivity (>10 ohm-m), which might signify the presence of fluids in the middle and lower crust. Copyright ?? 2007 The Geological Society of America.

Resistivity structure of Sumatran Fault (Aceh segment) derived from 1-D magnetotelluric modeling

NASA Astrophysics Data System (ADS)

Nurhasan, Sutarno, D.; Bachtiar, H.; Sugiyanto, D.; Ogawa, Y.; Kimata, F.; Fitriani, D.

2012-06-01

Sumatran Fault Zone is the most active fault in Indonesia as a result of strike-slip component of Indo-Australian oblique convergence. With the length of 1900 km, Sumatran fault was divided into 20 segments starting from the southernmost Sumatra Island having small slip rate and increasing to the north end of Sumatra Island. There are several geophysical methods to analyze fault structure depending on physical parameter used in these methods, such as seismology, geodesy and electromagnetic. Magnetotelluric method which is one of geophysical methods has been widely used in mapping and sounding resistivity distribution because it does not only has the ability for detecting contras resistivity but also has a penetration range up to hundreds of kilometers. Magnetotelluric survey was carried out in Aceh region with the 12 total sites crossing Sumatran Fault on Aceh and Seulimeum segments. Two components of electric and magnetic fields were recorded during 10 hours in average with the frequency range from 320 Hz to 0,01 Hz. Analysis of the pseudosection of phase and apparent resistivity exhibit vertical low phase flanked on the west and east by high phase describing the existence of resistivity contras in this region. Having rotated the data to N45°E direction, interpretation of the result has been performed using three different methods of 1D MT modeling i.e. Bostick inversion, 1D MT inversion of TM data, and 1D MT inversion of the impedance determinant. By comparison, we concluded that the use of TM data only and the impedance determinant in 1D inversion yield the more reliable resistivity structure of the fault compare to other methods. Based on this result, it has been shown clearly that Sumatra Fault is characterized by vertical contras resistivity indicating the existence of Aceh and Seulimeum faults which has a good agreement with the geological data.

Magnetotelluric Studies of Fault Zones Surrounding the 2016 Pawnee, Oklahoma Earthquake

NASA Astrophysics Data System (ADS)

Evans, R. L.; Key, K.; Atekwana, E. A.

2016-12-01

Since 2008, there has been a dramatic increase in earthquake activity in the central United States in association with major oil and gas operations. Oklahoma is now considered one the most seismically active states. Although seismic networks are able to detect activity and map its locus, they are unable to image the distribution of fluids in the fault responsible for triggering seismicity. Electrical geophysical methods are ideally suited to image fluid bearing faults since the injected waste-waters are highly saline and hence have a high electrical conductivity. To date, no study has imaged the fluids in the faults in Oklahoma and made a direct link to the seismicity. The 2016 M5.8 Pawnee, Oklahoma earthquake provides an unprecedented opportunity for scientists to provide that link. Several injection wells are located within a 20 km radius of the epicenter; and studies have suggested that injection of fluids in high-volume wells can trigger earthquakes as far away as 30 km. During late October to early November, 2016, we are collecting magnetotelluric (MT) data with the aim of constraining the distribution of fluids in the fault zone. The MT technique uses naturally occurring electric and magnetic fields measured at Earth's surface to measure conductivity structure. We plan to carry out a series of short two-dimensional (2D) profiles of wideband MT acquisition located through areas where the fault recently ruptured and seismic activity is concentrated and also across the faults in the vicinity that did not rupture. The integration of our results and ongoing seismic studies will lead to a better understanding of the links between fluid injection and seismicity.

The Kumamoto Mw7.1 mainshock: deep initiation triggered by the shallow foreshocks

NASA Astrophysics Data System (ADS)

Shi, Q.; Wei, S.

2017-12-01

The Kumamoto Mw7.1 earthquake and its Mw6.2 foreshock struck the central Kyushu region in mid-April, 2016. The surface ruptures are characterized with multiple fault segments and a mix of strike-slip and normal motion extended from the intersection area of Hinagu and Futagawa faults to the southwest of Mt. Aso. Despite complex surface ruptures, most of the finite fault inversions use two fault segments to approximate the fault geometry. To study the rupture process and the complex fault geometry of this earthquake, we performed a multiple point source inversion for the mainshock using the data on 93 K-net and Kik-net stations. With path calibration from the Mw6.0 foreshock, we selected the frequency ranges for the Pnl waves (0.02 0.26 Hz) and surface waves (0.02 0.12 Hz), as well as the components that can be well modeled with the 1D velocity model. Our four-point-source results reveal a unilateral rupture towards Mt. Aso and varying fault geometries. The first sub-event is a high angle ( 79°) right-lateral strike-slip event at the depth of 16 km on the north end of the Hinagu fault. Notably the two M>6 foreshocks is located by our previous studies near the north end of the Hinagu fault at the depth of 5 9 km, which may give rise to the stress concentration at depth. The following three sub-events are distributed along the surface rupture of the Futagawa fault, with focal depths within 4 10 km. Their focal mechanisms present similar right-lateral fault slips with relatively small dip angles (62 67°) and apparent normal-fault component. Thus, the mainshock rupture initiated from the relatively deep part of the Hinagu fault and propagated through the fault-bend toward NE along the relatively shallow part of the Futagawa fault until it was terminated near Mt. Aso. Based on the four-point-source solution, we conducted a finite-fault inversion and obtained a kinematic rupture model of the mainshock. We then performed the Coulomb Stress analyses on the two foreshocks and the mainshock. The results support that the stress alternation after the foreshocks may have triggered the failure on the fault plane of the Mw7.1 earthquake. Therefore, the 2016 Kumamoto earthquake sequence is dominated by a series of large triggering events whose initiation is associated with the geometric barrier in the intersection of the Futagawa and Hinagu faults.

Evaluation of feasibility of mapping seismically active faults in Alaska

NASA Technical Reports Server (NTRS)

Gedney, L. D. (Principal Investigator); Vanwormer, J. D.

1973-01-01

The author has identified the following significant results. ERTS-1 imagery is proving to be exceptionally useful in delineating structural features in Alaska which have never been recognized on the ground. Previously unmapped features such as seismically active faults and major structural lineaments are especially evident. Among the more significant results of this investigation is the discovery of an active strand of the Denali fault. The new fault has a history of scattered activity and was the scene of a magnitude 4.8 earthquake on October 1, 1972. Of greater significance is the disclosure of a large scale conjugate fracture system north of the Alaska Range. This fracture system appears to result from compressive stress radiating outward from around Mt. McKinley. One member of the system was the scene of a magnitude 6.5 earthquake in 1968. The potential value of ERTS-1 imagery to land use planning is reflected in the fact that this earthquake occurred within 10 km of the site which was proposed for the Rampart Dam, and the fault on which it occurred passes very near the proposed site for the bridge and oil pipeline crossing of the Yukon River.

Near-surface structure of the Central Scandinavian Caledonides in northern Trøndelag, Norway, from correlation of seismic and MT profiles using gravity and magnetic data

NASA Astrophysics Data System (ADS)

Ebbing, J.; Goerigk, L.; Nasuti, A.; Roberts, D.; Korja, T. J.; Smirnov, M.

2014-12-01

The deep geology of northern Trøndelag is somewhat speculative as the Central Scandinavian Caledonides are intersected by the Møre-Trøndelag Fault Complex (MTFC) and only a few depth-penetrating geophysical profiles exist. Here, we correlate the mapped geological units and faults between a seismic-reflection profile and a MT profile. The seismic-reflection data were acquired in 5 segments over the period 1986-1990. The westernmost section of the seismic profile is dominated by a complex pattern of reflections and diffractions. This type of pattern is typical of polydeformed terranes with a mixture of contrasting felsic and mafic lithologies. The two steeply-dipping strands of the MTFC (Hitra-Snåsa and Verran faults) that transect the profile do not show any distinctive signature in the seismic data. The MT data were acquired in 2007 from the Swedish border to the Norwegian coast. The conductivity profile shows some distinct vertical changes as well as changes from the near-surface to shallow depths. The strands of the MTFC show especially a distinctive change in conductivity. The two profiles are almost parallel but separated by 100 km. To correlate the structures seen on both profiles, we have applied lineament analysis and 3D modelling of the gravity and magnetic field. The tilt derivative of the magnetic and isostatic gravity anomaly clearly allows us to identify and link the main geological boundaries between the profiles and to trace the strands of the MTFC from one profile to the other. This trend analysis indicates that at least the Verran Fault visibly modifies the pattern of seismic reflections. However, the main change in crustal lithology occurs farther to the west, almost at the coast where the Tarva Fault intersects the MT profile. This integrated analysis shows the benefit of combining gravity and magnetic interpretations with MT and seismic data to enable us to understand the near-surface geology and structure in more detail.

Petrologic considerations for hot dry rock geothermal site selection in the Clear Lake Region, California

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

Stimac, J.; Goff, F.; Hearn, B.C. Jr.

1992-01-01

The Clear Lake area is well known for anomalous heat flow, thermal springs, hydrothermal mineral deposits, and Quaternary volcanism. These factors, along with the apparent lack of a large reservoir of geothermal fluid north of Collayomi fault make the Clear Lake area an attractive target for hot dry rock (HDR) geothermal development. Petrologic considerations provide some constraints on site selection for HDR development. Spatial and temporal trends in volcanism in the Coast Ranges indicate that magmatism has migrated to the north with time, paralleling passage of the Mendocino triple junction and propagation of the San Andreas fault. Volcanism in themore » region may have resulted from upwelling of hot asthenosphere along the southern margin of the subducted segment of the Gorda plate. Spatial and temporal trends of volcanism within the Clear Lake volcanic field are similar to larger-scale trends of Neogene volcanism in the Cost Ranges. Volcanism (especially for silicic compositions) shows a general migration to the north over the {approximately}2 Ma history of the field, with the youngest two silicic centers located at Mt. Konocti and Borax Lake. The Mt. Konocti system (active from {approximately} 0.6 to 0.3 Ma) was large and long-lived, whereas the Borax Lake system is much smaller but younger (0.09 Ma). Remnants of silicic magma bodies under Mt. Konocti may be in the latter stages of cooling, whereas a magma body centered under Borax Lake may be in the early stages of development. The existence of an upper crustal silicic magma body of under Borax Lake has yet to be demonstrated by passive geophysics, however, subsurface temperatures in the area as high (> 200{degrees}C at 2000 m) as those beneath the Mt. Konocti area. Based on petrologic considerations alone, the Mt. Konocti-Borax Lake area appears to be the most logical choice for HDR geothermal development in the region.« less

Electrical conductivity of a locked fault: investigation of the Ganos segment of the North Anatolian Fault using three-dimensional magnetotellurics

NASA Astrophysics Data System (ADS)

Karaş, Mustafa; Tank, Sabri Bülent; Özaydın, Sinan

2017-08-01

This study attempts to reveal the fault zone characteristics of the locked Ganos Fault based on electrical resistivity studies including audio-frequency (AMT: 10,400-1 Hz) and wide-band (MT: 360-0.000538 Hz) magnetotellurics near the epicenter of the last major event, that is, the 1912 Mürefte Earthquake ( M w 7.4). The AMT data were collected at twelve stations, closely spaced from north to south, to resolve the shallow resistivity structure to 1 km depth. Subsequently, 13 wide-band MT stations were arranged to form a grid enclosing the AMT profile to decipher the deeper structure. Three-dimensional inverse modeling indicates highly conductive anomalies representing fault zone conductors along the Ganos Fault. Subsidiary faults around the Ganos Fault, which are conductive structures with individual mechanically weak features, merge into a greater damage zone, creating a wide fluid-bearing environment. This damage zone is located on the southern side of the fault and defines an asymmetry around the main fault strand, which demonstrates distributed conduit behavior of fluid flow. Ophiolitic basement occurs as low-conductivity block beneath younger formations at a depth of 2 km, where the mechanically weak to strong transition occurs. Resistive structures on both sides of the fault beneath this transition suggest that the lack of seismicity might be related to the absence of fluid pathways in the seismogenic zone.[Figure not available: see fulltext.

Upper mantle diapers, lower crustal magmatic underplating, and lithospheric dismemberment of the Great Basin and Colorado Plateau regions, Nevada and Utah; implications from deep MT resistivity surveying

NASA Astrophysics Data System (ADS)

Wannamaker, P. E.; Doerner, W. M.; Hasterok, D. P.

2005-12-01

In the rifted Basin and Range province of the southwestern U.S., a common faulting model for extensional basins based e.g. on reflection seismology data shows dominant displacement along master faults roughly coincident with the main topographic scarp. On the other hand, complementary data such as drilling, earthquake focal mechanisms, volcanic occurrences, and trace indicators such as helium isotopes suggest that there are alternative geometries of crustal scale faulting and material transport from the deep crust and upper mantle in this province. Recent magnetotelluric (MT) profiling results reveal families of structures commonly dominated by high-angle conductors interpreted to reflect crustal scale fault zones. Based mainly on cross cutting relationships, these faults appear to be late Cenozoic in age and are of low resistivity due to fluids or alteration (including possible graphitization). In the Ruby Mtns area of north-central Nevada, high angle faults along the margins of the core complex connect from near surface to a regional lower crustal conductor interpreted to contain high-temperature fluids and perhaps melts. Such faults may exemplify the high angle normal faults upon which the major earthquakes of the Great Basin appear to nucleate. A larger-scale transect centered on Dixie Valley shows major conductive crustal-scale structures connecting to conductive lower crust below Dixie Valley, the Black Rock desert in NW Nevada, and in east-central Nevada in the Monitor-Diamond Valley area. In the Great Basin-Colorado Plateau transition of Utah, the main structures revealed are a series of nested low-angle detachment structures underlying the incipient development of several rift grabens. All these major fault zones appear to overlie regions of particularly conductive lower crust interpreted to be caused by recent basaltic underplating. In the GB-CP transition, long period data show two, low-resistivity upper mantle diapirs underlying the concentrated conductive lower crust and nested faults, and these are advanced as melt source regions for the underplating. MT, with its wide frequency bandwidth, allows views of nearly a complete melting and emplacement process, from mantle source region, through lower crustal intrusion, to brittle regime deformational response.

Evidence for a Battle Mountain-Eureka crustal fault zone, north-central Nevada, and its relation to Neoproterozoic-Early Paleozoic continental breakup

USGS Publications Warehouse

Grauch, V.J.S.; Rodriguez, B.D.; Bankey, V.; Wooden, J.L.

2003-01-01

Combined evidence from gravity, radiogenic isotope, and magnetotelluric (MT) data indicates a crustal fault zone that coincides with the northwest-trending Battle Mountain-Eureka (BME) mineral trend in north-central Nevada, USA. The BME crustal fault zone likely originated during Neoproterozoic-Early Paleozoic rifting of the continent and had a large influence on subsequent tectonic events, such as emplacement of allochthons and episodic deformation, magmatism, and mineralization throughout the Phanerozoic. MT models show the fault zone is about 10 km wide, 130-km long, and extends from 1 to 5 km below the surface to deep crustal levels. Isotope data and gravity models imply the fault zone separates crust of fundamentally different character. Geophysical evidence for such a long-lived structure, likely inherited from continental breakup, defies conventional wisdom that structures this old have been destroyed by Cenozoic extensional processes. Moreover, the coincidence with the alignment of mineral deposits supports the assertion by many economic geologists that these alignments are indicators of buried regional structures.

When probabilistic seismic hazard climbs volcanoes: the Mt. Etna case, Italy - Part 1: Model components for sources parameterization

NASA Astrophysics Data System (ADS)

Azzaro, Raffaele; Barberi, Graziella; D'Amico, Salvatore; Pace, Bruno; Peruzza, Laura; Tuvè, Tiziana

2017-11-01

The volcanic region of Mt. Etna (Sicily, Italy) represents a perfect lab for testing innovative approaches to seismic hazard assessment. This is largely due to the long record of historical and recent observations of seismic and tectonic phenomena, the high quality of various geophysical monitoring and particularly the rapid geodynamics clearly demonstrate some seismotectonic processes. We present here the model components and the procedures adopted for defining seismic sources to be used in a new generation of probabilistic seismic hazard assessment (PSHA), the first results and maps of which are presented in a companion paper, Peruzza et al. (2017). The sources include, with increasing complexity, seismic zones, individual faults and gridded point sources that are obtained by integrating geological field data with long and short earthquake datasets (the historical macroseismic catalogue, which covers about 3 centuries, and a high-quality instrumental location database for the last decades). The analysis of the frequency-magnitude distribution identifies two main fault systems within the volcanic complex featuring different seismic rates that are controlled essentially by volcano-tectonic processes. We discuss the variability of the mean occurrence times of major earthquakes along the main Etnean faults by using an historical approach and a purely geologic method. We derive a magnitude-size scaling relationship specifically for this volcanic area, which has been implemented into a recently developed software tool - FiSH (Pace et al., 2016) - that we use to calculate the characteristic magnitudes and the related mean recurrence times expected for each fault. Results suggest that for the Mt. Etna area, the traditional assumptions of uniform and Poissonian seismicity can be relaxed; a time-dependent fault-based modeling, joined with a 3-D imaging of volcano-tectonic sources depicted by the recent instrumental seismicity, can therefore be implemented in PSHA maps. They can be relevant for the retrofitting of the existing building stock and for driving risk reduction interventions. These analyses do not account for regional M > 6 seismogenic sources which dominate the hazard over long return times (≥ 500 years).

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.

High resolution shallow co-seismic and post-seismic slip from the 2016 central Italy earthquake sequence captured using terrestrial laser scanning, structure from motion and low-cost near-field GNSS

NASA Astrophysics Data System (ADS)

Wedmore, L. N. J.; Gregory, L. C.; McCaffrey, K. J. W.; Wilkinson, M.; Walters, R. J.

2017-12-01

Coseismic fault slip in the shallow crust is poorly constrained by many of the conventional tools used to record deformation during earthquakes. GNSS stations are often distributed too far from faults and radar images tend to decorrelate across earthquake surface ruptures. As a result, our understanding of near-field fault slip, shallow slip deficits, and off-fault deformation is limited. We present evidence from the 2016 central Italy earthquake sequence, during which we captured shallow coseismic and post-seismic slip using a combination of terrestrial laser scanning (TLS), structure-from-motion (SfM), and near-field low-cost GNSS recording at 1Hz. Three Mw>6 earthquakes on the 24th August, 26th and 30th October all involved slip on the Mt Vettore-Mt Bove fault system. We collected TLS and SfM point clouds across three separate segments of this system. Each segment experienced a different record of slip during the earthquake sequence; all three ruptured in the largest event (Mw 6.6. on October 30th) but two segments also ruptured during either the 24th August or the 26th October earthquakes. Following the Mw 6.6 earthquake, the faults were repeatedly surveyed using TLS, with the first scan collected c. 5 hours following the earthquake. This represents the first known instance where shallow co-seismic slip has been recorded by pre- and post-event terrestrial laser scanning. Displacement continuously measured across GNSS pairs at 1 Hz demonstrates that permanent near field displacement developed across the fault in the immediate seconds following the initiation of the rupture. However, a discrepancy between on-fault field measurements of surface displacement and the GNSS recorded displacement over 1km long baselines hints at a more complex rupture processes and the possibility of high slip gradients in the shallow subsurface. Displacement measured by differential TLS confirms the presence of these shallow slip deficits but suggests that shallow slip gradient may be controlled by the pattern and timing of slip in the preceding earthquakes. Postseismic afterslip captured by repeated TLS surveys hints at more complicated temporal evolution of nearfield afterslip than is currently predicted by logarithmic models for this process.

Detailed Surface Rupture Geometry from the 2016 Amatrice Earthquake

NASA Astrophysics Data System (ADS)

Mildon, Z. K.; Iezzi, F.; Wedmore, L. N. J.; Gregory, L. C.; McCaffrey, K. J. W.; Wilkinson, M. W.; Faure Walker, J.; Roberts, G.; Livio, F.; Vittori, E.; Michetti, A.; Frigerio, C.; Ferrario, F.; Blumetti, A. M.; Guerrieri, L.; Di Manna, P.; Comerci, V.

2016-12-01

The Amatrice earthquake was generated by co-rupture of the Mt. Vettore and Laga faults at depth. Surface ruptures were observed for 5km along the Mt. Vettore fault, with no clear observations on the Laga fault reported to date. The surface rupture on Mt. Vettore manifests as a 15-20cm pale stripe at the base of a 60-80o dipping bedrock fault scarp and similar magnitude vertical offsets of colluvial deposits. We have measured the strike and dip of the fault alongside the coseismic throw, heave, and slip azimuth along the length of the rupture with high spatial resolution (c.2-6m, >2000 measurements). The slip azimuth is relatively constant between 210-270° even where the rupture faces uphill at its SE termination which is consistent with the regional NW-SE extension direction, defined by focal mechanisms and borehole break-out data. The simplest coseismic throw profile that would be expected is quasi-symmetric. However we found the highest values of throw (Inter Quartile Range 15-19.5cm) are skewed towards the NW end on a 1.7 km section of the fault that is oblique relative to the overall fault strike. In the centre of the rupture, orientated close to the overall fault strike, the throw is lower (IQR 7.5-13cm) and discontinuous along strike. We suggest that the skewed throw profile occurs because the strike, dip and throw must vary systematically in order to preserve the principal strain rate across a fault, in agreement with previous publications. The density of our measurements, crucially including the slip azimuth, allows us to resolve the regional debate over whether normal fault ruptures are primary tectonic features or landslides of hangingwall sediments. If the surface offsets are due to landslides, then the slip azimuth should correlate with the downslope direction of the hangingwall. We show using an available 10m DEM that this is not the case and hence the surface offsets described herein are a primary tectonic feature. This presentation offers new insights into rupture processes because of the high resolution of the dataset collected rapidly after the earthquake, but crucially because it includes the slip vector azimuth, allowing a full description of the kinematics of the faulting relative to the regional stress field and local topographic variations.

The Ionian and Alfeo-Etna fault zones: New segments of an evolving plate boundary in the central Mediterranean Sea?

NASA Astrophysics Data System (ADS)

Polonia, A.; Torelli, L.; Artoni, A.; Carlini, M.; Faccenna, C.; Ferranti, L.; Gasperini, L.; Govers, R.; Klaeschen, D.; Monaco, C.; Neri, G.; Nijholt, N.; Orecchio, B.; Wortel, R.

2016-04-01

The Calabrian Arc is a narrow subduction-rollback system resulting from Africa/Eurasia plate convergence. While crustal shortening is taken up in the accretionary wedge, transtensive deformation accounts for margin segmentation along transverse lithospheric faults. One of these structures is the NNW-SSE transtensive fault system connecting the Alfeo seamount and the Etna volcano (Alfeo-Etna Fault, AEF). A second, NW-SE crustal discontinuity, the Ionian Fault (IF), separates two lobes of the CA subduction complex (Western and Eastern Lobes) and impinges on the Sicilian coasts south of the Messina Straits. Analysis of multichannel seismic reflection profiles shows that: 1) the IF and the AEF are transfer crustal tectonic features bounding a complex deformation zone, which produces the downthrown of the Western lobe along a set of transtensive fault strands; 2) during Pleistocene times, transtensive faulting reactivated structural boundaries inherited from the Mesozoic Tethyan domain which acted as thrust faults during the Messinian and Pliocene; and 3) the IF and the AEF, and locally the Malta escarpment, accommodate a recent tectonic event coeval and possibly linked to the Mt. Etna formation. Regional geodynamic models show that, whereas AEF and IF are neighboring fault systems, their individual roles are different. Faulting primarily resulting from the ESE retreat of the Ionian slab is expressed in the northwestern part of the IF. The AEF, on the other hand, is part of the overall dextral shear deformation, resulting from differences in Africa-Eurasia motion between the western and eastern sectors of the Tyrrhenian margin of northern Sicily, and accommodating diverging motions in the adjacent compartments, which results in rifting processes within the Western Lobe of the Calabrian Arc accretionary wedge. As such, it is primarily associated with Africa-Eurasia relative motion.

Tectonics and seismicity of the southern Washington Cascade range

USGS Publications Warehouse

Stanley, W.D.; Johnson, S.Y.; Qamar, A.I.; Weaver, C.S.; Williams, J.M.

1996-01-01

Geophysical, geological, and seismicity data are combined to develop a transpressional strain model for the southern Washington Cascades region. We use this model to explain oblique fold and fault systems, transverse faults, and a linear seismic zone just west of Mt. Rainier known as the western Rainier zone. We also attempt to explain a concentration of earthquakes that connects the northwest-trending Mount St. Helens seismic zone to the north-trending western Rainier zone. Our tectonic model illustrates the pervasive effects of accretionary processes, combined with subsequent transpressive forces generated by oblique subduction, on Eocene to present crustal processes, such as seismicity and volcanism.

Laboratory study of the characteristics of fault breccias in Busan area in Korea

NASA Astrophysics Data System (ADS)

Woo, I.; Um, J.

2012-12-01

The physical and mechanical characteristics of fault breccias from near the Mt. Kumjung were estimated from laboratory tests on fractured fault breccias. Mt. Kumjung is surrounded by Yangsan Fault and Dongrae Fault which are major faults traversing the southeast part of Korea in the direction of NE-SW. The undisturbed samples were obtained from boreholes drilled in this region. The microscopic analysis on the thin sections of fault breccias showed the microstructure and the porosity of breccias. The fault breccias are composed of mainly fine quartz grains, and of angular quartz grains and weathered microcline grains. This microstructure of fault breccias might be formed by the catalasis during brittle deformation processes of the fault. 20 to 40% porosity of fault breccias could play an important role in the passage of groundwater and then in the development of fault gouge in the core part of fault. The mechanical characteristics were estimated by means of uniaxial compressive strength tests on the undisturbed breccias samples. Since fault breccias are not cohesive enough to use it directly as a test specimen, the epoxy resin was utilized to fix the outer surface of core samples. The thin plastic wrap had been enveloped before the epoxy resin was applied in order that the epoxy resin could not penetrate into the core specimens. The thickness of epoxy resin was less than 1mm not to disturb the results of uniaxial compressive strength of core samples. The measured uniaxial compressive strengths are 10 to 15MPa for the only physically fractured breccias and 8 to 10 MPa for the core specimens with hydrothermally altered surface. These results can be compared with the Hoek and Brown failure criteria : 7 to 10MPa for GSI value 40 to 50 for fault breccias with fresh surface. The overall measured strength of fault breccias is less than the strength obtained empirically by Hoek and Brown failure criteria.; ;

Cenozoic exhumation history of South China: A case study from the Xuefeng Mt. Range

NASA Astrophysics Data System (ADS)

Wang, Yannan; Zhang, Jin; Zhang, Beihang; Zhao, Heng

2018-01-01

New apatite fission track (AFT) dating was applied to the Xuefeng Mt. Range and Yuanma Basin to constrain the Cenozoic exhumation process of the southeastern Yangtze Block, South China. The analyzed samples in this study have AFT ages ranging from 27.9 ± 2.5 to 61.5 ± 5.9 Ma, which are younger than the deposition or crystallization ages of the host rocks. The AFT analysis and thermal history modeling indicate that both the Xuefeng Mt. Range and the Yuanma Basin underwent significant exhumation during the early Cenozoic (ca. 60-40 Ma). These samples were rapidly exhumed to near the surface during this period. Our results suggest that an important tectonic event occurred along or near regional fault zones (e.g., the Qinhang Fault) in South China during the early Cenozoic (ca. 60-40 Ma). However, it is difficult to relate this event to the Eastern Sichuan fold belt, which is much older and is characterized by large-scale folding and thrusting. Combined with fieldwork in the Yuanma, Xupu, and Xinning basins, we refute the Cretaceous "Pan-Yangtze Basin" that was proposed to have been separated by the uplifted Xuefeng Mt. Range after the Late Cretaceous. The exhumation stage from ca. 60 Ma to 40 Ma was an important period during which plate movements across the eastern Asian and Pacific regions were reorganized. The early Cenozoic tectonothermal event in South China can be attributed to a change in the direction and speed of the subduction of the Pacific Plate beneath the Eurasian Plate. An Oligocene-Miocene cooling event was also recorded in the eastern Xuefeng Mt. Range, which we tentatively attribute to the activity of dextral faults in this area as a far-field effect of the collision between the Indian and Eurasian plates.

Spatial distribution of soil radon as a tool to recognize active faulting on an active volcano: the example of Mt. Etna (Italy).

PubMed

Neri, Marco; Giammanco, Salvatore; Ferrera, Elisabetta; Patanè, Giuseppe; Zanon, Vittorio

2011-09-01

This study concerns measurements of radon and thoron emissions from soil carried out in 2004 on the eastern flank of Mt. Etna, in a zone characterized by the presence of numerous seismogenic and aseismic faults. The statistical treatment of the geochemical data allowed recognizing anomaly thresholds for both parameters and producing distribution maps that highlighted a significant spatial correlation between soil gas anomalies and tectonic lineaments. The seismic activity occurring in and around the study area during 2004 was analyzed, producing maps of hypocentral depth and released seismic energy. Both radon and thoron anomalies were located in areas affected by relatively deep (5-10 km depth) seismic activity, while less evident correlation was found between soil gas anomalies and the released seismic energy. This study confirms that mapping the distribution of radon and thoron in soil gas can reveal hidden faults buried by recent soil cover or faults that are not clearly visible at the surface. The correlation between soil gas data and earthquakes depth and intensity can give some hints on the source of gas and/or on fault dynamics. Copyright © 2011 Elsevier Ltd. All rights reserved.

Preliminary interpretation of high resolution 3D seismic data from offshore Mt. Etna, Italy

NASA Astrophysics Data System (ADS)

Gross, F.; Krastel, S.; Chiocci, F. L.; Ridente, D.; Cukur, D.; Bialas, J.; Papenberg, C. A.; Crutchley, G.; Koch, S.

2013-12-01

In order to gain knowledge about subsurface structures and its correlation to seafloor expressions, a hydro-acoustic dataset was collected during RV Meteor Cruise M86/2 (December 2011/January 2012) in Messina Straits and offshore Mt. Etna. Especially offshore Mt. Etna, the data reveals an obvious connection between subsurface structures and previously known morphological features at the sea floor. Therefore a high resolution 3D seismic dataset was acquired between Riposto Ridge and Catania Canyon close to the shore of eastern Sicily. The study area is characterized by a major structural high, which hosts several ridge-like features at the seafloor. These features are connected to a SW-NE trending fault system. The ridges are bended in their NE-SW direction and host major escarpments at the seafloor. Furthermore they are located directly next to a massive amphitheater structure offshore Mt. Etna with slope gradients of up to 35°, which is interpreted as remnants of a massive submarine mass wasting event off Sicily. The new 3D seismic dataset allows an in depth analysis of the ongoing deformation of the east flank of Mt. Etna.

Monitoring an EGS injection at Newberry Volcano using Magnetotelluric dimensionality analysis

NASA Astrophysics Data System (ADS)

Bowles-martinez, E.; Schultz, A.; Rose, K.; Urquhart, S.

2016-12-01

The sensitivity of magnetotelluric (MT) data to the presence of electrically conductive subsurface features makes it applicable for determining the extent of injected fluids in enhanced geothermal systems (EGS). We use MT to monitor fluid injection during tests of a proposed EGS site at Newberry Volcano in Central Oregon, USA. Newberry is a large shield volcano located where fault systems of the northern Basin and Range meet the Cascade Arc and the high lava plains. Its strong potential for geothermal energy has made it a target for energy exploration for over 40 years. MT measurements were made before, during, and after an EGS stimulation in 2014 in an effort to detect subsurface pathways taken by fluids that are attributable to stimulation. We begin by creating a baseline model from inverting over 200 wideband MT stations located in the western half of the volcano. This model is constrained by well logs, as well as by high resolution gravity and seismic velocity modeling. Our model shows conductive regions associated with the caldera's ring fault, likely showing where hydrothermal fluids or their mineral alteration products are present. However, as this is an EGS study, we are interested in detecting fluid intrusion into hot, dry rock. Therefore, our primary target is a resistive zone on the western flank of Newberry volcano that is interpreted as a series of hot intrusive sequences. Well bottom temperatures in this area have been measured in excess of 300 °C. The stimulation's effect on resistivity is subtle, in part because the injected fluid is fresh groundwater, the injected volume is modest, and the target depth is 2,000-3,000 m below ground level. We found that it is advantageous to look at the impedance tensor data directly to detect injected fluids. Because fluids and their associated change in resistivity are expected to be concentrated around the injection well, the injection will exhibit a highly three-dimensional resistivity structure. Therefore, we examine the impedance tensor for changes in dimensionality to mark the arrival of injected fluids. We then present a method of inverting MT data for changes in impedance rather than for resistivity.

Joint Services Electronics Program.

DTIC Science & Technology

1993-03-05

Mary- land, June 1992. Interconnection Network Design Based on Packaging Considerations Professor Abhiram Ranade with M. T. Raghunath A central...characterized by our abstract models of packaging technology. JSEP Publications [1] M.T. Raghunath and Abhiram Ranade, "Customizing Interconnection...94720, January 1993. [21 M.T. Raghunath and Abhiram Ranade, "Fault-Tolerant Routing in Partitioned Butterfly Networks," submitted to the 1993

Investigation of the heat source(s) of the Surprise Valley Geothermal System, Northern California

NASA Astrophysics Data System (ADS)

Tanner, N.; Holt, C. D.; Hawkes, S.; McClain, J. S.; Safford, L.; Mink, L. L.; Rose, C.; Zierenberg, R. A.

2016-12-01

Concerns about environmental impacts and energy security have led to an increased interest in sustainable and renewable energy resources, including geothermal systems. It is essential to know the permeability structure and possible heat source(s) of a geothermal area in order to assess the capacity and extent of the potential resource. We have undertaken geophysical surveys at the Surprise Valley Hot Springs in Cedarville, California to characterize essential parameters related to a fault-controlled geothermal system. At present, the heat source(s) for the system are unknown. Igneous bodies in the area are likely too old to have retained enough heat to supply the system, so it is probable that fracture networks provide heat from some deeper or more distributed heat sources. However, the fracture system and permeability structure remain enigmatic. The goal of our research is to identify the pathways for fluid transport within the Surprise Valley geothermal system using a combination of geophysical methods including active seismic surveys and short- and long-period magnetotelluric (MT) surveys. We have collected 14 spreads, consisting of 24 geophones each, of active-source seismic data. We used a "Betsy Gun" source at 8 to 12 locations along each spread and have collected and analyzed about 2800 shot-receiver pairs. Seismic velocities reveal shallow lake sediments, as well as velocities consistent with porous basalts. The latter, with velocities of greater than 3.0 km/s, lie along strike with known hot springs and faulted and tilted basalt outcrops outside our field area. This suggests that basalts may provide a permeable pathway through impermeable lake deposits. We conducted short-period (10Hz-60kHz) MT measurements at 33 stations. Our short-period MT models indicate shallow resistive blocks (>100Ωm) with a thin cover of more conductive sediments ( 10Ωm) at the surface. Hot springs are located in gaps between resistive blocks and are connected to deeper low resistivity zones ( 1Ωm), suggestive of a fluid pathway. In order to refine these models and extend them to greater depths, we have deployed long-period (0.002Hz-10Hz) MT instruments in three locations. The data were collected over several weeks and are currently being processed and analyzed.

The Quaternary Silver Creek Fault Beneath the Santa Clara Valley, California

USGS Publications Warehouse

Wentworth, Carl M.; Williams, Robert A.; Jachens, Robert C.; Graymer, Russell W.; Stephenson, William J.

2010-01-01

The northwest-trending Silver Creek Fault is a 40-km-long strike-slip fault in the eastern Santa Clara Valley, California, that has exhibited different behaviors within a changing San Andreas Fault system over the past 10-15 Ma. Quaternary alluvium several hundred meters thick that buries the northern half of the Silver Creek Fault, and that has been sampled by drilling and imaged in a detailed seismic reflection profile, provides a record of the Quaternary history of the fault. We assemble evidence from areal geology, stratigraphy, paleomagnetics, ground-water hydrology, potential-field geophysics, and reflection and earthquake seismology to determine the long history of the fault in order to evaluate its current behavior. The fault formed in the Miocene more than 100 km to the southeast, as the southwestern fault in a 5-km-wide right step to the Hayward Fault, within which the 40-km-long Evergreen pull-apart basin formed. Later, this basin was obliquely cut by the newly recognized Mt. Misery Fault to form a more direct connection to the Hayward Fault, although continued growth of the basin was sufficient to accommodate at least some late Pliocene alluvium. Large offset along the San Andreas-Calaveras-Mt Misery-Hayward Faults carried the basin northwestward almost to its present position when, about 2 Ma, the fault system was reorganized. This led to near abandonment of the faults bounding the pull-apart basin in favor of right slip extending the Calaveras Fault farther north before stepping west to the Hayward Fault, as it does today. Despite these changes, the Silver Creek Fault experienced a further 200 m of dip slip in the early Quaternary, from which we infer an associated 1.6 km or so of right slip, based on the ratio of the 40-km length of the strike-slip fault to a 5-km depth of the Evergreen Basin. This dip slip ends at a mid-Quaternary unconformity, above which the upper 300 m of alluvial cover exhibits a structural sag at the fault that we interpret as a negative flower structure. This structure implies some continuing strike slip on the Silver Creek Fault in the late Quaternary as well, with a transtensional component but no dip slip. Our only basis for estimating the rate of this later Quaternary strike slip on the Silver Creek Fault is to assume continuation of the inferred early Quaternary rate of less than 2 mm/yr. Faulting evident in a detailed seismic reflection profile across the Silver Creek Fault extends up to the limit of data at a depth of 50 m and age of about 140 ka, and the course of Coyote Creek suggests Holocene capture in a structural depression along the fault. No surface trace is evident on the alluvial plain, however, and convincing evidence of Holocene offset is lacking. Few instrumentally recorded earthquakes are located near the fault, and those that are near its southern end represent cross-fault shortening, not strike slip. The fault might have been responsible, however, for two poorly located moderate earthquakes that occurred in the area in 1903. Its southeastern end does mark an abrupt change in the pattern of abundant instrumentally recorded earthquakes along the Calaveras Fault-in both its strike and in the depth distribution of hypocenters-that could indicate continuing influence by the Silver Creek Fault. In the absence of convincing evidence to the contrary, and as a conservative estimate, we presume that the Silver Creek Fault has continued its strike-slip movement through the Holocene, but at a very slow rate. Such a slow rate would, at most, yield very infrequent damaging earthquakes. If the 1903 earthquakes did, in fact, occur on the Silver Creek Fault, they would have greatly reduced the short-term future potential for large earthquakes on the fault.

The Qartaba Structure: An Active Backthrust In Central Mt-Lebanon.

NASA Astrophysics Data System (ADS)

Elias, Ata Richard

2016-04-01

The Qartaba structure in central Mt-Lebanon is a 15x5km box fold running parallel to the restraining bend of the sinsitral Yammouneh Fault, the main fault of the central segment of the Dead Sea Transform. The Qartaba structure has long been described as a "horst" and associated with Mesozoic normal faulting. However, the Qartaba anticline is suitably oriented with the direction of maximum compression along the restraining bend. Jurassic carbonate rocks form the core of this anticline culminating at ~1953m asl to the east, of the highest structural elevation of the Mt-Lebanon range indicating important tectonic uplift rate. The fold is asymmetric. The western limb is steep and bordered by the Lebanese Flexure, a prominent continuous monocline of Upper Jurassic to Mid Cretaceous rocks, running along the western flank of Mt-Lebanon. The eastern limb of the anticline has a very steep dip, and forms a 200m high cliff well marked in the topography. Its Jurassic layers are almost vertical and end up overhanging Lower Cretaceous beds. Our study suggest that the Qartaba structure is a growing anticline, built by active thrusting over a west dipping thrust fault that cuts the surface at the base of the eastern limb of the anticline. The fault plane can be seen dipping 30-35 degrees to the west. At depth, this thrust is likely to connect with the blind thrust ramp of the Mt-Lebanon Flexure. The Qartaba backthrust with a dip to the west, is opposite to the general vergence of similar structures in the area. On some of the segments of the steep cliff forming the faulted eastern limb, a fresh scarp with smooth and polished surfaces bearing vertical slickensides can be followed over ~700m along the base of the cliff. It corresponds with the location of the thrust fault tip. Talus accumulation over the steep eastern limb covers most of the cliff base, and may be masking further extent of this scarp. We interpret this scarp as the freeface of a co-seismic rupture on the underlying Qartaba backthrust. Moreover a first paleoseismic trench was opened in the loose deposits that cover the base of the eastern limb, over a topographic slope break aligned with the direction of the backthrust. The preliminary results clearly show tectonic deformation structures in C14 dated Holocene sediments, compatible with the general compressive style of the backthrust. This new interpretation of the Qartaba structure has important, implications on the geological interpretation of the area. The Qartaba backthrust is clearly an active structure that is capable of generating Mw~6.4 earthquakes in central Lebanon, significantly adding to the seismic hazard of the area. Moreover, the different interpretations of the geology of this area for petroleum prospects studies should be reviewed in the light of these new results.

Internal structure and volcanic hazard potential of Mt Tongariro, New Zealand, from 3D gravity and magnetic models

NASA Astrophysics Data System (ADS)

Miller, Craig A.; Williams-Jones, Glyn

2016-06-01

A new 3D geophysical model of the Mt Tongariro Volcanic Massif (TgVM), New Zealand, provides a high resolution view of the volcano's internal structure and hydrothermal system, from which we derive implications for volcanic hazards. Geologically constrained 3D inversions of potential field data provides a greater level of insight into the volcanic structure than is possible from unconstrained models. A complex region of gravity highs and lows (± 6 mGal) is set within a broader, 20 mGal gravity low. A magnetic high (1300 nT) is associated with Mt Ngauruhoe, while a substantial, thick, demagnetised area occurs to the north, coincident with a gravity low and interpreted as representing the hydrothermal system. The hydrothermal system is constrained to the west by major faults, interpreted as an impermeable barrier to fluid migration and extends to basement depth. These faults are considered low probability areas for future eruption sites, as there is little to indicate they have acted as magmatic pathways. Where the hydrothermal system coincides with steep topographic slopes, an increased likelihood of landslides is present and the newly delineated hydrothermal system maps the area most likely to have phreatic eruptions. Such eruptions, while small on a global scale, are important hazards at the TgVM as it is a popular hiking area with hundreds of visitors per day in close proximity to eruption sites. The model shows that the volume of volcanic material erupted over the lifespan of the TgVM is five to six times greater than previous estimates, suggesting a higher rate of magma supply, in line with global rates of andesite production. We suggest that our model of physical property distribution can be used to provide constraints for other models of dynamic geophysical processes occurring at the TgVM.

Deep crustal faults and the origin and long-term flank stability of Mt. Etna : First results from the CIRCEE cruise (Oct. 2013)

NASA Astrophysics Data System (ADS)

Gutscher, Marc-Andre; Dominguez, Stephane; Mercier de Lepinay, Bernard; Pinheiro, Luis; Babonneau, Nathalie; Cattaneo, Antonio; LeFaou, Yann; Barreca, Giovanni; Micallef, Aaron; Rovere, Marzia

2014-05-01

The relation between deep crustal faults and the origin of Mount Etna, the largest and most active volcano in Europe has long been suspected due to its unusual geodynamic location. Results from a new marine geophysical survey offshore Eastern Sicily reveal the detailed geometry (location, length, dip and orientation) of a two-branched 200-km long, lithospheric scale fault system, long sought for as being the cause of Mount Etna. Using high-resolution bathymetry and seismic profiling, we image a 60-km long, previously unidentified, NW trending fault with evidence of recent displacement at the seafloor, offsetting Holocene sediments. This newly identified fault connects NE of Catania, to a known 40-km long, offshore-onshore fault system dissecting the southeastern flank of Mount Etna, generally interpreted as purely gravitational collapse structures. Geological and morphological field studies together with earthquake focal mechanisms indicate active dextral strike-slip motion along the onshore and shallow offshore portion of this 40 + 60 km long segment. The southern 100 km branch of the fault is associated with a sub-vertical lithospheric scale tear fault showing pure down to the East normal faulting and a 500+m thick elongate basin marked by syn-tectonic Plio-quaternary sediment fill. Together they represent two kinematically distinct strands of the long sought "STEP" (Subduction Tear Edge Propagator) fault, whose expression at depth controls the position of Mount Etna. Both 100-km long branches of the fault system are mechanically capable of generating magnitude 7 earthquakes (e.g. - like the 1693 Catania earthquake, the strongest in Italian history, causing 40,000 deaths). We conclude this deep-rooted lithospheric weakness guides gradual down slope creep of Mount Etna and may lead to long-term catastrophic flank collapse with associated tsunami by large-scale mass wasting.

Structure and geometry of the Aksay restraining double bend along the Altyn Tagh Fault, northern Tibet, imaged using magnetotelluric method

NASA Astrophysics Data System (ADS)

Xiao, Qibin; Yu, Guo; Liu-Zeng, Jing; Oskin, Michael E.; Shao, Guihang

2017-05-01

Large restraining bends along active strike-slip faults locally enhance the accumulation of clamping tectonic normal stresses that may limit the size of major earthquakes. In such settings, uncertain fault geometry at depth limits understanding of how effectively a bend arrests earthquake ruptures. Here we demonstrate fault imaging within a major restraining bend along the Altyn Tagh Fault of western China using the magnetotelluric (MT) method. The new MT data were collected along two profiles across the Aksay restraining double bend, which is bounded by two subparallel strands of the Altyn Tagh Fault: Northern (NATF) and Southern (SATF). Both two-dimensional (2-D) and three-dimensional (3-D) inversion models show that the Aksay bend may be the center of a positive flower structure, imaged as a high-resistivity body extending to an 40 km depth and bounded by subvertical resistivity discontinuities corresponding to the NATF and SATF. In the western section of the Aksay bend, both the NATF and SATF show similar low-resistivity structure, whereas in the eastern part of the bend, the low-resistivity anomaly below the SATF is wider and more prominent than that below the NATF. This observation indicates that the SATF shear zone may be wider and host more fluid than the NATF, lending structural support to the contention that fault slip at depth is asymmetrically focused on the SATF, even though surface slip is focused on the NATF. A south dipping, low-resistivity interface branching upward from the SATF toward the NATF indicates a fault link between these strands at depth.

Gold mineralisation throughout about 45 Ma of Archaean orogenesis: protracted flux of gold in the Golden Mile, Yilgarn craton, Western Australia

NASA Astrophysics Data System (ADS)

Bateman, Roger; Hagemann, Steffen

2004-10-01

The Golden Mile deposit was discovered in 1893 and represents today the largest Archaean orogenic lode gold system in the world (50 M oz produced gold). The Golden Mile deposit comprises three major styles of gold mineralisation: Fimiston, Oroya and Charlotte styles. Fimiston-style lodes formed at 250 to 350 °C and 100 to 200 MPa and are controlled by brittle ductile fault zones, their subsidiary fault zone and vein networks including breccias and open-cavity-infill textures and hydrothermally altered wall rock. Fimiston lodes were formed late D1, prior to D2 regional upright folding. Hydrothermal alteration haloes comprise a progression toward the lode of diminishing chlorite, an increase in sericite and in Fe content of carbonates. Lodes contain siderite, pyrite, native gold, 17 different telluride minerals (Au Ag tellurides contain ~25% of total gold), tourmaline, haematite, sericite and V-rich muscovite. Oroya-style lodes formed at similar P T conditions as the Fimiston lodes and are controlled by brittle ductile shear zones, associated dilational jogs that are particularly well developed at the contact between Paringa Basalt and black shale interflow sedimentary rocks and altered wall rock. The orebodies are characterised by micro-breccias and zones of intense shear zone foliation, very high gold grades (up to 100,000 g/t Au) and the common association of tellurides and vanadian mica (green leader). Oroya lodes crosscut Fimiston lodes and are interpreted to have formed slightly later than Fimiston lodes as part of one evolving hydrothermal system spanning D1 and D2 deformation (ca. 2,675 2,660 Ma). Charlotte-style lodes, exemplified by the Mt Charlotte deposit, are controlled by a sheeted vein (stockwork) complex of north-dipping quartz veins and hydrothermally altered wall rock. The Mt Charlotte orebody formed at 120 to 440 °C and 150 to 250 MPa during movement along closely spaced D4 (2,625 Ma) and reactivated D2 faults with the quartz granophyre in the Golden Mile Dolerite exerting a strong lithological control on gold mineralisation. Veins consist of quartz carbonate minor scheelite, and wall-rock alteration comprises chlorite destruction and growth of ferroan carbonate sericite pyrite native gold. Pyrite pyrrhotite is zoned on the scale of vein haloes and of the entire mine, giving a vertical temperature gradient of 50 100 °C over 1,000 vertical metres. The structural hydrothermal model proposed consists of four major stages: (1) D1 thrusting and formation of Fimiston-style lodes, (2) D2 reverse faulting and formation of Oroya-style lodes, (3) D3 faulting and dissecting of Fimiston- and Oroya-style lodes, and (4) D4 faulting and formation of Mt Charlotte-style sheeted quartz vein system. The giant accumulation of gold in the Golden Mile deposit was formed due to protracted gold mineralisation throughout episodes of an Archaean orogeny that spanned about 45 Ma. Fluid conduits formed early in the tectonic history and persisted throughout orogenesis with the plumbing system showing a rare high degree of focussing, efficiency and duration. In addition to the long-lasting fluid plumbing system, the wide variety of transient structural and geochemical traps, multiple fluid sources and precipitation mechanism contributed towards the richest golden mile in the world.

Permeability evolution associated to creep and episodic slow slip of a fault affecting clay formations: Results from the FS fault activation experiment in Mt Terri (Switzerland).

NASA Astrophysics Data System (ADS)

Guglielmi, Y.; Nussbaum, C.; Birkholzer, J. T.; De Barros, L.; Cappa, F.

2017-12-01

There is a large spectrum of fault slow rupture processes such as stable creep and slow slip that radiate no or little seismic energy, and which relationships to normal earthquakes and fault permeability variations are enigmatic. Here we present measurements of a fault slow rupture, permeability variation and seismicity induced by fluid-injection in a fault affecting the Opalinus clay (Mt Terri URL, Switzerland) at a depth of 300 m. We observe multiple dilatant slow slip events ( 0.1-to-30 microm/s) associated with factor-of-1000 increase of permeability, and terminated by a magnitude -2.5 main seismic event associated with a swarm of very small magnitude ones. Using fully coupled numerical modeling, we calculate that the short term velocity strengthening behavior observed experimentally at laboratory scale is overcome by longer slip weakening that may be favored by slip induced dilation. Two monitoring points set across the fault allow estimating that, at the onset of the seismicity, the radius of the fault patch invaded by pressurized fluid is 9-to-11m which is in good accordance with a fault instability triggering when the dimensions of the critical slip distance are overcome. We then observe that the long term slip weakening is associated to an exponential permeability increase caused by a cumulated effective normal stress drop of about 3.4MPa which controls the successive slip activation of multiple fracture planes inducing a 0.1MPa shear stress drop in the fault zone. Therefore, our data suggest that the induced earthquake that terminated the rupture sequence may have represented enough dynamic stress release to arrest the fault permeability increase, suggesting the high sensitivity of the slow rupture processes to the structural heterogeneity of the fault zone hydromechanical properties.

Hydrogeochemical response of groundwater springs during central Italy earthquakes (24 August 2016 and 26-30 October 2016)

NASA Astrophysics Data System (ADS)

Archer, Claire; Binda, Gilberto; Terrana, Silvia; Gambillara, Roberto; Michetti, Alessandro; Noble, Paula; Petitta, Marco; Rosen, Michael; Pozzi, Andrea; Bellezza, Paolo; Brunamonte, Fabio

2017-04-01

Co-seismic hydrological and chemical response at groundwater springs following strong earthquakes is a significant concern in the Apennines, a region in central Italy characterized by regional karstic groundwater systems interacting with active normal faults capable of producing Mw 6.5 to 7.0 seismic events. These aquifers also provide water supply to major metropolitan areas in the region. On August 24, 2016, a Mw 6.0 earthquake hit Central Italy in the area where Latium joins Umbria, Marche and Abruzzi; this was immediately followed one hour later by a Mw 5.4 shock. The epicenter of the event was located at the segment boundary between the Mt. Vettore and Mt. Laga faults. On October 26, 2016 and on October 30, 2016, three other big shocks (Mw 5.5, Mw 6.0 and Mw 6.5) ruptured again the Vettore Fault and its NW extension. Immediately after Aug. 24, we sampled springs discharging different aquifers in the Rieti area, including the Peschiera spring, which feeds the aqueduct of Rome. Thermal springs connected with deep groundwater flowpaths were also sampled. These springs, sampled previously in 2014 and 2015, provide some pre-earthquake data. Moreover, we sampled 4 springs along the Mt. Vettore fault system: 3 small springs at Forca di Presta, close to the trace of the earthquake surface ruptures, and two in Castel Sant'Angelo sul Nera. The latter are feeding the Nera aqueduct and the Nerea S.p.A. mineral water plant, which also kindly allowed us to collect bottled water samples from the pre-seismic period. The aim of this study is to evaluate the strong earthquake sequence effects on the hydrochemistry and flow paths of groundwater from different aquifer settings based on analysis before and after seismic events. The comparison between the responses of springs ca. 40 km from the epicenter (Rieti basin) and the springs located near the epicenter (Castelsantangelo sul Nera and Forca di Presta) is especially significant for understanding the resilience of groundwater systems in an active tectonic zone because these springs are located near parallel active fault segments within the same extensional regime. The epicentral springs are subject to the direct effects of the shaking and coseismic fault displacement; the more distal ones to the tectonic displacement of large hydrogeologic structures, which affect the chemical composition and flow path even with late responses, lasting for weeks and months after the mainshocks. Temporal trend analysis, based on pre-earthquake and post-earthquake chemical-physical data, point out alteration of different parameters. For example, the lowering of different trace metals in all areas after the first earthquake. These changes could be due to fluctuations in redox equilibria related to degassing and/or interactions with deeper fluid flow. In the Rieti springs, the EC, alkalinity, and trace metals show small transient responses within 1-3 days following the main shocks, however δ2H vs. δ18O remain stable and plot with previous data, indicating no major change in recharge source. Analysis is ongoing and preliminary results will be presented here.

A rapid calculation system for tsunami propagation in Japan by using the AQUA-MT/CMT solutions

NASA Astrophysics Data System (ADS)

Nakamura, T.; Suzuki, W.; Yamamoto, N.; Kimura, H.; Takahashi, N.

2017-12-01

We developed a rapid calculation system of geodetic deformations and tsunami propagation in and around Japan. The system automatically conducts their forward calculations by using point source parameters estimated by the AQUA system (Matsumura et al., 2006), which analyze magnitude, hypocenter, and moment tensors for an event occurring in Japan in 3 minutes of the origin time at the earliest. An optimized calculation code developed by Nakamura and Baba (2016) is employed for the calculations on our computer server with 12 core processors of Intel Xeon 2.60 GHz. Assuming a homogeneous fault slip in the single fault plane as the source fault, the developed system calculates each geodetic deformation and tsunami propagation by numerically solving the 2D linear long-wave equations for the grid interval of 1 arc-min from two fault orientations simultaneously; i.e., one fault and its conjugate fault plane. Because fault models based on moment tensor analyses of event data are used, the system appropriately evaluate tsunami propagation even for unexpected events such as normal faulting in the subduction zone, which differs with the evaluation of tsunami arrivals and heights from a pre-calculated database by using fault models assuming typical types of faulting in anticipated source areas (e.g., Tatehata, 1998; Titov et al., 2005; Yamamoto et al., 2016). By the complete automation from event detection to output graphical figures, the calculation results can be available via e-mail and web site in 4 minutes of the origin time at the earliest. For moderate-sized events such as M5 to 6 events, the system helps us to rapidly investigate whether amplitudes of tsunamis at nearshore and offshore stations exceed a noise level or not, and easily identify actual tsunamis at the stations by comparing with obtained synthetic waveforms. In the case of using source models investigated from GNSS data, such evaluations may be difficult because of the low resolution of sources due to a low signal to noise ratio at land stations. For large to huge events in offshore areas, the developed system may be useful to decide to starting or stopping preparations and precautions against tsunami arrivals, because calculation results including arrival times and heights of initial and maximum waves can be rapidly available before their arrivals at coastal areas.

Magnetotelluric and Audio-magnetotelluric measurements in Alasehir Graben for geothermal exploration purposes

NASA Astrophysics Data System (ADS)

Tekesin-Cankurtaranlar, Ozge; Tuysuz, Okan; Riza Kilic, Ali

2017-04-01

In this study, we present the results of Magnetotelluric (MT) and Audio-magnetotelluric (AMT) soundings over a potential geothermal field. Study area is located in the northeasternmost part of the Alasehir (or Gediz) Graben, Western Anatolia, which is delimited by NW-SE trending fault systems and is filled by Miocene to Recent sediments. Study area is also very close to the Kula Quaternary volcanic region, a possible geothermal heat source for the region, last eruption of which was 12.000 years ago. Relatively thin crust, high heat flow values and intense tectonic activity of the Western Anatolia possibly refers to the high geothermal potential. In fact, along the southern and central part of the graben there are many productive areas reaching up to 300 degrees Celsius. By this motivation, to determine the geothermal potential of the study area MT and AMT measurements had been carried out on a total of 45 stations covering about 8 km2 area. All profiles shows higher resistivity values (>140 ohm.m) at greater depths, possibly indicating a metamorphic basement covered by Miocene to Recent sediments. This metamorphic basement gets shallower towards the North where the geothermally weathered schists and marbles crop out. Furthermore, a normal fault interface between metamorphic basement and Neogene sediments shows high resistivity contrast. Results indicate that the metamorphic basement is a less conductive block located at a depth of 1500 - 2000 m at the south and gets shallower towards the north as normal fault blocks.

Peculiar Active-Tectonic Landscape Within the Sanctuary of Zeus at Mt. Lykaion (Peloponnese, Greece)

NASA Astrophysics Data System (ADS)

Davis, G. H.

2008-12-01

The Sanctuary of Zeus (Mt. Lykaion) lies in the Peloponnese within the Pindos fold and thrust belt. It is the object of investigation of the Mt. Lykaion Excavation and Survey (http://lykaionexcavation.org/). Mt. Lykaion is a thrust klippe, on the summit of which is an upper sanctuary marked by an ash altar, temenos, and column bases. Earliest objects recovered from the ash altar go back to 3000 BCE, leading Dr. David Romano (University of Pennsylvania), a principal leader of the project, to conclude that worship of divinities on the summit is ancient. Detailed structural geological mapping reveals one dimension of the "power" of the site. Crisscrossing the upper sanctuary are scree bands that mark the traces of active normal faults, which are expressions of tectonic stretching of the Aegean region. The scree bands, composed of cinder-block-sized limestone blocks, range up to 10 m in outcrop breadth, 100 m in length, and 5 m in thickness. Though discontinuous, most of the scree bands lie precisely on the traces of through-going faults, which cut and displace the sedimentary formations of the Pindos group. Some cut the thrust fault, whose elliptical trace defines the Lykaion klippe. What makes the scree bands of this active-tectonic landscape "peculiar" is that there are no cliffs from which the scree descends. Rather, the bands of scree occur along flanks of smooth, rounded hillslopes and ridges. The scree bands coincide with modest steps in the topography, ranging from tens of centimeters to several tens of meters. The specific bedrock formation where the bands are best developed is an Upper Cretaceous limestone whose average platy-bedding thickness (approximately 20 cm) matches closely the average joint spacing. The limestone has little mechanical integrity. It cannot support itself as a scarp footwall and instead collapses into a pile of scree, whose upper-surface inclination conforms to a stable angle of repose. Evidence of the contemporary nature of this faulting includes a scree band that nearly completely covers stone structures built by shepherds. Though the scree bands conceal surface ruptures, it is expected that trenching will determine that the scree cover may have preserved beneath it some expressions of surface rupture, and perhaps fault surfaces themselves.

The interaction between active normal faulting and large scale gravitational mass movements revealed by paleoseismological techniques: A case study from central Italy

NASA Astrophysics Data System (ADS)

Moro, M.; Saroli, M.; Gori, S.; Falcucci, E.; Galadini, F.; Messina, P.

2012-05-01

Paleoseismological techniques have been applied to characterize the kinematic behaviour of large-scale gravitational phenomena located in proximity of the seismogenic fault responsible for the Mw 7.0, 1915 Avezzano earthquake and to identify evidence of a possible coseismic reactivation. The above mentioned techniques were applied to the surface expression of the main sliding planes of the Mt. Serrone gravitational deformation, located in the southeastern border of the Fucino basin (central Italy). The approach allows us to detect instantaneous events of deformation along the uphill-facing scarp. These events are testified by the presence of faulted deposits and colluvial wedges. The identified and chronologically-constrained episodes of rapid displacement can be probably correlated with seismic events determined by the activation of the Fucino seismogenic fault, affecting the toe of the gravitationally unstable rock mass. Indeed this fault can produce strong, short-term dynamic stresses able to trigger the release of local gravitational stress accumulated by Mt. Serrone's large-scale gravitational phenomena. The applied methodology could allow us to better understand the geometric and kinematic relationships between active tectonic structures and large-scale gravitational phenomena. It would be more important in seismically active regions, since deep-seated gravitational slope deformations can evolve into a catastrophic collapse and can strongly increase the level of earthquake-induced hazards.

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).

Hazard connected to tunnel construction in Mt Stena karstic area (Rosandra Valley, Classical Karst)

NASA Astrophysics Data System (ADS)

Cucchi, F.; Boschin, W.; Visintin, L.; Zini, L.

2009-04-01

Rosandra Valley -a unique geomorphological environment- is located in the western side of the Classical Karst plateau. This deep limestone gorge is crossed by a stream that is fed by a large basin located in Slovenia. Rosandra Valley is the only example of Classical Karst river valley with surface hydrography; the torrent digs a deep gully into the rock, rich in rapids, swirl holes, small waterfalls, enclosed meanders and basins; here, the first seepage phenomena occur, and part of the water feeds the underground aquifer. Rosandra Valley is theatre to complex structural situation; the NE slope culminates in the structure of Mt Stena, a limestone tectonic scale located between two faults and firmly rooted in the karst platform. Tectonics is quite important for the development of deep karst in this area; Mt Stena, in particular, hosts a comprehensive net of articulated and diversely shaped caves, basically organised on several levels, which stretches over a total of 9,000 metres, bearing testimony to ancient geological and hydrogeological origins. The deepest areas of the system reach a suspended aquifer that is probably sustained by an overthrust and placed about 100 meters above Rosandra torrent underground aquifer. During feasibility studies about Trieste-Divača high velocity railway link, interaction between project and karst features was examined; in fact the proximity of proposal project and Mt Stena karst system suggest to improve the knowledge related to karst and hydrogeological aspects of the massif. Compatibly with the project requirements, risk of voids intersection and water contamination were analyzed. In fact the Mt Stena suspended aquifer partially feeds Rosandra torrent which flows in a protected natural area. Karst features were represented in a 3D model in order to better understand the spatial relationship between railway project and karst system.

New geophysical views of Mt.Melbourne Volcano (East Antarctica)

NASA Astrophysics Data System (ADS)

Armadillo, E.; Gambetta, M.; Ferraccioli, F.; Corr, H.; Bozzo, E.

2009-05-01

Mt. Melbourne volcano is located along the transition between the Transantarctic Mountains and the West Antarctic Rift System. Recent volcanic activity is suggested by the occurrence of blankets of pyroclastic pumice and scoria fall around the eastern and southern flanks of Mt Melbourne and by pyroclastic layers interbedded with the summit snows. Geothermal activity in the crater area of Mount Melbourne may be linked to the intrusion of dykes within the last 200 years. Geophysical networks suggest that Mount Melbourne is a quiescent volcano, possibly characterised by slow internal dynamics. During the 2002-2003 Italian Antarctic campaign a high-resolution aeromagnetic survey was performed within the TIMM (Tectonics and Interior of Mt. Melbourne area) project. This helicopter-borne survey was flown at low-altitude and in drape-mode configuration (305 m above terrain) with a line separation less than 500 m. Our new high-resolution magnetic maps reveal the largely ice-covered magmatic and tectonic patters in the Mt. Melbourne volcano area. Additionally, in the frame of the UK-Italian ISODYN-WISE project (2005-06), an airborne ice-sounding radar survey was flown. We combine the sub-ice topography with images and models of the interior of Mt. Melbourne volcano, as derived from the high resolution aeromagnetic data and land gravity data. Our new geophysical maps and models also provide a new tool to study the regional setting of the volcano. In particular we re-assess whether there is geophysical evidence for coupling between strike-slip faulting, the Terror Rift, and Mount Melbourne volcano.

Tertiary volcanic rocks and uranium in the Thomas Range and northern Drum Mountains, Juab County, Utah

USGS Publications Warehouse

Lindsey, David A.

1982-01-01

The Thomas Range and northern Drum Mountains have a history of volcanism, faulting, and mineralization that began about 42 m.y. (million years) ago. Volcanic activity and mineralization in the area can be divided into three stages according to the time-related occurrence of rock types, trace-element associations, and chemical composition of mineral deposits. Compositions of volcanic rocks changed abruptly from rhyodacite-quartz latite (42-39 m.y. ago) to rhyolite (38-32 m.y. ago) to alkali rhyolite (21 and 6-7 m.y. ago); these stages correspond to periods of chalcophile and siderophile metal mineralization, no mineralization(?), and lithophile metal mineralization, respectively. Angular unconformities record episodes of cauldron collapse and block faulting between the stages of volcanic activity and mineralization. The youngest angular unconformity formed between 21 and 7 m.y. ago during basin-and-range faulting. Early rhyodacite-quartz latite volcanism from composite volcanoes and fissures produced flows, breccias, and ash-flow tuff of the Drum Mountains Rhyodacite and Mt. Laird Tuff. Eruption of the Mt. Laird Tuff about 39 m.y. ago from an area north of Joy townsite was accompanied by collapse of the Thomas caldera. Part of the roof of the magma chamber did not collapse, or the magma was resurgent, as is indicated by porphyry dikes and plugs in the Drum Mountains. Chalcophile and siderophile metal mineralization, resulting in deposits of copper, gold, and manganese, accompanied early volcanism. Te middle stage of volcanic activity was characterized by explosive eruption of rhyolitic ash-flow tuffs and collapse of the Dugway Valley cauldron. Eruption of the Joy Tuff 38 m.y. ago was accompanied by subsidence of this cauldron and was followed by collapse and sliding of Paleozoic rocks from the west wall of the cauldron. Landslides in The Dell were covered by the Dell Tuff, erupted 32 m.y. ago from an unknown source to the east. An ash flow of the Needles Range(?) Formation was erupted 30-31 m.y. ago from an unknown source. Mineralization probably did not occur during the rhyolitic stage of volcanism. The last stage of volcanism was contemporaneous with basin-and-range faulting and was characterized by explosive eruption of ash and pumice, forming stratified tuff, and by quiet eruption of alkali rhyolite as viscous flows and domes. The first episode of alkali rhyolite volcanism deposited the beryllium tuff and porphyritic rhyolite members of the Spor Mountain Formation 21 m.y. ago. After a period of block faulting, the stratified tuff and alkali rhyolite of the Topaz Mountain Rhyolite were erupted 6-7 m.y. ago along faults and fault intersections. Erosion of Spor Mountain, as well as explosive eruptions through dolomite, provided abundant dolomite detritus to the beryllium tuff member. The alkali rhyolite of both formations is fluorine rich, as is evident from abundant topaz, and contains anomalous amounts of lithophile metals. Alkali rhyolite volcanism was accompanied by lithophile metal mineralization which deposited fluorite, beryllium, and uranium. The structure of the area is dominated by the Thomas caldera and the younger Dugway Valley cauldron, which is nested within the Thomas caldera; the Thomas caldera is surrounded by a rim of Paleozoic rocks at Spor Mountain and Paleozoic to Precambrian rocks in the Drum Mountains. The Joy fault and Dell fault system mark the ring-fracture zone of the Thomas caldera. These structural features began to form about 39 m.y. ago during eruption of the Mt. Laird Tuff and caldera subsidence. The Dugway Valley cauldron sank along a series of steplike normal faults southeast of Topaz Mountain in response to collapse of the magma chamber of the Joy Tuff. Caldera structure was modified by block faulting between 21 and 7 m.y. ago, the time of widespread extensional faulting in the Basin and Range Province. Vents erupted alkali rhyolite 6-7 m.y. ago along basin-and-range faults.

Geophysical model of Mt. Labo geothermal field, Southeastern Luzon, Philippines

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

Los Banos, C.F. Jr.; Layugan, D.B.; Maneja, F.C.

1996-12-31

The geophysical model of Mt. Labo geothermal field, based on the results of the regional gravity and magnetotelluric (MT) surveys, indicates a geothermal reservoir centered beneath the Mabahong Labo thermal ground. The heat source of the present hydrothermal system is provided by a cooling intrusive body, mapped as a gravity high, associated with the Mt. Labo volcanic activity. The geothermal fluids circulate along fractures within the low-density reservoir rocks of the Susung Dalaga Formation. This reservoir rock shows relatively high resistivity values of 30 to 40 ohm-m. Directly overlying the resistive reservoir, occurring between -1000 m to -1500 m, ismore » a thick alteration halo formed within the basal unit of the Labo Volcanics (Lbu). The predominantly hydrous, low-temperature clay minerals which compose the alteration halo give low resistivity values of 1 to 4 ohm-m. Outflow of hot fluids to the south-southwest, which possibly feeds the thermal springs at Kilbay and Alawihaw, may be channeled along the thinning low resistivity Lbu. The geophysical model also shows a possible separate hydrothermal system in the west associated with a relatively shallower intrusive body, also defined by positive gravity values. This intrusion, which could be related to the cluster of volcanic domes located south of Bakilid Fault, may provide the heat that drives the hot springs at Kilbay and Alawihaw. It could also be possible that the Kilbay and Alawihaw springs originate from both systems. Based on the interpretation of the gravity and MT data, wells LB-1D and LB-5D lie closest to the intrusive, LB-313 and LB-4D are located in the center of the resource, while LB-2D and LB-6D lie along the margin or outside of the resource. The size of this resource, as defined by the 5 ohm-m MT low resistivity anomaly, is about 10 sq. km.« less

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.

Structural Analysis of Mt. Epomeo Resurgent Block (ischia, Italy): Deformational Features, Uplifting Mechanism and Implications For Volcanic Hazard Assessment.

NASA Astrophysics Data System (ADS)

de Vita, S.; Marotta, E.; Orsi, G.

The studies carried out on the resurgent calderas of Campi Flegrei, Pantelleria and Is- chia, evidenced that the geometry of the resurgent blocks and the arial distribution of volcanic vents active after the caldera collapse, are not compatible with the commonly accepted resurgent dome model. For these areas a simple shearing block resurgence mechanism, that take in account all the geological and volcanological constraints, has been proposed. In order to define the structural setting of a resurgent block for which this mechanism has been proposed, a detailed structural study has been carried out on the island of Ischia, where the Mt. Epomeo was uplifted of about 900 m in the past 30 ka. The attitude of 1400 planar surfaces has been measured in 50 different sites around the resurgent block. These features have been distinguished in: a) faults; b) joints; c) fracture cleavages. It has been observed that the resurgent area is composed of differentially displaced blocks whose uplifting is maximum for the Mt. Epomeo and decreases southeastward. The resurgent area has a poligonal shape resulting from the reactivation of regional faults and by the activation of faults directly related to volcan- otectonism. Northeastward the limit of the resurgent area is not defined, as along the coastline are exposed beach deposits displaced at variable elevation by E-W and NW- SE trending faults. The western sector is bordered by inward dipping, high angle re- verse faults, whose directions vary from N40E to NS and N50W from the northwestern to the southwestern parts of the block, testifying a compressional stress regime active in this area. These features are cut by late outward dipping normal faults due to grav- itational readjustment of the slopes. The northeastern and the southwestern sides are bordered by vertical faults with right transtensive and left transpressive movements, respectively. The area located to the east of the most uplifted block is characterized by a tensile stress regime and has been deformed by N-S, N40-70E and N15W trending normal faults, which demonstrates that the maximum elongation direction is N50W. The results of this study, together with the volcanological data available for the past 3 ka of activity, suggest that the eastern part of the resurgent block is the area with the highest probability of vent opening in case of renewal of volcanism.

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.

Segmentation of the Cascadia Forearc in Southwestern Washington—Evidence from New Potential-Field Data

NASA Astrophysics Data System (ADS)

Blakely, R. J.; Wells, R. E.; Sherrod, B. L.; Brocher, T. M.

2016-12-01

Newly acquired potential-field data, geologic mapping, and recorded seismicity indicate that the Cascadia subduction zone is segmented in southwestern Washington by a left-stepping, possibly active crustal structure spanning nearly the entire onshore portion of the forearc. The east-striking, southward verging Doty thrust fault is an important part of this trans-forearc structure. As mapped, the eastern end of the 50-km-long Doty fault connects with the northwestern termination of ongoing seismicity on the north-northwest-striking Mt. St. Helens seismic zone (MSHSZ), suggesting that the Doty fault and MSHSZ may be kinematically linked. Westward, the mapped Doty fault terminates at and may link to mapped faults striking northwestward to 35 km north of Grays Harbor, a total northwest distance of 85 km. A newly acquired aeromagnetic survey over the Doty fault and MSHSZ, and existing gravity data, emphasize Crescent Formation and other Eocene volcanic rocks in the hanging wall of the Doty fault with up to 4 km of vertical throw. Most MSHSZ epicenters fall within a broad (5- to 10-km wide) magnetic low extending 50 km north-northwestward from Mt. St Helens. The magnetic low skirts around the western margin of the Miocene-age Spirit Lake pluton, but otherwise is not obviously associated with topography or mapped geology. We suggest that dextral slip on the MSHSZ is distributed across a broad, northwest-striking area that includes the magnetic low and is transferred to compressional slip on the Doty fault. The Doty fault demarcates a clear north-to-south decrease in the density of episodic tremor, suggesting that the thrust fault may intersect or modulate over-pressured fluids generated above the slab (Wells et al., in review). The Doty fault, MSHSZ, and neighboring structures are consistent with a dextral shear couple (Wells and Coe, 1985) and consequent clockwise crustal rotation extending across the entire landward portion of the Cascadia forearc, from the Pacific Coast to the Cascadia arc and from Grays Harbor to the Portland basin in northwestern Oregon.

Seismic study of the Mesozoic carbonate basement around Mt. Somma Vesuvius, Italy

NASA Astrophysics Data System (ADS)

Bruno, Pier Paolo G.; Cippitelli, Giuseppe; Rapolla, Antonio

1998-09-01

Fifteen seismic reflection lines from AGIP surveys, in and around the Campanian Plain and Mt. Somma-Vesuvius (south Italy) have been interpreted. The attention has been focused to the horizon pertinent to the top of the Mesozoic carbonate sequence and the Quaternary faults dissecting it. As a matter of fact, both are very important elements for understanding the origin of the volcanic activity in the area, that often in the past, has been the topic of debates not supported by reliable data. In the study area, referring to the depth of the carbonate basement, comparison between the result achieved by the seismic prospecting and previous gravity studies has been made. It shows coherence in some areas but large discrepancy within others. Near the town of S. Anastasia, the gravity and seismic depth estimates differ as much as 1000 m or more. Furthermore, the seismic data show that the source of the greatest volcanic eruption in the area (the so-called `Campanian Ignimbrite') is probably not located in the Acerra depression, as suggested by other authors. A main NE-SW fault directed toward Vesuvius, considered as playing a primary role on volcanogenetic processes and previously recognised only offshore by marine seismic survey, has been now identified also inland using this new seismic information. The results presented here strengthen the hypothesis that Mt. Vesuvius is located at the crossing point of two regional Quaternary sets of fault heading NW-SE and NE-SW.

Interpretation of VLF-EM & VLF-R data using tipper and impedance analyses: A case study from Candi Umbul-Telomoyo, Magelang, Indonesia

NASA Astrophysics Data System (ADS)

Prastyani, Erina; Niasari, Sintia Windhi

2017-07-01

The goal of all geophysical survey techniques is to image the properties of the Earth's subsurface. Very Low Frequency (VLF) is one of the geophysical survey technique that has been commonly used for ore exploration and mapping faults or fracture zones. Faults or fracture zones are necessary components in providing the fluid pathway in geothermal systems. The Candi Umbul-Telomoyo is one of the geothermal prospect sites in Indonesia, which is located in Magelang, Central Java. Recent studies hypothesized that this site was an outflow area of Telomoyo volcano geothermal complex. We used the VLF-EM and VLF-R techniques to infer faults or fracture zones that might be a path for geothermal fluids in the Candi Umbul-Telomoyo. From the measurements, we got tilt angle, ellipticity, primary and secondary magnetic fieldfor VLF-EM data; and apparent resistivity, phase angle, electric and magnetic field for VLF-R data. To interpret the data, we used tipper and impedance analyses. The result of both analyses show similarities in the directions and positions of anomalous current concentrations. We conclude these anomalous current concentrations as faults. Our interpretation is agreeing with the Geologic Map of the Semarang and Magelang Quadrangles that shows the expected fault beneath the Mt. Telomoyo.

The December 2015 Mount Etna eruption: An analysis of inflation/deflation phases and faulting processes

NASA Astrophysics Data System (ADS)

Aloisi, Marco; Jin, Shuanggen; Pulvirenti, Fabio; Scaltrito, Antonio

2017-06-01

During the first days of December 2015, there were four paroxysmal events at the ;Voragine; crater on Mount Etna, which were among the most violent observed during the last two decades. A few days after the ;Voragine; paroxysms, the Pernicana - Provenzana fault system, located near the crater area, underwent an intense seismic swarm with a maximum ;local; magnitude ML of 3.6. This paper investigates the relationship between the eruptive phenomenon and the faulting process in terms of Coulomb stress changes. The recorded seismicity is compatible with a multicausal stress redistribution inside the volcano edifice, occurring after the four paroxysmal episodes that interrupted the usual trend of inflation observed at Mt. Etna. The recorded seismicity falls within the framework of a complex chain of various and intercorrelated processes that started with the inflation preparing the ;Voragine; magmatic activity. This was followed with the rapid deflation of the volcano edifice during the paroxysmal episodes. We determined that the recorded deflation was not the direct cause of the seismic swarm. In fact, the associated Coulomb stress change, in the area of seismic swarm, was of about -1 [bar]. Instead, the fast deflation caused the rarely observed inversion of dislocation in the eastern flank at the same time as intense hydrothermal activity that, consequently, underwent an alteration. This process probably reduced the friction along the fault system. Then, the new phase of inflation, observed at the end of the magmatic activity, triggered the faulting processes.

A deep crustal fluid channel into the San Andreas Fault system near Parkfield, California

USGS Publications Warehouse

Becken, M.; Ritter, O.; Park, S.K.; Bedrosian, P.A.; Weckmann, U.; Weber, M.

2008-01-01

Magnetotelluric (MT) data from 66 sites along a 45-km-long profile across the San Andreas Fault (SAF) were inverted to obtain the 2-D electrical resistivity structure of the crust near the San Andreas Fault Observatory at Depth (SAFOD). The most intriguing feature of the resistivity model is a steeply dipping upper crustal high-conductivity zone flanking the seismically defined SAF to the NE, that widens into the lower crust and appears to be connected to a broad conductivity anomaly in the upper mantle. Hypothesis tests of the inversion model suggest that upper and lower crustal and upper-mantle anomalies may be interconnected. We speculate that the high conductivities are caused by fluids and may represent a deep-rooted channel for crustal and/or mantle fluid ascent. Based on the chemical analysis of well waters, it was previously suggested that fluids can enter the brittle regime of the SAF system from the lower crust and mantle. At high pressures, these fluids can contribute to fault-weakening at seismogenic depths. These geochemical studies predicted the existence of a deep fluid source and a permeable pathway through the crust. Our resistivity model images a conductive pathway, which penetrates the entire crust, in agreement with the geochemical interpretation. However, the resistivity model also shows that the upper crustal branch of the high-conductivity zone is located NE of the seismically defined SAF, suggesting that the SAF does not itself act as a major fluid pathway. This interpretation is supported by both, the location of the upper crustal high-conductivity zone and recent studies within the SAFOD main hole, which indicate that pore pressures within the core of the SAF zone are not anomalously high, that mantle-derived fluids are minor constituents to the fault-zone fluid composition and that both the volume of mantle fluids and the fluid pressure increase to the NE of the SAF. We further infer from the MT model that the resistive Salinian block basement to the SW of the SAFOD represents an isolated body, being 5-8km wide and reaching to depths >7km, in agreement with aeromagnetic data. This body is separated from a massive block of Salinian crust farther to the SW. The NE terminus of resistive Salinian crust has a spatial relationship with a near-vertical zone of increased seismic reflectivity ???15km SW of the SAF and likely represents a deep-reaching fault zone. ?? 2008 The Authors Journal compilation ?? 2008 RAS.

The 2016 Central Italy "reverse" seismic sequence

NASA Astrophysics Data System (ADS)

Chiaraluce, Lauro; Di Stefano, Raffaele; Tinti, Elisa; Scognamiglio, Laura; Michele, Maddalena; Cattaneo, Marco; De Gori, Pasquale; Chiarabba, Claudio; Monachesi, Giancarlo; Lombardi, Annamaria; Valoroso, Luisa; Latorre, Diana; Marzorati, Simone

2017-04-01

The 2016 seismic sequence consists so far of a series of moderate to large earthquakes that within three month's time activated a 60 km long segmented normal fault system located in the Central Italy and almost contiguous to the 1997 Colfiorito and 2009 L'Aquila normal fault systems. The first mainshock of the sequence occurred with MW6.0 on the 24th of August at 01:36 UTC close to the Accumoli and Amatrice villages producing evidence for centimetres' surface ruptures along the Mt. Vettore normal fault outcrop. Two months later on the 26th of October at 19:18 UTC another mainshock with MW5.9 occurred 25 km to the north activating another normal fault segment approximately on the along strike continuation of the first structure. Then, four days later on the 30th of October at 06:40 UTC the largest shock of the sequence with MW6.5 close to Norcia, in the middle part of the fault system activated two months before. We reconstruct the first order anatomy of the activated normal faults system, by analysing the spatial and temporal distribution of 25,354 aftershocks with 0.1

Three-dimensional magnetotelluric imaging of the 1997 Kagoshima earthquake doublet, Southwest Japan

NASA Astrophysics Data System (ADS)

Asamori, K.; Makuuchi, A.; Umeda, K.

2013-12-01

The 1997 Kagoshima earthquake doublet struck on unrecognized active faults lacking clear surface expression where very few large earthquakes have occurred. Two shallow moderate earthquakes occurred in the northwestern part of Kagoshima province, on March 26 (Mw 6.1) and May 13 (Mw 6.0) in 1997, both followed by intensive aftershock sequences. Aftershock distribution of the 1997 earthquake doublet reflects complicated rupture process attributed to the geological (rheological) conditions and coupling of hydraulic pressure as well as tectonic shear stress. For advanced understanding of dynamic interactions between fluids and faulting, it is imperative to obtain three-dimensional (3-D) images of the electrical resistivity structure around the seismogenic faults. In this study, we conduct magnetotelluric (MT) soundings in and around the source region of the 1997 Kagoshima earthquake sequence and perform a 3-D inversion of wideband MT data above a depth of 30 km. MT stations were deployed around the aftershock area of the 1997 Kagoshima earthquake. All of 42 MT sites were set up in the land area. The data were collected using five component (three magnetic and two telluric components) wide-band MT instruments (Phoenix MTU-5 system) in February, 2013. The data were acquired in the frequency range from 0.000343 to 320 Hz. The recording duration ranged from 2 to 8 days. As the cultural noises severely affect the measurements, the time series analysis focused on the nocturnal data when there were fewer noise. A simultaneous remote reference measurement was carried out at the Sawauchi site (1300 km northeast of the study area). Using the remote reference technique (Gamble et al., 1979), we were able to reduce the unfavorable cultural noises. The observed apparent resistivity and phase data were inverted simultaneously using the 3-D inversion code of Sasaki (2004). In this inversion, the 3-D blocks were set up in the crust and upper mantle. These block size in the horizontal and vertical directions were 2-6 km and 0.9-20 km, respectively. The obtained 3-D resistivity model acquired through the inversion shows as follows. (1) Two anomalous conductive bodies (< 30 ohm-m) are clearly visible in the upper and lower crust beneath the seismic source region, and seem to be combined and extend down to the uppermost mantle. (2) These conductive bodies are located just beside the two mainshocks in the upper crust. (3) These results suggest that the generation of two large earthquakes is not a pure mechanical process, but is closely related to heterogeneities in the material property and stress field due to the relatively effective transfer of fluids from the upper mantle.

The subsurface cross section resistivity using magnetotelluric method in Pelabuhan Ratu area, West Java, implication for geological hazard mitigation

NASA Astrophysics Data System (ADS)

Gaffar, Eddy Z.

2016-02-01

Pelabuhan Ratu area is located on the south coast of West Java. Pelabuhan Ratu area's rapid development and population growth were partly stimulated by the Indonesian Government Regulation No. 66 the year 1998 that made Pelabuhan Ratu the capital city of the district of Sukabumi. Because of this fact, it is very important to create a geological hazard mitigation plan for the area. Pelabuhan Ratu were passed by two major faults: Cimandiri fault in the western and Citarik fault in the eastern. Cimandiri fault starts from the upstream of Cimandiri River to the southern of Sukabumi and Cianjur city. While Citarik fault starts from the Citarik River until the Salak Mountain. These two faults needs to be observed closely as they are prone to cause earthquake in the area. To mitigate earthquake that is estimated will occur at Cimandiri fault or the Citarik fault, the Research Center for Geotechnology LIPI conducted research using Magnetotelluric (MT) method with artificial Phoenix MT tool to determine the cross-section resistivity of the Pelabuhan Ratu and the surrounding area. Measurements were taken at 40 points along the highway towards Jampang to Pelabuhan Ratu, and to Bandung towards Cibadak with a distance of less than 500 meters between the measuring points. Measurement results using this tool will generate AMT cross-section resistivity to a depth of 1500 meters below the surface. Cross-section resistivity measurement results showed that there was a layer of rock with about 10 Ohm-m to 1000 Ohm-m resistivity. Rocks with resistivity of 10 Ohm-m was interpreted as conductive rocks that were loose or sandstone containing water. If an earthquake to occur in this area, it will lead to a strong movement and liquefaction that will destroy buildings and potentially cause casualties in this area.

Pulsed magnetization transfer contrast MRI by a sequence with water selective excitation

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

Schick, F.

1996-01-01

A water selective SE imaging sequence was developed providing suitable properties for the assessment of magnetization transfer (MT) effects in tissues with considerable amounts of fat. The sequence with water selective excitation and slice selective refocusing combines the following features: The RIF exposure on the macromolecular protons is relatively low for single slice imaging without MT prepulses, since no additional pulses for fat saturation are necessary. Water selection by frequency selective excitation diminishes faults in the subtraction of images recorded with and without MT prepulses (which might arise from movements). High differences in the signal amplitudes from hyaline cartilage andmore » muscle tissue were obtained comparing images recorded with irradiation of the series of prepulses for MT and those lacking MT prepulses. Utilizations of the described water selective approach for the assessment of MT effects in lesions of cartilage and bone are demonstrated. MT saturation was also examined in muscles with fatty degeneration of patients suffering from progressive muscular dystrophy. The described technique allows determination of MT effects with good precision in a single slice, especially in regions with dominating fat signals. 22 refs., 5 figs.« less

Three-dimensional magnetotelluric inversion in practice—the electrical conductivity structure of the San Andreas Fault in Central California

NASA Astrophysics Data System (ADS)

Tietze, Kristina; Ritter, Oliver

2013-10-01

3-D inversion techniques have become a widely used tool in magnetotelluric (MT) data interpretation. However, with real data sets, many of the controlling factors for the outcome of 3-D inversion are little explored, such as alignment of the coordinate system, handling and influence of data errors and model regularization. Here we present 3-D inversion results of 169 MT sites from the central San Andreas Fault in California. Previous extensive 2-D inversion and 3-D forward modelling of the data set revealed significant along-strike variation of the electrical conductivity structure. 3-D inversion can recover these features but only if the inversion parameters are tuned in accordance with the particularities of the data set. Based on synthetic 3-D data we explore the model space and test the impacts of a wide range of inversion settings. The tests showed that the recovery of a pronounced regional 2-D structure in inversion of the complete impedance tensor depends on the coordinate system. As interdependencies between data components are not considered in standard 3-D MT inversion codes, 2-D subsurface structures can vanish if data are not aligned with the regional strike direction. A priori models and data weighting, that is, how strongly individual components of the impedance tensor and/or vertical magnetic field transfer functions dominate the solution, are crucial controls for the outcome of 3-D inversion. If deviations from a prior model are heavily penalized, regularization is prone to result in erroneous and misleading 3-D inversion models, particularly in the presence of strong conductivity contrasts. A `good' overall rms misfit is often meaningless or misleading as a huge range of 3-D inversion results exist, all with similarly `acceptable' misfits but producing significantly differing images of the conductivity structures. Reliable and meaningful 3-D inversion models can only be recovered if data misfit is assessed systematically in the frequency-space domain.

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.

Three-Dimensional Seismic Image of a Geothermal Prospect: Tinguiririca, Central Andes, Chile

NASA Astrophysics Data System (ADS)

Lira, E.; Comte, D.; Giavelli, A.; Clavero, J. E.; Pineda, G.

2010-12-01

Seismic monitoring has been widely used by the oil and gas industry, as a valuable input for the reservoir characterization. This tool has also been used in geothermal productive systems, particularly to understand permeability controls usually associated to shallow crustal fault systems that are seismically actives. Faults can be considered either “migration path” or “seals” in Petroleum Systems, depending on their activity story (they are carriers while actives and seals when the activity cease due to diagenetic processes in the fault plain). On the other hand, is well known that seismic velocities are strongly related to rock properties, in particular Vp/Vs and VpVs relationship has been successfully used to emphasize the variations in the physical rock properties due to fluid content and porosity. In geothermal systems, P and S-wave velocities are expected to be noticeably affected by massive hydrothermal alteration and/or to the presence of hot water in the fault related fractures of the rocks. In this job, the results of three months of seismic monitoring and a seismic velocity tomography are presented. Sixteen short period continuous recording, three components seismic stations were deployed in an area of approximately 20x10 Km2, and a large 8.8 magnitude earthquake took place during the recording period. The study area corresponds to the Tinguiririca volcanic complex (70°21''W, 35°48''S), in the high mountain of the Central Andes near the Chile-Argentina border. These preliminary results are complemented with some MT profiles, delineating potentially interesting geothermal features.

Preliminary Results From the Serpentinite, Extension and Regional Porosity Experiment Across the Nicaraguan Trench (SERPENT)

NASA Astrophysics Data System (ADS)

Key, K. W.; Constable, S.; Evans, R. L.; Naif, S.; Matsuno, T.; Lizarralde, D.

2010-12-01

Water plays an important role in the volcanic processes occurring at convergent margins, as the release of water from the downgoing slab affects the rheology of the mantle, increases melting by lowering the solidus temperature, and alters the chemistry of arc-lavas. Yet, one of the major uncertainties in terms of fluid inputs into the subduction factory concerns the extent of serpentinization of the oceanic upper mantle and the volumes of water that are being carried into the subduction system through this route. In April 2010 we conducted a large-scale marine electromagnetic experiment along a 300 km profile offshore Nicaragua in a region that shows evidence for substantial fault related fluid circulation in the crust and possibly upper mantle, and high Ba/La ratios and water contents in adjacent onshore volcanics that suggest a strong slab fluid input into the arc-melting. Our project is the largest combined controlled-source electromagnetic (CSEM) and magnetotelluric (MT) data set ever collected on an active subduction zone. During the single 28 day research cruise aboard the R/V Melville we collected 54 stations of broadband marine magnetotelluric (MT) data and deep-towed nearly 800 km of controlled-source electromagnetic (CSEM) data. Robust multiple-station array processing of the MT data yields high quality MT responses from 10 to 20,000 s period. The MT responses are fairly 1D over the abyssal plain, showing the effects of a thin veneer of conductive sediments overlying a resistive lithosphere and a deeper conductive mantle. The responses become strongly 2D on the trench outer rise and exhibit large 3D distortions at the bottom of the trench, likely due to a combination of effects from severe topography and seafloor conductivity variations. Two circular CSEM tows of 30 km radius were measured by special long-wire EM (LEM) sensors on the abyssal plain and the outer rise. The LEM data reveals a distinct pattern of electromagnetic polarization that is characteristic of mantle transverse anisotropy. Since the conductive axis is aligned with the fossil ridge-parallel direction and reactivated normal faults in the trench, we interpret this to be caused by conductive serpentinized mantle penetrating faults. Conventional CSEM data recorded at a broad suite of transmission frequencies along the 300 km long profile and a 50 km along strike profile provide constraints on crustal conductivity variations. The analysis of these data is ongoing and will provide a comprehensive picture of the electrical conductivity structure from the seafloor to the upper mantle, representing the entire input into this part of the Central American subduction system. Since conductivity is highly dependent on thermal structure, crack porosity and the presence of serpentinite, our experiment will provide constraints on the depth of active fluid circulation within the oceanic crust and mantle, the variation of fluid circulation with distance from the trench and hence with the degree of plate bending, and the extent of dewatering of the subducting slab in the shallow portion of the mantle wedge.

Model for the Evolution of an Oceanic Core Complex and its Hydrothermal Vent on the Ultraslow-Spreading Mid Cayman Spreading Center

NASA Astrophysics Data System (ADS)

Harding, J.; Van Avendonk, H. J.; Hayman, N. W.; Grevemeyer, I.; Peirce, C.

2016-12-01

The Mid Cayman Spreading Center (MCSC) is an ultraslow-spreading center (15 mm yr-1 full rate) along the Caribbean-North American plate boundary. Despite the paradigm that ultraslow-spreading centers are amagmatic and cold, two hydrothermal vent fields have recently been discovered along the MCSC. The Beebe Vent Field is a black smoker in the northern axial deep, and the Von Damm Vent Field (VDVF) is a moderate-temperature, talc precipitating vent found atop an oceanic core complex (OCC). This OCC, "Mt. Dent", is a large (3 km high) massif that formed beneath a detachment fault, which exhumed lower crustal and upper mantle material. The CaySeis Experiment was conducted in April, 2015 in order to collect wide-angle refraction data of the MCSC crust and upper mantle. We modeled the across-axis crustal structure of Mt. Dent as well as the surrounding lithosphere using 2.5D P-wave tomography. Using this tomographic model, along with geochemistry, we propose a model for the formation and evolution of the OCC Mt. Dent and the VDVF. A detachment fault formed in a magma-poor environment due to a pulse of magmatism, producing a large gabbro body that was then exhumed and rotated into the OCC footwall. Once magmatism waned and the gabbroic body cooled, the OCC was faulted and fractured due to plate flexure and increased tectonic extensional stress in the naturally cold and thick lithosphere. These faults provide a permeable and deep network of hydrothermal pathways that mine deep lithospheric heat and expose gabbro and fresh mantle peridotite. This model is consistent with the basalt geochemistry, hydrothermal fluid geochemistry, and the distribution of brittle vs. ductile structures along the detachment shear zone. The VDVF is therefore a product of a pulse of magmatism in an overall melt-poor environment, conditions that may be found at other ultraslow-spreading ridges.

Expert System for Test Program Set Fault Candidate Selection

DTIC Science & Technology

1989-09-01

Mark Herbst Mr. Paul Janusz Mr. Wayne Lee Ms. Patricia Lyon Ms. Sharyn McDowell Mr. Richard Payne Ms. Elizabeth Parliman Mr. Albert Stanbury Ms. Allison...SMCAR-ESP-L AMSMC-QA(R) AMSMC-QAK-B(R), R. Fer Rock Island, IL 61299-6000 28 Commander U.S. Army Materiel Command ATTN: AMCQA-E, Mr. Chris Neubert AMCPD...ATTN: AMSEL-PA-MT-S, Mr. Paul Kogut Mr. Andy Mills AMSEL-PA AMSEL-PA-DL AMSEL-RD-SE-CRM-CM AMSEL-RD-SE-AST Ft. Monmouth, NJ 07703-5023 35 Director U.S

Geothermal mineralized scales in the pipe system of the geothermal Piancastagnaio power plant (Mt. Amiata geothermal area): a key to understand the stibnite, cinnabarite and gold mineralization of Tuscany (central Italy)

NASA Astrophysics Data System (ADS)

Morteani, Giulio; Ruggieri, Giovanni; Möller, Peter; Preinfalk, Christine

2011-02-01

The CO2-rich geothermal fluids produced in the Piancastagnaio geothermal field (Mt. Amiata geothermal area, Southern Tuscany, Italy) show temperatures up to 360°C and pressures of about 200 bar at depths of around 3,500 m (Giolito, Ph.D. thesis, Università degli Studi di Firenze, Italy, pp 1-147, 2005). CaCO3- and/or SiO2-dominated scales are deposited in the pipes leading to the pressure and atmospheric separators of the geothermal wells. High content of metastibnite and/or stibnite in both calcite and silica scales and Sb contents of up to 50 mg/L in the fluids indicate their mineralising potential. The red or black colours of the scales depend on the predominance of red metastibnite or black stibnite, respectively. In our condensation experiments, as well as during deposition of the scales, metastibnite is the first Sb2S3 mineral to form. In a second stage, metastibnite is transformed to stibnite. During depressurization the Hg content of geothermal fluids partitions preferentially into the gas phase, whereas Sb and As remain in the liquid phase. This separation explains the often observed areal separation of Hg and Sb mineralization. The multistage deposition of Sb in the mining district of Tuscany is due to a periodic restoration of the permeability of the ore-bearing faults by microseismic events and subsequent host rock brecciation. The still ongoing microseismic events are induced by the accumulation of high-pressure CO2-rich fluids along faults followed by mechanical failure of the faults.

Coulomb Fault Mechanics at Work in the Proterozoic: Strike-Slip Faults and Regional-Scale Veining in the Mt. Isa Inlier, Australia

NASA Astrophysics Data System (ADS)

Begbie, M. J.; Sibson, R. H.; Ghisetti, F. C.

2005-12-01

The Proterozoic Mt Isa inlier, comprising greenschist to amphibolite facies metamorphic assemblages intruded by granites during the Isan Orogeny (1590-1500 Ma), is disrupted by brittle, late- or post-orogenic strike-slip faults. The faults occur in two mutually cross-cutting sets; a set of NE-SW subvertical dextral strike-slip faults, and a conjugate set of NW-SE sinistral faults. These faults thus define a regional stress field with σ1 oriented approximately E-W and σ3 oriented approximately N-S. Locally, the faults outcrop as linear blade-like ridges of silicified microbreccias-cataclasites and quartz veining that extends for kilometres across the semi-arid terrain. The informally named Spinifex Fault is one of the dextral set of subvertical faults. This fault is a classic example of coulomb fault mechanics at work in the Proterozoic. The Spinifex Fault trends ~065° across an outcropping granitic pluton, the margins of which it offsets dextrally by ~0.75 km. Locally within the pluton, the fault refracts to ~075° across an amphibolite layer. In the surrounding granitic pluton the fault trace is comparatively inconspicuous and unmineralized but where it transects the amphibolite it is defined by an upstanding ridge of silicified microbreccia-cataclasite (~10 m thick). Associated with the Spinifex Fault is a swarm of predominantly extensional subvertical quartz veins (cm to m thick) trending 090-95° and a series of mineralised fault splays trending 070-080°. Extension veins define the σ1-σ2 plane, with the Spinifex fault lying at an angle of ~25-30° to the inferred σ1. These veins are composed of colloform and crustiform banded quartz, brecciated fragments of quartz vein and wallrock that are typically rimmed with cockade overgrowths and bladed quartz after calcite pseudomorphs. Mineralised fault splays are < 50 m or so wide with a composite brittle fabric comprising: (1) bounding subvertical cataclastic `walls' <10 m or so thick made up of silicified microbreccias and cataclasites containing vein fragments; (2) innumerable subvertical quartz veins (cm to m thick) lying subparallel to the bounding shear zones with textures ranging from pure dilation to multiply recemented breccias of wallrock and quartz fragments; (3) irregular non-systematic veins; and (4) occasional minor faults from the complementary set. Mutual cross-cutting relationships between all the structural components indicate penecontemporaneous development within the inferred stress field. Slickenfibers and striations along fault components indicate predominantly strike slip motion on subvertical planes. Homogenisation temperatures from quartz hosted fluid inclusions cluster at ~210°C while vein textures record histories of incremental hydrothermal deposition under low effective stress, probably in the epizonal environment (<1-2 km depth). This regional study demonstrates the existence of a rather uniform stress province, corresponding to an Andersonian regime and initiation of faults in accord with the coulomb failure criterion.

Magnetotelluric study to characterize Kachchh Mainland Fault (KMF) and Katrol Hill Fault (KHF) in the western part of Kachchh region of Gujarat, India

NASA Astrophysics Data System (ADS)

Mohan, Kapil; Chaudhary, Peush; Patel, Pruthul; Chaudhary, B. S.; Chopra, Sumer

2018-02-01

The Kachchh Mainland Fault (KMF) is a major E-W trending fault in the Kachchh region of Gujarat extending >150 km from Lakhpat village in the west to the Bhachau town in the east. The Katrol Hill Fault (KHF) is an E-W trending intrabasinal fault located in the central region of Kachchh Basin and the south of KMF. The western parts of both of the faults are characterized, and the sediment thickness has been estimated in the region using a Magnetotelluric (MT) survey at 17 sites along a 55 km long north-south profile with a site spacing of 2-3 km. The analysis reveals that the maximum sediment thickness is 2.3 km (Quaternary, Tertiary, and Mesozoic) in the region, out of which, the Mesozoic sediments feature a maximum thickness of 2 km. The estimated sediment thickness is found consistent with the thickness suggested by a deep borehole (depth approx. 2.5 km) drilled by Oil and Natural Gas Corporation (ONGC) at Nirona (Northern part of the study area). From 2-D inversion of the MT data, three conductive zones are identified from north to south. The first conductive zone is dipping nearly vertical down to 7-8 km depth. It becomes north-dipping below 8 km depth and is inferred as KMF. The second conductive zone is found steeply dipping into the southern limbs near Manjal village (28 km south of Nirona), which is inferred as the KHF. A vertical-dipping (down to 20 km depth) conductive zone has also been observed near Ulat village, located 16 km north of Manjal village and 12 km south of Nirona village. This conductive zone becomes listric north-dipping beyond 20 km depth. It is reported first time by a Geophysical survey in the region.

Seismic Activity Related to the 2002-2003 Mt. Etna Volcano Eruption (Italy): Fault Plane Solutions and Stress Tensor Computation

NASA Astrophysics Data System (ADS)

Barberi, G.; Cammarata, L.; Cocina, O.; Maiolino, V.; Musumeci, C.; Privitera, E.

2003-04-01

Late on the night of October 26, 2002, a bi-lateral eruption started on both the eastern and the southeastern flanks of Mt. Etna. The opening of the eruptive fracture system on the NE sector and the reactivation of the 2001 fracture system, on the S sector, were accompanied by a strong seismic swarm recorded between October 26 and 28 and by sharp increase of volcanic tremor amplitude. After this initial phase, on October 29 another seismogenetic zone became active in the SE sector of the volcano. At present (January 2003) the eruption is still in evolution. During the whole period a total of 862 earthquakes (Md≫1) was recorded by the local permanent seismic network run by INGV - Sezione di Catania. The maximum magnitude observed was Md=4.4. We focus our attention on 55 earthquakes with magnitude Md≫ 3.0. The dataset consists of accurate digital pickings of P- and S-phases including first-motion polarities. Firstly earthquakes were located using a 1D velocity model (Hirn et alii, 1991), then events were relocated by using two different 3D velocity models (Aloisi et alii, 2002; Patane et alii, 2002). Results indicate that most of earthquakes are located to the east of the Summit Craters and to northeast of them. Fault plane solutions (FPS) obtained show prevalent strike-slip rupture mechanisms. The suitable FPSs were considered for the application of Gephart and Forsyth`s algorithm in order to evaluate seismic stress field characteristics. Taking into account the preliminary results we propose a kinematic model of the eastern flank eastward movement in response of the intrusion processes in the central part of the volcano. References Aloisi M., Cocina O., Neri G., Orecchio B., Privitera E. (2002). Seismic tomography of the crust underneath the Etna volcano, Sicily. Physics of the Earth and Planetary Interiors 4154, pp. 1-17 Hirn A., Nercessian A., Sapin M., Ferrucci F., Wittlinger G. (1991). Seismic heterogeneity of Mt. Etna: structure and activity. Geophys. J. Int., 105, 139-153. Patane D., Chiarabba C., Cocina O., De Gori P., Moretti M., Boschi E. (2002). Tomographic images and 3D earthquake locations of the seismic swarm preceding the 2001 Mt. Etna eruption: Evidence for a dyke intrusion. Geophys. Res. Lett., 29, 10, 135-138.

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

Magnetotelluric studies of the Caldas Novas geothermal reservoir, Brazil

NASA Astrophysics Data System (ADS)

de Lugão, Patricia Pastana; LaTerra, Emanuele Francesco; Kriegshäuser, Berthold; Fontes, Sergio L.

2002-01-01

A magnetotelluric (MT) survey was conducted on the Caldas Novas geothermal reservoir located in the state of Goiás, Central Brazil. The region of Caldas Novas is a popular tourist spot because of the occurrence of hot water springs. The purpose of the first MT survey in this area is to provide more information on the geoelectrical structure of this important geothermal reservoir. The MT method is a frequency domain technique that utilizes naturally occurring magnetic and electric signals as source to obtain a resistivity map of the subsurface. Since temperature and permeability are some of the factors controlling electrical resistivity, MT is widely utilized for surveying geothermal areas such as Caldas Novas. Data were acquired along two profiles crossing the Serra de Caldas (Caldas Mountains) with a total of 25 MT stations. Frequencies of acquisition were in the range from 0.008 to 176 Hz. Spacing between stations were usually around 5 km. Apparent resistivity and phase data from the transverse electric (TE) and transverse magnetic (TM) modes were computed for both profiles. Very high (100,000 Ω m) apparent resistivity values in the TM mode indicate distortion, possibly caused by 3-D resistive structures. In this work, we focus on Profile 2, which was acquired aligned at N40°E, approximately following the direction of weakness N50°E. Two-dimensional (2-D) inversion suggests a basin-like model with very high-resistivity block structures associated with concentric faulting below the Caldas Mountains inside a resistive basin that extends to depths of approximately 25-30 km. This model is in good agreement with gravity data and the available geological information in the area and can help delineate areas of new geothermal reservoirs. The high resistivity associated with the depression in the MT model can be interpreted as caused by the low-permeability quartzites that form the Caldas Mountains. Although the survey configuration does not allow for a full three-dimensional (3-D) interpretation, a 3-D resistivity model was constructed and the MT responses computed. The 3-D synthetic data explains the behavior of both the TE and TM modes in this faulted resistive environment.

The limits of seaward spreading and slope instability at the continental margin offshore Mt Etna, imaged by high-resolution 2D seismic data

NASA Astrophysics Data System (ADS)

Gross, Felix; Krastel, Sebastian; Geersen, Jacob; Behrmann, Jan Hinrich; Ridente, Domenico; Chiocci, Francesco Latino; Bialas, Jörg; Papenberg, Cord; Cukur, Deniz; Urlaub, Morelia; Micallef, Aaron

2016-01-01

Mount Etna is the largest active volcano in Europe. Instability of its eastern flank is well documented onshore, and continuously monitored by geodetic and InSAR measurements. Little is known, however, about the offshore extension of the eastern volcano flank, defining a serious shortcoming in stability models. In order to better constrain the active tectonics of the continental margin offshore the eastern flank of the volcano, we acquired a new high-resolution 2D reflection seismic dataset. The data provide new insights into the heterogeneous geology and tectonics at the continental margin offshore Mt Etna. The submarine realm is characterized by different blocks, which are controlled by local- and regional tectonics. A compressional regime is found at the toe of the continental margin, which is bound to a complex basin system. Both, the clear link between on- and offshore tectonic structures as well as the compressional regime at the easternmost flank edge, indicate a continental margin gravitational collapse as well as spreading to be present at Mt Etna. Moreover, we find evidence for the offshore southern boundary of the moving flank, which is identified as a right lateral oblique fault north of Catania Canyon. Our findings suggest a coupled volcano edifice/continental margin instability at Mt Etna, demonstrating first order linkage between on- and offshore tectonic processes.

Structural setting of Fimiston- and Oroya-style pyrite-telluride-gold lodes, Paringa South mine, Golden Mile, Kalgoorlie: 1. Shear zone systems, porphyry dykes and deposit-scale alteration zones

NASA Astrophysics Data System (ADS)

Mueller, Andreas G.

2017-07-01

The Golden Mile in the 2.7 Ga Eastern Goldfields Province of the Yilgarn Craton, Western Australia, has produced 385 million tonnes of ore at a head grade of 5.23 g/t gold (1893-2016). Gold-pyrite ore bodies (Fimiston Lodes) trace kilometre-scale shear zone systems centred on the D2 Golden Mile Fault, one of three northwest striking sinistral strike-slip faults segmenting upright D1 folds. The Fimiston shear zones formed as D2a Riedel systems in greenschist-facies (actinolite-albite) tholeiitic rocks, the 700-m-thick Golden Mile Dolerite (GMD) sill and the Paringa Basalt (PB), during left-lateral displacement of up to 12 km on the D2 master faults. Pre-mineralisation granodiorite dykes were emplaced into the D2 shear zones at 2674 ± 6 Ma, and syn-mineralisation diorite porphyries at 2663 ± 11 Ma. The widespread infiltration of hydrothermal fluid generated chlorite-calcite and muscovite-ankerite alteration in the Golden Mile, and paragonite-ankerite-chloritoid alteration southeast of the deposit. Fluid infiltration reactivated the D2 shear zones causing post-porphyry displacement of up to 30 m at principal Fimiston Lodes moving the southwest block down and southeast along lines pitching 20°SE. D3 reverse faulting at the southwest dipping GMD-PB contact of the D1 Kalgoorlie Anticline formed the 1.3-km-long Oroya Shoot during late gold-telluride mineralisation. Syn-mineralisation D3a reverse faulting alternated with periods of sinistral strike-slip (D2c) until ENE-WSW shortening prevailed and was accommodated by barren D3b thrusts. North-striking D4 strike-slip faults of up to 2 km dextral displacement crosscut the Fimiston Lodes and the barren thrusts, and control gold-pyrite quartz vein ore at Mt. Charlotte (2651 ± 9 Ma).

Seismotectonic segmentation along the Chilean megathrust (Invited)

NASA Astrophysics Data System (ADS)

Melnick, D.; Moreno, M.

2010-12-01

This study focuses on understanding seismotectonic segmentation of megathrusts (MT). Recent research suggests elements associated to MT segmentation include: oceanic features, such as seamounts, seismic and aseismic ridges, and fracture zones; thickness and nature of trench sediments; and upper-plate heterogeneities as changes in density, lithology, and presence of splay faults or microplates, features usually manifested in coastline morphology. The 3500-km-long Chilean MT includes all these elements with various amplitudes under fairly constant kinematics and strike. Along the Nazca-South America boundary, the dense GPS network and knowledge of MT geometry allows inverting for the degree of interplate coupling or locking rate. Here we compare locking, historical MT ruptures, and long-term structure. Along-strike changes in locking rate occur at wavelengths of ~100-500 km, and locally correlate with historical ruptures as well as with lower and/or upper plate features, but without a clear systematic pattern. The transition between the 1960 M9.5 and 2010 M8.8 earthquake segments at Arauco (38.5S) has 100 km overlap deduced from land-level changes. Coherent deformation suggest this boundary has been stationary over 4 Myr, and is associated to margin-parallel collision of a forearc microplate along a Paleozoic shear zone. Seismically-active reverse splay faults bound the Peninsula and may absorb coseismic MT slip and stall rupture propagation. To the north, rupture of the 2010 M8.8 event stopped before the prominent J.Fernandez Ridge and its boundary may be associated to the Pichilemu fault, a steep oblique structure that generated a M6.9 aftershock. The change from accretionary to erosive character across this Ridge, from variable thickness of trench sediments, is manifested in narrowing of the coupling zone northwards and a small local decrease in locking rate. This local decrease is coincident with the Maipo orocline axis and a sharp bend in the orogen, which formed at 10 Ma. A sharp decrease in locking rates appears at 32.5S, near the northern end of the 1906 M8.5 earthquake. The 1906 segment appears to be highly coupled in the pre-2010 GPS data. High locking characterizes the southern edge of the 1922 M8.5 event at the Choros Peninsulas, diffusing northward. The Mejillones Peninsula, a prominent discontinuity in the coastline that marks the transition between the 1995 M8 and 1877 M8.7 earthquakes, is associated to a regional lineament of Paleogene paleomagnetic rotation and major discontinuities in Andean structural style along the fore-, intra-, and foreland regions. Minor changes in trench sediment thickness along the erosive segment may be reflected in local variations in locking rate. Two regions with localized decrease in locking rate are spatially associated to the intersection of prominent oceanic ridges at 27.5 and 21.5S, but not to boundaries of historical earthquakes. In general terms, oceanic features seem to have minor influence on earthquake rupture, except for the southern limit of the 1960 event, but are reflected as discrete lows in locking rate. Seismotectonic segmentation along the Chile MT seems to be rather controlled by upper-plate discontinuities such as splay faults and lithological boundaries inherited from the Paleozoic pre-Andean tectonic history of the margin.

Geophysical and geochemical methods applied to investigate fissure-related hydrothermal systems on the summit area of Mt. Etna volcano (Italy)

NASA Astrophysics Data System (ADS)

Maucourant, Samuel; Giammanco, Salvatore; Greco, Filippo; Dorizon, Sophie; Del Negro, Ciro

2014-06-01

A multidisciplinary approach integrating self-potential, soil temperature, heat flux, CO2 efflux and gravity gradiometry signals was used to investigate a relatively small fissure-related hydrothermal system near the summit of Mt. Etna volcano (Italy). Measurements were performed through two different surveys carried out at the beginning and at the end of July 2009, right after the end of the long-lived 2008-2009 flank eruption and in coincidence with an increase in diffuse flank degassing related to a reactivation of the volcano, leading to the opening of a new summit vent (NSEC). The main goal was to use a multidisciplinary approach to the detection of hidden fractures in an area of evident near-surface hydrothermal activity. Despite the different methodologies used and the different geometry of the sampling grid between the surveys, all parameters concurred in confirming that the study area is crossed by faults related with the main fracture systems of the south flank of the volcano, where a continuous hydrothermal circulation is established. Results also highlighted that hydrothermal activity in this area changed both in space and in time. These changes were a clear response to variations in the magmatic system, notably to migration of magma at various depth within the main feeder system of the volcano. The results suggest that this specific area, initially chosen as the optimal test-site for the proposed approach, can be useful in order to get information on the potential reactivation of the summit craters of Mt. Etna.

Gravity-driven postseismic deformation following the Mw 6.3 2009 L’Aquila (Italy) earthquake

PubMed Central

Albano, Matteo; Barba, Salvatore; Saroli, Michele; Moro, Marco; Malvarosa, Fabio; Costantini, Mario; Bignami, Christian; Stramondo, Salvatore

2015-01-01

The present work focuses on the postseismic deformation observed in the region of L’Aquila (central Italy) following the Mw 6.3 earthquake that occurred on April 6, 2009. A new, 16-month-long dataset of COSMO-SkyMed SAR images was analysed using the Persistent Scatterer Pairs interferometric technique. The analysis revealed the existence of postseismic ground subsidence in the mountainous rocky area of Mt Ocre ridge, contiguous to the sedimentary plain that experienced coseismic subsidence. The postseismic subsidence was characterized by displacements of 10 to 35 mm along the SAR line of sight. In the Mt Ocre ridge, widespread morphological elements associated with gravitational spreading have been previously mapped. We tested the hypothesis that the postseismic subsidence of the Mt Ocre ridge compensates the loss of equilibrium induced by the nearby coseismic subsidence. Therefore, we simulated the coseismic and postseismic displacement fields via the finite element method. We included the gravitational load and fault slip and accounted for the geometrical and rheological characteristics of the area. We found that the elastoplastic behaviour of the material under gravitational loading best explains the observed postseismic displacement. These findings emphasize the role of gravity in the postseismic processes at the fault scale. PMID:26553120

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.

Kinematics of the 2015 San Ramon, California earthquake swarm: Implications for fault zone structure and driving mechanisms

NASA Astrophysics Data System (ADS)

Xue, Lian; Bürgmann, Roland; Shelly, David R.; Johnson, Christopher W.; Taira, Taka'aki

2018-05-01

Earthquake swarms represent a sudden increase in seismicity that may indicate a heterogeneous fault-zone, the involvement of crustal fluids and/or slow fault slip. Swarms sometimes precede major earthquake ruptures. An earthquake swarm occurred in October 2015 near San Ramon, California in an extensional right step-over region between the northern Calaveras Fault and the Concord-Mt. Diablo fault zone, which has hosted ten major swarms since 1970. The 2015 San Ramon swarm is examined here from 11 October through 18 November using template matching analysis. The relocated seismicity catalog contains ∼4000 events with magnitudes between - 0.2

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.

Using faults for PSHA in a volcanic context: the Etna case (Southern Italy)

NASA Astrophysics Data System (ADS)

Azzaro, Raffaele; D'Amico, Salvatore; Gee, Robin; Pace, Bruno; Peruzza, Laura

2016-04-01

At Mt. Etna volcano (Southern Italy), recurrent volcano-tectonic earthquakes affect the urbanised areas, with an overall population of about 400,000 and with important infrastructures and lifelines. For this reason, seismic hazard analyses have been undertaken in the last decade focusing on the capability of local faults to generate damaging earthquakes especially in the short-term (30-5 yrs); these results have to be intended as complementary to the regulatory seismic hazard maps, and devoted to establish priority in the seismic retrofitting of the exposed municipalities. Starting from past experience, in the framework of the V3 Project funded by the Italian Department of Civil Defense we performed a fully probabilistic seismic hazard assessment by using an original definition of seismic sources and ground-motion prediction equations specifically derived for this volcanic area; calculations are referred to a new brand topographic surface (Mt. Etna reaches more than 3,000 m in elevation, in less than 20 km from the coast), and to both Poissonian and time-dependent occurrence models. We present at first the process of defining seismic sources that includes individual faults, seismic zones and gridded seismicity; they are obtained by integrating geological field data with long-term (the historical macroseismic catalogue) and short-term earthquake data (the instrumental catalogue). The analysis of the Frequency Magnitude Distribution identifies areas in the volcanic complex, with a- and b-values of the Gutenberg-Richter relationship representative of different dynamic processes. Then, we discuss the variability of the mean occurrence times of major earthquakes along the main Etnean faults estimated by using a purely geologic approach. This analysis has been carried out through the software code FISH, a Matlab® tool developed to turn fault data representative of the seismogenic process into hazard models. The utilization of a magnitude-size scaling relationship specific for volcanic areas is a key element: the FiSH code may thus calculate the most probable values of characteristic expected magnitude (Mchar) with the associated standard deviation σ, the corresponding mean recurrence times (Tmean) and the aperiodicity factor  for each fault. Finally, we show some results obtained by the OpenQuake-engine by considering a conceptual logic tree model organised in several branches (zone and zoneless, historical and geological rates, Poisson and time-dependent assumptions). Maps are referred to various exposure periods (10% exceeding probability in 30-5 years) and different spectral accelerations. The volcanic region of Mt. Etna represents a perfect lab for fault-based PSHA; the large dataset of input parameters used in the calculations allows testing different methodological approaches and validating some conceptual procedures.

Effect of microstructure and THCM processes on fault weakening

NASA Astrophysics Data System (ADS)

Stefanou, I.; Sulem, J.; Rattez, H.

2017-12-01

Field observations of exhumed mature faults and outcrops, i.e. faults that have experienced a large slip, suggest that shear localization occurs in a narrow zone of few millimeters thick or even less inside the fault core. The size of this zone plays a major role in the energy budget of the system as it controls the feedback of the dissipative terms in the energy balance equation.Strain localization in narrow bands can be seen as a bifurcation from the homogeneous deformation solution of the underlying mathematical problem, and is favored by softening behavior. Here we model the shearing of a saturated fault gouge under various multi-physical couplings to investigate the influence of these coupled processes on the softening response. The major drawback of classical continuum theories is that they lead to infinitely narrow shear localized zone. This can be remedied by resorting to Cosserat continuum theory for which constitutive models contain a material length. Moreover, Cosserat models are appropriate for taking into account the granular microstructure of the fault gouge for which the Cosserat material length is naturally related to the grain size of the gouge. Thus, bifurcation analysis of the sheared layer includes the calculation of the evolution of the thickness of the localized zone.A numerical analysis including the effect of shear heating and pore fluid thermal pressurization is performed and the results of the bifurcation analysis are compared to field observations in terms of the localized zone thickness. At high temperature rise, thermally induced mineral transformation such as dehydration of clayey minerals or decomposition of carbonates can occur. The effect of these chemical reactions on the shear band thickness evolution is investigated and the numerical results are compared to observations of the Mt. Maggio fault located in the Northern Apennines of Italy.

Reservoir uncertainty, Precambrian topography, and carbon sequestration in the Mt. Simon Sandstone, Illinois Basin

USGS Publications Warehouse

Leetaru, H.E.; McBride, J.H.

2009-01-01

Sequestration sites are evaluated by studying the local geological structure and confirming the presence of both a reservoir facies and an impermeable seal not breached by significant faulting. The Cambrian Mt. Simon Sandstone is a blanket sandstone that underlies large parts of Midwest United States and is this region's most significant carbon sequestration reservoir. An assessment of the geological structure of any Mt. Simon sequestration site must also include knowledge of the paleotopography prior to deposition. Understanding Precambrian paleotopography is critical in estimating reservoir thickness and quality. Regional outcrop and borehole mapping of the Mt. Simon in conjunction with mapping seismic reflection data can facilitate the prediction of basement highs. Any potential site must, at the minimum, have seismic reflection data, calibrated with drill-hole information, to evaluate the presence of Precambrian topography and alleviate some of the uncertainty surrounding the thickness or possible absence of the Mt. Simon at a particular sequestration site. The Mt. Simon is thought to commonly overlie Precambrian basement granitic or rhyolitic rocks. In places, at least about 549 m (1800 ft) of topographic relief on the top of the basement surface prior to Mt. Simon deposition was observed. The Mt. Simon reservoir sandstone is thin or not present where basement is topographically high, whereas the low areas can have thick Mt. Simon. The paleotopography on the basement and its correlation to Mt. Simon thickness have been observed at both outcrops and in the subsurface from the states of Illinois, Ohio, Wisconsin, and Missouri. ?? 2009. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

New Insights on Mt. Etna's Crust and Relationship with the Regional Tectonic Framework from Joint Active and Passive P-Wave Seismic Tomography

NASA Astrophysics Data System (ADS)

Díaz-Moreno, A.; Barberi, G.; Cocina, O.; Koulakov, I.; Scarfì, L.; Zuccarello, L.; Prudencio, J.; García-Yeguas, A.; Álvarez, I.; García, L.; Ibáñez, J. M.

2018-01-01

In the Central Mediterranean region, the production of chemically diverse volcanic products (e.g., those from Mt. Etna and the Aeolian Islands archipelago) testifies to the complexity of the tectonic and geodynamic setting. Despite the large number of studies that have focused on this area, the relationships among volcanism, tectonics, magma ascent, and geodynamic processes remain poorly understood. We present a tomographic inversion of P-wave velocity using active and passive sources. Seismic signals were recorded using both temporary on-land and ocean bottom seismometers and data from a permanent local seismic network consisting of 267 seismic stations. Active seismic signals were generated using air gun shots mounted on the Spanish Oceanographic Vessel `Sarmiento de Gamboa'. Passive seismic sources were obtained from 452 local earthquakes recorded over a 4-month period. In total, 184,797 active P-phase and 11,802 passive P-phase first arrivals were inverted to provide three different velocity models. Our results include the first crustal seismic active tomography for the northern Sicily area, including the Peloritan-southern Calabria region and both the Mt. Etna and Aeolian volcanic environments. The tomographic images provide a detailed and complete regional seismotectonic framework and highlight a spatially heterogeneous tectonic regime, which is consistent with and extends the findings of previous models. One of our most significant results was a tomographic map extending to 14 km depth showing a discontinuity striking roughly NW-SE, extending from the Gulf of Patti to the Ionian Sea, south-east of Capo Taormina, corresponding to the Aeolian-Tindari-Letojanni fault system, a regional deformation belt. Moreover, for the first time, we observed a high-velocity anomaly located in the south-eastern sector of the Mt. Etna region, offshore of the Timpe area, which is compatible with the plumbing system of an ancient shield volcano located offshore of Mt. Etna.

Representing energy efficiency diagnosis strategies in cognitive work analysis.

PubMed

Hilliard, Antony; Jamieson, Greg A

2017-03-01

This article describes challenges encountered in applying Jens Rasmussen's Cognitive Work Analysis (CWA) framework to the practice of energy efficiency Monitoring & Targeting (M&T). Eight theoretic issues encountered in the analysis are described with respect to Rasmussen's work and the modeling solutions we adopted. We grappled with how to usefully apply Work Domain Analysis (WDA) to analyze categories of domains with secondary purposes and no ideal grain of decomposition. This difficulty encouraged us to pursue Control Task (ConTA) and Strategies (StrA) analysis, which are under-explored as bases for interface design. In ConTA we found M&T was best represented by two interlinked work functions; one controlling energy, the other maintaining knowledge representations. From StrA, we identified a popular representation-dependent strategy and inferred information required to diagnose faults in system performance and knowledge representation. This article presents and discusses excerpts from our analysis, and outlines their application to diagnosis support tools. Copyright © 2015 Elsevier Ltd. All rights reserved.

A 3D Magnetotelluric Perspective on the Galway Granite, Western Ireland

NASA Astrophysics Data System (ADS)

Farrell, Thomas; Muller, Mark; Vozar, Jan; Feely, Martin; Hogg, Colin

2017-04-01

Magnetotelluric (MT) and audi-magnetotelluric (AMT) data were acquired at 75 locations across the exposed calc-alkaline Caledonian Galway granite batholith and surrounding country rocks into which the granite intruded. The Galway granite is located in western Ireland on the north shore of Galway bay, and has an ESE-WNW long axis. The granite is cut by trans-batholith faults, the Shannawona Fault Zone (SFZ) in the western part of the batholith, which has a NE-SW trend, and the Bearna Fault Zone (BFZ) in the eastern sector that has a NW-SE trend. Geobarometry data indicate that the central granite block between these fault zones has been uplifted, with the interpretation being that the granite in this central block is thinned. To the west of the SFZ, much of the Galway granite is below sea level, with the majority of the southern granite contact also beneath the sea in Galway bay. To the east of the batholith, the Carboniferous successions, consisting of mainly limestone with shale, overlie the basement rocks. The country rock to the north includes the metagabbro-gneiss suite, which itself intruded the deformed Dalradian successions that were deposited on the Laurentian margin of the Iapetus Ocean. The deformation of the Dalradian rocks, the intrusion of the metagabbro-gneiss suite and the intrusion of the Galway granite were major events in the protracted closure of the Iapetus Ocean. It is clear from geological mapping, from geobarometry and from the present submergence by the sea of a large part of the Galway granite, that inversion of MT data in this structurally complex geology is likely to require a 3D approach. We present a summary of 3D inversion of the Galway MT and AMT data. The study shows that the structure of the Galway granite is quite different from the pre-existing perspective. The central block, thought by its uplifting to be thinned, is shown to be the thickest part of the batholith. A geological model of granite intrusion is offered to explain this structure.

Airborne and Ground Electrical Surveys for Subsurface Mapping of the Arbuckle Aquifer, Central Oklahoma

NASA Astrophysics Data System (ADS)

Smith, D.; Smith, B. D.; Blome, C. D.; Osborn, N.

2008-12-01

Airborne and ground electrical surveys have been conducted to map the subsurface hydrogeologic character of the Arbuckle-Simpson aquifer in south central Oklahoma. An understanding of the geologic framework and hydrogeologic characteristics is necessary to evaluate groundwater flow through the highly faulted, structurally complex, carbonate aquifer. Results from this research will further understanding of the aquifer and will assist in managing the water resources of the region. The major issues include water quality, the allocation of water rights, and the potential impacts of pumping on springs and stream. Four areas in the Hunton anticline area, with distinctly different geology, were flown with a frequency domain helicopter electromagnetic system (HEM) in March, 2007. Ground electrical studies include dc resistivity imaging and natural field audiomagnetotelluric (AMT), and magnetotelluric (MT) surveys. The HEM resistivity and total field magnetic survey was flown in four blocks, A through D, mostly with a line spacing of 400 m. Block A extends from the Chickasaw National Recreational Area (CHIC) to Mill Creek on the west side of the anticline. The surface geology of this block is mostly dolomitic limestone of the Arbuckle Group that is in fault contact with younger Paleozoic clastic rocks. The flight line spacing was 800 meters in the western half of the block and 400 meters in the eastern part. Airborne magnetic data indicate that the Sulphur fault bends south to merge with the Mill Creek fault which substantiates an earlier hypothesis first made from interpretation of gravity data. Block B, located on the north side of the anticline consists of mostly of Arbuckle and Simpson Group rocks. Block C, covering most of the Clarita horst on the east side of the anticline, consists of the Upper Ordovician to the Lower Pennsylvanian shales. Block D, which was flown to include a deep test well site at Spears ranch, consisted of eight lines spaced at 400 meters. The HEM data are being used to more precisely locate faults, refine the lithostratigraphic units, and to map the depth and extent of shallow epikarst. The MT and AMT data revealed deep structural contacts and a transition between fresh and highly mineralized ground water between springs in the CHIC. The dc resistivity survey has greatly helped in mapping major faults both within dolomitic limestone and clastic units. Ground resistivity surveys also suggest that, in places, the faults within limestone are zones of lower resistivity and map low resistivity surficial epikarst a several meters thick. Ground penetrometer data also has been used to define the depth extent of epikarst in selected areas and the data correlate well with the dc resistivity and HEM resistivity depth sections.

A magnetotelluric feasibility study of the Alps

NASA Astrophysics Data System (ADS)

Ritter, O.; Weckmann, U.

2016-12-01

The Alps are a famous and extensive mountain range system in central Europe. The mountains were formed as the African and Eurasian tectonic plates collided and they have been a prime target for geological and geophysical investigations since the beginning of modern geosciences. Consequently, the Alps have been investigated with active and passive seismological methods and extensive sets of potential field data exist. Hardly anything is known, however, about the deep electrical conductivity structure, as it has been notoriously difficult to acquire magnetotelluric (MT) data in the Alps. The Alps are densely populated and a lot of infrastructure for tourism has been built over the years. MT measurements, which rely on natural variations of the electromagnetic background fields, are severely hampered by this man-made noise. Here, we report on a feasibility study to acquire MT data in the Alps, where all stations are deployed outside the valleys, on high mountain ranges and alpine pastures. Overall we recorded MT data at 7 stations, along an approximately north-south profile centred on Mayrhofen in the Austrian Alps. The average station spacing was 5 kilometers. The data were processed using robust remote-reference processing and the results clearly show that MT measurements are feasible. We used Mare2DEM for 2D inversion to include a somewhat realistic topography. The 2D section indicates moderate resistivity for the top 2 - 5 km, consistent with the regional geology, which suggests (meta-) sedimentary sequences. From depths of 5 km and below resistivities exceed 5,000 Ohmm. This means we can sense very deep with MT but also, that we should be cautious with an interpretation of this short profile. The data also clearly indicate 3D effects. We therefore propose to deploy an array of stations covering the entire Alps in USArray style, e.g. with a station spacing of approximately 50 km, to derive a 3D model of the deep electrical resistivity structure of the Alps. Such a model could also serve as reference for more detailed investigations of key structures such as major fault systems or nappe structures. It will be essential to install stations on high ground, as far away as possible from valleys and cultural installations.

Thermochronologic constraints on mylonite and detachment fault development, Kettle Highlands, northeastern Washington and southern British Columbia

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

Berger, B.R.; Snee, L.W.

1992-01-01

The Kettle dome, northeastern Washington and southern British Columbia, is one of several large metamorphic core complexes in the region. New Ar-40/Ar-39 cooling dates from the mylonite immediately beneath the Kettle River detachment fault at Barney's Junction, a cross-cutting mafic dike, and the youngest Eocene lavas in the Republic graben set constraints on kinematic models of the tectonic evolution of the dome and related grabens: Amphibolite--hornblende (59.0 [+-] 0.2); Pegmatite--muscovite (49.3 [+-] 0.2); Pegmatite--K-feldspar (49.2 [+-] 1); Augen gneiss--K-feldspar (48.0 [+-] 1); Mafic dike--hornblende (54.5 [+-] 0.1) and biotite (49.6 [+-] 0.1); Klondike Mt. Formation lava--feeder dike (48.8 [+-] 1).more » The authors interpret the dates to indicate that the tectonized amphibolite, part of a Cretaceous and older metamorphosed terrane, had formed and cooled to [approx] 500 C by Late Paleocene, the mylonite zone was being domed above the ductile zone by Early Eocene at the time of emplacement of the dike--temporally equivalent to the Keller Butte suite, Eocene Colville batholith--which crosscuts the mylonite, and incipient rifting was occurring in the Republic graben as evidenced by dike swarms. The mylonite complex reached 300 C by 49Ma coincident with the termination of Sanpoil volcanism, and then cooled rapidly to near or below 150 C by 48 Ma. At about this time, mafic Klondike Mt. lavas mark the termination of Republic graben rifting and possibly detachment faulting along the Kettle River fault.« less

The 2016 Kumamoto-Oita earthquake sequence: aftershock seismicity gap and dynamic triggering in volcanic areas

NASA Astrophysics Data System (ADS)

Uchide, Takahiko; Horikawa, Haruo; Nakai, Misato; Matsushita, Reiken; Shigematsu, Norio; Ando, Ryosuke; Imanishi, Kazutoshi

2016-11-01

The 2016 Kumamoto-Oita earthquake sequence involving three large events ( M w ≥ 6) in the central Kyushu Island, southwest Japan, activated seismicities in two volcanic areas with unusual and puzzling spatial gaps after the largest earthquake ( M w 7.0) of April 16, 2016. We attempt to reveal the seismic process during the sequence by following seismological data analyses. Our hypocenter relocation result implies that the large events ruptured different faults of a complex fault system. A slip inversion analysis of the largest event indicates a large slip in the seismicity gap (Aso gap) in the caldera of Mt. Aso, which probably released accumulated stress and resulted in little aftershock production. We identified that the largest event dynamically triggered a mid-M6 event at Yufuin (80 km northeast of the epicenter), which is consistent with existence of the 20-km long zone where seismicity was activated and surface offset was observed. These findings will help us study the contribution of the identified complexity in fault geometries and the geotherm in the volcanic areas to the revealed seismic process and consequently improve our understanding of the seismo-volcano tectonics.[Figure not available: see fulltext.

The importance of topographic corrections on magnetotelluric response data from rugged regions of Anatolia

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

Guerer, A.; Ilkisik, O.M.

1997-01-01

Topographic irregularities cause some distortions of magnetotelluric (MT) fields. In the vicinity of a topographic feature, the TM-mode distortion increases with the height and inclination of the slope. It is well-known that TM-mode topographic effects are much greater than TE-mode distortions. The authors have made a study of MT anomalies in TM-mode due to two-dimensional topography. In order to reduce these effects, the distortion tensor stripping technique was used. After corrections, the resulting data can be interpreted as if they were obtained over a flat surface and depend only on the subsurface structure. However, this technique sometimes causes some geometricalmore » distortions of the real subsurface structure. One of the aims is to overcome this failure. The authors have modified the correction coefficients by considering the actual one-dimensional geology. Model studies showed that this approach is especially useful in removing the terrain effects on complex 2D subsurface structures. The other purpose of this study is to emphasize the importance of a proper terrain correction for data from sites having mountainous topography over complex geology, e.g., strike-slip faults, suture zones and rift valleys. Some examples of MT data sets collected from the North Anatolian Fault Zone and from the thrust regions of the Western Taurides will be presented.« less

Crustal velocity structure and earthquake processes of Garhwal-Kumaun Himalaya: Constraints from regional waveform inversion and array beam modeling

NASA Astrophysics Data System (ADS)

Negi, Sanjay S.; Paul, Ajay; Cesca, Simone; Kamal; Kriegerowski, Marius; Mahesh, P.; Gupta, Sandeep

2017-08-01

In order to understand present day earthquake kinematics at the Indian plate boundary, we analyse seismic broadband data recorded between 2007 and 2015 by the regional network in the Garhwal-Kumaun region, northwest Himalaya. We first estimate a local 1-D velocity model for the computation of reliable Green's functions, based on 2837 P-wave and 2680 S-wave arrivals from 251 well located earthquakes. The resulting 1-D crustal structure yields a 4-layer velocity model down to the depths of 20 km. A fifth homogeneous layer extends down to 46 km, constraining the Moho using travel-time distance curve method. We then employ a multistep moment tensor (MT) inversion algorithm to infer seismic moment tensors of 11 moderate earthquakes with Mw magnitude in the range 4.0-5.0. The method provides a fast MT inversion for future monitoring of local seismicity, since Green's functions database has been prepared. To further support the moment tensor solutions, we additionally model P phase beams at seismic arrays at teleseismic distances. The MT inversion result reveals the presence of dominant thrust fault kinematics persisting along the Himalayan belt. Shallow low and high angle thrust faulting is the dominating mechanism in the Garhwal-Kumaun Himalaya. The centroid depths for these moderate earthquakes are shallow between 1 and 12 km. The beam modeling result confirm hypocentral depth estimates between 1 and 7 km. The updated seismicity, constrained source mechanism and depth results indicate typical setting of duplexes above the mid crustal ramp where slip is confirmed along out-of-sequence thrusting. The involvement of Tons thrust sheet in out-of-sequence thrusting indicate Tons thrust to be the principal active thrust at shallow depth in the Himalayan region. Our results thus support the critical taper wedge theory, where we infer the microseismicity cluster as a result of intense activity within the Lesser Himalayan Duplex (LHD) system.

Attenuation tomography of the main volcanic regions of the Campanian Plain.

NASA Astrophysics Data System (ADS)

de Siena, Luca; Del Pezzo, Edoardo; Bianco, Francesca

2010-05-01

Passive, high resolution attenuation tomography is used to image the geological structure in the first upper 4 km of shallow crust beneath the Campanian Plain. Images were produced by two separate attenuation tomography studies of the main volcanic regions of the Campanian Plain, Southern Italy, Mt. Vesuvius volcano and Campi Flegrei caldera. The three-dimensional S wave attenuation tomography of Mt. Vesuvius has been obtained with multiple measurements of coda-normalized S-wave spectra of local small magnitude earthquakes. P-wave attenuation tomography was performed using classical spectral methods. The images were obtained inverting the spectral data with a multiple resolution approach expressively designed for attenuation tomography. This allowed to obtain a robust attenuation image of the volumes under the central cone at a maximum resolution of 300 m. The same approach was applied to a data set recorded in the Campi Flegrei area during the 1982-1984 seismic crisis. Inversion ensures a minimum cell size resolution of 500 meters in the zones with sufficient ray coverage, and 1000 meters outside these zones. The study of the resolution matrix as well as the synthetic tests guarantee an optimal reproduction of the input anomalies in the center of the caldera, between 0 and 3.5 km in depth. Results allowed an unprecedented view of several features of the medium, like the residual part of solidified magma from the last eruption, under the central cone of Mt. Vesuvius, and the feeding systems and top of the carbonate basement, 3 km depth below both volcanic areas. Vertical Q contrast image important fault zones, such as the La Starza fault, as well as high attenuation structures that correspond to gas or fluid reservoirs, and reveal the upper part of gas bearing conduits connecting these high attenuation volumes with the magma sill revealed at about 7 km in depth by passive travel-time tomography under the whole Campanian Plain.

Integrated geophysical imaging of the Aluto-Langano geothermal field (Ethiopia).

NASA Astrophysics Data System (ADS)

Rizzello, Daniele; Armadillo, Egidio; Verdoya, Massimo; Pasqua, Claudio; Kebede, Solomon; Mengiste, Andarge; Hailegiorgis, Getenesh; Abera, Fitsum; Mengesha, Kebede; Meqbel, Naser

2017-04-01

The Aluto-Langano geothermal system is located in the central part of the Main Ethiopian Rift, one of the world's most tectonically active areas, where continental rifting has been occurring since several Ma and has yielded widespread volcanism and enhanced geothermal gradient. The geothermal system is associated to the Mt Aluto Volcanic Complex, located along the eastern margin of the rift and related to the Wonji Fault Belt, constituted by Quaternary NNE-SSW en-echelon faults. These structures are younger than the NE-SW border faults of the central Main Ethiopian Rift and were originated by a stress field oblique to the rift direction. This peculiar tectonism yielded local intense rock fracturing that may favour the development of geothermal reservoirs. In this paper, we present the results of an integrated geophysical survey carried out in 2015 over an area of about 200 km2 covering the Mt Aluto Volcanic Complex. The geophysical campaign included 162 coincident magnetotelluric and time domain electromagnetic soundings, and 207 gravity stations, partially located in the sedimentary plain surrounding the volcanic complex. Three-dimensional inversion of the full MT static-corrected tensor and geomagnetic tipper was performed in the 338-0.001 Hz band. Gravity data processing comprised digital enhancement of the residual Bouguer anomaly and 2D-3D inverse modelling. The geophysical results were compared to direct observations of stratigraphy, rock alteration and temperature available from the several deep wells drilled in the area. The magnetotelluric results imaged a low-resistivity layer which appears well correlated with the mixed alteration layer found in the wells and can be interpreted as a low-temperature clay cap. The clay-cap bottom depth is well corresponds to a change of thermal gradient. The clay cap is discontinuous, and in the central area of the volcanic complex is characterised by a dome-shape structure likely related to isotherm rising. The propilitic alteration layer, pinpointed as the 80-Ohm-m isosurface, shows two dome-shape highs. The first is NNE-trending, and may be interpreted as an upflow zone along a fault of the Wonji belt. Two productive wells are located along the borders of this area, as well as the alignements of fumaroles and altered grounds. The second is linked to a wide resistive area, located at shallow depth, where no clay cap was detected. It could be interpreted as a fossil high-temperature alteration zone reaching shallow depths, and it is associated to several fumaroles. Modeling of 2D/3D gravity data shows that the anomalies are due to shallow density variations likely related to lithology. The deep lateral variations due to structural lineaments inferred from well stratigraphy have no detectable signature. However, the trend analysis performed on the residual Bouguer anomaly (via horizontal and tilt derivative computations), allowed to identify five lineaments. Three of them exhibit NNE-SSW strike, corresponding to the Wonji Fault Belt Trend, whereas two have NNW-SSE strike, corresponding to the Red Sea Rift trend, which in this area is of minor evidence. The signature of shallow structures is then indicative of major regional structures. One of the lineaments marks the presence of a major fumarolic zone.

Quaternary extensional growth folding beneath Reno, Nevada, imaged by urban seismic profiling

USGS Publications Warehouse

Stephenson, William J.; Frary, Roxy N.; Louie, John; Odum, Jackson K.

2013-01-01

We characterize shallow subsurface faulting and basin structure along a transect through heavily urbanized Reno, Nevada, with high‐resolution seismic reflection imaging. The 6.8 km of P‐wave data image the subsurface to approximately 800 m depth and delineate two subbasins and basin uplift that are consistent with structure previously inferred from gravity modeling in this region of the northern Walker Lane. We interpret two primary faults that bound the uplift and deform Quaternary deposits. The dip of Quaternary and Tertiary strata in the western subbasin increases with greater depth to the east, suggesting recurrent fault motion across the westernmost of these faults. Deformation in the Quaternary section of the western subbasin is likely evidence of extensional growth folding at the edge of the Truckee River through Reno. This deformation is north of, and on trend with, previously mapped Quaternary fault strands of the Mt. Rose fault zone. In addition to corroborating the existence of previously inferred intrabasin structure, these data provide evidence for an active extensional Quaternary fault at a previously unknown location within the Truckee Meadows basin that furthers our understanding of both the seismotectonic framework and earthquake hazards in this urbanized region.

Resolving the deep electrical resistivity structure at Central Pontides, Northern Turkey by three-dimensional magnetotelluric modeling

NASA Astrophysics Data System (ADS)

Özaydın, Sinan; Bülent Tank, Sabri; Karaş, Mustafa; Sandvol, Eric

2017-04-01

Wide-band magnetotelluric (MT) (360 Hz - 1860 sec) data were acquired at 25 sites along a north - south aligned profile cutting across the Central Pontides, which are made up of highly metamorphosed formations and their tectonic boundaries including: a Lower Cretaceous-aged turbidite sequence, Central Pontides Metamorphic Supercomplex (CPMS), North Anatolian Fault Zone (NAFZ) and Izmir-Ankara-Erzincan Suture Zone (IAESZ). Dimensionality analyses over all observation points demonstrated high electrical anisotropy, which indicates complex geological and tectonic structures. This dimensional complexity and presence of the electrically conductive Black Sea augmented the requirement for a three-dimensional analysis. Inverse modeling routines, ModEM (Egbert and Kelbert, 2012) and WSINV3DMT (Siripunvaraporn et al., 2005) were utilized to reveal the geo-electrical implications over this unusually complicated region. Interpretations of the resultant models are summarized as follows: (i) Çangaldaǧ and Domuzdaǧ complexes appear as highly resistive bodies bounded by north dipping faults. (ii) Highly conductive Tosya Basin sediments overlain the ophiolitic materials as a thin cover located at the south of the NAFZ. (iii) North Anatolian Fault and some auxiliary faults within the system exhibit conductive-resistive interfaces that reach to lower crustal levels. (iv) IAESZ is a clear feature marked by the resistivity contrast between NAFZ-related sedimentary basins and Neo-Tethyan ophiolites.

Relationships between tectonism, volcano-tectonism and volcanism: the Ischia island (Italy) case.

NASA Astrophysics Data System (ADS)

Marotta, E.; de Vita, S.; Orsi, G.; Sansivero, F.

2005-12-01

The resurgent calderas of Ischia, Campi Flegrei and Pantelleria are characterized by differentially displaced blocks, and distribution of later eruption vents in a well defined sector of the resurgent area. These features suggest a simple shearing block resurgence mechanism. Moreover, the studies carried out on Ischia and Campi Flegrei evidenced a very complex structural pattern due to deformation related to the local stress regime induced by magmatism and volcanism and also to reactivation of regional structures. In order to better define the relationships among tectonic, volcano-tectonic and caldera resurgence mechanism, a structural study has been carried out at Ischia, where the Mt. Epomeo has been uplifted of about 900 m in the past 30 ka. The measures taken on 1,400 planar surfaces (faults, joints and fracture cleavages) show that the resurgent area is composed of differentially displaced blocks whose uplifting is maximum for the Mt. Epomeo and decreases southeastward. The resurgent area has a poligonal shape resulting from the reactivation of regional faults and by the activation of faults directly related to volcano-tectonism. The limit of the resurgent area is not defined towards the north, as beach deposits displaced at variable elevation by E-W and NW-SE trending faults, are exposed along the coastline. The western sector is bordered by inward-dipping, high-angle reverse faults, whose directions vary from N40E to NS and N50W from NW to SW of the block, testifying a compressional stress regime active in this area. These features are cut by late outward-dipping normal faults due to gravitational readjustment of the slopes. Vertical faults border the block at NE ad SW with right transtensive and left transpressive movements, respectively. The area located to the east of the most uplifted block, characterized by a tensile stress regime, has been deformed by N-S, N40-70E and N15W trending normal faults, with maximum elongation direction along N50W. The results of our study and the volcanological data of the past 3 ka, suggest that the eastern part of the resurgent block is the area with highest probability of vent opening in case of renewal of volcanism. Occurrence of landslides just before and after eruptions, suggest that resurgence occurs through discontinuous vertical movements which likely trigger the volcanic activity.

The structural geometry and development of the central Appalachian fold-and thrust belt across the Pennsylvania salient: The effects of syntectonic loading

NASA Astrophysics Data System (ADS)

Evans, Mark

2017-04-01

The Pennsylvania salient is a classic arcuate fold-and-thrust belt that was deformed during the Late Paleozoic Alleghenian orogeny. 38 regional cross-sections with an along-strike spacing of 5 to 10 km were constructed, and show that the structural geometry varies significantly from the 030°-striking southwestern segment to 060°-striking northeastern segment. The primary competent lithotectonic unit is the 2 to 3 km thick Cambro-Ordovician carbonate sequence which is detached along a Cambrian clastic unit. The 5 to 7 km thick preserved Upper Paleozoic sequence is less homogeneous, and locally exhibits significant internal deformation. In the southwest part of the salient, the hinterland part of the fold belt is defined by a series of imbricated Cambro-Ordovician carbonate horses with leading-edge fault-propagation style folds that have a structural amplitude of 5 to 7 km. In the central part of the fold belt, the Broadtop synclinorium exhibits little to no imbrication of the Cambro-Ordovician unit, while in the western part of the belt toward the foreland, two additional carbonate horses with leading-edge fault-propagation style folds comprise the Wills Mt. anticlinorium. In the central and eastern parts of the salient, the structural geometry toward the foreland is defined by a duplex with 4 -5 imbricate horses of Cambro-Ordovician carbonates that transitions to an antiformal stack of two to three carbonate thrust sheets comprising the Nittany anticlinorium. Toward the hinterland, the Cambro-Ordovician carbonate sequence is faulted into broadly-spaced fault-related folds, and includes the regionally continuous (>160 km) Jacks Mt. - Berwick anticline that spans both limbs of the salient. Upon retrodeformation of the cross sections, the 060°-striking northeastern segment restoration path curves 25°-30° to the east, while the 030°-striking southwestern segment curves 20°-25° to the south. The major fault underlying the presently curved Jacks Mt. - Berwick anticline structure, as well as those structures toward the hinterland, restore to a nearly straight fault traces oriented 045°-050°. The relatively straight restored faults require a rigid indenter colliding from the southeast to impose the curvature to the salient. The regional variation in structural style and ramp spacing may be related to the distribution of Late Carboniferous to Permian syn-tectonic loads during thrusting. Paleo-overburden thicknesses were determined from fluid inclusion microthermometry data of CH4±CO2 and aqueous fluid inclusions from syn-tectonic veins. In general, on the retrodeformed sections, restored overburdens are typically less above anticlinoria (<1.5 to 4.0 km), while much larger (4.3 to 6.1 km) above synclinoria. This suggests that syn-tectonic loading in the synclinoria due to sedimentation and/or overthrusting increased pore-fluid pressure enabling forelandward transport. Areas with less syntectonic overburden were prone to develop high-amplitude fold structures.

Orogenic remagnetizations and paleomagnetic analysis of fault propagation folds in Lower Carboniferous carbonates, Northern Rockies, NW Montana and SW Alberta

NASA Astrophysics Data System (ADS)

Zechmeister, M. S.; O'Brien, V. J.; Elmore, R. D.; Evans, M. A.

2006-12-01

Results from paleomagnetic analysis of Lower Carboniferous carbonates in the Sawtooth Range, northwestern Montana and the Livingstone range in Southwestern Alberta are presented. Paleomagnetic cores were collected from both limbs of four fault propagation folds, one at Swift Dam in MT as well as one along Green Creek and two along Oldman River in Alberta. The Swift Dam Fold is in the Madison Group and contains a widespread characteristic remanent magnetization (ChRM) that resides in magnetite with southerly declinations and moderately steep up inclinations. A tilt test reveals a synfolding ChRM, and the paleopole suggests remanence acquisition in the Cretaceous to Early Tertiary. This result contrasts with results from another fold in MT, the Teton anticline, which is a buckle fold where a similar ChRM is pretilting. The reason for the differences in the fold test results are under investigation. The ChRM is not thermoviscous in origin based on a comparison of unblocking temperature with the low burial temperatures and is interpreted as a chemical remanent magnetization (CRM). Preliminary data from the folds in Livingstone Range suggest a similar ChRM in the organic rich lithologies of the Livingstone, Banff and Mount Head formations. Tilt test results for the fault propagation folds in Alberta will be presented as well as a discussion on the origin of orogenic remagnetizations.

Paleomagnetic Reorientation of Structural Elements in Drill Cores: an example from Tolhuaca Geothermal Field

NASA Astrophysics Data System (ADS)

Perez-Flores, P.; Veloso, E. E.; Cembrano, J. M.; Sánchez, P.; Iriarte, S.; Lohmar, S.

2013-12-01

Reorientation of mesoscopic faults, veins and fractures recovered from drilling is critical to construct reliable structural models that can account for their architecture and deformation regime. However, oriented cores are expensive and time consuming to drill. Some techniques achieve reorientation by introducing tools into the borehole. Problems arise when boreholes are unstable or collapse. One alternative technique allowing reorientation is to obtain reliable paleomagnetic vectors to reorient each core piece after drilling. Here, we present stable and reliable remnant magnetic vectors calculated from the Tol-1 core to analyze the geometry of the fracture network and its relationship to regional tectonic. Tol-1 core is a vertical, 1073 m deep geothermal well, drilled at the Tolhuaca Geothermal Field in the Southern Volcanic Zone of the Andes by MRP Geothermal Chile Ltda (formerly GGE Chile SpA) in 2009. The core consists of basaltic/andesitic volcanic rocks with subordinate pyroclastic/volcaniclastic units, with probable Pleistocene age. Fault planes with slickenlines and mineral fiber kinematic indicators are common in the upper 700 m of the core. Calcite, quartz and calcite-quartz veins are recognized along of entire core, whereas epidote-quartz and calcite-epidote veins occur in the last 350 m, minor chlorite, anhydrite and clay-minerals are present. Orientations of structural features in the core were measured with a goniometer using the core's axis and a false north for each piece; hence, orientation data has a false strike but a real dip. To achieve total reorientation of the pieces, we collected 200 standard-size paleomagnetic specimens, ensuring that at least four of them were recovered from continuous pieces. Thermal (up to 700°C) and alternating field demagnetization (up to 90mT on steps of 2mT) methods were used to isolate a stable remnant magnetization (RM) vector, and each technique yielded similar results. RM vectors were recovered between 0 to 25mT, and between 0 to 625°C. The declination of RM vectors was used to bring pieces to a common anchor orientation calculated through the Geocentric Axial Dipole Model (GAD). The paleomagnetic technique proved to be reliable to reorient the Tol-1 core. Structural analyses along the core show N50-60E-striking preferential vein orientation. In addition, N40-50E- and N60-70W-striking preferential fault orientations were identified. Kinematic analysis of fault-slip data shows a N60E-striking bulk fault plane solution with normal strain regime. The veins and faults orientation show strain axes compatible with published regional stress field (σmax N238E).

Fault Zone Resistivity Structure and Monitoring at the Taiwan Chelungpu Drilling Project from AMT data

NASA Astrophysics Data System (ADS)

Chiang, C.-W.; Unsworth, M. J.; Chen, C.-S.; Chen, C.-C.; Lin, A.-T.; Hsu, H.-L.

2009-04-01

The Chi-Chi earthquake occurred on September 21st, 1999 in the Western Foothills of central Taiwan. This Mw=7.6 earthquake produced a 90 km long surface rupture and caused severe damage across Taiwan. The coseismic displacement on the Chelungpu fault was one of the largest ever observed. The Taiwan Chelungpu drilling project (TCDP) began in 2003 and resulted in a 2,000 m well that recovered cores from the fault zone at A-hole and finished in 2005 with two boreholes (A-hole and B-hole) being completed. The Chelungpu fault that caused the Chi-Chi earthquake was observed in the core at a depth of 1,111 m (FAZ1111). Another fault zone (Sanyi Fault - FAZ1710) was observed at depths of 1,500~1,710 m. Since the electrical resistivity of rocks is sensitive to the presence of fluids, geophysical methods that remotely sense sub-surface resistivity, such as Magnetotellurics (MT), can be a powerful tool in investigating the fluid distribution in the shallow crust. The effectiveness of MT in imaging fault zones has been demonstrated by studies of the San Andreas Fault zone in California, the U.S. and elsewhere. In magnetotellurics, the depth of exploration increases as the signal frequency decreases. Thus for imaging shallow fault zone structure at the TCDP site, the higher frequency audio-magnetotelluric (AMT) method is the most suitable. In this paper, AMT data collected at the TCDP site from 2004 to 2006 are presented. Spatial and temporal variations are described and interpreted in terms of the tectonic setting. Audio-magnetotelluric (AMT) measurements were used to investigate electrical resistivity structure at the TCDP site from 2004~2006. These data show a geoelectric strike direction of N15°E to N30°E. Inversion and forward modeling of the AMT data were used to generate a 1-D resistivity model that has a prominent low resistivity zone (< 10 ohm-m) between depths of 1,100 and 1,500 m. When combined with porosity measurements, the AMT measurements imply that the ground water has a resistivity of 0.55 ohm-m at the depth of the fault zone. Time variations in the measured AMT data were observed from 2004~2005 with maximum changes of 43% in apparent resistivity and 18° in phase. The change in apparent resistivity is greatest in the 1,000~100 Hz frequency band. These frequencies are sensitive to the resistivity structure of the upper 500 m of the hanging wall of the Chelungpu Fault. The decrease in resistivity over time appears to be robust and could be caused by an increase in porosity and a re-distribution of the groundwater.

Sulfide geochronlogy along the Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Yang, W.; Tao, C.; Li, H.; Liang, J.; Liao, S.

2017-12-01

Dragon Flag and Duanqiao hydrothermal field is located between the Indomed and Gallieni fracture zones in the ultraslow-spreading Southwest Indian Ridge (SWIR). Ten subsamples from active and inactive vents of Dragon Flag hydrothermal field and twenty-eight subsamples from Duanqiao hydrothermal field were dated using the 230Th/238U method. Four main episodes of hydrothermal activity of Duanqiao were determined according to the restricted results: 68.9-84.3, 43.9-48.4, 25.3-34.8, and 0.7-17.3 kyrs. Hydrothermal activity of Duanqiao probably started about 84.3 (±0.5) kyrs ago and ceased about 0.737 (±0.023) kyrs ago. And sulfide samples from the nearby Dragon Flag filed at the same time and the results show that the ages of most sulfides from Dragon Flag field range from 1.496(±0.176) to 5.416 (±0.116) kyrs with the oldest age estimated at 15.997 (±0.155) kyrs Münch et al. (2001) reconstructed the evolution history of Mt. Jourdanne hydrothermal field. The age dating results indicate activity in two episodes, at 70-40 and 27-13 kyrs. The hydrothermal activity in Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. The massive sulfides are younger than the sulfides from other hydrothermal fields such as Rainbow, Sonne and Ashadze-2. All these results suggest that hydrothermal activity of Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. Mt. Jourdanne is situated on an axial volcanic ridge which has both volcanic and tectonic activity. This is necessary to develop the heat source and pathways for the fluid convection, which enables the hydrothermal circulation. Hydrothermal activity in Dragon Flag Field is located next to the detachment fault termination. The detachment fault system provides a pathway for hydrothermal convection. Such style of heat source can contribute to continuous hydrothermal activity for over 1000 years. Duanqiao field is located near the central volcano and there is a hot mantle and/or fertile melt beneath Duanqiao field. The crust thickness is 9.5 km, suggesting the existence of AMC (Axial Magma Chamber) which provides magma source to the field (Li et al. 2015; Mendel et al. 2003). The periodic hydrothermal activity at Duanqiao may be related to the heat source provided by the local interaction of magmatism and tectonism.

MT data inversion and sensitivity analysis to image electrical structure of Zagros collision zone

NASA Astrophysics Data System (ADS)

Layegh Haghighi, T.; Montahaei, M.; Oskooi, B.

2018-01-01

Magnetotelluric (MT) data from 46 stations on a 470-km-long profile across the Zagros fold-thrust belt (ZFTB) that marks the Arabia-Eurasia collision zone were inverted to derive 2-D electrical resistivity structure between Busher on the coast of Persian Gulf and Posht-e-Badam, 160 km north east of Yazd. The model includes prominent anomalies in the upper and lower crust, beneath the brittle-ductile transition depth and mostly related to the fluid distribution and sedimentary layers beneath the profile. The conductivities and dimensions of the fault zone conductors (FZCs) and high conductivity zones (HCZs) as the major conductive anomalies in a fault zone conceptual model vary significantly below the different faults accommodated in this region. The enhanced conductivity below the site Z30 correlates well with the main Zagros thrust (MZT), located at the western boundary of Sanandaj-Sirjan zone (SSZ) and known as the transition between the two continents. The depth extent of the huge conductor beneath the south west of the profile, attributed to the thick sedimentary columns of the Arabian crust, cannot be resolved due to the smearing effect of the smoothness constraint employed in the regularized inversion procedure and the sensitivity of MT data to the conductance of the subsurface. We performed different tests to determine the range of 2-D models consistent with the data. Our approach was based on synthetic studies, comprising of hypothesis testing and the use of a priori information throughout the inversion procedure as well as forward modeling. We conclude that the minimum depth extent of the conductive layer beneath the southwest of the profile can be determined as approximately deeper than 15 km and also the screening effect of the conductive overburden is highly intense in this model and prevents the deep structures from being resolved properly.

Imaging an off-axis volcanic field in the Main Ethiopian Rift using 3-D magnetotellurics

NASA Astrophysics Data System (ADS)

Huebert, J.; Whaler, K. A.; Fisseha, S.; Hogg, C.

2017-12-01

In active continental rifts, asthenospheric upwelling and crustal thinning result in the ascent of melt through the crust to the surface. In the Main Ethiopian Rift (MER), most volcanic activity is located in magmatic segments in the rift centre, but there are areas of significant off-axis magmatism as well. The Butajira volcanic field is part of the Silti Debre Zeyt Fault (SDZF) zone in the western Main Ethiopian Rift. It is characterized by densely clustered volcanic vents (mostly scoria cones) and by limited seismic activity, which is mainly located along the big border faults that form the edge of a steep escarpment. Seismic P-Wave tomography reveals a crustal low velocity anomaly in this area. We present newly collected Magnetotelluric (MT) data to image the electrical conductivity structure of the area. We deployed 12 LMT instruments and 27 broadband stations in the western flank of the rift to further investigate the along-rift and depth extent of a highly conductive region under the SDZF which was previously identified by MT data collected on the central volcano Aluto and along a cross-rift transverse. This large conductor was interpreted as potential pathways for magma and fluid in the crust. MT Stations were positioned in five NW-SE running 50 km long profiles, covering overall 100km along the rift and providing good coverage for a 3-D inversion of the data to image this enigmatic area of the MER.

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

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

Schermer, E.R.

1993-04-01

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

Evidence for Ring Structures and Fracture Zones in the Tectonics of Kerguelen Archipelago, Indian Ocean

NASA Astrophysics Data System (ADS)

Mathieu, L.; Byrne, P. K.; van Wyk de Vries, B.; Moine, B.

2009-12-01

Little work has been done on the tectonics of the emergent areas of the Kerguelen Archipelago, even though the extensive outcrop renders the islands especially good for structural work. The results of two field campaigns and remote sensing analysis carried out in the central part of the archipelago around the Val Travers valley and the Mt Ross volcano are presented. The Archipelago is part of the Kerguelen Plateau, a Large Igneous Province that has developed in the Indian Ocean from the early Cretaceous. It spread along the newly formed SE Indian mid-oceanic ridge (SEIR) during the early Tertiary. The rifting event produced NW-SE, N-S and E-W striking grabens in the plateau that are respectively, parallel to the SEIR, related to sinistral strike-slip movements along the SEIR, and of unknown origin. The Kerguelen Archipelago formed after the rifting event over the plateau but nevertheless, it contains the bulk of structural directions mentioned above. The lavas (Plateau Basalts) that make up most of the area are densely fractured, crossed by many veins and some small faults as well as dykes. The rare faults identified are either normal or affected by sinistral transtensional movements. The fractures have mainly a NW-SE orientation that is consistent with extension related to the SEIR. Dykes, veins and normal faults strike E-W and are related to a dominant N-S directed regional extension. The scarcity of discrete faults contrasts with the density of fractures and other lineaments that appear to cover the bulk of land exposed to remote sensing observations. Such structures were formed by regional deformation too small to produce large discrete faults. We also have found a 20 km-wide polygonal fracture pattern encircling Mt Ross Volcano. This structure could be linked to repeated deflation and inflation of the ground related to a buried intrusive complex. Again, the movements are too small to produce discrete faults. Instead, they produce a polygon of deformation whose edges are parallel to buried rifting faults re-activated by the vertical movements. This work outlines the structure of the central part of the Kerguelen Archipelago that is affected by regional stresses and is imprinted by local tectonic structures related to intrusive activity. Kerguelen provides a structural situation that can be compared with Iceland and also with volcano-tectonic structures on other planets.

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

Aurelio, Mario; Taguibao, Kristine Joy; Vargas, Edmundo

In the selection of sites for disposal facilities involving low- and intermediate-level radioactive waste (LILW), International Atomic Energy Agency (IAEA) recommendations require that 'the region in which the site is located shall be such that significant tectonic and surface processes are not expected to occur with an intensity that would compromise the required isolation capability of the repository'. Evaluating the appropriateness of a site therefore requires a deep understanding of the geological and tectonic setting of the area. The Philippines sits in a tectonically active region frequented by earthquakes and volcanic activity. Its highly variable morphology coupled with its locationmore » along the typhoon corridor in the west Pacific region subjects the country to surface processes often manifested in the form of landslides. The Philippine LILW near surface repository project site is located on the north eastern sector of the Island of Luzon in northern Philippines. This island is surrounded by active subduction trenches; to the east by the East Luzon Trough and to the west by the Manila Trench. The island is also traversed by several branches of the Philippine Fault System. The Philippine LILW repository project is located more than 100 km away from any of these major active fault systems. In the near field, the project site is located less than 10 km from a minor fault (Dummon River Fault) and more than 40 km away from a volcanic edifice (Mt. Caguas). This paper presents an analysis of the potential hazards that these active tectonic features may pose to the project site. The assessment of such geologic hazards is imperative in the characterization of the site and a crucial input in the design and safety assessment of the repository. (authors)« less

Dimensionality and regional strike analyses of the Cibeber segment, Cimandiri fault zone, West Jawa, Indonesia

NASA Astrophysics Data System (ADS)

Febriani, F.; Handayani, L.; Setyani, A.; Anggono, T.; Syuhada; Soedjatmiko, B.

2018-03-01

The dimensionality and regional strike analyses of the Cimandiri Fault, West Java, Indonesia have been investigated. The Cimandiri Fault consists of six segments. They are Loji, Cidadap, Nyalindung, Cibeber, Saguling and Padalarang segments. The magnetotelluric (MT) investigation was done in the Cibeber segment. There were 42 observation points of the magnetotelluric data, which were distributed along 2 lines. The magnetotelluric phase tensor has been applied to determine the dimensionality and regional strike of the Cibeber segment, Cimandiri Fault, West Java. The result of the dimensionality analysis shows that the range values of the skew angle value which indicate the dimensionality of the study area are -5 ≤ β ≥ 5. These values indicate if we would like to generate the subsurface model of the Cibeber segment by using the magnetotelluric data, it is safe to assume that the Cibeber segment has the 2-D. While the regional strike analysis presents that the regional strike of the Cibeber segment is about N70-80°E.

b-value distribution in and around Mt. Tarumae, Japan

NASA Astrophysics Data System (ADS)

Chiba, K.

2017-12-01

Mt. Tarumae is an active volcano located in southeastern Shikotsu caldera, Hokkaido, Japan. Recently, crustal expansion occurred in 1999-2000 and 2013 near the summit of Mt. Tarumae, with a M5.6 earthquake recorded west of the summit on 8 July 2014. In this study, I determined hypocenter distributions and then performed b-value analysis for the period between 1 August 2014 and 12 August 2016 to improve our understanding of the magma system geometry beneath the summit of Mt. Tarumae. Hypocenters are mainly distributed in two regions: 3 - 5 km west of Mt. Tarumae, and beneath the volcano. I then determined b-value distributions. Regions with relatively high b-values ( 1.3) are located at depths of -0.5 to 2.0 km beneath the summit and at depths greater than 6.0 km in the northwestern part at about 1.5 - 3.0 km from the summit, while a region with relatively low b-values ( 0.6) is located at depths of 2.0 - 6.0 km beneath the summit. Compared the b-value distributions with other geophysical observations, it was found that the high b-value region from -0.5 to 2.0 km depth corresponds to regions of lower resistivity, positive self-potential anomaly, and an inflation source observed in 1999-2000. It is thus inferred that this region is generated by crustal heterogeneity, a decrease in effective normal stress, and change of a frictional property due to the development of faults and fissures, and the circulation of hydrothermal fluids. On the other hand, the inflation source observed in 2013 was located near the boundary between the low b-value region beneath the summit and the deeper high b-value region in the northwestern part at about 1.5 - 3.0 km from the summit. Studies of other volcanoes suggest that such a high-b-value region likely corresponds to a magma chamber. From the deeper high b-value region estimated in this study, I am able to point out that the magma chamber is located to depths greater than 6.0 km in the northwestern part at about 1.5 - 3.0 km from the summit. Thus, these findings contribute to our understanding of the magma plumbing system beneath the summit of Mt. Tarumae.

Soro West: A non-seismically defined, fault cut-off prospect in the Papuan Fold and Thrust Belt, Papua New Guinea

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

Robinson, W.F.; Swift, C.M. Jr.

Soro West is a fault cut-off prospect located in the frontal portion of the Papuan Fold and Thrust Belt. Prospective Toro and Imburu sandstones are interpreted to be in the hanging wall of the Soro Thrust. Truncation against the thrust, both updip and through lateral ramps, provides the trapping mechanism. The Soro West Prospect was defined using geological, geochemical, remote sensing, and geophysical data. The definition and location of the trap is a primary risk and work was focused on this aspect. Surface geological data (lithology, strikes, and dips) topography and synthetic aperture radar imagery were incorporated into the evaluation.more » Statistical curvature analysis techniques helped define the shape of the structure and the locations of the lateral ramps. Strontium isotope analyses of Darai Limestone surface samples refined erosional levels using a locally-derived reference curve. Severe karst precludes the acquisition of coherent surface seismic data, so the primary geophysical tool used was magnetotellurics (MT). A detailed, pre-survey feasibility study defined expected responses from alternative structural models. The MT data demonstrated that the limestone at surface is underlain by thick conductive clastics and not another Darai Limestone sheet. The data also constrained the range of fault cut-off positions significantly. Multiple, three-dimensionally consistent, restorable alternative structural models were created using results from all analyses. These led to a positive assessment of the prospect and an exploratory test is to be drilled in 1996.« less

Post-depositional alteration of titanomagnetite in a Miocene sandstone, south Texas (U.S.A.)

USGS Publications Warehouse

Reynolds, R.L.

1982-01-01

Petrographic and geochemical studies have yielded information on the time-space relationships of the post-depositional alteration of detrital titanomagnetite (Ti-mt) in fine- to medium-grained sandstone from unoriented core samples (taken below the water table at depths of 30-45 m) of the Miocene Catahoula Sandstone, south Texas. Aqueous sulfide introduced from sour gas reservoirs along a growth fault into part of the Catahoula shortly after deposition resulted in the replacement at the periphery of Ti-mt grains by iron disulfide (FeS2) minerals. Remnants of Ti-mt in cores of the partly sulfidized grains show no evidence of earlier hematitic oxidation. After sulfidization, part of the sandstone body was invaded by oxygenated groundwaters flowing down a shallowly inclined (1??) hydrologic gradient. The boundary between oxidized and reduced facies is clearly defined by the distribution of ferric and ferrous iron minerals, and the concentrations of Mo, U, and Se. In oxidized (light-red) strata that had not been previously subjected to sulfidic-reducing conditions but that are correlative with strata containing FeS2 minerals, Ti-mt has been partly to entirely replaced pseudomorphously by hematite to form martite. The absence of hematitic alteration of Ti-mt in the reduced facies is strong evidence that martite in the oxidized facies formed after deposition. ?? 1982.

Structure, alteration, and geochemistry of the Charlotte quartz vein stockwork, Mt Charlotte gold mine, Kalgoorlie, Australia: time constraints, down-plunge zonation, and fluid source

NASA Astrophysics Data System (ADS)

Mueller, Andreas G.

2015-02-01

The Kalgoorlie district in the Archean Yilgarn Craton, Western Australia, comprises two world-class gold deposits: Mt Charlotte (144 t Au produced to 2013) in the northwest and the Golden Mile (1,670 t Au) in the southeast. Both occur in a folded greenschist-facies gabbro sill adjacent to the Golden Mile Fault (D2) in propylitic alteration associated with porphyry dikes. At Mt Charlotte, a shear array of fault-fill veins within the Golden Mile Fault indicates sinistral strike-slip during Golden Mile-type pyrite-telluride mineralization. The pipe-shaped Charlotte quartz vein stockwork, mined in bulk more than 1 km down plunge, is separated in time by barren D3 thrusts from Golden Mile mineralization and alteration, and occurs between two dextral strike-slip faults (D4). Movement on these faults generated an organized network of extension and shear fractures opened during the subsequent infiltration of high-pressure H2S-rich fluid at 2,655 ± 13 Ma (U-Pb xenotime). Gold was deposited during wall rock sulphidation in overlapping vein selvages zoned from deep albite-pyrrhotite (3 g/t Au) to upper muscovite-pyrite assemblages (5 g/t Au bulk grade). Chlorite and fluid inclusion thermometry indicate that this kilometre-scale zonation is due to fluid cooling from 410-440 °C at the base to 350-360 °C at the top of the orebody, while the greenstone terrane remained at 250 °C ambient temperature and at 300 MPa lithostatic pressure. The opened fractures filled with barren quartz and scheelite during the retrograde stage (300 °C) of the hydrothermal event. During fracture sealing, fluid flux was periodically restricted at the lower D3 thrust. Cycles of high and low up-flow, represented by juvenile H2O-CO2 and evolved H2O-CO2-CH4 fluid, respectively, are recorded by the REE and Sr isotope compositions of scheelite oscillatory zones. The temperature gradient measured in the vein stockwork points to a hot (>600 °C) fluid source 2-4 km below the mine workings, and several kilometres above the base of the greenstone belt. Mass balance calculations involving bulk ore indicate enrichment of both felsic (K, Rb, Cs, Li, Ba, W) and mafic elements (Ca, Sr, Mg, Ni, V, Cr, Te), a source signature compatible with the local high-Mg porphyry suite but not with the meta-gabbro host rock. The initial 87Sr/86Sr ratios of the vein scheelites (0.7014-0.7016) are higher than the mantle ratio of the meta-gabbro (0.7009-0.7011) and overlap those of high-Mg monzodiorite intrusions (0.7016-0.7018) emplaced along the Golden Mile Fault at 2,662 ± 6 Ma to 2,658 ± 3 Ma.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

The Mt. Ochi melange (South Evvia Island, Greece): a case study for HP metamorphism and syn-convergent exhumation.

NASA Astrophysics Data System (ADS)

Moustaka, Eleni; Soukis, Konstantinos; Huet, Benjamin; Lozios, Stylianos; Magganas, Andreas

2014-05-01

The Attic-Cycladic complex (central Aegean Sea, Greece) experienced profound extension since at least the Oligo-Miocene boundary during which the previously thickened crust was reworked by a series of detachments forming the NE directed North Cycladic Detachment System (NCDS) and the SSW directed West Cycladic Detachment System (WCDS). South Evvia Island is located at the northwestern part of the Attic Cycladic complex linking the highly thinned and polymetamorphosed central part of the complex with mainland Greece. Furthermore, greenschists-facies retrograde metamorphism has only partially overprinted the HP mineral assemblages. Consequently, it is an ideal area to study tectonic processes associated with subduction, HP metamorphism and subsequent exhumation from eclogitic depths to the surface. Geological mapping in 1:2:000 scale revealed that the tectonostratigraphy of Mt. Ochi includes three distinct units all metamorphosed in HP conditions followed by greenschist facies overprint. These units are from top to bottom a) the Ochi Unit, a thick metavolcanosedimentary sequence with some intensely folded cipoline marble intercalations and isolated occurrences of metabasic rocks b) the ophiolitic mélange (metagabbros, metawherlites, peridotites, metabasites within a metasedimentary+serpentinite matrix) and c) the lowermost Styra Unit, a cipoline marble-dominated unit with thin mica schists and rare quartzitic layers often boudinaged. The thrust fault that was responsible for the juxtaposition of these three units acted in an early stage during HP metamorphism and it was isoclinally folded and sheared by the following syn-metamorphic deformation events. Detailed structural study in meso- and microscopic scale combined with petrological and geochemical analyses of the Mt Ochi rocks led to the distinction of at least three syn-metamorphic and two post-metamorphic deformation episodes that affected all units. The oldest structure identified is a relic foliation formed by the mineral assemblage Na-amphibole + lawsonite seen as inclusion in epidote porphyroblasts within the melange. It could represent a structure of the prograde path but it could also have formed during the peak HP event. This is followed by successive folding episodes that are related to axial plane foliations and a ~E-W intersection/stretching lineation formed by typical blueschist- to epidote-blueschist facies mineral assemblages. The main foliation that can be observed in all three units is a greenschist-facies axial plane foliation accompanied by a ~ENE-WSW stretching lineation. The shear sense during the prograde path is constantly towards the WSW. In the greenschists-facies an unambiguous top-to ENE can be observed mostly in mylonitic rocks. The following deformation episodes include semi-brittle to brittle structures (shear bands brittle open folds, crenulation cleavage, and faults with increasingly higher-angle) that are not as penetrative and record the passage of the units through the brittle-ductile transitions and to higher structural levels. The kinematics of these late episodes is also towards the NE. Based on the above, the Mt Ochi HP units exhibit a common tectonometamorphic evolution since at least the early stages of the prograde path. The Ochi Unit/Styra Unit contact is a structure that formed prior to or during peak HP metamorphism and therefore it couldn't have served as the normal fault to an extrusion wedge.

Volcanic unrest leading to the July-August 2001 lateral eruption at Mt. Etna: Seismological constraints

NASA Astrophysics Data System (ADS)

Sicali, Simona; Barberi, Graziella; Cocina, Ornella; Musumeci, Carla; Patanè, Domenico

2015-10-01

A close relationship between earthquake swarms, volcanic eruptions, and ground deformation at Mt. Etna was well documented shortly before the beginning of the July-August 2001 eruption. Past experiences at this volcano suggest how magma/dike intrusion in the shallow crust or in the upper part of the volcanic pile normally occurs after several years/months of internal recharging. Since seismic investigations provide a means to study the scale and origin of stress perturbations at active volcanoes, allowing to better investigating the preparation phase of an eruption, in this paper, we performed a close examination of the seismic activity recorded at Mt. Etna in the months preceding the 2001 eruption and in particular between November 2000 and July 2001. After integrating data recorded by the two networks operating during that time and run by the Istituto Internazionale di Vulcanologia and SISTEMA POSEIDON, we relocated 522 earthquakes by using the tomoDD code in a 3D velocity model, and then we computed their fault plane solutions. The application of different selection criteria enabled obtaining a good-quality revised data set consisting of 111 fault plane solutions. The high-precision locations identified well-defined seismic clusters, in different periods, suggesting a link with the magma migration from a depth of 8-13 km b.s.l. towards shallower zones. Moreover, the computed maximum compressive stress axis, as inferred from earthquake focal mechanisms, indicated a roughly W-E-oriented σ1. This findings reflect an overpressure of the mid to shallow crust due to the progressive magma uprising in central portion of the volcano and also highlighted a rotation of the local stress field with respect to the regional one N-S trending. In addition, P-axis distribution pointed out the presence of a center of pressure located to the south of the Central Craters. These results provide particularly compelling evidence for a direct causal link between pressurization of the mid-level volcanic plumbing system by ascending magma and precursory local stress field reorientations, demonstrating that seismological analysis can be used to detect subtle local stress changes that herald eruptive activity.

Seismic Supercycles of Normal Faults in Central Italy over Various Time Scales Revealed by 36Cl Cosmogenic Dating

NASA Astrophysics Data System (ADS)

Benedetti, L. C.; Tesson, J.; Perouse, E.; Puliti, I.; Fleury, J.; Rizza, M.; Billant, J.; Pace, B.

2017-12-01

The use of 36Cl cosmogenic nuclide as a paleoseismological tool for normal faults in the Mediterranean has revolutionized our understanding of their seismic cycle (Gran Mitchell et al. 2001, Benedetti et al. 2002). Here we synthetized results obtained on 13 faults in Central Italy. Those records cover a period of 8 to 45 ka. The mean recurrence time of retrieved seismic events is 5.5 ±6 ka, with a mean slip per event of 2.5 ± 1.8 m and a mean slip-rate from 0.1 to 2.4 mm/yr. Most retrieved events correspond to single events according to scaling relationships. This is also supported by the 2 m-high co-seismic slip observed on the Mt Vettore fault after the October 30, 2016 M6.5 earthquake in Central Italy (EMERGEO working group). Our results suggest that all faults have experienced one or several periods of slip acceleration with bursts of seismic activity, associated with very high slip-rate of 1.7-9 mm/yr, corresponding to 2-20 times their long-term slip-rate. The duration of those bursts is variable from a fault to another (from < 2 kyr to 4-10 kyr). Those periods of acceleration are generally separated by longer periods of quiescence with no or very few events. Those alternating periods correspond to a long-term variation of the strain level with all faults oscillating between strain maximum and minimum, the length of strain loading and release being significantly different from one fault to another, those supercycles occurring over periods of 8 to 45 ka. We found relationships between the mean slip-rate, the mean slip per event and the mean recurrence time. This might suggest that the seismic activity of those faults could be controlled by their intrinsic properties (e.g. long-term slip-rate, fault-length, state of structural maturity). Our results also show events clustering with several faults rupturing in less than 500 yrs on adjacent or distant faults within the studied area. The Norcia-Amatrice seismic sequence, ≈ 50 km north of our study area, also evidenced this clustering behaviour, with over the last 20 yrs several successive events of Mw 5 to 6.5 (from north to south: Colfiorito 1997 Mw6.0, Norcia 2016 Mw6.5, L'Aquila 2009 Mw6.3), rupturing various fault systems, over a total length of ≈100 km. This sequence will allow to better understand earthquake kinematics and spatiotemporal slip distribution during those seismic bursts.

Magnetotelluric characterization of the northern margin of the Yilgarn Craton (Western Australia)

NASA Astrophysics Data System (ADS)

Piña-Varas, Perla; Dentith, Michael

2017-04-01

The northern margin of the Yilgarn Craton (Western Australia) was deformed during the convergence and collision with the Pilbara Craton and the intervening Glenburgh Terrain that created the Capricorn Orogen. The Yilgarn Craton is one of the most intensively mineralised areas of continental crust with world class deposits of gold and nickel. However, the region to its north has surprisingly few deposits. Cratonic margins are considered to be key indicators of prospectivity at a regional scale. The northern limit of the Yilgarn Craton within the Capricorn Orogen is not well resolved at date because of overlying Proterozoic sedimentary basins. We present here some of the results of an extensive magnetotelluric (MT) study that is being performed in the area. This study is a component of large multi-disciplinary geoscience project on the 'Distal Footprints of Giant Ore Systems' in the Capricorn Orogen. The MT dataset consists of a total of 240 broadband magnetotelluric stations (BBMT) and 84 long period stations (LMT). Analysis of the dataset reveals a clear 3-D geoelectrical behaviour and extreme complexity for most of the sites, including an extremely high number of sites with phases out-of-quadrant at long periods. 3-D inverse modelling of the MT data shows high resistivity Archean units and low resistivity Paleoproterozoic basins, including very low resistivity structures at depth. These strong resistivity contrasts allow us to successfully map northern margin of the Yilgarn Craton beneath basin cover, as well as identifying major lateral conductivity changes in the deep crust suggestive of different tectonic blocks. Upper crustal conductive zones can be correlated with faults on seismic reflection data. Our results suggest MT surveys are a useful tool for regional-scale exploration in the study area and in area of thick cover in general.

Spreading and slope instability at the continental margin offshore Mt Etna, imaged by high-resolution 2D seismic data

NASA Astrophysics Data System (ADS)

Gross, Felix; Krastel, Sebastian; Behrmann, Jan-Hinrich; Papenberg, Cord; Geersen, Jacob; Ridente, Domenico; Latino Chiocci, Francesco; Urlaub, Morelia; Bialas, Jörg; Micallef, Aaron

2015-04-01

Mount Etna is the largest active volcano in Europe. Its volcano edifice is located on top of continental crust close to the Ionian shore in east Sicily. Instability of the eastern flank of the volcano edifice is well documented onshore. The continental margin is supposed to deform as well. Little, however, is known about the offshore extension of the eastern volcano flank and its adjacent continental margin, which is a serious shortcoming in stability models. In order to better constrain the active tectonics of the continental margin offshore the eastern flank of the volcano, we acquired and processed a new marine high-resolution seismic and hydro-acoustic dataset. The data provide new detailed insights into the heterogeneous geology and tectonics of shallow continental margin structures offshore Mt Etna. In a similiar manner as observed onshore, the submarine realm is characterized by different blocks, which are controlled by local- and regional tectonics. We image a compressional regime at the toe of the continental margin, which is bound to an asymmetric basin system confining the eastward movement of the flank. In addition, we constrain the proposed southern boundary of the moving flank, which is identified as a right lateral oblique fault movement north of Catania Canyon. From our findings, we consider a major coupled volcano edifice instability and continental margin gravitational collapse and spreading to be present at Mt Etna, as we see a clear link between on- and offshore tectonic structures across the entire eastern flank. The new findings will help to evaluate hazards and risks accompanied by Mt Etna's slope- and continental margin instability and will be used as a base for future investigations in this region.

Modélisation magnétotellurique de la structure géologique profonde de l’unité granulitique de l’In Ouzzal (Hoggar occidental)

NASA Astrophysics Data System (ADS)

Bouzid, Abderrezak; Akacem, Nouredine; Hamoudi, Mohamed; Ouzegane, Khadidja; Abtout, Abdeslam; Kienast, Jean-Robert

2008-11-01

Magnetotelluric modeling of the deep geologic structure of In Ouzzal Granulitic Unit (western Hoggar). The In Ouzzal Granulitic Unit (IOGU) or In Ouzzal Terrane (IOT) is an Archaean block belonging to the Hoggar terrane mosaic. It has been reworked during the Eburnean and is characterized by ultrahigh temperature metamorphism of the structures, which are likely to be old dome and basin structures. The aim of this study, based on a survey of 12 magnetotelluric (MT) soundings, was to characterize the IOGU deep lateral boundaries and to see if it is possible to reconstruct some of these old dome and basin structures after their transformation by metamorphism and deformation. MT data analysis and modeling show that IOGU boundaries extend downwards, at least down to the crust's basement, and may represent suture zones. Inside the terrane, the MT observations do not allow separation between dome and basin structures, because these features are severely stretched. However, the main MT transverse response feature is a deeply rooted great accident, which may be interpreted as a major fault that separates IOGU into two compartments.

The use of ERTS/LANDSAT imagery in relation to airborne remote sensing for terrain analysis in western Queensland, Australia

NASA Technical Reports Server (NTRS)

Cole, M. M.; Wen-Jones, S. (Principal Investigator)

1976-01-01

The author has identified the following significant results. Series of linears were identified on the March imagery of Lady Annie-Mt. Gordon fault zone area. The series with a WSW-ENE orientation which is normal to the major structural units and also several linears with NNW-SSE orientation appears to be particularly important. Copper mineralization is known at several localities where these linears are intersected by faults. Automated outputs using supervised methods involving the selection of training sets selected by visual recognition of spectral signatures on the color composites obtained from combinations of MSS bands 4, 5 and 7 projected through appropriate filters, were generated.

Deep resistivity structure of Yucca Flat, Nevada Test Site, Nevada

USGS Publications Warehouse

Asch, Theodore H.; Rodriguez, Brian D.; Sampson, Jay A.; Wallin, Erin L.; Williams, Jackie M.

2006-01-01

The Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) at their Nevada Site Office are addressing groundwater contamination resulting from historical underground nuclear testing through the Environmental Management program and, in particular, the Underground Test Area project. One issue of concern is the nature of the somewhat poorly constrained pre Tertiary geology and its effects on ground-water flow in the area adjacent to a nuclear test. Ground water modelers would like to know more about the hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Yucca Flat Corrective Action Unit (CAU). During 2003, the U.S. Geological Survey, supported by the DOE and NNSA-NSO, collected and processed data from 51 magnetotelluric (MT) and audio-magnetotelluric (AMT) stations at the Nevada Test Site in and near Yucca Flat to assist in characterizing the pre-Tertiary geology in that area. The primary purpose was to refine the character, thickness, and lateral extent of pre Tertiary confining units. In particular, a major goal has been to define the upper clastic confining unit (late Devonian - Mississippian-age siliciclastic rocks assigned to the Eleana Formation and Chainman Shale) in the Yucca Flat area. The MT and AMT data have been released in separate USGS Open File Reports. The Nevada Test Site magnetotelluric data interpretation presented in this report includes the results of detailed two-dimensional (2 D) resistivity modeling for each profile (including alternative interpretations) and gross inferences on the three dimensional (3 D) character of the geology beneath each station. The character, thickness, and lateral extent of the Chainman Shale and Eleana Formation that comprise the Upper Clastic Confining Unit are generally well determined in the upper 5 km. Inferences can be made regarding the presence of the Lower Clastic Confining Unit at depths below 5 km. Large fault structures such as the CP Thrust fault, the Carpetbag fault, and the Yucca fault that cross Yucca Flat are also discernable as are other smaller faults. The subsurface electrical resistivity distribution and inferred geologic structures determined by this investigation should help constrain the hydrostratigraphic framework model that is under development.

Elastostatic effects around a magma reservoir and pathway due to historic earthquakes: a case study of Mt. Fuji, Japan

NASA Astrophysics Data System (ADS)

Hosono, Masaki; Mitsui, Yuta; Ishibashi, Hidemi; Kataoka, Jun

2016-12-01

We discuss elastostatic effects on Mt. Fuji, the tallest volcano in Japan, due to historic earthquakes in Japan. The 1707 Hoei eruption, which was the most explosive historic eruption of Mt. Fuji, occurred 49 days after the Hoei earthquake (Mw 8.7) along the Nankai Trough. It was previously suggested that the Hoei earthquake induced compression of a basaltic magma reservoir and unclamping of a dike-intruded region at depth, possibly triggering magma mixing and the subsequent Plinian eruption. Here, we show that the 1707 Hoei earthquake was a special case of induced volumetric strain and normal stress changes around the magma reservoir and pathway of Mt. Fuji. The 2011 Tohoku earthquake (Mw 9), along the Japan Trench, dilated the magma reservoir. It has been proposed that dilation of a magma reservoir drives the ascent of gas bubbles with magma and further depressurization, leading to a volcanic eruption. In fact, seismicity notably increased around Mt. Fuji during the first month after the 2011 Tohoku earthquake, even when we statistically exclude aftershocks, but the small amount of strain change (< 1 μ strain) may have limited the ascent of magma. For many historic earthquakes, the magma reservoir was compressed and the magma pathway was wholly clamped. This type of interaction has little potential to mechanically trigger the deformation of a volcano. Thus, Mt. Fuji may be less susceptible to elastostatic effects because of its location relative to the sources of large tectonic earthquakes. As an exception, a possible local earthquake in the Fujikawa-kako fault zone could induce a large amount of magma reservoir dilation beneath the southern flank of Mt. Fuji.

A helium isotope cross-section study through the Vulture line, southern Apennines

NASA Astrophysics Data System (ADS)

Caracausi, Antonio; Martelli, Mauro; Nuccio, Mario; Paternoster, Michele; Stuart, Finlay

2013-04-01

We report the results of a geochemical study of gas emissions and spring waters collected along a NE-SW transect through the southern Apennines in order to quantify the contribution of mantle-derived helium in crustal fluids and consequently to evaluate the existence of a structural discontinuity (the "Vulture line"). This tectonic discontinuity is interpreted as N40°-50° trending deep fault, cutting the entire chain-foreland system in southern Apennines (Schiattarella et al., 2005). The lithospheric discontinuity was generated by variation in the velocity of subduction rollback along the length of the subducting plate and has generated a vertical slab window (i.e., Doglioni et al., 1994; D'Orazio et al., 2007), that is responsible for the origin of Mt. Vulture volcano. Mount Vulture is the eastern-most occurrence of the Quaternary Italian volcanism, and is the only volcano to the east of the Apennine mountain belt. Its volcanic activity started at 742±11 kyr and continued until 142±11 kyr, interrupted by several long inter-eruptive periods (Buettner et al., 2006, and references therein). The volcanism is strongly silica undersaturated, from alkaline potassic to ultrapotassic affinities. We investigated lavas from the Mt. Vulture displaying 3He/4He (up to ~6.0 Ra) and Sr isotopes that are consistent with an origin in mantle that has had minimal pollution from subducted Adriatic slab. This value is rather constant along the history of the volcano, and represent the highest helium isotope signature of the Italian peninsular magmatism even if it is slightly lower than that of the most uncontaminated Sicilian terms. Similar 3He/4He in fluids from around Mt. Vulture indicate that the deep volcanic system is still degassing. The 3He/4He of the investigated fluids along the NE-SW transect of the Vulture line highlights that degassing of mantle-derived helium occur from the Apulian foreland to the Tyrrhenian sea. The highest contribution of mantle-derived fluids is present at Mt. Vulture volcano and the surrounding area, while it decreases toward the Tyrrhenian sea. This may be due to different causes: a) volatiles degassing from near-surface melts beneath Mt. Vulture are quantitatively dominant with respect to crustal gases, in contrast to gas emissions located close to the peri-Thyrrenian area and/or b) the 3He/4He of the peri-Tyrrhenian magmas is expected to be lower than 6 Ra. Our data suggest the active role of Vulture line (lithospheric faults) to transfer towards the surface mantle-derived fluids from magmatic bodies or from asthenospheric upwelling of hot, possible molten material (Ökeler et al., 2009) accumulated to the base of the crust. Buettner, A., Principe, C., Villa, I.M., Bocchini, D., 2006. 39Ar-40Ar geochronology of Monte Vulture. In: Principe, C. (Ed.), La Geologia del Monte Vulture. Grafiche Finiguerra, Lavello, Italy, pp. 73-86. Doglioni, C., Mongelli, F., Pieri, P., 1994. The Puglia uplift (SE Italy): an anomaly in the foreland of the Apenninic subduction due to buckling of a thick continental lithosphere. Tectonics 13 (5), 1309-1321. D'Orazio, M., Innocenti, F., Tonarini, S., Doglioni, C., 2007. Carbonatites in a subduction system: the Pleistocene alvikites from Mt. Vulture (southern Italy). Lithos 98, 313-334. Ökeler, A., Gu, Y.J., Lerner-Lam, A., Steckler, M.S., 2009. Seismic structure of the southern Apennines as revealed by wave form modelling of regional surface waves. Geophysical Journal International 178, 1473-1492. Schiattarella, M., Beneduce, P., Giano, S.I., Giannandrea, P., Principe, C., 2005. Assetto strutturale ed evoluzione morfotettonica quaternaria del vulcano del Monte Vulture (Appennino Lucano). Bollettino della Societa Geologica Italiana 124, 543-562.

High-Precision Locations and the Stress Field from Instrumental Seismicity, Moment Tensors, and Short-Period Mechanisms through the Mina Deflection, Central Walker Lane

NASA Astrophysics Data System (ADS)

Ruhl, C. J.; Smith, K. D.

2012-12-01

The Mina Deflection (MD) region of the central Walker Lane of eastern California and western Nevada, is a complex zone of northeast-trending normal, and primarily left-lateral strike-slip to oblique-slip faulting that separates the Southern Walker Lane (SWL) from a series of east-tilted normal fault blocks in the Central Walker Lane (CWL) (Faulds and Henry, 2008; Surpless, 2008). The MD accommodates the transfer of right-lateral strike-slip motion from northwest-striking faults in the SWL to a series of left-stepping northwest-striking right-lateral strike-slip faults in the CWL, east of the Wassuk Range near Hawthorne, NV. The ~50 km wide ~80 km long right-step is a distinct transition in regional physiography that has been attributed to strain accommodation through pre-Cenozoic lithospheric structures. Several slip transfer mechanisms have been proposed within the MD, from clockwise rotation of high-angle fault blocks (Wesnousky, 2005), to low-angle displacement within the Silver Peak-Lone Mountain complex (Oldow et al., 2001), and curved fault arrays associated with localized basins and tectonic depressions (Ferranti et al., 2009). The region has been a regular source of M4+ events, the most recent being an extended sequence that included twenty-seven M 3.5+ earthquakes (largest event M 4.6) south of Hawthorne in 2011. These earthquakes (< 5 km depth) define shallow W-dipping (dip ~56°) and NW-dipping (dip ~70°) normal faulting constrained by moment tensor (MT) solutions and earthquake relocations. Temporary stations deployed in the source area provide good control. A distributed sequence in 2004, between Queen Valley and Mono Lake, primarily associated with the Huntoon Valley fault, included three M 5+ left-lateral strike-slip faulting events. A 1997 sequence in northern Fish Lake Valley (east of the White Mountains), with mainshock Mw 5.3 (Ichinose et al., 2003), also showed high-angle northeast-striking left-lateral strike-slip motion. Historical events include the 1934 M 6.5 Excelsior Mountains event south of Mina, NV, and the 1932 M 7.1 Cedar Mountains earthquake east of the Pilot Mountains. Another persistent feature in the seismicity is an ~40 km long arcuate distribution of activity extending from approximately Queen Valley, north of the White Mountains, to Mono Lake that appears to reflect a southwestern boundary to northeast-striking structures in the MD. Here we develop high-precision relocations of instrumental seismicity in the MD from 1984 through 2012, including relocations of the 2004 sequence, and account for the historical seismic record. MT solutions from published reports and computed from recent M 3.5+ earthquakes as well as available and developed short-period focal mechanisms are compiled to evaluate the stress field to assess mechanisms of slip accommodation. Based on the complex distribution of fault orientations, the stress field varies locally northward from the SWL throughout the MD; however, in many cases, fault plane alignments can be isolated from high-precision locations, providing better constraints on stress and slip orientations.

Gravitational slope-deformation of a resurgent caldera: New insights from the mechanical behaviour of Mt. Nuovo tuffs (Ischia Island, Italy)

NASA Astrophysics Data System (ADS)

Marmoni, G. M.; Martino, S.; Heap, M. J.; Reuschlé, T.

2017-10-01

Ischia Island (Italy) is an impressive example of the rare phenomenon of caldera resurgence. The emplacement and replenishment of magmas at shallow depth resulted in a vertical uplift of about 900 m, concentrated in the western portion of Mt. Epomeo (789 m a.s.l.). As a consequence of this uplift, the island has experienced several slope instabilities at different scales since the Holocene, from shallow mass movements to large rock and debris avalanches. These mass wasting events, which mobilised large volumes of greenish alkali-trachytic tuff (the Mt. Epomeo Green Tuff, MEGT), were strictly related to volcano-tectonic activity and the interaction between the volcanic slopes and the hydrothermal system beneath the island. Deep-Seated Gravitational Slope Deformation (DSGSD) at Mt. Nuovo, located adjacent to densely populated coastal villages, is an ongoing process that covers an area of 1.6 km2. The Mt. Nuovo DSGSD involves a rock mass volume of 190 Mm3 and is accommodated by a main shear zone and a series of sub-vertical fault zones associated with high-angle joint sets. To improve our understanding of this gravity-induced process, we performed a physical (porosity and permeability) and mechanical (uniaxial and triaxial deformation experiments) characterisation of two ignimbrite deposits - both from the MEGT - that form a significant component of the NW sector of Mt. Epomeo. The main conclusions drawn from our experiments are twofold. First, the presence of water dramatically reduces the strength of the tuffs, suggesting that the movement of fluids within the hydrothermal system could greatly impact slope stability. Second, the transition from brittle (dilatant) to ductile (compactant) behaviour in the tuffs of the MEGT occurs at a very low effective pressure, analogous to a depth of a couple of hundred metres, and that this transition is likely moved closer to the surface in the presence of water. We hypothesise that compactant (porosity decreasing) behaviour at the base of the layer could therefore facilitate slope instability. Although our results show that transient exposure to 300 °C does not influence the short-term strength of the tuff, we speculate that the high in-situ temperature could increase the efficiency of brittle and compactant creep and therefore increase the rate of slope deformation. Taken together, our experimental data highlight a potentially important role for the hydrothermal system (that reaches a minimum depth of 1 km) in dictating the DSGSD at Mt. Nuovo. An understanding of this deformation process is not only important for the proximal coastal villages, at risk of engulfment by a large debris avalanche, but also for the towns and cities along the coast of the Gulf of Naples that are at risk to a secondary consequence of such an avalanche - a tsunami wave.

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Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-23

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Gravity and Magnetotelluric Modeling of the Santo Domingo Basin, Northern New Mexico

NASA Astrophysics Data System (ADS)

Zamudio, K. D.; Keithline, N.; Blum, C.; Cunningham, E.; Fromont, A.; Jorgensen, M.; Lee, R.; McBride, K.; Saez Berrios, P.; Harper, C.; Pellerin, L.; McPhee, D.; Ferguson, J. F.

2015-12-01

The Santo Domingo Basin, one of a series of basins within the Rio Grande Rift, is located between Santa Fe and Albuquerque, NM, and has been the focus of research by the Summer of Geophysical Experience (SAGE) program since 2000. Gravity, magnetotelluric (MT), and seismic data have been collected throughout the region, although we are concentrating on gravity and MT data collected during SAGE 2014 and 2015. The study area is located in the center of the Santo Domingo basin, an extensional, Miocene age, rift basin, in an area that was minimally involved in the preceding local Laramide orogenic activity. Rift sediments (~3.5 km thick) are underlain by Eocene age sediments that were shed from adjacent uplifts. Up to 3 km of Mesozoic and Paleozoic sediments are preserved above the Precambrian basement. Geologic outcrop, borehole and seismic reflection data, and known density values were used in the construction of a ~100 km-long, generalized geologic cross section from which a gravity response was calculated. The modeled gravity response makes fairly definitive predictions about the geometry of the basin as well as the stratigraphy and faulting within and bounding the basin. MT data was collected at ten stations within the basin. The MT sounding curves exhibit one-dimensional behavior at short periods (<10 s), not surprisingly considering the relatively flat local structure in the area. Layered-earth MT models, without geologic constraints, show a conductive (<10 ohm-m) layer at ~1.5 km above a more resistive layer (>1000 ohm-m) at ~ 3.5-4 km. Conductivities of the major stratigraphic units have been determined from well logs and previous MT modeling. Forward and inverse MT models constrained by the gravity-modeled geologic cross section are used to develop a conductivity model consistent with the geology, and are a step towards a better unified treatment of MT, seismic and gravity data.

Edaphics, active tectonics and animal movements in the Kenyan Rift - implications for early human evolution and dispersal

NASA Astrophysics Data System (ADS)

Kübler, Simon; Owenga, Peter; Rucina, Stephen; King, Geoffrey C. P.

2014-05-01

The quality of soils (edaphics) and the associated vegetation strongly controls the health of grazing animals. Until now, this has hardly been appreciated by paleo-anthropologists who only take into account the availability of water and vegetation in landscape reconstruction attempts. A lack of understanding the importance of the edaphics of a region greatly limits interpretations of the relation between our ancestors and animals over the last few million years. If a region lacks vital trace elements then wild grazing and browsing animals will avoid it and go to considerable length and take major risks to seek out better pasture. As a consequence animals must move around the landscape at different times of the year. In complex landscapes, such as tectonically active rifts, hominins can use advanced group behaviour to gain strategic advantage for hunting. Our study in the southern Kenya rift in the Lake Magadi region shows that the edaphics and active rift structures play a key role in present day animal movements as well as the for the location of an early hominin site at Mt. Olorgesailie. We carried out field analysis based on studying the relationship between the geology and soil development as well as the tectonic geomorphology to identify 'good' and 'bad' regions both in terms of edaphics and accessibility for grazing animals. We further sampled different soils that developed on the volcanic bedrock and sediment sources of the region and interviewed the local Maasai shepherds to learn about present-day good and bad grazing sites. At the Olorgesailie site the rift valley floor is covered with flood trachytes; basalts only occur at Mt. Olorgesailie and farther east up the rift flank. The hominin site is located in lacustrine sediments at the southern edge of a playa that extends north and northwest of Mt. Olorgesailie. The lakebeds are now tilted and eroded by motion on two north-south striking faults. The lake was trapped by basalt flows from Mt. Olorgesailie and was released by the fault motion leading to deep river incision and exposure of the site. To the west and the north steep fault scarps bound the playa forming a natural barrier for animals. Field observations and information from local shepherds suggest that the trachytes at the valley floor produce rather poor soils whereas the soils developed on lacustrine and alluvial sediments close to the hominin site are much more attractive grazing sites for present-day animals. This is supported by first results from soil analysis. With a lake in the past the Olorgesailie site represents an key example of how early hominins may have used strategic advance of the landscape. While steep fault scarps blocked the northern pathway, the southern lakeshore represented one of the few accessible places for animals to be suffiently provided with nutrients and thus, was an excellent location for hominins to stalemate and hunt down prey. Future studies will include additional sites in the central and northern Kenya rift.

Interior Western U. S. Deformation Coming into Focus with Maturing Survey and Continuous GPS Networks

NASA Astrophysics Data System (ADS)

Thatcher, W. R.; Svarc, J. L.

2010-12-01

Active Basin and Range (BR) extension produces spectacular fault-generated topography spread over ~800 km in the interior western US. However, present-day deformation rates are relatively low east of the San Andreas fault system and Cascadia subduction zone and ± 1 mm/yr precision in GPS velocity is needed to pinpoint the major faults that accommodate extension. Typically, 3 years of continuous (CGPS) operation and 8 years of sparsely repeated survey (SGPS) network occupations are required to attain this precision. U. S. Geological Survey (USGS) survey networks and Plate Boundary Observatory (PBO) continuous station records are now long enough to meet these requirements. USGS and PBO station coverage is generally complementary. PBO coverage established since 2005 within the ~1000 km x 1500 km deforming zone is relatively complete at ~100 km station spacing; USGS survey-mode profiles established during 1999-2003 are dense; typical station spacing is ~25 km and results are sufficiently precise to determine localized velocity gradients of 1 mm/yr or greater (over ~25-50 km distances) across mapped active strike-slip and normal faults traversed by the SGPS profiles. The great majority of geologically young faults appear to slip at rates less than 1 mm/yr but rates are measurably higher near the western and eastern edges of the BR. There is a marked transition in NE California from strike-slip faulting at rates of ~ 4 mm/yr across the northern Walker Lane zone to pure extension north of about Mt. Lassen. This distinct boundary is apparently related to the prevalence of strike-slip tractions on the San Andreas plate boundary south of the Mendocino triple junction (MTJ) to tensile stresses caused by Cascadia slab retreat north of the MTJ. A horizontal extension rate of 3 mm/yr is observed across the north-striking Hat Creek and related normal faults immediately north of Lassen, but this extension decreases to no more than 1 mm/yr in the Klamath Basin, about 150 km to the north. Extension rates could be as high as ~1 mm/yr across the Surprise Valley fault (near the California-Nevada border) and the Steens Mountain-Pueblo Mountains fault (SE Oregon). But elsewhere in Oregon, Idaho and Montana, extension rates are < 1 mm/yr and only on the eastern edge of the BR, across the Wasatch and related faults in central Utah, do rates reach 3 mm/yr.

Sedimentary control of volcanic debris-avalanche structures and transformation into lahars

NASA Astrophysics Data System (ADS)

Bernard, Karine; van Wyk de Vries, Benjamin; Thouret, Jean-Claude; Roche, Olivier; Samaniego Eguiguren, Pablo

2017-04-01

Volcanic debris avalanche structures and related transformations into lahars have been extensively analysed in order to establish a sedimentary classification of the deposits. Textural and structural variations of eight debris-avalanche deposits (DADs) have been correlated with Shape Preferred Orientation of 30,000 clasts together with grain-size distributions and statistical parameters from 156 sieved matrix samples. Granular segregation patterns have been observed with structural fault controls: proximal granular-segregation structures of the Tutupaca DAD ridges in Peru, basal sheared bands along overthrust lateral levee (Mt. Dore, France), mixing and cataclasis of fault-controlled deposits in half-graben during lateral spreading of distal thrust lobe (Pichu-Pichu, Peru), neo-cataclasis at the frontal thrust lobe (Meager, Canada and Mt. Dore, France). A logarithmic regression characterises the % matrix vs. matrix/gravels showing proximal and primary cataclasis, hybrid DADs with polymodal matrix and mixed facies up to transformations into lahar (Misti, Mt Dore). The sequential fragmentation helps to distinguish DAD that belong to Andean and Cascade Volcanic arcs (Tutupaca and Misti, Peru; Meager, Canada) to the hybrid DADs, before distal transformation into lahars (Pichu-Pichu); and hydrovolcanic fragmentation characterises the transformed lahar deposits (Misti). The fractal values of 150 sieved samples range between 2.3 and 2.7, implying extensional fractures with granular disaggregation. Skewness vs. kurtosis values help to distinguish the proximal mass wasting deposits and the transformed deposits by dilution. The sorting vs. median values enable us to differentiate the hybrid DADs with the transformed deposits by dilution. The sedimentological statistical parameters with Shape Preferred Orientation analysis that have been correlated with textural and structural observations show textural fabrics resulting from kinematic processes: cataclasis, hybrid matrix facies and transformations. Inherited fractures from tectono-volcanic structures contribute to the particle size distributions of DAD and associated deposits such as pyroclastic and lahar deposits (Misti, Mt Dore, Tutupaca). The statistical results highlight granular structure and kinematic process of DAD transformations into lahars and associated deposits, which would contribute to understand the rheological process behind the excess DAD run-out and to test granular models for DAD transformations. Key words: volcanic debris-avalanche deposits, lahar transformation, structure, sedimentology, hazard

A new tectonic model for southern Alaska

NASA Astrophysics Data System (ADS)

Reeder, J. W.

2013-12-01

S Alaska consists of a complex tectonic boundary that is gradational from subduction of Pacific Plate (PAC) beneath N American Plate (NA) in the W to a transform fault between these two plates in the SE. Adding complexity, the Yakutat Plate (YAK) is in between. The YAK is exposed in NE Gulf of Alaska and has been well mapped (Plafker, 1987). It is bound by the NA to the E at the Fairweather fault and by the PAC to the S. Relative to NA, YAK is moving 47 mm/yr N30°W and PAC is moving 51 mm/yr N20°W (Fletcher & Freymueller, 2003). The YAK and deeper PAC extend NW beneath the NA as flat slabs (Brocher et al., 1994). They subduct to the W and NW in Cook Inlet region (Ratchkovsky et al., 1997), resulting in the Cook Inlet volcanic arc. They also subduct farther NNW toward the Denali volcanic gap and fault. The subducted part of the YAK is split by a transform fault exposed at Montana Creek (MC) at 62°06'N to 62°10'N at 150°W. It extends S60°W toward the most N Cook Inlet volcano, Hayes, and extends N60°E beyond Talkeetna Mts. Right-lateral WSW motion and thick fault gauge have been documented by McGee (1978) on MC and a S60°W fault scarp cutting Quaternary deposits has been mapped (Reed & Nelson, 1980). Fuis et al. (2008) seismically recognized 110 km of missing YAP NW of Talkeetna Mts, which he thought was due to a 'tear' in the YAK to the far S. Nikoli Greenstone has been found in the Talkeetna Mts just S of this transform (Schmidt, 2003) that is 70 km SW of any other mapped Nikoli. This fault offset is also shown by 7.8 km/sec Vp depth contours, which represent the YAK (Eberhart-Phillips et al., 2006), as 110 km at N60°W. Based on magnetic data (Csejtey & Griscom, 1978; Saltus et al., 2007), the fault is regionally recognized as a 10× km zone on the WSW margin of the large S Alaska magnetic high. The fault zone has narrow WSW magnetic highs and depressions. This fault is also recognized on digital relief (Riehle et al., 1996); but, another pronounced N60°E linear feature also exists 20× km S, which trends into Mt. Spurr volcano. It could be another transform. If the MC transform is taking all the discrepancy between PAC and YAK, the S part of the fault would be moving relatively 9 mm/yr to S60°W. This transform has possibly been active for 12 million years. The Wrangell volcanoes with respect to YAK are associated with a spreading ridge. Yet, with respect to PAC, they are associated with a subduction zone (Stevens et al., 1984). The Totschunda and Fairweather faults are the new westward developing Denali transform. The Castle Mountain fault, located about 65 km to the SE of the MC transform, is oriented N65°E. It has had significant right-lateral offset of at least 30 km based on 7.8 km/sec Vp depth contours and of 26 km by magnetic offsets (Haeussler & Saltus, 2004). This older transform probably corresponds to Tertiary volcanics SW of the Mt Spurr/Hayes volcanic complex. Two active megathrust faults exist in south central Alaska; a 1964 type megathrust between PAC and YAK (Plafker, 1969), and a more continental megathrust between YAK and NA (Reeder, 2012). Based on Knik Arm subsidence events, these two types alternate and the next megathrust should occur in 350× years. This more continental megathrust would result in uplift of the N side of the Castle Mountain fault. It might even correspond to significant right-lateral movement on the seismically quiet MC transform.

Geometries of geoelectrical structures in central Tibetan Plateau from INDEPTH magnetotelluric data

NASA Astrophysics Data System (ADS)

Vozar, Jan; Jones, Alan G.; Le Pape, Florian

2013-04-01

Magnetotelluric (MT) data collected on N-S profiles crossing the Banggong-Nujiang Suture, which separates the Qiangtang and Lhasa Terranes in central Tibet, as a part of InterNational DEep Profiling of Tibet and the Himalaya project (INDEPTH) are modeled by 2D and 3D inversion codes. The 2D deep MT model of line 500 confirms previous observations concluding that the region is characterized to first-order by a resistive upper crust and a conductive, partially melted, middle to lower crust that extends from the Lhasa Terrane to the Qiangtang Terrane with varying depth. The same conductive structure setting, but in shallower depths is also present on the eastern 400 line. From deep electromagnetic sounding, supported by independent 1D integrated petro-physical investigation, we can estimate the next upper-mantle conductive layer at depths from 200 km to 250 km below the Lhasa Terrane and less resistive Tibetan lithosphere below the Qiangtang Terrane with conductive upper-mantle in depths about 120 km. The anisotropic 2D modeling reveals lower crustal anisotropy in Lhasa Terrane, which can interpreted as crustal channel flow. The 3D inversion models of all MT data from central Tibet show dominant 2D regional strike of mid and lower crustal structures equal N110E. This orientation is parallel to Shuanghu suture, BengCo Jiali strike-slip fault system and perpendicular to convergence direction. The lower crust conductor in central Lhasa Terrane can be interpreted more likely as 3D lower Indian crust structure, located to the east from line 500, than geoelectrical anisotropic crustal flow.

Electrical resistivity structure beneath the Hangai Dome, Mongolia: intraplate volcanism and deformation imaged with magnetotelluric data

NASA Astrophysics Data System (ADS)

Comeau, M. J.; Becken, M.; Kaeufl, J.; Kuvshinov, A. V.; Kamm, J.; Grayver, A.; Demberel, S.; Usnikh, S. U.; Batmagnai, E.; Tserendug, S.

2017-12-01

The Hangai Dome in central Mongolia is characterized by intraplate volcanism on a high-elevation intra-continental plateau. Volcanism dates from the Oligocene to the Holocene and is thought to be coincident with the onset of the uplift of the Hangai Dome, indicating that the processes may be linked. However, the processes and driving mechanisms responsible for creating this region remain largely unexplained, due in part to a lack of high-resolution geophysical data over the area. An extensive magnetotelluric (MT) data set was collected over the Hangai Dome in 2016 and 2017, with broadband data (0.002 - 5,000 s) collected at a total of 294 sites. This data set consists of a large array ( 50 km site spacing) and several long ( 600 km) and dense ( 5 km site spacing) profiles that cross the uplifted Hangai Dome. Additionally, they cross the bounding faults of the Hangai block, the Bulnay fault in the north and the Bogd fault of the Gobi-Altai in the south, which have had several M>8 earthquakes in the past century. These MT data have been used to generate electrical resistivity models of the crust and upper mantle in this region. Anomalous, low resistivity ( 30 ohm-m) zones in the lower crust ( 25 - 50 km depth) are spatially associated with the surface expressions of volcanism and modern-day hydrothermal activity. These zones indicate the presence of local accumulations of fluids below the brittle-ductile transition zone. Interestingly, this feature terminates sharply at the South Hangai Fault Zone. Furthermore, lower resistivity pathways in the upper crust (0 - 25 km depth) connect the deeper features to the surface. This is prominently observed below the Hangai's youngest volcanic zones of Tariat/Khorgo and Chuluut, as well as the hot spring area of Tsenkher, near Tsetserleg. Additionally, an electrical signature can be associated with known fault zones and mineralized zones (such as the Bayankhongor mineral belt). An anomalous low-resistivity zone in the upper mantle ( 70 - 100 km) directly below the Hangai Dome can be explained by the presence of a small amount of partial melt. This zone likely represents the region of melt generation for intraplate volcanism and gives evidence for a small-scale (<100 km) asthenospheric upwelling, which contributes to intraplate deformation.

Three-dimensional P-wave velocity structure of Mt. Etna, Italy

USGS Publications Warehouse

Villasenor, A.; Benz, H.M.; Filippi, L.; De Luca, G.; Scarpa, R.; Patane, G.; Vinciguerra, S.

1998-01-01

The three-dimensional P-wave velocity structure of Mt. Etna is determined to depths of 15 km by tomographic inversion of first arrival times from local earthquakes recorded by a network of 29 permanent and temporary seismographs. Results show a near-vertical low-velocity zone that extends from beneath the central craters to a depth of 10 km. This low-velocity region is coincident with a band of steeply-dipping seismicity, suggesting a magmatic conduit that feeds the summit eruptions. The most prominent structure is an approximately 8-km-diameter high-velocity body located between 2 and 12 km depth below the southeast flank of the volcano. This high-velocity body is interpreted as a remnant mafic intrusion that is an important structural feature influencing both volcanism and east flank slope stability and faulting.

A basic tool for post-seismic rebuilding: the new 1:5.000 scale geological map of Amatrice town

NASA Astrophysics Data System (ADS)

Mancini, Marco; Vignaroli, Gianluca; Ardizzone, Francesca; Bucci, Francesco; Cardinali, Mauro; Cavinato, Gian Paolo; Cosentino, Giuseppe; Di Salvo, Cristina; Fiorucci, Federica; Gaudiosi, Iolanda; Giallini, Silvia; Peronace, Edoardo; Polpetta, Federica; Putignano, Maria Luisa; Reichenbach, Paola; Santangelo, Michele; Scionti, Veronica; Simionato, Maurizio; Sirianni, Pietro; Stigliano, Francesco

2017-04-01

A geological survey has been carried out in the area of Amatrice, the most damaged town after the 24 August 2016 event, to provide a basic reference for geophysical and geotechnical data useful for seismic response analyses and microzonation studies. The morphologies and the stratigraphic-structural setting of the investigated area are detailed on a 1:5000 scale geological map and cross sections, which derive from the integration of field-based observations and photo-geological interpretation. The Amatrice basin is filled by the one km-thick Laga Formation, composed of Messinian syn-orogenic marine sandstones and siltstones (Marini et al., 2015) and covered with disconformity by Quaternary conglomerates and sands, referred to alluvial fans, fluvial terraces and landslides. Presently, the Amatrice basin is a structurally-controlled depression bounded eastward by the Gorzano Mt ridge, and westward by the Sibillini Mts thrust front (Koopman, 1983). Our observations focus on (i) relationships between geometry and extent of cover deposits, (ii) bedding of the substratum, and (iii) areal arrangement and distribution of the main fault systems. Amatrice is located on a N-S trending mesa bounded by steep escarpments. The siliciclastic substratum was folded by syn-orogenic movements, broadly forming a NW-SE-trending synform, and is dissected by two main fault systems of the Plio-Quaternary post-orogenic tectonics. The first system consists of N-S striking high angle normal fault segments, each one having continuous length of up to 2 km; the second consists of E-W-striking normal-to-strike slip fault systems dissecting the first one. N-S-striking faults are morphologically expressed by fault plane scarps and triangular facets, and control the areal distribution of the Quaternary fluvial deposits. These are up to 50 m thick below Amatrice and thin to few metres along the north west direction. East of Amatrice, the stratigraphic setting is dominated by SW-prograding alluvial fans, downlapping the substratum, while on the West the stratigraphic setting is strongly complicated by large scale deformations (folding and tectonic repetitions) produced by shortening mechanisms. The recognized morphological irregularities, stratigraphic heterogeneities, and structural alignments are considered critical elements to define, at local scale, subsoil models useful for evaluating seismic amplification effects. References Koopman, A., (1983) Detachment tectonics in the central Apennines, Italy. Geol. Ultraiectina, 30, 1-155. Marini M., Milli S., Ravnås R., Moscatelli M. (2015) A comparative study of confined vs. semi-confined turbidite lobes from the Lower Messinian Laga Basin (Central Apennines, Italy): Implications for assessment of reservoir architecture. Mar. and Petrol. Geol., 63, 142-165.

Controls on hydrothermal fluid flow within the Rotokawa geothermal field, New Zealand: insights from 3D geological models

NASA Astrophysics Data System (ADS)

Bardsley, C.; Sewell, S.; Cumming, W. B.; Minnick, M.; Rowland, J. V.; O'Brien, J.; Price, L.

2012-12-01

Identifying permeable zones is essential for economically viable exploration and development of conventional geothermal reservoirs with naturally high permeability. Except very close to boreholes, the resolution of geological and geophysical tools is at a much larger scale than the centimetre aperture of most geothermal fluid pathways important to production. A case study from the >250°C Rotokawa Geothermal Field, currently producing 175 MWe within the Taupo Volcanic Zone in New Zealand, illustrates how a 3D visualization of a subset of available data that are conceptually relevant at the scales of interest has enhanced the understanding of fluid flow within this system. Geoscience data sets including subsurface formation geometry and permeable zones in wells; the natural state temperature pattern deduced from wells and MT resistivity; microearthquakes (MEQ) induced by injection, and surface geology have been integrated with engineering data including production pressure responses and injection rates to constrain the location and general hydraulic properties of one of the most influential faults in the field. Stratigraphic offsets of >500 m, recorded in core and cuttings from wells drilled on either side of the field, confirm the presence of this fault, initially suspected based on a surface lineation of eight young (<22 ka) hydrothermal eruption craters. The 3D visualization of the MEQ occurrence pattern in space and time helps constrain the mechanism of the MEQs themselves and, importantly, the confinement of most of the MEQs to the eastern side of the fault closest to the injection wells. Hosted within the Mesozoic meta-sedimentary basement formation, this has provided an important conceptual constraint that explains the lack of injection fluid on the western side of this fault. Further to this, if this fault is acting as a barrier at the Mesozoic meta-sedimentary level today, this could imply a switch in the behaviour of this structure as it is inferred, based on the alignment of the hydrothermal eruption vents, that these vents were triggered by a rupture along this fault, implying it was once a conduit to fluid flow.

Collisional Tectonics in the St. Elias Orogen, Alaska Observed by GPS

NASA Astrophysics Data System (ADS)

Elliott, J.; Freymueller, J. T.; Larsen, C. F.

2008-12-01

The rugged topography of the St. Elias orogen of southern Alaska and the adjacent region of Canada is the result of the on-going collision of the Yakutat block with southern Alaska. Nearly 45 mm/yr of NW-SE directed convergence from the collision is currently accommodated within the St. Elias orogen. A key to understanding this complex collisional boundary is knowing the locations of the structures taking up the convergence. GPS provides a snapshot of the present-day strain field and helps to delineate active structures. As part of the St. Elias Erosion/Tectonics Project (STEEP), we re-surveyed 70 campaign GPS sites across the St. Elias orogen during the summer of 2008. Strain rates derived from our GPS data highlight several areas within the St. Elias orogen. The highest strain rates occur across Icy Bay and the western edge of the Malaspina Glacier. Rates there approach -1 microstrain/yr, a value higher than that observed in the Himalaya. Lower, but still significant, strain rates of about -0.2 microstrain/yr extend north from Icy Bay to the region surrounding Mt. St. Elias. The second major focus of compressive strain in the orogen is centered over the Yakataga fold-and-thrust belt. Strain rates there are in the range of -0.40 to -0.50 microstrain/yr. Little significant strain is seen across the Bagley icefield or to the north of that feature. These results suggest that most of the convergence across the St. Elias orogen is currently accommodated on structures located south of the Bagely icefield, specifically in the Icy Bay, upper Malaspina/Mt. St. Elias, and Yakataga fold-and-thrust belt regions. We use block modeling techniques to describe the tectonic elements of the St. Elias orogen and connect them with the tectonic regime in southeast Alaska. Our preliminary results indicate that a single thrust fault through Icy Bay cannot explain the data there; multiple NW and N directed thrust faults through Icy Bay, along the western edge of the Malaspina Glacier, and between Icy Bay and Mt. St. Elias are required. Over half of the relative convergence between the Yakutat block and southern Alaska may be accommodated by elastic strain accumulation on these faults.

The fault pattern in the northern Negev and southern Coastal Plain of Israel and its hydrogeological implications for groundwater flow in the Judea Group aquifer

NASA Astrophysics Data System (ADS)

Weinberger, G.; Rosenthal, E.

1994-03-01

On the basis of a broadly expanding data base, the hydrogeological properties of the Judea Group sequence in the northern Negev and southern Coastal Plain of Israel have been reassessed. The updated subsurface model is based on data derived from water- and oil-wells and on recent large-scale geophysical investigations. A new regional pattern of the reassessed geological through the subsurface of the study area has been revealed. In view of the reassessed geological and hydrological subsurface setting, it appears that the Judea Group aquifer should not be regarded as one continuous and undisturbed hydrological unit; owing to the occurrence of regional faults, its subaquifers are locally interconnected. These subaquifers, which contain mainly high-quality water, are juxtaposed, as a result of faulting, against Kurnub Group sandstones containing brackish paleowater. The latter Group is faulted against late Jurassic formations containing highly saline groundwater. In the Beer Sheva area, the Judea Group aquifer is vertically displaced against the Senonian and Eocene Mt. Scopus and Avdat Groups, which also contain brackish and saline water. In the southern Coastal Plain, major faults locally dissect also the Pleistocene Kurkar Group, facilitating inflow of Mg-rich groundwater deriving from Judea Group dolomites. The new geological evidence and its hydrogeological implications provide new solutions for previously unexplained salinization phenomena.

Petrology and tectonic history of the Green Bay Schist, Portmore, St. Catherine Parish, Jamaica

USGS Publications Warehouse

Abbott, Richard N.; West, David P.; Bandy, Betsy R.; McAleer, Ryan J.

2016-01-01

There are three occurrences of medium- to high-grade metamorphic rocks in Jamaica: amphibolite facies Westphalia Schist, blueschist/greenschist facies Mt. Hibernia Schist, and the hitherto poorly characterized amphibolite facies Green Bay Schist. New trace element data and thermodynamic calculations show that Green Bay Schist is closely related to Westphalia Schist. The protoliths for both are very similiar (basalt-andesitic basalt, C-MORB), consistent with a subducted ocean-ridge tectonic environment, hence arc-related. The protolith for Mt. Hibernia Schist is quite different (basalt, P-MORB), related to the Caribbean Large Igneous Province. Whereas the P-T-t paths for Green Bay Schist and Westphalia Schist prior to the middle Campanian (>78 Ma) are inferred to be similar, the late Campanian, Maastrichtian and Cenozoic P-T-t paths are very different. New 40Ar/39Ar age determinations show the following: (1) While the difference in the late Campanian and Maastrichtian remains problematic, (2) the difference in the Cenozoic clearly reflects the location relative to the NW-trending, NE-dipping Wagwater Fault: Westphalia Schist to the NE (hanging wall); Green Bay Schist to the SW (foot wall). The Cenozoic P-T-t paths are complementary, and consistent with the behavior of the Wagwater Fault: 65-50 Ma, normal motion (transtension); 50-10 Ma, inactive (quiescent); 10 Ma-present, reverse motion (transpression).

Geological and edaphic constraints on early hominin landscape exploitation in the Kenya Rift

NASA Astrophysics Data System (ADS)

Kuebler, S.; King, G. C. P.; Rucina, S.

2017-12-01

Our study in the Kenya Rift shows that soil edaphics and active rift structures play a key role in present day animal movements as well as the for the location of early hominin sites. Based on studying the relationship between the geology, tectonics and soil development we identified 'good' and 'bad' regions both in terms of edaphics and accessibility for grazing animals. We created palaeoenvironmental reconstructions for interpreting human land use and exploitation of large mammals in the Kenya Rift for the relevant time frame of 1 Ma BP. At Olorgesailie the hominin site is located in lacustrine sediments at the southern edge of a playa that extends north and northwest of Mt. Olorgesailie. Lakebeds are now tilted and eroded by motion on two north-south striking faults. The lake was trapped by volcanic flows and alluvial fans from Mt. Olorgesailie and was released by fault motion leading to deep river incision and exposure of the site. To the west and the north steep fault scarps bound the playa forming a natural barrier for animals. Field observations and information from local shepherds suggest that the abundant trachytes at the valley floor produce poor soils whereas the soils developed on lacustrine and alluvial sediments close to the hominin site provide much more attractive grazing sites for present-day animals. This is supported by our soil analysis. With a lake in the past the Olorgesailie site represents an key example of how early hominins may have used the landscape for their strategic advantage. At Kariandusi site we investigated the tectonic and volcanic history of the region, and the system of lakes that have undergone periodic expansion and contraction during the Pleistocene in response to climatic and tectonic controls. We used this information to reconstruct topographic features as they would have existed at different periods of the past and their likely influence on patterns of large-mammal movements, and linked this with information from soil analysis. Our results show that Kariandusi occupied a unique window of opportunity in place and time for trapping mammals constrained to move through a narrowly defined topographic bottleneck between edaphically-rich areas during the lake highstand 1 Ma BP. Results of our study suggests that both Olorgesailie and Kariandusi sites were used for a simple form of ambush hunting.

In-soil radon anomalies as precursors of earthquakes: a case study in the SE slope of Mt. Etna in a period of quite stable weather conditions.

PubMed

Vizzini, Fabio; Brai, Maria

2012-11-01

In-soil radon concentrations as well as climatic parameters (temperature, atmospheric pressure and relative humidity) were collected in St. Venerina (Eastern Sicily - Italy) from March 19th to May 22nd 2009, close to an active fault system called Timpe Fault System (TFS), which is strictly linked to the geodynamics of Mt. Etna. During the monitoring period no drastic climatic variations were observed and, on the other hand, important seismic events were recorded close to the monitoring site. A seismic swarm composed of 5 earthquakes was observed in the Milo area on March 25th (M(max) = 2.7) at just 5.1 km from the site, and on May 13th an earthquake of 3.6 magnitude was recorded in the territory of St. Venerina, at just 3.2 km from the site; the earthquake was felt by the population and reported by all local and regional media. The in-soil radon concentrations have shown anomalous increases possibly linked to the earthquakes recorded, but certainly not attributable to local meteorology. To verify this assumption the average radon concentration and the standard deviation (σ) have been calculated and the regions of ±1.5σ and ±2σ deviation from the average concentration have been investigated. Moreover, to further minimise the contribution of the meteorological parameters on the in-soil radon fluctuations, a multiple regressions method has been used. To distinguish those earthquakes which could generate in-soil radon anomalies as precursors, the Dobrovolsky radius has been applied. The results obtained suggests that a clear correlation between earthquakes and in-soil radon increases exist, and that the detection of the in-soil radon anomalies becomes surely simpler in particular favourable conditions: weather stability, earthquakes within the Dobrovolsky radius and close to the monitoring area. Moreover, the absence of large variations of the climatic parameters, which could generate incoherent noise components to the radon signal, has made the radon fluctuations more evident and so more legible. Copyright © 2012 Elsevier Ltd. All rights reserved.

Electromagnetic imaging the of the Pacific-North American plate boundary in central California, USA

NASA Astrophysics Data System (ADS)

Wheelock, B. D.; Constable, S.; Key, K. W.

2010-12-01

The continental margin of central California lies adjacent to a segment of the San Andreas fault (SAF) that exhibits a transition between locked behavior south of the town of Cholame, and freely slipping (creeping) behavior north of the town of Parkfield. Recent reports of non-volcanic tremor (NVT) near the town of Cholame represent the first observation of NVT in a strike-slip environment. Dense clusters of tremor episodes located at the northern limit of the locked section of the SAF were found to originate within the ductile lower crust at depths between 15 and 30~km, and have been interpreted as evidence of high pore fluid pressure. An excess of fluids in this region is likely given its history of subduction, which transports large quantities of water into the forearc crust and mantle. We present a study that uses deep electromagnetic imaging methods to estimate the abundance and distribution of pore fluids at depths associated with non-volcanic tremor. This study extends a previously collected terrestrial profile of magnetotelluric (MT) data (Becken et al. 2008, Geophysical Journal International) into the offshore environment. We deployed 21 seafloor instruments that collected controlled-source electromagnetic (CSEM) and MT data in a line extending from the coast near Morro Bay, across the continental shelf, and out onto the Pacific plate. The marine MT data results in apparent resistivity and phase estimates at periods between 1~s and 20,000~s, sufficient for probing the upper 100~km of regional conductivity. A significant coast effect, marked by asymptotic behavior in the TE mode of the MT responses, is observed at the deep water sites. This necessitates accurate bathymetry modeling when inverting. The CSEM transmitter was towed by all receivers broadcasting a compact broadband binary waveform with a 0.25~Hz fundamental frequency. The controlled-source signal is observed above the noisefloor at source-receiver offsets up to 6~km, which provides constraints on the conductivity structure of the upper 3~km of the crust. By extending the preceding line of terrestrial MT measurements to the west, we are able to constrain any differences in crust and mantle conductivity associated with the transition across the continental boundary. Furthermore, we address whether the deeply-sourced fluids migrating into the root of the SAF identified in Becken et al. (2008) are related to the fossil subduction zone. Inversion of this combined data set aims to detect the source region of these deep fluids, put constraints on their abundance, and further reveal any pathways by which they may reach the San Andreas fault.

Co-seismic Static Stress Drops for Earthquake Ruptures Nucleated on Faults After Progressive Strain Localization

NASA Astrophysics Data System (ADS)

Griffith, W. A.; Nielsen, S.; di Toro, G.; Pollard, D. D.; Pennacchioni, G.

2007-12-01

We estimate the coseismic static stress drop on small exhumed strike-slip faults in the Mt. Abbot quadrangle of the central Sierra Nevada (California). The sub-vertical strike-slip faults cut ~85 Ma granodiorite, were exhumed from 7-10 km depth, and were chosen because they are exposed along their entire lengths, ranging from 8 to 13 m. Net slip is estimated using offset aplite dikes and shallowly plunging slickenlines on the fault surfaces. The faults show a record of progressive strain localization: slip initially nucleated on joints and accumulated from ductile shearing (quartz-bearing mylonites) to brittle slipping (epidote-bearing cataclasites). Thin (< 1 mm) pseudotachylytes associated with the cataclasites have been identified along some faults, suggesting that brittle slip may have been seismic. The brittle contribution to slip may be distinguished from the ductile shearing because epidote-filled, rhombohedral dilational jogs opened at bends and step-overs during brittle slip, are distributed periodically along the length of the faults. We argue that brittle slip occurred along the measured fault lengths in single slip events based on several pieces of evidence. 1) Epidote crystals are randomly oriented and undeformed within dilational jogs, indicating they did not grow during aseismic slip and were not broken after initial opening and precipitation. 2) Opening-mode splay cracks are concentrated near fault tips rather than the fault center, suggesting that the reactivated faults ruptured all at once rather than in smaller slip patches. 3) The fact that the opening lengths of the dilational jogs vary systematically along the fault traces suggests that brittle reactivation occurred in a single slip event along the entire fault rather than in multiple slip events. This unique combination of factors distinguishes this study from previous attempts to estimate stress drop from exhumed faults because we can constrain the coseismic rupture length and slip. The static stress drop is calculated for a circular fault using the length of the mapped faults and their slip distributions as well as the shear modulus of the host granodiorite measured in the laboratory. Calculations yield stress drops on the order of 100-200 MPa, one to two orders of magnitude larger than typical seismological estimates. The studied seismic ruptures occurred along small, deep-seated faults (10 km depth), and, given the fault mineral filling (quartz-bearing mylonites) these were "strong" faults. Our estimates are consistent with static stress drops estimated by Nadeau and Johnson (1998) for small repeated earthquakes.

Structure of the Hat Creek graben region: Implications for the structure of the Hat Creek graben and transfer of right-lateral shear from the Walker Lane north of Lassen Peak, northern California, from gravity and magnetic anomalies

USGS Publications Warehouse

Langenheim, Victoria; Jachens, Robert C.; Clynne, Michael A.; Muffler, L. J. Patrick

2016-01-01

Interpretation of magnetic and new gravity data provides constraints on the geometry of the Hat Creek Fault, the amount of right-lateral offset in the area between Mt. Shasta and Lassen Peak, and confirmation of the influence of pre-existing structure on Quaternary faulting. Neogene volcanic rocks coincide with short-wavelength magnetic anomalies of both normal and reversed polarity, whereas a markedly smoother magnetic field occurs over the Klamath Mountains and its Paleogene cover. Although the magnetic field over the Neogene volcanic rocks is complex, the Hat Creek Fault, which is one of the most prominent normal faults in the region and forms the eastern margin of the Hat Creek Valley, is marked by the eastern edge of a north-trending magnetic and gravity high 20-30 km long. Modeling of these anomalies indicates that the fault is a steeply dipping (~75-85°) structure. The spatial relationship of the fault as modeled by the potential-field data, the youngest strand of the fault, and relocated seismicity suggests that deformation continues to step westward across the valley, consistent with a component of right-lateral slip in an extensional environment. Filtered aeromagnetic data highlight a concealed magnetic body of Mesozoic or older age north of Hat Creek Valley. The body’s northwest margin strikes northeast and is linear over a distance of ~40 km. Within the resolution of the aeromagnetic data (1-2 km), we discern no right-lateral offset of this body. Furthermore, Quaternary faults change strike or appear to end, as if to avoid this concealed magnetic body and to pass along its southeast edge, suggesting that pre-existing crustal structure influenced younger faulting, as previously proposed based on gravity data.

Plio-Pleistocene synsedimentary fault compartments, foundation for the eastern Olduvai Basin paleoenvironmental mosaic, Tanzania.

PubMed

Stollhofen, Harald; Stanistreet, Ian G

2012-08-01

Normal faults displacing Upper Bed I and Lower Bed II strata of the Plio-Pleistocene Lake Olduvai were studied on the basis of facies and thickness changes as well as diversion of transport directions across them in order to establish criteria for their synsedimentary activity. Decompacted differential thicknesses across faults were then used to calculate average fault slip rates of 0.05-0.47 mm/yr for the Tuff IE/IF interval (Upper Bed I) and 0.01-0.13 mm/yr for the Tuff IF/IIA section (Lower Bed II). Considering fault recurrence intervals of ~1000 years, fault scarp heights potentially achieved average values of 0.05-0.47 m and a maximum value of 5.4 m during Upper Bed I, which dropped to average values of 0.01-0.13 m and a localized maximum of 0.72 m during Lower Bed II deposition. Synsedimentary faults were of importance to the form and paleoecology of landscapes utilized by early hominins, most traceably and provably Homo habilis as illustrated by the recurrent density and compositional pattern of Oldowan stone artifact assemblage variation across them. Two potential relationship factors are: (1) fault scarp topographies controlled sediment distribution, surface, and subsurface hydrology, and thus vegetation, so that a resulting mosaic of microenvironments and paleoecologies provided a variety of opportunities for omnivorous hominins; and (2) they ensured that the most voluminous and violent pyroclastic flows from the Mt. Olmoti volcano were dammed and conduited away from the Olduvai Basin depocenter, when otherwise a single or set of ignimbrite flows might have filled and devastated the topography that contained the central lake body. In addition, hydraulically active faults may have conduited groundwater, supporting freshwater springs and wetlands and favoring growth of trees. Copyright © 2011 Elsevier Ltd. All rights reserved.

Monitoring eruption activity using temporal stress changes at Mount Ontake volcano.

PubMed

Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

2016-02-19

Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards.

Monitoring eruption activity using temporal stress changes at Mount Ontake volcano

PubMed Central

Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

2016-01-01

Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards. PMID:26892716

The use of LANDSAT imagery in relation to air survey imagery for terrain analysis in northwest Queensland, Australia, volume 1

NASA Technical Reports Server (NTRS)

Cole, M. M.; Owen-Jones, E. S. (Principal Investigator)

1977-01-01

The author has identified the following significant results. Distinctive spectral signatures discriminated areas underlain by distinctive lithological/stratigraphical units where bedrock either outcrops or is relatively near to surface in the Lady Annie-Mt. Gordon fault zone, the Mary Kathleen, and Dugald River-Naraku areas. Spectral signatures associated with discrete plant communities distinguished different types of superficial deposits over the Cloncurry Plains. Distinctive spectral signatures also revealed the presence and nature of concealed bedrock beneath cover of residuum and superficial deposits where this is relatively thin in the Cloncurry Plains. Major faults were clearly displayed in areas of outcropping and near surface bedrock. Sets of lineaments with preferred orientations were identified in the Lady Annie and Dugald River areas. Known base metal deposits occur along these features.

Fault structures in the focal area of the 2016 Kumamoto earthquake revealed by derivatives and structure parameters of a gravity gradient tensor

NASA Astrophysics Data System (ADS)

Hiramatsu, Y.; Matsumoto, N.; Sawada, A.

2016-12-01

We analyze gravity anomalies in the focal area of the 2016 Kumamoto earthquake, evaluate the continuity, segmentation and faulting type of the active fault zones, and discuss relationships between those features and the aftershock distribution. We compile 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). We apply terrain corrections with 10 m DEM and a low-pass filter, then remove a linear trend to obtain Bouguer anomalies. We calculate the first horizontal derivative (HD), the first vertical derivative (VD), the normalized total horizontal derivative (TDX) (Cooper and Cowan, 2006), the dimensionality index (Di) (Beki and Pedersen, 2010), and dip angle (β) (Beki, 2013) from a gravity gradient tensor. The HD, VD and TDX show the existence of the continuous fault structure along the Futagawa fault zone, extending from the Uto peninsula to the Beppu Bay except Mt. Aso area. Aftershocks are distributed along this structural boundary from the confluence of the Futagawa and the Hinagu fault zones to the east end of the Aso volcano. The distribution of dip angle β along the Futagawa fault zone implies a normal faulting, which corresponds to the coseismic faulting estimated geologically and geomorphologically. We observe the S-shaped distribution of the Bouguer anomalies around the southern part of the Hinagu segment, indicating a right lateral faulting. The VD and TDX support the existence of the fault structure along the segment but it is not so clear. We can recognize no clear structural boundaries along the Takano-Shirahata segment. TDX implies the existence of a structural boundary with a NW-SE trend around the boundary between the Hinagu and Takano-Shirahata segments. The Di shows that this boundary has a 3D-like structure rather than a 2D-like one, suggesting the discontinuity of 2D-like fault structure along the fault zone. A geological map indicates that this structure boundary corresponds to a boundary between the metamorphic rock and the sedimentary rock. The active area of the aftershocks does not extend to the south beyond this structure boundary, implying that the spatial extent of the source fault is controlled by this boundary.

Two-dimensional magnetotelluric model of deep resistivity structure in the Bodie-Aurora district of California

USGS Publications Warehouse

Sampson, Jay A.

2006-01-01

Introduction: Magnetotelluric data were acquired during October 2001 by the U.S. Geological Survey (USGS) as part of a study to examine the structural nature of basins in the transition zone between the Sierra Nevada Mountains of California and the Basin and Range province of Nevada. Magnetotelluric (MT) geophysical studies assist the mapping of geologic structure and the inference of lithologic packages that are concealed beneath the Earth's surface. The Basin and Range province has a complicated geologic history, which includes extension and compression of the Earth's crust to form the basins and ranges that blanket much of Nevada. The basins and ranges in the vicinity of this study trend northeastward and are bounded by steeply dipping strike slip faults. Interestingly, deep east-west magnetic trends occur in the aeromagnetic data of this study area indicating that the northeast-trending basins and ranges represent only thin-skinned deformation at the surface with an underlying east-west structure. To investigate this issue, MT data were acquired at seven stations in eastern California, 20 km east of Mono Lake. The purpose of this report is to present a two-dimensional apparent resistivity model of the MT data acquired for this study.

Digital Communications Terminal High Order Programming Language Study (DCT HOL Study). Volume I.

DTIC Science & Technology

1980-11-26

3-3 PASCAL/M Digital Marketing ......... 3-3 PASCAL/MT MT MicroSystems .................... 3-3 PASCAL/Z Ithaca IntersysteMs...II Avocet Systems, Inc. 3.6 PASCAL - ISO PASCAL Whitesmith, Ltd. - PASCAL 64000 lbwlett-Packard - PASCAL/H Digital Marketing - PASCAL/MT MT

Seasonal variability in Tibetan seismicity 1991-2013

NASA Astrophysics Data System (ADS)

Randolph-Flagg, N. G.; Day, J.; Burgmann, R.; Manga, M.

2013-12-01

Seismicity in the High Himalaya in Nepal (Bollinger et al., GRL, 2007, Bettinelli et al., EPSL, 2008), the San Andreas fault near Parkfield, California (Christiansen et al., 2007), Mt. Hochstaufen in Germany (Hainzl et al., 2006), and some Cascade Range volcanoes (Christiansen et al., GRL, 2005; Saar and Manga, EPSL, 2003) shows seasonal modulation. From 1991 to 2013, seismicity throughout the ~500 km by ~1000 km Tibetan Plateau also appears to be modulated with 66% more shallow (depth < 20km) earthquakes in spring and fall than in the summer and winter. This variation cannot be explained by seasonal changes in seismic network coverage or triggering by (or occurrence of) large magnitude earthquakes. Significant foreshocks and aftershocks of the 2008 M7.9 Wenchuan earthquake in Sichuan dominate the seismic record from 2008 to 2009 and those years are not considered in the statistical analysis. The Tibetan seismicity, although weaker, is very similar to the modulation observed in Nepal and in the locked section of the San Andreas fault at Parkfield. To explain this biannual signal, we assess the possible effects of hydrologic loading (and unloading), pore pressure diffusion, fault plane orientation, evapotranspiration, earth tides, and atmospheric pressure. The similarity in seasonal signals throughout the area suggests that many faults on the Tibetan Plateau are critically stressed and sensitive to small transient stresses.

Late Cenozoic extensional faulting in Central-Western Peloponnesus, Greece

NASA Astrophysics Data System (ADS)

Skourtsos, E.; Fountoulis, I.; Mavroulis, S.; Kranis, H.

2012-04-01

A series of forearc-dipping, orogen-parallel extensional faults are found in the central-western Peloponnesus, (south-western Aegean) which control the western margin of Mt Mainalon. The latter comprises HP/LT rocks of the Phyllites-Quartzites Unit (PQ), overlain by the carbonates and flysch of the Tripolis Unit while the uppermost nappe is the Pindos Unit, a sequence of Mesozoic pelagic sequence, topped by a Paleocene flysch. Most of the extensional structures were previously thought of as the original thrust between the Pindos and Tripolis Units. However, the cross-cutting relationships among these structures indicate that these are forearc (SW-dipping) extensional faults, downthrowing the Pindos thrust by a few tens or hundreds of meters each, rooting onto different levels of the nappe pile. In SW Mainalon the lowermost of the extensional faults is a low-angle normal fault dipping SW juxtaposing the metamorphic rocks of the PQ Unit against the non-metamorphic sequence of the Tripolis Unit. High-angle normal faults, found further to the west, have truncated or even sole onto the low-angle ones and control the eastern margin of the Quaternary Megalopolis basin. All these extensional structures form the eastern boundary of a series of Neogene-Quaternary tectonic depressions, which in turn are separated by E-W horsts. In the NW, these faults are truncated by NE to NNE-striking, NW-dipping faults, which relay the whole fault activity to the eastern margin of the Pyrgos graben. The whole extensional fault architecture has resulted (i) in the Pindos thrust stepping down from altitudes higher than 1000 m in Mainalon in the east, to negative heights in North Messinia and Southern Ilia in the west; and (ii) the gradual disappearance of the Phyllite-Quartzite metamorphics of Mainalon towards the west. The combination of these extensional faults (which may reach down to the Ionian décollement) with the low-angle floor thrusts of the Pindos, Tripolis and Ionian Units leads to additional ENE-WSW shortening, normal to the Hellenic Arc, west of the Peloponnesus.

HCMM: Soil moisture in relation to geologic structure and lithology, northern California. [Sacremento Valley

NASA Technical Reports Server (NTRS)

Rich, E. I. (Principal Investigator)

1979-01-01

The author has identified the following significant results. A preliminary analysis of the HCMM imagery of the project area indicated that locally some differentiation of lithologic units within the Northern Coast Range may be possible. Of significance, however, was a thermally cool linear area that appeared on the 30 May 1978 Nite-IR. This linear feature seemed to coincide with the Bear Mt. Fault and with the axis of the Chico Monocline along the eastern margin of the Sacramento Valley.

High resolution digital mapping and geomorphological analysis of the 2010 Mount Meager rock-debris avalanche (BC, Canada).

NASA Astrophysics Data System (ADS)

Roberti, Gioachino; van Wyk de vries, Benjamin; Ward, Brent; Clague, John; Friele, Pierre; Perotti, Luigi; Giardino, Marco

2016-04-01

This study examines the large landslide that occurred at Mt. Meager, 200 km NNW of Vancouver, British Columbia, Canada, on August 6, 2010. We studied the source area and deposits to reconstruct the failure of the south flank of Mt. Meager from slow deformation to catastrophic collapse, the subsequent transformation into a debris avalanche, and the 11 km run-out. We use a Structure from Motion (SfM) photogrammetric approach and processed both historical British Columbia Provincial airphotos (1948, 1962, 1964-1965, 1973, 1981, 1990, and 2006) and digital images taken with a commercial camera during low-level helicopter traverses. The SfM products have been used to calculate volumes and the geometry of the south flank of Mt. Meager before and after the catastrophic failure, and to produce an orthophoto that we have used to map and describe the deposit. Oblique helicopter photos provide information on the scar geometry and rock units exposed by the failure. The SfM-derived orthophoto and ground observations allowed us to map deposit facies, lithologies, and structures, including thrust, normal, and strike-slip faults. We identified five sub-areas in the accumulation zone based on the association of facies and deformation structures. Based on our interpretation of the remotely sensed data and ground observations, we propose that the landslide had two main rheological phases: one richer in water and highly mobile, and another massive and water-poor. The water-rich phase spread quickly and superelevated high on valley walls as it moved down valley. It left a discontinuous veneer of debris, typically <1 m thick. The main, unsaturated mass moved more slowly and left a thicker (up to about 20 m) deposit with hummocks and brittle-ductile faults and shear zone in the distal part of the run-out zone.

The Late Cambrian Takaka Terrane, NW Nelson, New Zealand: Accretionary-prism development and arc collision followed by extension and fan-delta deposition at the SE margin of Gondwana

NASA Astrophysics Data System (ADS)

Pound, K. S.

2013-12-01

Re-evaluation of field and lab data indicates that the Cambrian portion of the Takaka Terrane in the Cobb Valley area of NW Nelson, New Zealand preserves the remnants of an accretionary prism complex, across which the Lockett Conglomerate fan-delta was deposited as a consequence of extension. Previous work has recognized that the structurally disrupted lower Takaka Terrane rocks present an amalgam of sedimentary and igneous rocks generated prior to convergence (Junction Formation) or during convergence (Devil River Volcanics Group, Haupiri Group), including arc-related and MORB components. Portions of the sequence have in the past been loosely described as an accretionary prism. Reevaluation of the detailed mapping, sedimentological and provenance studies shows that remnants of a stratigraphic sequence (Junction Formation, Devil River Volcanics Group, Haupiri Group) can be traced through 10 fault-bounded slices, which include a mélange-dominated slice (Balloon Mélange). These slices are the remnants of the accretionary prism; the stratigraphy within each slice generally youngs to the east, and the overall pattern of aging (based on relative age from provenance studies, sparse fossils, stratigraphic relations, and limited isotopic data) indicates that the older rocks generally dominate fault slices to the east, and younger rocks dominate fault slices to the west, delineating imbricate slices within an eastward-dipping subduction zone, in which the faults record a complex history of multi-phase reactivation. The Lockett Conglomerate is a ~500-m thick fan-delta conglomerate that is the preserved within one of the fault slices, where it is stratigraphically and structurally highest unit in the lower Takaka Terrane; it is also present as blocks within the Balloon Melange. The Lockett Conglomerate is marine at its base and transitions upwards to fluvial facies. The Lockett Conglomerate has previously been interpreted to result from erosion consequent on continued convergence, but is reinterpreted here as a ';true' fan-delta deposit, sedimentologically similar to deposits associated with extension. Textural and compositional data for the Lockett Conglomerate indicates rapid supply of new material (including quartzite, granite, gabbro, and amphibolitic metavolcanics). The Lockett Conglomerate is proposed here to record the initiation of extension, during which basement faults in the hinterland exposed previously buried source rocks. This new interpretation of the Lockett Conglomerate places that initiation of extension and subsequent passive margin sedimentation (Mt. Ellis and Mt. Arthur Groups) earlier (late Middle Cambrian) than previous work has suggested (Late Cambrian or Early Ordovician). These new interpretations provide input useful for correlations and interpretations of the complex mosaic that preserves a record of tectonic activity and processes at the Antarctic, Tasmanian and SE Australian portions of the Cambrian Gondwana margin.

Unfaulting the Sardarapat Ridge, Southwest Armenia

NASA Astrophysics Data System (ADS)

Wetmore, P.; Connor, C.; Connor, L. J.; Savov, I. P.; Karakhanyan, A.

2012-12-01

Armenia is located near the core of contractional deformation associated with the collision between the Arabian and Eurasian tectonic plates. Several studies of this region, including portions of adjacent Georgia, Iran, and Turkey, have indicated that 1-2 mm/yr of intra-plate, north-south shortening is primarily accommodated by a network of E-W trending thrust faults, and NW-trending (dextral) and NE-trending (sinistral) strike-slip faults. One proposed fault in this network, the Sardarapat Fault (SF), was investigated as part of a regional seismic hazard assessment ahead of the installation of a replacement reactor at the Armenian Nuclear Power Plant (ANPP). The SF is primarily defined by the Sardarapat Ridge (SR), which is a WNW-trending, 40-70 m high topographic feature located just north of the Arax River and the Turkey-Armenia border. The stratigraphy comprising this ridge includes alluvium overlying several meters of lacustrine deposits above a crystal-rich basaltic lava flow that yields an Ar-Ar age of 0.9 +/- 0.02 Ma. The alluvial sediments on the ridge contain early Bronze age (3832-3470 BP) artifacts at an elevation 25 m above those of the surrounding alluvial plane. This has lead to the suggestion that the SR is bound to the south (the steepest side) by the SF, which is uplifting the ridge at a rate of 0.7 mm/yr. However, despite the prominence and trend of the ridge there are no unequivocal observations, such as scarps or exposures of fault rocks, to support the existence of the SF. The goal of the investigation of the SR area was to test various models for the formation of the ridge including faulting and combined volcanic and erosional processes. We therefore collected gravimetric, magnetic, magneto-tellurics (MT), and transient electromagnetic (TEM) data across an area of ~400 km2, and used correlations of stratigraphic data from coreholes drilled proximal to the study area to define the geometry of the contact between the basement and basin fill to help constrain modeling of the geophysical data. Additionally, the archeological sites where artifacts were observed within the upper-most fluvial deposits were revisited and assessed anew. The results of this investigation include: 1) the presence of a 20 mgal gravity gradient trending SW-NE oblique to the trend of the ridge; 2) the observation that magnetic data, including MT and TEM, do not identify faults in the shallow subsurface; and 3) artifacts are not in the stratigraphic section with the alluvial sediments. These results do not support a fault model to explain uplift of the SR. Gravity and TEM data do suggest a NW-trending boundary between differing basement types at depth crossing the SR obliquely near the NW terminus. This structure does not appear to have any surface expression, nor is it associated with topography on the basement-basin fill contact. An alternative for the SR may be that the long linear, basaltic lava-cored ridge actually represents a lava flow that exploited an earlier channel of the Arax River. It was subsequently buried and later erosion inverted the topography of this region, preferentially removing the unconsolidated sediments.

Can multi-scale calibrations allow MT-derived resistivities to be used to probe the structure of the deep crust?

NASA Astrophysics Data System (ADS)

Toy, Virginia; Billia, Marco; Easingwood, Richard; Kirilova, Martina; Kluge, Emma; Sauer, Katrina; Sutherland, Rupert; Timms, Nicholas; Townend, John

2017-04-01

Our current knowledge of microstructural and mechanical controls on rock resistivity is such that identical magnetotelluric (MT) anomalies could result from a highly mineralized but extinct shear zone, or from an unmineralized, fluid saturated, active shear zone. In pursuit of the ability to interpret the structure and activity (rather than just the presence) of buried geological structures from electromagnetic data, we are investigating correlations between rock structure and electrical properties of ductile shear zone rocks recovered from the active Alpine Fault Zone, New Zealand. Multi-scale measurements of resistivity exist for this zone: its ductile portions have anomalously high electrical conductivity identified in MT models constructed as part of the South Island Geophysical Transect (SIGHT). Additionally wireline resistivities were measured in situ to 820 m depth during the recent Deep Fault Drilling Project (DFDP-2), and resisistivity of hand samples has been measured at laboratory conditions [Kluge et al., Abstract EGU2017-10139]. In exhumed and borehole samples, the distributions and arrangements of conductivity carriers - graphite, amorphous carbon, and grain boundary pores that would have contained brines or other conductive fluids at depth, have been characterised. These vary systematically according to the total ductile shear strain they have accommodated [Kirilova et al., Abstract EGU2017-5773; Sauer et al., Abstract EGU2017-10485]. Transmission electron microscopy analyses of grain boundaries also indicate that they contain carbon. The next phases of our investigation involve: (i) construction of crustal fluid composition models by quantitative microstructural and compositional/mineralogical mapping of fluid remnants and their solid residues and calibration of these using in situ measurements of fluid composition in DFDP-2 at depths to 820 m; (ii) calculation of resistivities for real microstructures based on electrical properties of the individual component minerals and fluids - for microstructures fully characterised in three-dimensions; (iii) measurement of the effects of dynamic linking of phases during ductile creep of solid rock on complex resistivity of DFDP samples at a range of realistic crustal temperatures and pressures. A particular challenge in this study is to determine appropriate scaling relationships of electrical properties among samples, boreholes, and MT models because dielectric constants of minerals depend on frequency of the imposed current, which varies with scale and, consequently, measurement method. We invite discussion of strategies to overcome this.

Quaternary crustal deformation along a major branch of the San Andreas fault in central California

USGS Publications Warehouse

Weber, G.E.; Lajoie, K.R.; Wehmiller, J.F.

1979-01-01

Deformed marine terraces and alluvial deposits record Quaternary crustal deformation along segments of a major, seismically active branch of the San Andreas fault which extends 190 km SSE roughly parallel to the California coastline from Bolinas Lagoon to the Point Sur area. Most of this complex fault zone lies offshore (mapped by others using acoustical techniques), but a 4-km segment (Seal Cove fault) near Half Moon Bay and a 26-km segment (San Gregorio fault) between San Gregorio and Point Ano Nuevo lie onshore. At Half Moon Bay, right-lateral slip and N-S horizontal compression are expressed by a broad, synclinal warp in the first (lowest: 125 ka?) and second marine terraces on the NE side of the Seal Cove fault. This structure plunges to the west at an oblique angle into the fault plane. Linear, joint0controlled stream courses draining the coastal uplands are deflected toward the topographic depression along the synclinal axis where they emerge from the hills to cross the lowest terrace. Streams crossing the downwarped part of this terrace adjacent to Half Moon Bay are depositing alluvial fans, whereas streams crossing the uplifted southern limb of the syncline southwest of the bay are deeply incised. Minimum crustal shortening across this syncline parallel to the fault is 0.7% over the past 125 ka, based on deformation of the shoreline angle of the first terrace. Between San Gregorio and Point Ano Nuevo the entire fault zone is 2.5-3.0 km wide and has three primary traces or zones of faulting consisting of numerous en-echelon and anastomozing secondary fault traces. Lateral discontinuities and variable deformation of well-preserved marine terrace sequences help define major structural blocks and document differential motions in this area and south to Santa Cruz. Vertical displacement occurs on all of the fault traces, but is small compared to horizontal displacement. Some blocks within the fault zone are intensely faulted and steeply tilted. One major block 0.8 km wide east of Point Ano Nuevo is downdropped as much as 20 m between two primary traces to form a graben presently filling with Holocene deposits. Where exposed in the sea cliff, these deposits are folded into a vertical attitude adjacent to the fault plane forming the south-west margin of the graben. Near Point Ano Nuevo sedimentary deposits and fault rubble beneath a secondary high-angle reverse fault record three and possibly six distinct offset events in the past 125 ka. The three primary fault traces offset in a right-lateral sense the shoreline angles of the two lowest terraces east of Point Ano Nuevo. The rates of displacement on the three traces are similar. The average rate of horizontal offset across the entire zone is between 0.63 and 1.30 cm/yr, based on an amino-acid age estimate of 125 ka for the first terrace, and a reasonable guess of 200-400 ka for the second terrace. Rates of this magnitude make up a significant part of the deficit between long-term relative plate motions (estimated by others to be about 6 cm/yr) and present displacement rates along other parts of the San Andreas fault system (about 3.2 cm/yr). Northwestward tilt and convergence of six marine terraces northeast of Ano Nuevo (southwest side of the fault zone) indicate continuous gentle warping associated with right-lateral displacement since early or middle Pleistocene time. Minimum local crustal shortening of this block parallel to the fault is 0.2% based on tilt of the highest terrace. Five major, evenly spaced terraces southeast of Ano Nuevo on the southwest flank of Mt. Ben Lomond (northeast side of the fault zone) rise to an elevation of 240 m, indicating relatively constant uplift (about 0.19 m/ka and southwestward tilt since Early or Middle Pleistocene time (Bradley and Griggs, 1976). ?? 1979.

Global Examination of Triggered Tectonic Tremor following the 2017 Mw8.1 Tehuantepec Earthquake in Mexico

NASA Astrophysics Data System (ADS)

Chao, K.; Gonzalez-Huizar, H.; Tang, V.; Klaeser, R. D.; Mattia, M.; Van der Lee, S.

2017-12-01

Triggered tremor is one type of slow earthquake that activated by teleseismic surfaces waves of large magnitude earthquake. Observations of triggered tremor can help to evaluate the background ambient tremor rate and slow slip events in the surrounding region. The Mw 8.1 Tehuantepec earthquake in Mexico is an ideal tremor-triggering candidate for a global search for triggered tremor. Here, we examine triggered tremor globally following the M8.1 event and model the tremor-triggering potential. We examine 7,000 seismic traces and found a widely spread triggered tremor along the western coast of the North America occur during the surface waves of the Mw 8.1 event. Triggered tremor appeared in the San Jacinto Fault, San Andreas Fault around Parkfield, and Calaveras Fault in California, in Vancouver Island in Cascadia subduction zone, in Queen Charlotte Margin and Eastern Denali Fault in Canada, and in Alaska and Aleutian Arc. In addition, we observe a newly found triggered tremor source in Mt. Etna in Sicily Island, Italy. However, we do not find clear triggered tremor evidences in the tremor active regions in Japan, Taiwan, and in New Zealand. We model tremor-triggering potential at the triggering earthquake source and triggered tremor sources. Our modeling results suggest the source parameters of the M8.1 triggering events and the stress at the triggered fault zone are two critical factors to control tremor-triggering threshold.

Brief communication: Co-seismic displacement on 26 and 30 October 2016 (Mw = 5.9 and 6.5) - earthquakes in central Italy from the analysis of a local GNSS network

NASA Astrophysics Data System (ADS)

De Guidi, Giorgio; Vecchio, Alessia; Brighenti, Fabio; Caputo, Riccardo; Carnemolla, Francesco; Di Pietro, Adriano; Lupo, Marco; Maggini, Massimiliano; Marchese, Salvatore; Messina, Danilo; Monaco, Carmelo; Naso, Salvatore

2017-11-01

On 24 August 2016 a strong earthquake (Mw = 6.0) affected central Italy and an intense seismic sequence started. Field observations, DInSAR (Differential INterferometry Synthetic-Aperture Radar) analyses and preliminary focal mechanisms, as well as the distribution of aftershocks, suggested the reactivation of the northern sector of the Laga fault, the southern part of which was already rebooted during the 2009 L'Aquila sequence, and of the southern segment of the Mt Vettore fault system (MVFS). Based on this preliminary information and following the stress-triggering concept (Stein, 1999; Steacy et al., 2005), we tentatively identified a potential fault zone that is very vulnerable to future seismic events just north of the earlier epicentral area. Accordingly, we planned a local geodetic network consisting of five new GNSS (Global Navigation Satellite System) stations located a few kilometres away from both sides of the MVFS. This network was devoted to working out, at least partially but in some detail, the possible northward propagation of the crustal network ruptures. The building of the stations and a first set of measurements were carried out during a first campaign (30 September and 2 October 2016). On 26 October 2016, immediately north of the epicentral area of the 24 August event, another earthquake (Mw = 5.9) occurred, followed 4 days later (30 October) by the main shock (Mw = 6.5) of the whole 2016 summer-autumn seismic sequence. Our local geodetic network was fully affected by the new events and therefore we performed a second campaign soon after (11-13 November 2016). In this brief note, we provide the results of our geodetic measurements that registered the co-seismic and immediately post-seismic deformation of the two major October shocks, documenting in some detail the surface deformation close to the fault trace. We also compare our results with the available surface deformation field of the broader area, obtained on the basis of the DInSAR technique, and show an overall good fit.

Long term fault system reorganization of convergent and strike-slip systems

NASA Astrophysics Data System (ADS)

Cooke, M. L.; McBeck, J.; Hatem, A. E.; Toeneboehn, K.; Beyer, J. L.

2017-12-01

Laboratory and numerical experiments representing deformation over many earthquake cycles demonstrate that fault evolution includes episodes of fault reorganization that optimize work on the fault system. Consequently, the mechanical and kinematic efficiencies of fault systems do not increase monotonically through their evolution. New fault configurations can optimize the external work required to accommodate deformation, suggesting that changes in system efficiency can drive fault reorganization. Laboratory evidence and numerical results show that fault reorganization within accretion, strike-slip and oblique convergent systems is associated with increasing efficiency due to increased fault slip (frictional work and seismic energy) and commensurate decreased off-fault deformation (internal work and work against gravity). Between episodes of fault reorganization, fault systems may become less efficient as they produce increasing off fault deformation. For example, laboratory and numerical experiments show that the interference and interaction between different fault segments may increase local internal work or that increasing convergence can increase work against gravity produced by a fault system. This accumulation of work triggers fault reorganization as stored work provides the energy required to grow new faults that reorganize the system to a more efficient configuration. The results of laboratory and numerical experiments reveal that we should expect crustal fault systems to reorganize following periods of increasing inefficiency, even in the absence of changes to the tectonic regime. In other words, fault reorganization doesn't require a change in tectonic loading. The time frame of fault reorganization depends on fault system configuration, strain rate and processes that relax stresses within the crust. For example, stress relaxation may keep pace with stress accumulation, which would limit the increase in the internal work and gravitational work so that irregularities can persist along active fault systems without reorganization of the fault system. Consequently, steady state behavior, for example with constant fault slip rates, may arise either in systems with high degree of stress-relaxation or occur only within the intervals between episodes of fault reorganization.

Magnetotelluric and aeromagnetic investigations for assessment of groundwater resources in Parnaiba basin in Piaui State of North-East Brazil

NASA Astrophysics Data System (ADS)

Chandrasekhar, E.; Fontes, Sergio L.; Flexor, Jean M.; Rajaram, Mita; Anand, S. P.

2009-06-01

In an attempt to locate the presence of possible groundwater resource regions in the semi-arid North-East Brazil, an integrated survey including aeromagnetic and magnetotelluric (MT) studies have been undertaken in the Guaribas region and only MT survey in the Caracol region. In the Guaribas region the aeromagnetic data, its analytic signal and Euler solutions reveal several subsurface small-scale faults and intrusives that are conducive to be potential groundwater resource regions. A total of about 22 broad-band magnetotelluric (MT) soundings in the period range of 0.006-300 s along two profiles on the marginal arcs of the intra-cratonic sedimentary Parnaíba basin in North-East Brazil have been made across the regional geological strike, the Senador Pompeu Lineament (SPL). SPL trends N40°E and marks a basement high reflecting an irregularity in the original basin geometry. While one of the MT profiles traverses across the SPL, the other lies only in the aeromagnetically surveyed sedimentary region. Two-dimensional inversion of MT data of both profiles shows that the sedimentary basin is conductive (100-150 Ω m) and shows as a thin graben with an average thickness of about 2-3 km beneath both profiles. The basin is located to be at shallow depths (from surface to about 500 m). Based on the facts that the study region falls on sedimentary region having low-to-very low permeability and also in accordance with the subsurface lithology around the study region, the mapped sedimentary basin largely manifests the zone of potential sedimentary aquifer having moderate resistivity of 50-250 Ω m and is located at relatively shallow depths. The identified aquifer zone is believed to have links with the Parnaiba River flowing at a distance of about 300 km NW from the study region. We discuss interpretation of our results of MT and aeromagnetic data sets in the light of hydrological features of the study region.

Magnetotelluric Imaging of the Lithosphere Across the Variscan Orogen (Iberian Autochthonous Domain, NW Iberia)

NASA Astrophysics Data System (ADS)

Alves Ribeiro, J.; Monteiro-Santos, F. A.; Pereira, M. F.; Díez Fernández, R.; Dias da Silva, Í.; Nascimento, C.; Silva, J. B.

2017-12-01

A new magnetotelluric (MT) survey comprising 17 MT soundings throughout a 30 km long N30°W transect in the Iberian autochthons domain of NW Iberia (Central Iberian Zone) is presented. The 2-D inversion model shows the resistivity structure of the continental crust up to 10 km depth, heretofore unavailable for this region of the Variscan Orogen. The MT model reveals a wavy structure separating a conductive upper layer underlain by a resistive layer, thus picturing the two main tectonic blocks of a large-scale D2 extensional shear zone (i.e., Pinhel shear zone). The upper layer represents a lower grade metamorphic domain that includes graphite-rich rocks. The lower layer consists of high-grade metamorphic rocks that experienced partial melting and are associated with granites (more resistive) emplaced during crustal thinning. The wavy structure is the result of superimposed crustal shortening responsible for the development of large-scale D3 folds (e.g., Marofa synform), later deflected and refolded by a D4 strike-slip shear zone (i.e., Juzbado-Penalva do Castelo shear zone). The later contribution to the final structure of the crust is marked by the intrusion of postkinematic granitic rocks and the propagation of steeply dipping brittle fault zones. Our study demonstrates that MT imaging is a powerful tool to understand complex crustal structures of ancient orogens in order to design future prospecting surveys for mineral deposits of economic interest.

Joint Inversion of Vp, Vs, and Resistivity at SAFOD

NASA Astrophysics Data System (ADS)

Bennington, N. L.; Zhang, H.; Thurber, C. H.; Bedrosian, P. A.

2010-12-01

Seismic and resistivity models at SAFOD have been derived from separate inversions that show significant spatial similarity between the main model features. Previous work [Zhang et al., 2009] used cluster analysis to make lithologic inferences from trends in the seismic and resistivity models. We have taken this one step further by developing a joint inversion scheme that uses the cross-gradient penalty function to achieve structurally similar Vp, Vs, and resistivity images that adequately fit the seismic and magnetotelluric MT data without forcing model similarity where none exists. The new inversion code, tomoDDMT, merges the seismic inversion code tomoDD [Zhang and Thurber, 2003] and the MT inversion code Occam2DMT [Constable et al., 1987; deGroot-Hedlin and Constable, 1990]. We are exploring the utility of the cross-gradients penalty function in improving models of fault-zone structure at SAFOD on the San Andreas Fault in the Parkfield, California area. Two different sets of end-member starting models are being tested. One set is the separately inverted Vp, Vs, and resistivity models. The other set consists of simple, geologically based block models developed from borehole information at the SAFOD drill site and a simplified version of features seen in geophysical models at Parkfield. For both starting models, our preliminary results indicate that the inversion produces a converging solution with resistivity, seismic, and cross-gradient misfits decreasing over successive iterations. We also compare the jointly inverted Vp, Vs, and resistivity models to borehole information from SAFOD to provide a "ground truth" comparison.

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

NASA Technical Reports Server (NTRS)

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

1989-01-01

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

Ground motion amplification at rock sites: the competing role of topography and fractured rocks in the San Giovanni fault, central Italy

NASA Astrophysics Data System (ADS)

Pischiutta, M.; Cara, F.; Di Giulio, G.; Vassallo, M.; Cultrera, G.

2017-12-01

Amplification at rock sites in areas of high topographic relief has been increasingly observed in the last years, with unexpected level of damage after strong earthquakes. In regions affected by recent tectonic activity, topographic irregularities can include fault damage zones. In such conditions, seismic waves can be locally amplified as a double effect of wave focusing along the topography and /or the presence of fractures/joints or locally weakened rocks. The role of topography vs. geological complexities in controlling the ground motion amplification at rock sites is a newly debated issue in the seismological community. The most crucial questions regard what is the real contribution of the topography shape and fracturing, and how to parameterize such effects for their inclusion in the seismic design codes. In this framework, the EMERSITO INGV task force installed 7 seismic stations across the San Giovanni fault, after the Amatrice mainshock of the 2016 sequence in Central Italy. This active normal fault is located in the area of the Montereale intermountain basin (Abruzzi region, Italy) and bounds the southwestern slope of Mt. Mozzano, a roughly 2D-shaped, up to 1450 m high pronounced topography. Moreover, this fault has been recently studied by several authors who performed detailed geological and geophysical surveys. Our stations recorded more than 100 earthquakes with magnitude ranging from 2.5 to 3.9 as well as a 4.4 M earthquake with hypocenter in Capitignano district, few kilometres far. We have analyzed in detail the recorded signals calculating the traditional spectral ratios at single station (HVSRs) and using the reference site (SSRs) using both ambient noise and earthquakes. In order to obtain a robust estimate of the site amplification effect at each station, we have investigated the influence of backazimuth and epicentral distance. We have also applied the time-domain covariance matrix analysis and the frequency domain polarization analysis. We have found that, in spite of the complexity of the seismic data, the observed polarization pattern is generally oriented orthogonal to the ridge elongation, as well as to the fault strike, suggesting the existence of a high angle relation between ground motion polarization and fracture systems.

Numerical modeling of fracking fluid and methane migration through fault zones in shale gas reservoirs

NASA Astrophysics Data System (ADS)

Taherdangkoo, Reza; Tatomir, Alexandru; Sauter, Martin

2017-04-01

Hydraulic fracturing operation in shale gas reservoir has gained growing interest over the last few years. Groundwater contamination is one of the most important environmental concerns that have emerged surrounding shale gas development (Reagan et al., 2015). The potential impacts of hydraulic fracturing could be studied through the possible pathways for subsurface migration of contaminants towards overlying aquifers (Kissinger et al., 2013; Myers, 2012). The intent of this study is to investigate, by means of numerical simulation, two failure scenarios which are based on the presence of a fault zone that penetrates the full thickness of overburden and connect shale gas reservoir to aquifer. Scenario 1 addresses the potential transport of fracturing fluid from the shale into the subsurface. This scenario was modeled with COMSOL Multiphysics software. Scenario 2 deals with the leakage of methane from the reservoir into the overburden. The numerical modeling of this scenario was implemented in DuMux (free and open-source software), discrete fracture model (DFM) simulator (Tatomir, 2012). The modeling results are used to evaluate the influence of several important parameters (reservoir pressure, aquifer-reservoir separation thickness, fault zone inclination, porosity, permeability, etc.) that could affect the fluid transport through the fault zone. Furthermore, we determined the main transport mechanisms and circumstances in which would allow frack fluid or methane migrate through the fault zone into geological layers. The results show that presence of a conductive fault could reduce the contaminant travel time and a significant contaminant leakage, under certain hydraulic conditions, is most likely to occur. Bibliography Kissinger, A., Helmig, R., Ebigbo, A., Class, H., Lange, T., Sauter, M., Heitfeld, M., Klünker, J., Jahnke, W., 2013. Hydraulic fracturing in unconventional gas reservoirs: risks in the geological system, part 2. Environ Earth Sci 70, 3855-3873. Myers, T., 2012. Potential contaminant pathways from hydraulically fractured shale to aquifers. Groundwater, 50(6), 872-882. Reagan, M.T., Moridis, G.J., Keen, N.D., Johnson, J.N., 2015. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport. Water Resources Research 51, 2543-2573. Tatomir, A., 2012. From Discrete to Continuum Concepts of Flow in Fractured Porous Media. Stuttgart University: University of Stuttgart.

The engine fuel system fault analysis

NASA Astrophysics Data System (ADS)

Zhang, Yong; Song, Hanqiang; Yang, Changsheng; Zhao, Wei

2017-05-01

For improving the reliability of the engine fuel system, the typical fault factor of the engine fuel system was analyzed from the point view of structure and functional. The fault character was gotten by building the fuel system fault tree. According the utilizing of fault mode effect analysis method (FMEA), several factors of key component fuel regulator was obtained, which include the fault mode, the fault cause, and the fault influences. All of this made foundation for next development of fault diagnosis system.

Eruption processes and deposit characteristics at the monogenetic Mt. Gambier Volcanic Complex, SE Australia: implications for alternating magmatic and phreatomagmatic activity

NASA Astrophysics Data System (ADS)

van Otterloo, Jozua; Cas, Raymond A. F.; Sheard, Malcolm J.

2013-08-01

The ˜5 ka Mt. Gambier Volcanic Complex in the Newer Volcanics Province, Australia is an extremely complex monogenetic, volcanic system that preserves at least 14 eruption points aligned along a fissure system. The complex stratigraphy can be subdivided into six main facies that record alternations between magmatic and phreatomagmatic eruption styles in a random manner. The facies are (1) coherent to vesicular fragmental alkali basalt (effusive/Hawaiian spatter and lava flows); (2) massive scoriaceous fine lapilli with coarse ash (Strombolian fallout); (3) bedded scoriaceous fine lapilli tuff (violent Strombolian fallout); (4) thin-medium bedded, undulating very fine lapilli in coarse ash (dry phreatomagmatic surge-modified fallout); (5) palagonite-altered, cross-bedded, medium lapilli to fine ash (wet phreatomagmatic base surges); and (6) massive, palagonite-altered, very poorly sorted tuff breccia and lapilli tuff (phreato-Vulcanian pyroclastic flows). Since most deposits are lithified, to quantify the grain size distributions (GSDs), image analysis was performed. The facies are distinct based on their GSDs and the fine ash to coarse+fine ash ratios. These provide insights into the fragmentation intensities and water-magma interaction efficiencies for each facies. The eruption chronology indicates a random spatial and temporal sequence of occurrence of eruption styles, except for a "magmatic horizon" of effusive activity occurring at both ends of the volcanic complex simultaneously. The eruption foci are located along NW-SE trending lineaments, indicating that the complex was fed by multiple dykes following the subsurface structures related to the Tartwaup Fault System. Possible factors causing vent migration along these dykes and changes in eruption styles include differences in magma ascent rates, viscosity, crystallinity, degassing and magma discharge rate, as well as hydrological parameters.

Synthetic Modeling of A Geothermal System Using Audio-magnetotelluric (AMT) and Magnetotelluric (MT)

NASA Astrophysics Data System (ADS)

Mega Saputra, Rifki; Widodo

2017-04-01

Indonesia has 40% of the world’s potential geothermal resources with estimated capacity of 28,910 MW. Generally, the characteristic of the geothermal system in Indonesia is liquid-dominated systems, which driven by volcanic activities. In geothermal exploration, electromagnetic methods are used to map structures that could host potential reservoirs and source rocks. We want to know the responses of a geothermal system using synthetic data of Audio-magnetotelluric (AMT) and Magnetotelluric (MT). Due to frequency range, AMT and MT data can resolve the shallow and deeper structure, respectively. 1-D models have been performed using AMT and MT data. The results indicate that AMT and MT data give detailed conductivity distribution of geothermal structure.

Merging high resolution geophysical and geochemical surveys to reduce exploration risk at glass buttes, Oregon

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

Walsh, Patrick; Fercho, Steven; Perkin, Doug

2015-06-01

The engineering and studies phase of the Glass Buttes project was aimed at reducing risk during the early stages of geothermal project development. The project’s inclusion of high resolution geophysical and geochemical surveys allowed Ormat to evaluate the value of these surveys both independently and in combination to quantify the most valuable course of action for exploration in an area where structure, permeability, and temperature are the most pressing questions. The sizes of the thermal anomalies at Glass Buttes are unusually large. Over the course of Phase I Ormat acquired high resolution LIDAR data to accurately map fault manifestations atmore » the surface and collected detailed gravity and aeromagnetic surveys to map subsurface structural features. In addition, Ormat collected airborne hyperspectral data to assist with mapping the rock petrology and mineral alteration assemblages along Glass Buttes faults and magnetotelluric (MT) survey to try to better constrain the structures at depth. Direct and indirect identification of alteration assemblages reveal not only the geochemical character and temperature of the causative hydrothermal fluids but can also constrain areas of upflow along specific fault segments. All five datasets were merged along with subsurface lithologies and temperatures to predict the most likely locations for high permeability and hot fluids. The Glass Buttes temperature anomalies include 2 areas, totaling 60 km2 (23 mi2) of measured temperature gradients over 165° C/km (10° F/100ft). The Midnight Point temperature anomaly includes the Strat-1 well with 90°C (194 °F) at 603 m (1981 ft) with a 164 °C/km (10°F/100ft) temperature gradient at bottom hole and the GB-18 well with 71°C (160 °F) at 396 m (1300 ft) with a 182°C/km (11°F/100ft) gradient. The primary area of alteration and elevated temperature occurs near major fault intersections associated with Brothers Fault Zone and Basin and Range systems. Evidence for faulting is observed in each data set as follows. Field observations include fault plane orientations, complicated fault intersections, and hydrothermal alteration apparently pre-dating basalt flows. Geophysical anomalies include large, linear gradients in gravity and aeromagnetic data with magnetic lows possibly associated with alteration. Resistivity low anomalies also appear to have offsets associated with faulting. Hyperspectral and XRF identified alteration and individual volcanic flow units, respectively. When incorporated into a 3D geologic model, the fault intersections near the highest proven temperature and geophysical anomalies provide the first priority targets at Midnight Point. Ormat geologists selected the Midnight Point 52-33 drilling target based on a combination of pre-existing drilling data, geologic field work, geophysical interpretation, and geochemical analysis. Deep temperatures of well 52-33 was lower than anticipated. Temperature gradients in the well mirrored those found in historical drilling, but they decreased below 1500 ft and were isothermal below 2000 ft.« less

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.

The rock avalanche of the Mt. Peron (Eastern Alps, Italy): new insights from 36Cl exposure dating

NASA Astrophysics Data System (ADS)

Martin, Silvana; Ivy-ochs, Susan; Alfimov, Vasili; Vockenhuber, %Christof; Surian, Nicola; Campedel, Paolo; Rigo, Manuel; Viganò, Alfio; De Zorzi, Manuel

2016-04-01

In the Late Pleistocene, in the southern side of the Eastern Alps (Veneto region, Italy), when the glacier tongues retreated from the end moraine system areas towards the Dolomitic region, large rock avalanches took place. In the Belluno Valley, occupied by the Piave river, the left side is represented by the Belluno Prealps range, corresponding to the northern flank of a km-scale WSW-ENE oriented alpine syncline formed by rocks from Late Triassic to Late Tertiary in age. The Mt. Peron, belonging to this mountain range, shows its southern lower slope covered by debris cones with scattered boulders and its higher slope, corresponding to the scarp, made of vertical rock strata. At the foot of Mt. Peron, at a distance varying from 500 to 4500 m, there is a 4.5 km2 fan like area delimited by a perimeter of about 15 km. This is a hilly area of poortly sorted, chaotic deposits composed of heterogeneous debris, sandy and silty gravels, angular blocks and very large boulders of carbonatic rocks up to 20 m in diameter. The average thickness of the deposit was estimated to be 80 m, with maximum of 120 m. According to previous works, the main event occurred during the first phases of deglaciation, between 17,000 and 15,000 years BP. Popular stories narrate about two legendary villages destroyed by a mass of stones rolling down in the valley. This is confirmed by archeological findings in the Piave valley which indicate the presence of almost one pre-historic settlement dating 40000-20000 years a B.P., (i.e. before the Last Glacial Maximum).. Recent 36Cl exposure dating have yielded historical ages for both the boulders at the foot of the Mt Peron and those located a few km far from the main scarp. According to these exposure ages we can not exclude the hypothesis that earthquakes related to the Venetian faults could have played a key role for triggering of the rock avalanche and that the main gravitational event took place in historical times rather than during the deglaciation.

3-D basin-scale reconstruction of natural gas hydrate system of the Green Canyon, Gulf of Mexico

NASA Astrophysics Data System (ADS)

Burwicz, Ewa; Reichel, Thomas; Wallmann, Klaus; Rottke, Wolf; Haeckel, Matthias; Hensen, Christian

2017-05-01

Our study presents a basin-scale 3-D modeling solution, quantifying and exploring gas hydrate accumulations in the marine environment around the Green Canyon (GC955) area, Gulf of Mexico. It is the first modeling study that considers the full complexity of gas hydrate formation in a natural geological system. Overall, it comprises a comprehensive basin reconstruction, accounting for depositional and transient thermal history of the basin, source rock maturation, petroleum components generation, expulsion and migration, salt tectonics, and associated multistage fault development. The resulting 3-D gas hydrate distribution in the Green Canyon area is consistent with independent borehole observations. An important mechanism identified in this study and leading to high gas hydrate saturation (>80 vol %) at the base of the gas hydrate stability zone (GHSZ) is the recycling of gas hydrate and free gas enhanced by high Neogene sedimentation rates in the region. Our model predicts the rapid development of secondary intrasalt minibasins situated on top of the allochthonous salt deposits which leads to significant sediment subsidence and an ensuing dislocation of the lower GHSZ boundary. Consequently, large amounts of gas hydrates located in the deepest parts of the basin dissociate and the released free methane gas migrates upward to recharge the GHSZ. In total, we have predicted the gas hydrate budget for the Green Canyon area that amounts to ˜3256 Mt of gas hydrate, which is equivalent to ˜340 Mt of carbon (˜7 × 1011 m3 of CH4 at STP conditions), and consists mostly of biogenic hydrates.

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.

3D implicit modeling of the Sishen Mine: new resolution of the geometry and origin of Fe mineralization

NASA Astrophysics Data System (ADS)

Stoch, B.; Anthonissen, C. J.; McCall, M.-J.; Basson, I. J.; Deacon, J.; Cloete, E.; Botha, J.; Britz, J.; Strydom, M.; Nel, D.; Bester, M.

2017-12-01

The Sishen deposit is one of the largest iron ore concentrations in current production. Hematite mineralization occurs along a strike length of 14 km, with a width of 3.2 km and a maximum vertical extent of 400 m below the original surface. The 986-Mt reserve incorporates a suite of individual orebodies, beneath a locally preserved tectonized unconformity, with a wide range of geometries, depths, and orientations. Fully constrained, implicit 3D modeling of the entire mining volume (> 70 km3), was undertaken to the original, pre-mining topography. The model incorporates 5287 mapping points and > 21,000 drillholes and provides exceptional insight into the original configuration of ore and its relationship to contacts, unconformities, and structures in the enclosing country rock. The bulk of ore occurs to the west of a strike-extensive, partially inverted normal fault (Sloep Fault), within an asymmetrical synclinal structure on its western flank. This linear, N-S distribution of deep, thick ore is punctuated by palaeosinkholes, wherein base-of-ore dips of greater than 45°, are concentrically arranged. Localized ore volumes also occur along faults and in fault-bounded, downthrown blocks, to the north of NW-SE- and NE-SW-trending strike-slip faults that show relatively minor uplift to the south, probably due to the Lomanian Namaqua-Natal Orogeny. The revised model demonstrates the proximity of ore to a tectonized unconformity and highlights the structural control on ore volumes, implying that Fe mineralization at Sishen cannot be exclusively attributed to supergene enrichment and concentric palaeosinkhole formation.

Preliminary paleoseismic observations along the western Denali fault, Alaska

NASA Astrophysics Data System (ADS)

Koehler, R. D.; Schwartz, D. P.; Rood, D. H.; Reger, R.; Wolken, G. J.

2013-12-01

The Denali fault in south-central Alaska, from Mt. McKinley to the Denali-Totschunda fault branch point, accommodates ~9-12 mm/yr of the right-lateral component of oblique convergence between the Pacific/Yakutat and North American plates. The eastern 226 km of this fault reach was part of the source of the 2002 M7.9 Denali fault earthquake. West of the 2002 rupture there is evidence of two large earthquakes on the Denali fault during the past ~550-700 years but the paleoearthquake chronology prior to this time is largely unknown. To better constrain fault rupture parameters for the western Denali fault and contribute to improved seismic hazard assessment, we performed helicopter and ground reconnaissance along the southern flank of the Alaska Range between the Nenana Glacier and Pyramid Peak, a distance of ~35 km, and conducted a site-specific paleoseismic study. We present a Quaternary geologic strip map along the western Denali fault and our preliminary paleoseismic results, which include a differential-GPS survey of a displaced debris flow fan, cosmogenic 10Be surface exposure ages for boulders on this fan, and an interpretation of a trench across the main trace of the fault at the same site. Between the Nenana Glacier and Pyramid Peak, the Denali fault is characterized by prominent tectonic geomorphic features that include linear side-hill troughs, mole tracks, anastamosing composite scarps, and open left-stepping fissures. Measurements of offset rills and gullies indicate that slip during the most recent earthquake was between ~3 and 5 meters, similar to the average displacement in the 2002 earthquake. At our trench site, ~ 25 km east of the Parks Highway, a steep debris fan is displaced along a series of well-defined left-stepping linear fault traces. Multi-event displacements of debris-flow and snow-avalanche channels incised into the fan range from 8 to 43 m, the latter of which serves as a minimum cumulative fan offset estimate. The trench, excavated into the fan across the main fault scarp and adjacent graben, exposed sheared debris fan parent material at its north and south ends, separated by a central zone of stacked scarp-derived colluvium and weakly developed peaty soils. Stratigraphic relations and upward fault terminations clearly record the occurrence of the past three surface-faulting earthquakes and suggest four or more such events. Results of pending 14C analyses are expected to provide new information on earthquake timing and recurrence. A Holocene slip rate for this section of the fault will be developed using back-slip models and an estimate of the age of the fan constrained by our detailed surveys of channel offsets and pending cosmogenic 10Be exposure ages for surface boulders, respectively.

Neuroprotective effects of metallothionein against rotenone-induced myenteric neurodegeneration in parkinsonian mice.

PubMed

Murakami, Shinki; Miyazaki, Ikuko; Sogawa, Norio; Miyoshi, Ko; Asanuma, Masato

2014-10-01

Parkinson's disease (PD) is a neurodegenerative disease with motor symptoms as well as non-motor symptoms that precede the onset of motor symptoms. Mitochondrial complex I inhibitor, rotenone, has been widely used to reproduce PD pathology in the central nervous system (CNS) and enteric nervous system (ENS). We reported previously that metallothioneins (MTs) released from astrocytes can protect dopaminergic neurons against oxidative stress. The present study examined the changes in MT expression by chronic systemic rotenone administration in the striatum and colonic myenteric plexus of C57BL mice. In addition, we investigated the effects of MT depletion on rotenone-induced neurodegeneration in CNS and ENS using MT-1 and MT-2 knockout (MT KO) mice, or using primary cultured neurons from MT KO mice. In normal C57BL mice, subcutaneous administration of rotenone for 6 weeks caused neurodegeneration, increased MT expression with astrocytes activation in the striatum and myenteric plexus. MT KO mice showed more severe myenteric neuronal damage by rotenone administration after 4 weeks than wild-type mice, accompanied by reduced astroglial activation. In primary cultured mesencephalic neurons from MT KO mice, rotenone exposure induced neurotoxicity in dopaminergic neurons, which was complemented by addition of recombinant protein. The present results suggest that MT seems to provide protection against neurodegeneration in ENS of rotenone-induced PD model mice.

Expanding the functional human mitochondrial DNA database by the establishment of primate xenomitochondrial cybrids

PubMed Central

Kenyon, Lesley; Moraes, Carlos T.

1997-01-01

The nuclear and mitochondrial genomes coevolve to optimize approximately 100 different interactions necessary for an efficient ATP-generating system. This coevolution led to a species-specific compatibility between these genomes. We introduced mitochondrial DNA (mtDNA) from different primates into mtDNA-less human cells and selected for growth of cells with a functional oxidative phosphorylation system. mtDNA from common chimpanzee, pigmy chimpanzee, and gorilla were able to restore oxidative phosphorylation in the context of a human nuclear background, whereas mtDNA from orangutan, and species representative of Old-World monkeys, New-World monkeys, and lemurs were not. Oxygen consumption, a sensitive index of respiratory function, showed that mtDNA from chimpanzee, pigmy chimpanzee, and gorilla replaced the human mtDNA and restored respiration to essentially normal levels. Mitochondrial protein synthesis was also unaltered in successful “xenomitochondrial cybrids.” The abrupt failure of mtDNA from primate species that diverged from humans as recently as 8–18 million years ago to functionally replace human mtDNA suggests the presence of one or a few mutations affecting critical nuclear–mitochondrial genome interactions between these species. These cellular systems provide a demonstration of intergenus mtDNA transfer, expand more than 20-fold the number of mtDNA polymorphisms that can be analyzed in a human nuclear background, and provide a novel model for the study of nuclear–mitochondrial interactions. PMID:9256447

IRETHERM: The geothermal energy potential of Irish radiothermal granites

NASA Astrophysics Data System (ADS)

Farrell, Thomas; Jones, Alan; Muller, Mark; Feely, Martin; Brock, Andrew; Long, Mike; Waters, Tim

2014-05-01

The IRETHERM project is developing a strategic understanding of Ireland's deep geothermal energy potential through integrated modelling of new and existing geophysical and geological data. One aspect of IRETHERM's research focuses on Ireland's radiothermal granites, where increased concentrations of radioelements provide elevated heat-production (HP), surface heat-flow (SHF) and subsurface temperatures. An understanding of the contribution of granites to the thermal field of Ireland is important to assessing the geothermal energy potential of this low-enthalpy setting. This study focuses on the Galway granite in western Ireland, and the Leinster and the buried Kentstown granites in eastern Ireland. Shallow (<250 m) boreholes were drilled into the exposed Caledonian Leinster and Galway granites as part of a 1980's geothermal project. These studies yielded HP = 2-3 μWm-3 and HF = 80 mWm-2 at the Sally Gap borehole in the Northern Units of the Leinster granite, to the SW of Dublin. In the Galway granite batholith, on the west coast of Ireland, the Costelloe-Murvey granite returned HP = 7 μWm-3 and HF = 77 mWm-2, measured at the Rossaveal borehole. The buried Kentstown granite, 35 km NW of Dublin, has an associated negative Bouguer anomaly and was intersected by two mineral exploration boreholes at depths of 660 m and 490 m. Heat production is measured at 2.4 μWm-3 in core samples taken from the weathered top 30 m of the granite. The core of this study consists of a program of magnetotelluric (MT) and audio-magnetotelluric (AMT) data acquisition across the three granite bodies, over three fieldwork seasons. MT and AMT data were collected at 59 locations along two profiles over the Leinster granite. Preliminary results show that the northern units of the Leinster granite (40 km SW of Dublin) extend to depths of 2-5 km. Preliminary results from the southern profile suggest a greater thickness of granite to a depth of 6-9 km beneath the Tullow pluton, 75 km SW of Dublin. Over the Galway granite, MT and AMT data have been collected at a total of 75 sites (33 consist of only AMT data acquisition, with both MT and AMT recorded at the remaining 42). Preliminary results show a deep resistor extending to depths of 15-20 km beneath the central block, with the resistive upper layer extending to depths of 3.5-7 km west of the Shannawona fault, a major structure that cuts the batholith. MT and AMT data acquired along a profile at 22 locations over the Kentstown granite suggests that this buried granite is at a depth of 400 m beneath the centre of the gravity anomaly. The MT and AMT data will be integrated with gravity and seismic refraction data (in the case of the Leinster granite) to identify deeply penetrating faults, which may provide conduits for hydrothermal fluids, and to produce a robust estimation of the volumetric extent of the granites, which is crucial in defining their geothermal energy potential. Thermal conductivity and geochemical data will be incorporated to constrain the heat contribution of granites to the Irish crust.

IRETHERM: Magnetotelluric studies of Irish radiothermal granites and their geothermal energy potential

NASA Astrophysics Data System (ADS)

Farrell, T. F.; Jones, A. G.; Muller, M. R.; Feely, M.

2013-12-01

The IRETHERM project seeks to develop a strategic understanding of Ireland's deep geothermal energy potential through integrated modeling of new and existing geophysical and geological data. One aspect of IRETHERM's research focuses on Ireland's radiothermal granites, where increased concentrations of radioelements provide elevated heat-production (HP), heat-flow (HF) and subsurface temperatures. An understanding of the contribution of granites to the thermal field of Ireland is of key importance in assessing the geothermal energy potential of this low-enthalpy setting. This study focuses on the Leinster granite, the Galway granite and the buried Kentstown granite. Shallow (<250 m) boreholes were drilled into the exposed Caledonian Leinster and Galway granites as part of an early 1980's EU-funded geothermal project. These studies yielded HP = 2-3 μWm-3 and HF = 80 mWm-2 at the Sally Gap borehole in the Northern Units of the Leinster granite. In the Galway granite batholith, the Costelloe-Murvey granite returned HP = 7 μWm-3 and HF = 77 mWm-2, measured at the Ros a Mhil borehole. The lower heat-flow encountered at the Ros a Mhil borehole suggests that the associated high heat production does not extend to great depth. The buried Kentstown granite has associated with it a significant negative Bouguer anomaly and was intersected by two mineral exploration boreholes at depths of 660 m and 485 m. Heat production has been measured at 2.4 μWm-3 in core samples taken from the weathered top 30m of the granite. The core of this study consists of an ambitious program of magnetotelluric (MT) and audio-magnetotelluric (AMT) data acquisition across the three granite bodies, extending over three fieldwork seasons. MT and AMT data were collected at 59 locations along two profiles over the Leinster granite. Preliminary results show that the northern units of the Leinster granite extend to depths of 2-5 km. Over the Galway granite, MT and AMT data have been collected at a total of 29 sites, with a further 46 sites to be collected in August 2013 (of these 75 sites, 33 will consist of AMT-only data acquisition, with both MT and AMT recorded at the remaining 42). Preliminary results derived from the 29 sites recorded in 2012 show a deep resistor extending to depths of 15-20 km beneath the central block of the batholith, with the resistive body extending to depths of 3.5-7.0 km west of the Shannawona fault. MT and AMT data acquired along a profile at 22 locations over the Kentstown granite suggests that the top of this buried granite is at a depth of 380m beneath the center of the gravity anomaly. The MT and AMT data will be integrated with gravity data and seismic refraction data (in the case of the Leinster granite) to identify deeply penetrating faults, which may provide pathways for hydrothermal fluids, and to produce a robust estimation of the volumetric extent of the granites. Geochemical data will also be incorporated to ultimately constrain the local and regional thermal contribution and geothermal energy potential of the granites.

Data-driven simultaneous fault diagnosis for solid oxide fuel cell system using multi-label pattern identification

NASA Astrophysics Data System (ADS)

Li, Shuanghong; Cao, Hongliang; Yang, Yupu

2018-02-01

Fault diagnosis is a key process for the reliability and safety of solid oxide fuel cell (SOFC) systems. However, it is difficult to rapidly and accurately identify faults for complicated SOFC systems, especially when simultaneous faults appear. In this research, a data-driven Multi-Label (ML) pattern identification approach is proposed to address the simultaneous fault diagnosis of SOFC systems. The framework of the simultaneous-fault diagnosis primarily includes two components: feature extraction and ML-SVM classifier. The simultaneous-fault diagnosis approach can be trained to diagnose simultaneous SOFC faults, such as fuel leakage, air leakage in different positions in the SOFC system, by just using simple training data sets consisting only single fault and not demanding simultaneous faults data. The experimental result shows the proposed framework can diagnose the simultaneous SOFC system faults with high accuracy requiring small number training data and low computational burden. In addition, Fault Inference Tree Analysis (FITA) is employed to identify the correlations among possible faults and their corresponding symptoms at the system component level.

Fault detection and isolation for complex system

NASA Astrophysics Data System (ADS)

Jing, Chan Shi; Bayuaji, Luhur; Samad, R.; Mustafa, M.; Abdullah, N. R. H.; Zain, Z. M.; Pebrianti, Dwi

2017-07-01

Fault Detection and Isolation (FDI) is a method to monitor, identify, and pinpoint the type and location of system fault in a complex multiple input multiple output (MIMO) non-linear system. A two wheel robot is used as a complex system in this study. The aim of the research is to construct and design a Fault Detection and Isolation algorithm. The proposed method for the fault identification is using hybrid technique that combines Kalman filter and Artificial Neural Network (ANN). The Kalman filter is able to recognize the data from the sensors of the system and indicate the fault of the system in the sensor reading. Error prediction is based on the fault magnitude and the time occurrence of fault. Additionally, Artificial Neural Network (ANN) is another algorithm used to determine the type of fault and isolate the fault in the system.

Analysis of a hardware and software fault tolerant processor for critical applications

NASA Technical Reports Server (NTRS)

Dugan, Joanne B.

1993-01-01

Computer systems for critical applications must be designed to tolerate software faults as well as hardware faults. A unified approach to tolerating hardware and software faults is characterized by classifying faults in terms of duration (transient or permanent) rather than source (hardware or software). Errors arising from transient faults can be handled through masking or voting, but errors arising from permanent faults require system reconfiguration to bypass the failed component. Most errors which are caused by software faults can be considered transient, in that they are input-dependent. Software faults are triggered by a particular set of inputs. Quantitative dependability analysis of systems which exhibit a unified approach to fault tolerance can be performed by a hierarchical combination of fault tree and Markov models. A methodology for analyzing hardware and software fault tolerant systems is applied to the analysis of a hypothetical system, loosely based on the Fault Tolerant Parallel Processor. The models consider both transient and permanent faults, hardware and software faults, independent and related software faults, automatic recovery, and reconfiguration.

Determining the origin of enigmatic bedrock structures using apatite (U-Th)/He thermochronology: Alabama and Poverty Hills, Owens Valley, California

NASA Astrophysics Data System (ADS)

Ali, G. A.; Reiners, P. W.; Ducea, M.

2008-12-01

The Alabama and Poverty Hills are enigmatic, topographic highs of crystalline basement surrounded by Neogene sediments in Owens Valley, California. The 150-km long Owens Valley, the westernmost graben of the Basin and Range Province, initiated at about 3 Ma, creating ~2-4 km of vertical relief from the Sierra Nevada and White/Inyos crests to the valley floor. Along the valley, the active right-lateral Owens Valley Fault Zone (OVFZ) accommodates a significant portion of Pacific-North American plate motion, creating an oblique dextral fault zone, with localized transpression along minor left-stepovers. The dominantly granitic Mesozoic rocks of the Alabama Hills are bounded by the OVFZ to the east, and the granitic and metavolcanic Mesozoic rocks of the Poverty Hills are located along an apparent 3-km left stepover of the OVFZ. The tectonic origin and geodynamic significance of both these structures are not known, but previously published hypotheses include: 1) transpressional uplifts as OVFZ-related flower structures; 2) down-dropped normal fault blocks; and 3) giant landslides from adjacent ranges. We measured apatite (U-Th)/He ages on 15 samples from the Alabama and Poverty Hills to understand the history of shallow crustal exhumation of these structures, and to potentially correlate them to rocks from adjacent ranges. Apatite He dating typically yields cooling ages corresponding to closure temperatures of ~55-65 °C, corresponding roughly to depths of ~2-3 km in the crust. The majority of apatite He ages from the Alabama Hills ranged from 58-70 Ma, but the far eastern, and lowest elevation sample showed ages of 51-55 Ma. The Poverty Hills shows younger ages of 40-65 Ma and no recognizable spatial pattern. Although the data do not conclusively rule out a transpressional uplift origin of the Poverty Hills, the rocks within them could not have been exhumed from depths greater than ~2-3 km in Owens Valley. Data from both structures are most consistent with down-dropping from adjacent ranges. Apatite He ages in the Alabama Hills correlate with He ages of rocks about 2.5-3 km higher, near Mt. Whitney in the adjacent Sierra Nevada. This, coupled with the spatial pattern of ages, strongly suggests that the Alabama Hills are a down-dropped normal fault block along the Sierra Nevada frontal fault zone or a related fault. A structural reconstruction using tilt-corrected Sierran apatite He age-elevation correlations requires 2.6 km of vertical, and 1.5 km of eastward motion for the Alabama Hills. The proximity of this extensive down- dropped basement block, directly east of the highest topography in the Sierra Nevada, suggests the possibility of localized isostatic response as a cause for locally high elevation in the Mt. Whitney area.

The innate immune system in host mice targets cells with allogenic mitochondrial DNA

PubMed Central

Ishikawa, Kaori; Nakada, Kazuto; Morimoto, Mami; Imanishi, Hirotake; Yoshizaki, Mariko; Sasawatari, Shigemi; Niikura, Mamoru; Takenaga, Keizo; Yonekawa, Hiromichi

2010-01-01

Mitochondrial DNA (mtDNA) has been proposed to be involved in respiratory function, and mtDNA mutations have been associated with aging, tumors, and various disorders, but the effects of mtDNA imported into transplants from different individuals or aged subjects have been unclear. We examined this issue by generating trans-mitochondrial tumor cells and embryonic stem cells that shared the syngenic C57BL/6 (B6) strain–derived nuclear DNA background but possessed mtDNA derived from allogenic mouse strains. We demonstrate that transplants with mtDNA from the NZB/B1NJ strain were rejected from the host B6 mice, not by the acquired immune system but by the innate immune system. This rejection was caused partly by NK cells and involved a MyD88-dependent pathway. These results introduce novel roles of mtDNA and innate immunity in tumor immunology and transplantation medicine. PMID:20937705

Flight elements: Fault detection and fault management

NASA Technical Reports Server (NTRS)

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

1990-01-01

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

Parkin absence accelerates microtubule aging in dopaminergic neurons.

PubMed

Cartelli, Daniele; Amadeo, Alida; Calogero, Alessandra Maria; Casagrande, Francesca Vittoria Marialuisa; De Gregorio, Carmelita; Gioria, Mariarosa; Kuzumaki, Naoko; Costa, Ilaria; Sassone, Jenny; Ciammola, Andrea; Hattori, Nobutaka; Okano, Hideyuki; Goldwurm, Stefano; Roybon, Laurent; Pezzoli, Gianni; Cappelletti, Graziella

2018-01-01

Loss-of-function caused by mutations in the parkin gene (PARK2) lead to early-onset familial Parkinson's disease. Recently, mechanistic studies proved the ability of parkin in regulating mitochondria homeostasis and microtubule (MT) stability. Looking at these systems during aging of PARK2 knockout mice, we found that loss of parkin induced an accelerated (over)acetylation of MT system both in dopaminergic neuron cell bodies and fibers, localized in the substantia nigra and corpus striatum, respectively. Interestingly, in PARK2 knockout mice, changes of MT stability preceded the alteration of mitochondria transport. Moreover, in-cell experiments confirmed that loss of parkin affects mitochondria mobility and showed that this defect depends on MT system as it is rescued by paclitaxel, a well-known MT-targeted agent. Furthermore, both in PC12 neuronal cells and in patients' induced pluripotent stem cell-derived midbrain neurons, we observed that parkin deficiencies cause the fragmentation of stable MTs. Therefore, we suggest that parkin acts as a regulator of MT system during neuronal aging, and we endorse the hypothesis that MT dysfunction may be crucial in the pathogenesis of Parkinson's disease. Copyright © 2017 Elsevier Inc. All rights reserved.

Advances in the understanding of mitochondrial DNA as a pathogenic factor in inflammatory diseases

PubMed Central

Boyapati, Ray K.; Tamborska, Arina; Dorward, David A.; Ho, Gwo-Tzer

2017-01-01

Mitochondrial DNA (mtDNA) has many similarities with bacterial DNA because of their shared common ancestry. Increasing evidence demonstrates mtDNA to be a potent danger signal that is recognised by the innate immune system and can directly modulate the inflammatory response. In humans, elevated circulating mtDNA is found in conditions with significant tissue injury such as trauma and sepsis and increasingly in chronic organ-specific and systemic illnesses such as steatohepatitis and systemic lupus erythematosus. In this review, we examine our current understanding of mtDNA-mediated inflammation and how the mechanisms regulating mitochondrial homeostasis and mtDNA release represent exciting and previously under-recognised important factors in many human inflammatory diseases, offering many new translational opportunities. PMID:28299196

Thrust-controlled, gold quartz-vein mineralisation at the Tom's Gully mine, Northern Territory, Australia

NASA Astrophysics Data System (ADS)

Sheppard, S.

1996-01-01

Metasedimentary and minor metavolcanic rocks of the Early Proterozoic Pine Creek Inlier rest unconformably on Late Archaean granitic basement. Three basin-wide, regional deformation events at ca.1885 1870 Ma are recognised: I) W- to NW-verging thrusts and recumbent folds (D2), II) upright, open to tight, doubly-plunging, NNE- to NNW-trending folds (D3), and III) open, upright, E-trending folds (D4). In the centre of the Pine Creek Inlier, post-tectonic granites (1835 1820 Ma) are spatially, temporally and probably genetically associated with mesothermal gold-quartz vein deposits. The Tom's Gully deposit consists of a shallowly S-dipping quartz reef in graphitic shale and siltstone within the thermal aureole of the post-tectonic (1831 ± 6 Ma) Mt Bundey pluton. Gold mineralisation comprises two(?) SSW-plunging sulphidic ore-shoots which are intimately associated with brecciation and recrystallisation of early barren quartz. Where early quartz is absent from the thrust, gold mineralisation is not developed, indicating that this secondary brittle fracturing was essential to sulphide and gold deposition. The ore-shoots plunge parallel to the trend of D3 fold axes. The reef is hosted by a D2 thrust fault with transport to the NW. D3 folds in the hangingwall and footwall decrease in amplitude toward the reef indicating that, during continued E-W compression, the thrust acted as a décollement zone. Field relationships and microstructural studies suggest that quartz and sulphide were deposited in a reactivated thrust during wrench shear along several NNE-trending faults associated with emplacement of the Mt Bundey pluton.

Three-dimensional Magnetotelluric Characterization of the Xinzhou Geothermal Field, Southeastern China

NASA Astrophysics Data System (ADS)

Han, Q.; Hu, X.; Cai, J.; Wei, W.

2016-12-01

Xinzhou geothermal field is located in the Guangdong province and adjacent to the China South Sea, and its hot springs can reach up to 92 degree Celsius. Yanshanian granite expose widely in the south of this geothermal field and four faults cut across each other over it. A dense grid of 176 magnetotelluric (MT) sites with broadband has been acquired over the Xinzhou geothermal field and its surrounding area. Due to the related electromagnetic (EM) noise one permanent observatory was placed as a remote reference to suppress this cultural EM noise interference. The datasets are processed using the mutual reference technique, static shift correction, and structural strike and dimensionality analysis based on tensor decomposition. Data analysis reveals that the underground conductivity structure has obvious three-dimensional characterization. For the high resolution result ,two and three dimensional inversion are both applied in this area employing the non-linear conjugate gradient method (NLCG).These MT data sets are supposed to detect the deep subsurface resistivity structure correlated to the distribution of geothermal reservoir (such as faults and fractured granite) and investigate the channel of the upwelling magma. The whole and cold granite usually present high resistivity but once it functions as reservoir the resistivity will decrease, sometimes it is hard to separate the reservoir from the cap layer. The 3D inversion results delineate three high resistivity anomalies distributed in different locations. At last we put forward that the large areas of granite form the major thermal source for the study area and discuss whether any melt under these magma intrusions exists.

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.

Paleoenvironmental change in the southern Kenya Rift System: A case study based on the Pleistocene Olorgesailie and Oltulelei Formations

NASA Astrophysics Data System (ADS)

Behrensmeyer, A. K.; Potts, R.; Deino, A. L.

2017-12-01

The Pleistocene paleoenvironmental history of the East African Rift in southern Kenya is recorded by the Olorgesailie Fm. (1.2 - 0.5 ma) and the overlying Oltulelei Fm. ( 320 ka - 50 ka), which occur in a depositional basin north of Mt. Olorgesailie that extends into the northern end of the Koora Graben west of the mountain. The two formations preserve abundant archeological sites and fossil remains that document hominin behavior and paleoecology during the time in Africa when Homo erectus evolved into Homo sapiens. Geochronological calibration, based primarily on Ar-Ar dates of interbedded tephras, shows shifts in the physical landscape on time scales of 104 - 105 yrs, with a prolonged period of primarily lacustrine deposition (Olorgesailie Fm.) followed by tectonically driven changes in base level leading to accelerating cycles of erosion and deposition (Oltulelei Fm.). Following major erosion of the Olorgesailie Fm. between 500 and 320 ka, the Oltulelei Fm. was deposited during three cycles of aggradation and erosion, with fluvial, lacustrine and wetlands deposits preserved in fault-controlled areas or temporarily blocked drainage valleys. Deposition occurred in three sub-basins with varying degrees of linkage, reflecting a changing balance of sediment input and accommodation space controlled by climate, volcanism, and periodic movement of faults in the volcanic basement. Large volumes of sediment were removed during erosive phases, requiring increased precipitation and through-flowing drainage into Koora Graben southwest and south of Mt. Olorgesailie. The southern Kenya rift provided a shifting array of habitats and environmental challenges for hominins, which were driven both by the dynamic tectonic setting and climate cycles. Portions of both the Olorgesailie and Oltulelei Fms. correlate geochronologically with a drill core record 20 km to the south (ODP-OLO12-1A), which will provide paleoclimate information for times when erosion and subaerial landscapes prevailed in the Olorgesailie Basin to the north. This sets the stage for paleoenvironmental reconstructions that relate closely in time and space to documented changes in the archeology and faunas, which record critical transitions in technology and mammalian communities over the past 1.2 ma.

Geochemical Investigations In Soils And Waters Of Ischia Island (southern Italy)

NASA Astrophysics Data System (ADS)

Avino, R.; Capaldi, G.; Di Matteo, V.; Pece, R.

The island of Ischia is localized in the Gulf of Naples and is a volcanic field belonging to the volcanic district of the Phlegraean Fields. It covers an area of about 42 Km2 and is characterized by a complex system of faults and fractures of tectonic and volcano- tectonic origin. The highest peak of the island is Mt Epomeo (787 m), situated in the central part of Ischia. The last eruption on this island took place in 1302 (Arso) and from that time the volcanic activity has reduced only to hydrothermal manifestations (fumaroles and thermal springs) localized especially along the faults that border Mt Epomeo. So the area around the Epomeo is an area of great interest for geochemical investigations, and in fact in this place high concentration of mercury, carbon dioxide and radon have been measured. In this work are presented the data of a study on the concentration of CO2 and mercury and of the activity of radon in the soils and in the waters of the island of Ischia. For these investigations 184 samples of soils have been collected and analyzed in laboratory to calculate the concentration of mercury using the Jerome 511 Mercury Vapor Analyzer. In the same sampling sites measurements of CO2 and of the activity of radon-222 in the soils have also been made using the Track- etch@ method. As regards the waters, a sampling of 50 wells localized all around the coast of the island has been carried out. In these waters measures of mercury and of the activity of some radioactive elements have been done. The measures of radioactivity has been carried out by gamma spectrometry with a HPE Ge detector. All the investigations (in soils and in waters) allow to have preliminary information about the concentrations of these investigated elements and will be a starting-point for a more detailed sampling in those place where anomalies have been found. This set of data can also help to better understand the degassing process of these elements through the principal structures of the island giving information on the nature of the deep fluids.

NO-FAULT COMPENSATION FOR MEDICAL INJURIES: TRENDS AND CHALLENGES.

PubMed

Kassim, Puteri Nemie

2014-12-01

As an alternative to the tort or fault-based system, a no-fault compensation system has been viewed as having the potential to overcome problems inherent in the tort system by providing fair, speedy and adequate compensation for medically injured victims. Proponents of the suggested no-fault compensation system have argued that this system is more efficient in terms of time and money, as well as in making the circumstances in which compensation is paid, much clearer. However, the arguments against no-fault compensation systems are mainly on issues of funding difficulties, accountability and deterrence, particularly, once fault is taken out of the equation. Nonetheless, the no-fault compensation system has been successfully implemented in various countries but, at the same time, rejected in some others, as not being implementable. In the present trend, the no-fault system seems to fit the needs of society by offering greater access to justice for medically injured victims and providing a clearer "road map" towards obtaining suitable redress. This paper aims at providing the readers with an overview of the characteristics of the no fault compensation system and some examples of countries that have implemented it. Qualitative Research-Content Analysis. Given the many problems and hurdles posed by the tort or fault-based system, it is questionable that it can efficiently play its role as a mechanism that affords fair and adequate compensation for victims of medical injuries. However, while a comprehensive no-fault compensation system offers a tempting alternative to the tort or fault-based system, to import such a change into our local scenario requires a great deal of consideration. There are major differences, mainly in terms of social standing, size of population, political ideology and financial commitment, between Malaysia and countries that have successfully implemented no-fault systems. Nevertheless, implementing a no-fault compensation system in Malaysia is not entirely impossible. A custom-made no-fault model tailored to suit our local scenario can be promising, provided that a thorough research is made, assessing the viability of a no-fault system in Malaysia, addressing the inherent problems and, consequently, designing a workable no-fault system in Malaysia.

ALS-based hummock size-distance relationship assessment of Mt Shasta debris avalanche deposit, Northern California, USA

NASA Astrophysics Data System (ADS)

Tortini, Riccardo; Carn, Simon; van Wyk de Vries, Benjamin

2015-04-01

The failure of destabilized volcano flanks is a likely occurrence during the lifetime of a stratovolcano, generating large debris avalanches and drastically changing landforms around volcanoes. The significant hazards associated with these events in the Cascade range were demonstrated, for example, by the collapse of Mt St Helens (WA), which triggered its devastating explosive eruption in 1980. The rapid modification of the landforms due to these events makes it difficult to estimate the magnitude of prehistoric avalanches. However, the widespread preservation of hummocks along the course of rockslide-debris avalanches is highly significant for understanding the physical characteristics of these landslides. Mt Shasta is a 4,317 m high, snow-capped, steep-sloped stratovolcano located in Northern California. The current edifice began forming on the remnants of an ancestral Mt Shasta that collapsed ~300-380k years ago producing one of the largest debris avalanches known on Earth. The debris avalanche deposit (DAD) covers a surface of ~450 km2 across the Shasta valley, with an estimated volume of ~26 km3. We analyze ALS data on hummocks from the prehistoric Shasta valley DAD in northern California (USA) to derive the relationship between hummock size and distance from landslide source, and interpret the geomorphic significance of the intercept and slope coefficients of the observed functional relationships. Given the limited extent of the ALS survey (i.e. 40 km2), the high-resolution dataset is used for validation of the morphological parameters extracted from freely available, broader coverage DTMs such as the National Elevation Dataset (NED). The ALS dataset also permits the identification of subtle topographic features not apparent in the field or in coarser resolution datasets, including a previously unmapped fault, of crucial importance for both seismic and volcanic hazard assessment in volcanic areas. We present evidence from the Shasta DAD of neotectonic deformation along a north south tending fault and a comparison with the NED-derived DTM. This work aims to improve our understanding of the Shasta DAD morphology and dynamics, and provide insight into the cause and timing of events as well as the mode of emplacement of the DAD. The Cascade range includes numerous large extinct, dormant or active stratovolcanoes. Size-distance relationships will enable us to estimate the volume of the collapsed mass and the travel distance of the avalanche, and the knowledge of the link between basement structures and the Shasta DAD will elucidate the causes of edifice instability and may be used to target priority areas for volcanic hazard mapping.

Crustal structure of Wrangellia and adjacent terranes inferred from geophysical studies along a transect through the northern Talkeetna Mountains

USGS Publications Warehouse

Glen, J.M.G.; Schmidt, J.; Pellerin, L.; McPhee, D.K.; O'Neill, J. M.

2007-01-01

Recent investigations of the Talkeetna Mountains in south-central Alaska were undertaken to study the region's framework geophysics and to reinterpret structures and crustal composition. Potential field (gravity and magnetic) and magnetotelluric (MT) data were collected along northwest-trending profiles as part of the U.S. Geological Survey's Talkeetna Mountains transect project. The Talkeetna Mountains transect area comprises eight 1:63,360 quadrangles (???9500 km2) in the Healy and Talkeetna Mountains 1?? ?? 3?? sheets that span four major lithostratigraphic terranes (Glen et al., this volume) including the Wrangellia and Peninsular terranes and two Mesozoic overlap assemblages inboard (northwest) of Wrangellia. These data were used here to develop 21/2-dimensional models for the three profiles. Modeling results reveal prominent gravity, magnetic, and MT gradients (???3.25 mGal/ km, ???100nT/km, ???300 ohm-m/km) corresponding to the Talkeetna Suture Zone-a first-order crustal discontinuity in the deep crust that juxtaposes rocks with strongly contrasting rock properties. This discontinuity corresponds with the suture between relatively dense magnetic crust of Wrangellia (likely of oceanic composition) and relatively less dense transitional crust underlying Jurassic to Cretaceous flysch basins developed between Wrangellia and North America. Some area of the oceanic crust beneath Wrangellia may also have been underplated by mafic material during early to mid-Tertiary volcanism. The prominent crustal break underlies the Fog Lakes basin approximately where theTalkeetna thrust faultwaspreviouslymappedas a surface feature. Potential fieldand MT models, however, indicate that the Talkeetna Suture Zone crustal break along the transect is a deep (2-8 km), steeply west-dipping structure-not a shallow east-dipping Alpine nappe-like thrust. Indeed, most of the crustal breaks in the area appear to be steep in the geophysical data, which is consistent with regional geologic mapping that indicates that most of the faults are steep normal, reverse, strike-slip, or oblique-slip faults. Mapping further indicates that many of these features, which likely formed during Jurassic and Cretaceous time, such as the Talkeetna Suture Zone have reactivated inTertiary time (O'Neill et al., 2005). Copyright ?? 2007 The Geological Society of America.

Paleomagnetic and Rock Magnetic Study of Oligocene-Holocene Sedimentary Rocks from Northern Dominican Republic: Evidence of Vertical Axis Rotations

NASA Astrophysics Data System (ADS)

Anson Sanchez, M.; Kodama, K. P.; Pueyo, E. L.; Soto, R.; Garcia-Senz, J.; Escuder-Viruete, J.; Pastor-Galan, D.

2017-12-01

A paleomagnetic and rock magnetic study was conducted in the northern Dominican Republic to detect vertical axis rotations in an active left-lateral, strike slip fault zone. 191 samples from 21 sites were collected from a variety of lithologies including limestones, conglomerates, calcarenites and marls that ranged in age from the Oligocene to the Holocene. The rock magnetic portion of the study focused on the identification of magnetic minerals using coercivity, and Curie temperature (c vs temperature) measurement, modeling of IRM acquisition curves, and thermal demagnetization of IRMs (Lowrie, 19901). In the paleomagnetic portion of the study characteristic remanences (ChRMs) were isolated using thermal demagnetization (19 steps up to 680ºC) and alternating field (AF) demagnetization (17 steps up to 100 mT). In most cases the characteristic remanence is carried by magnetite, with peak unblocking temperatures of 575ºC. This interpretation was supported by c vs. T results that yielded Curie temperatures of 580˚C. In only a few cases (7 samples) higher unblocking temperatures suggested hematite as the magnetic carrier. The modeling of IRM acquisition curves, that shows two coercivity components, further supports the presence of magnetite. 75% of the IRM is carried by the low-coercivity component (100-300 mT, magnetite). 25% of the IRM is carried by the high-coercivity component (1.2-1.6T) characteristic of hematite. The IRM acquisition data was collected from 24 samples (3-4 from each of the lithologies sampled). IRMs were acquired in fields from 4mT to 1T in 23 steps. The paleomagnetic results show a grouping by tectonic blocks with one group having westerly ChRM declinations (268˚-295˚) and a second group having northerly ChRM declinations (357˚-035˚). In most cases, inclinations are intermediate ( 35˚), in agreement with the 24˚-31˚ expected inclinations for Dominican Republic in the period Oligocene to Holocene. The rotation of the tectonic blocks, as detected by the declinations, is consistent with a left-lateral strike-slip motion across the main fault in the area. 1Lowrie, 1990, GRL, 17, 159-162

High-Intensity Radiated Field Fault-Injection Experiment for a Fault-Tolerant Distributed Communication System

NASA Technical Reports Server (NTRS)

Yates, Amy M.; Torres-Pomales, Wilfredo; Malekpour, Mahyar R.; Gonzalez, Oscar R.; Gray, W. Steven

2010-01-01

Safety-critical distributed flight control systems require robustness in the presence of faults. In general, these systems consist of a number of input/output (I/O) and computation nodes interacting through a fault-tolerant data communication system. The communication system transfers sensor data and control commands and can handle most faults under typical operating conditions. However, the performance of the closed-loop system can be adversely affected as a result of operating in harsh environments. In particular, High-Intensity Radiated Field (HIRF) environments have the potential to cause random fault manifestations in individual avionic components and to generate simultaneous system-wide communication faults that overwhelm existing fault management mechanisms. This paper presents the design of an experiment conducted at the NASA Langley Research Center's HIRF Laboratory to statistically characterize the faults that a HIRF environment can trigger on a single node of a distributed flight control system.

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.

Petrographic and geochemical investigation of magma chamber processes beneath small Quaternary volcanic centers between Mt. Jefferson and Mt. Hood volcanoes, Cascade Range Volcanic Arc

NASA Astrophysics Data System (ADS)

Cunningham, E.; Cribb, J. W.

2017-12-01

The northern Oregon Cascade Range has been dominated by andesite to rhyodacite lavas at both Mt. Jefferson (Conrey, 1991) and at Mt. Hood (Cribb and Barton, 1996) during the Quaternary period. Eruptive sequences at both Mt. Hood and Mt. Jefferson have been attributed to open-system mama mixing (Kent et al., 2010) (Ferrell et al., 2015), and the narrow range of lavas erupted at both centers has been derived from repeated cycles of magma mixing-fractionation (Cribb and Barton, 1996). This research examines major and trace element geochemistry as well as the petrographic characteristics of Clear Lake Butte (CLB), Pinhead Butte (PB), and Olallie Butte (OB), all of which are located between Mt. Hood and Mt. Jefferson, and have ben active in the Quaternary period. The research investigates whether the same type of open-system magma mixing known to have occurred at Mt. Hood and Mt. Jefferson has also occurred at CLB, PB, or OB, or whether those systems were closed to mixing and dominated by fractional crystallization. One of the main goals of this project is to highlight the similarities and differences exhibited by neighboring magmatic systems of similar age, but different scale. Disequilibrium textures observed in thin sections from CLB, OB, and PB suggest open-system magma mixing is likely occurring beneath all three buttes. This petrographic evidence includes plagioclase and pyroxene zoning, embayed margins, sieving, and reaction rims. Major element oxide trends at all three buttes are consistent with fractional crystallization, but show narrow concentrations and non-overlapping compositions between PB, CLB, and OB. All three buttes are characterized by narrow ranges of incompatible and compatible trace element concentrations. CLB, PB, and OB all exhibit LREE enrichment and lack significant HFSE depletions, with PB exhibiting greatest enrichment in REE.

Coordinated Fault-Tolerance for High-Performance Computing Final Project Report

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

Panda, Dhabaleswar Kumar; Beckman, Pete

2011-07-28

With the Coordinated Infrastructure for Fault Tolerance Systems (CIFTS, as the original project came to be called) project, our aim has been to understand and tackle the following broad research questions, the answers to which will help the HEC community analyze and shape the direction of research in the field of fault tolerance and resiliency on future high-end leadership systems. Will availability of global fault information, obtained by fault information exchange between the different HEC software on a system, allow individual system software to better detect, diagnose, and adaptively respond to faults? If fault-awareness is raised throughout the system throughmore » fault information exchange, is it possible to get all system software working together to provide a more comprehensive end-to-end fault management on the system? What are the missing fault-tolerance features that widely used HEC system software lacks today that would inhibit such software from taking advantage of systemwide global fault information? What are the practical limitations of a systemwide approach for end-to-end fault management based on fault awareness and coordination? What mechanisms, tools, and technologies are needed to bring about fault awareness and coordination of responses on a leadership-class system? What standards, outreach, and community interaction are needed for adoption of the concept of fault awareness and coordination for fault management on future systems? Keeping our overall objectives in mind, the CIFTS team has taken a parallel fourfold approach. Our central goal was to design and implement a light-weight, scalable infrastructure with a simple, standardized interface to allow communication of fault-related information through the system and facilitate coordinated responses. This work led to the development of the Fault Tolerance Backplane (FTB) publish-subscribe API specification, together with a reference implementation and several experimental implementations on top of existing publish-subscribe tools. We enhanced the intrinsic fault tolerance capabilities representative implementations of a variety of key HPC software subsystems and integrated them with the FTB. Targeting software subsystems included: MPI communication libraries, checkpoint/restart libraries, resource managers and job schedulers, and system monitoring tools. Leveraging the aforementioned infrastructure, as well as developing and utilizing additional tools, we have examined issues associated with expanded, end-to-end fault response from both system and application viewpoints. From the standpoint of system operations, we have investigated log and root cause analysis, anomaly detection and fault prediction, and generalized notification mechanisms. Our applications work has included libraries for fault-tolerance linear algebra, application frameworks for coupled multiphysics applications, and external frameworks to support the monitoring and response for general applications. Our final goal was to engage the high-end computing community to increase awareness of tools and issues around coordinated end-to-end fault management.« less

Role of endothelial-to-mesenchymal transition in the pathogenesis of central nervous system hemangioblastomas.

PubMed

Takada, Shigeki; Hojo, Masato; Takebe, Noriyoshi; Tanigaki, Kenji; Miyamoto, Susumu

2018-06-07

Hemangioblastomas (HBs) are benign vascular tumors of the central nervous system and histologically contain abundant microvessels. Therefore, they clinically exhibit vascular malformation-like characteristics. It has been described that endothelial-to-mesenchymal transition (EndMT) contributes to the pathogenesis of cerebral cavernous malformations. However, it remains unknown whether EndMT contributes to the pathogenesis of central nervous system HBs. The aim of our study was to investigate whether EndMT occurs in central nervous system HBs. Ten central nervous system HBs were immunohistochemically investigated. CD31 (an endothelial marker) and EndMT markers, such as α-smooth muscle actin (a mesenchymal marker) and CD44 (a mesenchymal stem cell marker), were expressed in the endothelial layer of microvessels in all cases. These findings suggest that endothelial cells (ECs) of microvessels in central nervous system HBs have acquired mesenchymal and stem-cell-like characteristics and undergone EndMT. In all cases, both ephrin-B2 and EphB4, which are not detected in adult normal brain vessels, were expressed in the endothelial layer of microvessels. These data suggest that ECs of microvessels in central nervous system HBs are immature or malformed cells and have both arterial and venous characteristics. This is the first report showing the possibility that EndMT contributes to the pathogenesis of central nervous system HBs. It is likely that ECs of microvessels in central nervous system HBs are immature or malformed cells and have both arterial and venous characteristics. EndMT is expected to be a new therapeutic target in central nervous system HBs. Copyright © 2018 Elsevier Inc. All rights reserved.

Association of metallothionein-III with oligodendroglial cytoplasmic inclusions in multiple system atrophy.

PubMed

Pountney, D L; Dickson, T C; Power, J H T; Vickers, J C; West, A J; Gai, W P

2011-01-01

Multiple system atrophy (MSA) is an adult-onset neurodegenerative disease characterised by Parkinsonian and autonomic symptoms and by widespread intracytoplasmic inclusion bodies in oligodendrocytes. These glial cytoplasmic inclusions (GCIs) are comprised of 9-10 nm filaments rich in the protein alpha-synuclein, also found in neuronal inclusion bodies associated with Parkinson's disease. Metallothioneins (MTs) are a class of low-molecular weight (6-7 kDa), cysteine-rich metal-binding proteins the expression of which is induced by heavy metals, glucocorticoids, cytokines and oxidative stress. Recent studies have shown a role for the ubiquitously expressed MT-I/II isoforms in the brain following a variety of stresses, whereas, the function of the brain-specific MT isoform, MT-III, is less clear. MT-III and MT-I/II immunostaining of post-mortem tissue in MSA and normal control human brains showed that the number of MT-III-positive cells is significantly increased in MSA in visual cortex, whereas MT-I/II isoforms showed no significant difference in the distribution of immunopositive cells in MSA compared to normal tissue. GCIs were immunopositive for MT-III, but were immunonegative for the MT-I/II isoforms. Immunofluorescence double labelling showed the co-localisation of alpha-synuclein and MT-III in GCIs in MSA tissue. In isolated GCIs, transmission electron microscopy demonstrated MT-III immunogold labelling of the amorphous material surrounding alpha-synuclein filaments in GCIs. High-molecular weight MT-III species in addition to MT-III monomer were detected in GCIs by Western analysis of the detergent-solubilised proteins of purified GCIs. These results show that MT-III, but not MT-I/II, is a specific component of GCIs, present in abnormal aggregated forms external to the alpha-synuclein filaments.

76 FR 57633 - Amendment of Class E Airspace; Miles City, MT

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-16

...-0515; Airspace Docket No. 11-ANM-11] Amendment of Class E Airspace; Miles City, MT AGENCY: Federal... Miles City, MT, to accommodate aircraft using a new Area Navigation (RNAV) Global Positioning System... proposed rulemaking to modify controlled airspace at Miles City, MT (76 FR 41725). Interested parties were...

Real time system design of motor imagery brain-computer interface based on multi band CSP and SVM

NASA Astrophysics Data System (ADS)

Zhao, Li; Li, Xiaoqin; Bian, Yan

2018-04-01

Motion imagery (MT) is an effective method to promote the recovery of limbs in patients after stroke. Though an online MT brain computer interface (BCT) system, which apply MT, can enhance the patient's participation and accelerate their recovery process. The traditional method deals with the electroencephalogram (EEG) induced by MT by common spatial pattern (CSP), which is used to extract information from a frequency band. Tn order to further improve the classification accuracy of the system, information of two characteristic frequency bands is extracted. The effectiveness of the proposed feature extraction method is verified by off-line analysis of competition data and the analysis of online system.

A fault isolation method based on the incidence matrix of an augmented system

NASA Astrophysics Data System (ADS)

Chen, Changxiong; Chen, Liping; Ding, Jianwan; Wu, Yizhong

2018-03-01

A new approach is proposed for isolating faults and fast identifying the redundant sensors of a system in this paper. By introducing fault signal as additional state variable, an augmented system model is constructed by the original system model, fault signals and sensor measurement equations. The structural properties of an augmented system model are provided in this paper. From the viewpoint of evaluating fault variables, the calculating correlations of the fault variables in the system can be found, which imply the fault isolation properties of the system. Compared with previous isolation approaches, the highlights of the new approach are that it can quickly find the faults which can be isolated using exclusive residuals, at the same time, and can identify the redundant sensors in the system, which are useful for the design of diagnosis system. The simulation of a four-tank system is reported to validate the proposed method.

Parameter Transient Behavior Analysis on Fault Tolerant Control System

NASA Technical Reports Server (NTRS)

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

2003-01-01

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

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.

A footwall system of faults associated with a foreland thrust in Montana

NASA Astrophysics Data System (ADS)

Watkinson, A. J.

1993-05-01

Some recent structural geology models of faulting have promoted the idea of a rigid footwall behaviour or response under the main thrust fault, especially for fault ramps or fault-bend folds. However, a very well-exposed thrust fault in the Montana fold and thrust belt shows an intricate but well-ordered system of subsidiary minor faults in the footwall position with respect to the main thrust fault plane. Considerable shortening has occurred off the main fault in this footwall collapse zone and the distribution and style of the minor faults accord well with published patterns of aftershock foci associated with thrust faults. In detail, there appear to be geometrically self-similar fault systems from metre length down to a few centimetres. The smallest sets show both slip and dilation. The slickensides show essentially two-dimensional displacements, and three slip systems were operative—one parallel to the bedding, and two conjugate and symmetric about the bedding (acute angle of 45-50°). A reconstruction using physical analogue models suggests one possible model for the evolution and sequencing of slip of the thrust fault system.

Integrated Approach To Design And Analysis Of Systems

NASA Technical Reports Server (NTRS)

Patterson-Hine, F. A.; Iverson, David L.

1993-01-01

Object-oriented fault-tree representation unifies evaluation of reliability and diagnosis of faults. Programming/fault tree described more fully in "Object-Oriented Algorithm For Evaluation Of Fault Trees" (ARC-12731). Augmented fault tree object contains more information than fault tree object used in quantitative analysis of reliability. Additional information needed to diagnose faults in system represented by fault tree.

Fault recovery for real-time, multi-tasking computer system

NASA Technical Reports Server (NTRS)

Hess, Richard (Inventor); Kelly, Gerald B. (Inventor); Rogers, Randy (Inventor); Stange, Kent A. (Inventor)

2011-01-01

System and methods for providing a recoverable real time multi-tasking computer system are disclosed. In one embodiment, a system comprises a real time computing environment, wherein the real time computing environment is adapted to execute one or more applications and wherein each application is time and space partitioned. The system further comprises a fault detection system adapted to detect one or more faults affecting the real time computing environment and a fault recovery system, wherein upon the detection of a fault the fault recovery system is adapted to restore a backup set of state variables.

Application of magnetotelluric in the modeling of underlying structure of Gour Oumelalen (Egere-Aleksod terrane, Central Hoggar, South of Algeria)

NASA Astrophysics Data System (ADS)

Boukhalfa, Zakaria; Abderrezak, Bouzid; Khadidja, Ouzegane; Abderrahmane, Bendaoud; Mohamed, Hamoudi; Abdeslam, Abtout; Abdelhamid, Bendekken; Sofiane Said, Bougchiche; Walid, Boukhlouf; Abdelgharfour, Boukar; Aboubakr, Deramchi; Mohamed, Bendali; Abdenaceur, Lemgharbi; Mohammed, Djeddi

2016-04-01

The results of a magnetotelluric experiment crossing Ounane granodiorite to the east until the Amadror Wadi to the West, passing through Adrar Ounane in our study area are presented. The magnetotelluric field survey was carried out in the Gour Oumelalen (GO) area during March 2015. We deployed 34 magnetotelluric sites along two parallel EW profiles of a hundred km long. Time series were collected using a V5 system 2000® of Phoenix Geophysics. The first profile located to the north is composed of 18 braodband measurement sites obtained from merging magnetotelluri with audio-magnetotelluric (AMT) data. The second one located 10 km south of the first, is composed of 15 MT sites. An inter-station distance of ~5 km provides good lateral resolution. The MT time series were recorded during about 20 hours which allows to reach a depth of 100 km or more and the AMT data 30 minutes. This allows to get broadband magnetotelluric soundings with good quality data in period range from 0.001 s to 3000 s. In this study we will use the south profile data for modeling the underlying structure of GO. The crustal part of the model shows a resistance bloc, divided by conductive parts which can be interpreted as faults, as regards the lithospheric part it less resistant the upper part, the transition crust / mantle corresponding to MOHO is estimated at more or less 35 km.

A missing element of the deep carbon cycle: CO2 degassing estimates from rift length analysis during Pangea fragmentation

NASA Astrophysics Data System (ADS)

Brune, S.; Williams, S.; Müller, D.

2016-12-01

The deep carbon cycle connects CO2 within the atmosphere and oceans to the vast CO2 reservoir in Earth's mantle: subducted lithosphere carries CO2 into the mantle, while extensional plate boundaries and arc volcanoes release it back to Earth's surface. The length of plate boundaries thereby exerts first-order control on global CO2 fluxes on geological time scales. Here we provide a worldwide census of extensional plate boundary length from the Triassic to present day, in one million year time intervals, using a novel analysis technique (Brune et al. 2016, Nature, doi:10.1038/nature18319). The most extensive rift phase during the fragmentation of Pangea occurred in the Cretaceous with extension along the South Atlantic (9700 km) and North Atlantic rifts (9100 km), within East Gondwana (8500 km), and the failed African rift systems (4900 km). The combined extent of these and several smaller rifts amounts to more than 30.000 km of simultaneously active continental rifting. It is well-accepted that volcanoes at plate boundaries release large amounts of CO2 from the Earth's interior. Recent work, however, revealed the importance of deep-cutting faults and diffuse degassing on CO2 emissions in the East African rift (Lee et al. 2016, Nature Geoscience, doi: 10.1038/ngeo2622). Upscaling these measured CO2 fluxes to all concurrently active global rift zones, we compute first-order estimates of total rift-related CO2 degassing rates for the last 240 Myr. Our results show that rift-related CO2 release rates may have reached 600 Mt/yr in the Early Cretaceous, while Cenozoic rates rarely exceeded 200 Mt/yr. By comparison, present-day estimates of CO2 release at mid-ocean ridges range between 53 and 97 Mt/yr. We suggest that rift-related degassing during supercontinental breakup played a major role in maintaining high atmospheric CO2 concentrations through Mesozoic times, which exceeded Quaternary values by 400%.

Stafford fault system: 120 million year fault movement history of northern Virginia

USGS Publications Warehouse

Powars, David S.; Catchings, Rufus D.; Horton, J. Wright; Schindler, J. Stephen; Pavich, Milan J.

2015-01-01

The Stafford fault system, located in the mid-Atlantic coastal plain of the eastern United States, provides the most complete record of fault movement during the past ~120 m.y. across the Virginia, Washington, District of Columbia (D.C.), and Maryland region, including displacement of Pleistocene terrace gravels. The Stafford fault system is close to and aligned with the Piedmont Spotsylvania and Long Branch fault zones. The dominant southwest-northeast trend of strong shaking from the 23 August 2011, moment magnitude Mw 5.8 Mineral, Virginia, earthquake is consistent with the connectivity of these faults, as seismic energy appears to have traveled along the documented and proposed extensions of the Stafford fault system into the Washington, D.C., area. Some other faults documented in the nearby coastal plain are clearly rooted in crystalline basement faults, especially along terrane boundaries. These coastal plain faults are commonly assumed to have undergone relatively uniform movement through time, with average slip rates from 0.3 to 1.5 m/m.y. However, there were higher rates during the Paleocene–early Eocene and the Pliocene (4.4–27.4 m/m.y), suggesting that slip occurred primarily during large earthquakes. Further investigation of the Stafford fault system is needed to understand potential earthquake hazards for the Virginia, Maryland, and Washington, D.C., area. The combined Stafford fault system and aligned Piedmont faults are ~180 km long, so if the combined fault system ruptured in a single event, it would result in a significantly larger magnitude earthquake than the Mineral earthquake. Many structures most strongly affected during the Mineral earthquake are along or near the Stafford fault system and its proposed northeastward extension.

The Southern Washington Cascades magmatic system imaged with magnetotellurics

NASA Astrophysics Data System (ADS)

Bowles-martinez, E.; Bedrosian, P.; Schultz, A.; Hill, G. J.; Peacock, J.

2016-12-01

The goal of the interdisciplinary iMUSH project (Imaging Magma Under Saint Helens) is to image the magmatic system of Mount Saint Helens (MSH), and to determine the relationship of this system to the greater Cascades volcanic arc. We are especially interested in an anomalously conductive crustal zone between MSH and Mount Adams known as the Southern Washington Cascades Conductor (SWCC), which early studies interpreted as accreted sediments, but more recently has been interpreted as a broad region of partial melt. MSH is located 50 km west of the main arc and is the most active of the Cascade volcanoes. Its 1980 eruption highlighted the need to understand this potentially hazardous volcanic system. We use wideband magnetotelluric (MT) data collected in 2014-2015 along with data from earlier studies to create a 3D model of the electrical resistivity throughout the region, covering MSH as well as Mount Adams and Mount Rainier along the main volcanic arc. We look at not only the volcanoes themselves, but also their relationship to one another and to regional geologic structures. Preliminary modeling identifies several conductive features, including a mid-crustal conductive region between MSH and Mount Adams that passes below Indian Heaven Volcanic Field and coincides with a region with a high Vp/Vs ratio identified in the seismic component of iMUSH. This suggests that it could be magmatic, but does not preclude the possibility of conductive sediments. Synthesis of seismic and MT data to address this question is ongoing. We also note a conductive zone running north-south just west of MSH that is likely associated with fluids within faults of the Saint Helens Seismic Zone. We finally note that curvature of the conductive lineament that defines the main Cascade arc suggests that the boundary of magmatism is influenced by compression within the Yakima Fold and Thrust Belt, east and southeast of Mount Adams.

Climate influence on volcano edifice stability and fluvial landscape evolution surrounding Mount Ruapehu, New Zealand

NASA Astrophysics Data System (ADS)

Tost, M.; Cronin, S. J.

2016-06-01

Large volcanic debris avalanches are triggered by failure of the steep flanks of long-lived composite cones. Their huge deposits change the landscape and drainage pattern surrounding stratovolcanoes for thousands of years. At Mt. Ruapehu, New Zealand, we identified seven major flank-collapse events that produced debris avalanches travelling down pre-existing river catchments for up to 90 km from source. In two cases the extreme mass flux into the river valleys led to their complete truncation from the volcano, while four drainage systems were subsequently re-established along similar pathways influenced by regional strike-slip faulting, which caused localized graben formation. In all cases the volcanic debris-avalanche deposits currently form distinctive plateaus at or near the highest topographic elevations of each river valley margin. The timing of the flank failures indicate that inter-eruptive cone destabilization of Mt. Ruapehu is affected by climate change and occurs most commonly during interstadials when glaciers on the cone are in retreat, whereas syn-eruptive collapses are most prominent during cold stages. Dated debris-avalanche deposit levels, along with those of up to four stadial-related aggradational gravel terraces between c. 125 and 18 ka, were used to calculate regional uplift rates in this area. Rates of between 0.2 ± 0.1 mm yr- 1 to 3.8 ± 0.8 mm yr- 1 are found for four river systems dissecting the central North Island of New Zealand. In three cases incision below the diamicton sequences and into the basement, allowed quantification of sediment-flux rates into the Tasman Sea of 107,000 ± 1,200 m3 yr- 1 to 177,000 ± 3,500 m3 yr- 1 since debris-avalanche emplacement.

Mitochondrial DNA damage is associated with damage accrual and disease duration in patients with Systemic Lupus Erythematosus

PubMed Central

López-López, Linnette; Nieves-Plaza, Mariely; Castro, María del R.; Font, Yvonne M.; Torres-Ramos, Carlos; Vilá, Luis M.; Ayala-Peña, Sylvette

2014-01-01

Objective To determine the extent of mitochondrial DNA (mtDNA) damage in systemic lupus erythematosus (SLE) patients compared to healthy subjects and to determine the factors associated with mtDNA damage among SLE patients. Methods A cross-sectional study was performed in 86 SLE patients (per American College of Rheumatology classification criteria) and 86 healthy individuals matched for age and gender. Peripheral blood mononuclear cells (PBMCs) were collected from subjects to assess the relative amounts of mtDNA damage. Quantitative polymerase chain reaction assay was used to measure the frequency of mtDNA lesions and mtDNA abundance. Socioeconomic-demographic features, clinical manifestations, pharmacologic treatment, disease activity, and damage accrual were determined. Statistical analyses were performed using t test, pairwise correlation, and Pearson’s chi-square test (or Fisher’s exact test) as appropriate. Results Among SLE patients, 93.0% were women. The mean (SD) age was 38.0 (10.4) years and the mean (SD) disease duration was 8.7 (7.5) years. SLE patients exhibited increased levels of mtDNA damage as shown by higher levels of mtDNA lesions and decreased mtDNA abundance as compared to healthy individuals. There was a negative correlation between disease damage and mtDNA abundance and a positive correlation between mtDNA lesions and disease duration. No association was found between disease activity and mtDNA damage. Conclusion PBMCs from SLE patients exhibited more mtDNA damage compared to healthy subjects. Higher levels of mtDNA damage were observed among SLE patients with major organ involvement and damage accrual. These results suggest that mtDNA damage have a potential role in the pathogenesis of SLE. PMID:24899636

Mitochondrial DNA damage is associated with damage accrual and disease duration in patients with systemic lupus erythematosus.

PubMed

López-López, L; Nieves-Plaza, M; Castro, M del R; Font, Y M; Torres-Ramos, C A; Vilá, L M; Ayala-Peña, S

2014-10-01

To determine the extent of mitochondrial DNA (mtDNA) damage in systemic lupus erythematosus (SLE) patients compared to healthy subjects and to determine the factors associated with mtDNA damage among SLE patients. A cross-sectional study was performed in 86 SLE patients (per American College of Rheumatology classification criteria) and 86 healthy individuals matched for age and gender. Peripheral blood mononuclear cells (PBMCs) were collected from subjects to assess the relative amounts of mtDNA damage. Quantitative polymerase chain reaction assay was used to measure the frequency of mtDNA lesions and mtDNA abundance. Socioeconomic-demographic features, clinical manifestations, pharmacologic treatment, disease activity, and damage accrual were determined. Statistical analyses were performed using t test, pairwise correlation, and Pearson's chi-square test (or Fisher's exact test) as appropriate. Among SLE patients, 93.0% were women. The mean (SD) age was 38.0 (10.4) years and the mean (SD) disease duration was 8.7 (7.5) years. SLE patients exhibited increased levels of mtDNA damage as shown by higher levels of mtDNA lesions and decreased mtDNA abundance as compared to healthy individuals. There was a negative correlation between disease damage and mtDNA abundance and a positive correlation between mtDNA lesions and disease duration. No association was found between disease activity and mtDNA damage. PBMCs from SLE patients exhibited more mtDNA damage compared to healthy subjects. Higher levels of mtDNA damage were observed among SLE patients with major organ involvement and damage accrual. These results suggest that mtDNA damage have a potential role in the pathogenesis of SLE. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Differential Extension, Displacement Transfer, and the South to North Decrease in Displacement on the Furnace Creek - Fish Lake Valley Fault System, Western Great Basin.

NASA Astrophysics Data System (ADS)

Katopody, D. T.; Oldow, J. S.

2015-12-01

The northwest-striking Furnace Creek - Fish Lake Valley (FC-FLV) fault system stretches for >250 km from southeastern California to western Nevada, forms the eastern boundary of the northern segment of the Eastern California Shear Zone, and has contemporary displacement. The FC-FLV fault system initiated in the mid-Miocene (10-12 Ma) and shows a south to north decrease in displacement from a maximum of 75-100 km to less than 10 km. Coeval elongation by extension on north-northeast striking faults within the adjoining blocks to the FC-FLV fault both supply and remove cumulative displacement measured at the northern end of the transcurrent fault system. Elongation and displacement transfer in the eastern block, constituting the southern Walker Lane of western Nevada, exceeds that of the western block and results in the net south to north decrease in displacement on the FC-FLV fault system. Elongation in the eastern block is accommodated by late Miocene to Pliocene detachment faulting followed by extension on superposed, east-northeast striking, high-angle structures. Displacement transfer from the FC-FLV fault system to the northwest-trending faults of the central Walker Lane to the north is accomplished by motion on a series of west-northwest striking transcurrent faults, named the Oriental Wash, Sylvania Mountain, and Palmetto Mountain fault systems. The west-northwest striking transcurrent faults cross-cut earlier detachment structures and are kinematically linked to east-northeast high-angle extensional faults. The transcurrent faults are mapped along strike for 60 km to the east, where they merge with north-northwest faults forming the eastern boundary of the southern Walker Lane. The west-northwest trending transcurrent faults have 30-35 km of cumulative left-lateral displacement and are a major contributor to the decrease in right-lateral displacement on the FC-FLV fault system.

77 FR 41939 - Proposed Establishment of Class E Airspace; Deer Lodge, MT

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-17

...-0379; Airspace Docket No. 12-ANM-7 Proposed Establishment of Class E Airspace; Deer Lodge, MT AGENCY... action proposes to establish Class E airspace at Deer Lodge-City-County Airport, Deer Lodge, MT... System (GPS) standard instrument approach procedures at Deer Lodge-City-County Airport, Deer Lodge, MT...

Satellite-based Observation of the Tectonics of Southern Tibet

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

Ryerson, F J; Finkel, R; van der Woerd, J

2003-02-06

The Himalayas and the Tibetan Plateau were formed as a result of the collision of India and Asia, and provide an excellent natural laboratory for the investigation of the mechanical response of the outer 100 km of the Earth (the lithosphere) to tectonic stress. Geophysicists are divided in their views on the nature of this response with one group advocating homogeneously distributed deformation in which the lithosphere deforms as a fluid continuum while others contend that deformation is highly localized with the lithosphere deforming as a system of rigid blocks. These rigid blocks or plate undergo little internal deformation. Themore » latter group draws support from the high slip-rates recently observed on strike-slip faults along the northern edge of the Plateau (the Altyn Tagh Fault, ATF), coupled with seismic observations suggesting that these faults penetrate the entire lithosphere. These ''lithospheric faults'' define continental lithospheric plates and facilitate the eastward extrusion of the ''central Tibet plate''. If extrusion of a rigid Tibet occurs then there must be equivalent features at its southern boundary with slip-rates similar to those in the north. The southern boundary of Tibet, defined by the Main Himalayan Thrust (MHT), has no lateral component of motion and is therefore kinematically incompatible with motion in the north. However, a series of features, the Karakorum Fault, the Karakorum-Jiali Fracture Zone (KJFZ), the Jiali Fault and the Red River Fault which lie to the north of the MHT may define the actual, kinematic, southern boundary of this ''central Tibet plate''. We have investigated the rate of slip along the Karakorum Fault (KKF), the major strike-slip fault in southwestern Tibet. If the KKF represents the actual, kinematic, southern boundary of this Tibet, and is the only feature accommodating eastward extrusion of Tibet, then its slip-rate should be similar to that of the ATF in the north. Offsets along the Karakorum Fault ranging from tens of meters to kilometers have been mapped using satellite imagery and field mapping, and samples ages determined by cosmic-ray exposure dating. Near Bulong Kol (39{sup o}N, 75{sup o}E) cosmogenic dating of a 40 m fluvial offset yields a slip rate of {approx}6.5 mm/yr. Near Mt. Kailas (31.5{sup o}N, 80.7{sup o}E), a glacial moraine offset by {approx}350 m has been dated at 32.3 {+-} 9.5 thousand years, yielding a slip rate of 10.8 {+-} 3.6 mm/yr. In the Gar Valley (32{sup o}N, 80{sup o}E) a river channel incised in glacial sediments yields an offset of 1750 m and an age of 283,000 years equivalent to a slip-rate of 6 mm/yr. Relative to the ATF, the slip rates on the KKF are lower than expected, and since these measurements cover almost the entire length of the KKF, the disparity cannot be attributed to along strike variation in the rate. Based upon the analysis of satellite images along the Karakorum Fault, we believe that this apparent slip deficit may be to the en echelon arrangement of multiple strike slip fault segments that characterize what should more appropriately be called the Karakorum Fault Zone. The geometric arrangement of parallel fault segments produces the ''pull apart'' basins that form the valleys along the KKF. Hence, at any given latitude, slip along the KKF may be distributed among numerous fault segments. This investigation supports efforts to understand the structure and mechanical response of the Earth's crust and supports the application of remote sensing methods.« less

Endothelial to mesenchymal transition in the cardiovascular system.

PubMed

Gong, Hui; Lyu, Xing; Wang, Qiong; Hu, Min; Zhang, Xiangyu

2017-09-01

Endothelial to mesenchymal transition (EndMT) is a special type of epithelial to mesenchymal transition. It is a process that is characterized by the loss of features of endothelial cells and acquisition of specific markers of mesenchymal cells. A variety of stimuli, such as inflammation, growth factors, and hypoxia, regulate EndMT through various signaling pathways and intracellular transcription factors. It has been demonstrated that epigenetic modifications are also involved in this process. Recent studies have identified the essential role of EndMT in the cardiovascular system. EndMT contributes to steps in cardiovascular development, such as cardiac valve formation and septation, as well as the pathogenesis of various cardiovascular disorders, such as congenital heart disease, myocardial fibrosis, myocardial infarction and pulmonary arterial hypertension. Thus, comprehensive understanding of the underlying mechanisms of EndMT will provide novel therapeutic strategies to overcome congenital heart disease due to abnormal development and other cardiovascular diseases. This review will focus on summarizing the currently understood signaling pathways and epigenetic modifications involved in the regulation of EndMT and the role of EndMT in pathophysiological conditions of the cardiovascular system. Copyright © 2017. Published by Elsevier Inc.

Assessment of metallothionein and antibodies to metallothionein in normal and autistic children having exposure to vaccine-derived thimerosal.

PubMed

Singh, Vijendra K; Hanson, Jeff

2006-06-01

Allergic autoimmune reaction after exposure to heavy metals such as mercury may play a causal role in autism, a developmental disorder of the central nervous system. As metallothionein (MT) is the primary metal-detoxifying protein in the body, we conducted a study of the MT protein and antibodies to metallothionein (anti-MT) in normal and autistic children whose exposure to mercury was only from thimerosal-containing vaccines. Laboratory analysis by immunoassays revealed that the serum level of MT did not significantly differ between normal and autistic children. Furthermore, autistic children harboured normal levels of anti-MT, including antibodies to isoform MT-I (anti-MT-I) and MT-II (anti-MT-II), without any significant difference between normal and autistic children. Our findings indicate that because autistic children have a normal profile of MT and anti-MT, the mercury-induced autoimmunity to MT may not be implicated in the pathogenesis of autism.

Multiple incipient sensor faults diagnosis with application to high-speed railway traction devices.

PubMed

Wu, Yunkai; Jiang, Bin; Lu, Ningyun; Yang, Hao; Zhou, Yang

2017-03-01

This paper deals with the problem of incipient fault diagnosis for a class of Lipschitz nonlinear systems with sensor biases and explores further results of total measurable fault information residual (ToMFIR). Firstly, state and output transformations are introduced to transform the original system into two subsystems. The first subsystem is subject to system disturbances and free from sensor faults, while the second subsystem contains sensor faults but without any system disturbances. Sensor faults in the second subsystem are then formed as actuator faults by using a pseudo-actuator based approach. Since the effects of system disturbances on the residual are completely decoupled, multiple incipient sensor faults can be detected by constructing ToMFIR, and the fault detectability condition is then derived for discriminating the detectable incipient sensor faults. Further, a sliding-mode observers (SMOs) based fault isolation scheme is designed to guarantee accurate isolation of multiple sensor faults. Finally, simulation results conducted on a CRH2 high-speed railway traction device are given to demonstrate the effectiveness of the proposed approach. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Discovery and Characterization of the 3-Hydroxyacyl-ACP Dehydratase Component of the Plant Mitochondrial Fatty Acid Synthase System1[OPEN

PubMed Central

Okazaki, Yozo; Lithio, Andrew; Jin, Huanan

2017-01-01

We report the characterization of the Arabidopsis (Arabidopsis thaliana) 3-hydroxyacyl-acyl carrier protein dehydratase (mtHD) component of the mitochondrial fatty acid synthase (mtFAS) system, encoded by AT5G60335. The mitochondrial localization and catalytic capability of mtHD were demonstrated with a green fluorescent protein transgenesis experiment and by in vivo complementation and in vitro enzymatic assays. RNA interference (RNAi) knockdown lines with reduced mtHD expression exhibit traits typically associated with mtFAS mutants, namely a miniaturized morphological appearance, reduced lipoylation of lipoylated proteins, and altered metabolomes consistent with the reduced catalytic activity of lipoylated enzymes. These alterations are reversed when mthd-rnai mutant plants are grown in a 1% CO2 atmosphere, indicating the link between mtFAS and photorespiratory deficiency due to the reduced lipoylation of glycine decarboxylase. In vivo biochemical feeding experiments illustrate that sucrose and glycolate are the metabolic modulators that mediate the alterations in morphology and lipid accumulation. In addition, both mthd-rnai and mtkas mutants exhibit reduced accumulation of 3-hydroxytetradecanoic acid (i.e. a hallmark of lipid A-like molecules) and abnormal chloroplastic starch granules; these changes are not reversible by the 1% CO2 atmosphere, demonstrating two novel mtFAS functions that are independent of photorespiration. Finally, RNA sequencing analysis revealed that mthd-rnai and mtkas mutants are nearly equivalent to each other in altering the transcriptome, and these analyses further identified genes whose expression is affected by a functional mtFAS system but independent of photorespiratory deficiency. These data demonstrate the nonredundant nature of the mtFAS system, which contributes unique lipid components needed to support plant cell structure and metabolism. PMID:28202596

Strike-slip fault propagation and linkage via work optimization with application to the San Jacinto fault, California

NASA Astrophysics Data System (ADS)

Madden, E. H.; McBeck, J.; Cooke, M. L.

2013-12-01

Over multiple earthquake cycles, strike-slip faults link to form through-going structures, as demonstrated by the continuous nature of the mature San Andreas fault system in California relative to the younger and more segmented San Jacinto fault system nearby. Despite its immaturity, the San Jacinto system accommodates between one third and one half of the slip along the boundary between the North American and Pacific plates. It therefore poses a significant seismic threat to southern California. Better understanding of how the San Jacinto system has evolved over geologic time and of current interactions between faults within the system is critical to assessing this seismic hazard accurately. Numerical models are well suited to simulating kilometer-scale processes, but models of fault system development are challenged by the multiple physical mechanisms involved. For example, laboratory experiments on brittle materials show that faults propagate and eventually join (hard-linkage) by both opening-mode and shear failure. In addition, faults interact prior to linkage through stress transfer (soft-linkage). The new algorithm GROW (GRowth by Optimization of Work) accounts for this complex array of behaviors by taking a global approach to fault propagation while adhering to the principals of linear elastic fracture mechanics. This makes GROW a powerful tool for studying fault interactions and fault system development over geologic time. In GROW, faults evolve to minimize the work (or energy) expended during deformation, thereby maximizing the mechanical efficiency of the entire system. Furthermore, the incorporation of both static and dynamic friction allows GROW models to capture fault slip and fault propagation in single earthquakes as well as over consecutive earthquake cycles. GROW models with idealized faults reveal that the initial fault spacing and the applied stress orientation control fault linkage propensity and linkage patterns. These models allow the gains in efficiency provided by both hard-linkage and soft-linkage to be quantified and compared. Specialized models of interactions over the past 1 Ma between the Clark and Coyote Creek faults within the San Jacinto system reveal increasing mechanical efficiency as these fault structures change over time. Alongside this increasing efficiency is an increasing likelihood for single, larger earthquakes that rupture multiple fault segments. These models reinforce the sensitivity of mechanical efficiency to both fault structure and the regional tectonic stress orientation controlled by plate motions and provide insight into how slip may have been partitioned between the San Andreas and San Jacinto systems over the past 1 Ma.

ISHM-oriented adaptive fault diagnostics for avionics based on a distributed intelligent agent system

NASA Astrophysics Data System (ADS)

Xu, Jiuping; Zhong, Zhengqiang; Xu, Lei

2015-10-01

In this paper, an integrated system health management-oriented adaptive fault diagnostics and model for avionics is proposed. With avionics becoming increasingly complicated, precise and comprehensive avionics fault diagnostics has become an extremely complicated task. For the proposed fault diagnostic system, specific approaches, such as the artificial immune system, the intelligent agents system and the Dempster-Shafer evidence theory, are used to conduct deep fault avionics diagnostics. Through this proposed fault diagnostic system, efficient and accurate diagnostics can be achieved. A numerical example is conducted to apply the proposed hybrid diagnostics to a set of radar transmitters on an avionics system and to illustrate that the proposed system and model have the ability to achieve efficient and accurate fault diagnostics. By analyzing the diagnostic system's feasibility and pragmatics, the advantages of this system are demonstrated.

Structural features of the Pernicana Fault (M. Etna, Sicily, Italy) inferred by high precise location of the microseismicity

NASA Astrophysics Data System (ADS)

Alparone, S.; Gambino, S.; Mostaccio, A.; Spampinato, S.; Tuvè, T.; Ursino, A.

2009-04-01

The north-eastern flank of Mt. Etna is crossed by an important and active tectonic structure, the Pernicana Fault having a mean strike WNW-ESE. It links westward to the active NE Rift and seems to have an important role in controlling instability processes affecting the eastern flank of the volcano. Recent studies suggest that Pernicana Fault is very active through sinistral, oblique-slip movements and is also characterised by frequent shallow seismicity (depth < 2 km bsl) on the uphill western segment and by remarkable creeping on the downhill eastern one. The Pernicana Fault earthquakes, which can reach magnitudes up to 4.2, sometimes with coseismic surface faulting, caused severe damages to tourist resorts and villages along or close this structure. In the last years, a strong increase of seismicity, also characterized by swarms, was recorded by INGV-CT permanent local seismic network close the Pernicana Fault. A three-step procedure was applied to calculate precise hypocentre locations. In a first step, we chose to apply cross-correlation analysis, in order to easily evaluate the similarity of waveforms useful to identify earthquakes families. In a second step, we calculate probabilistic earthquake locations using the software package NONLINLOC, which includes systematic, complete grid search and global, non-linear search methods. Subsequently, we perform relative relocation of correlated event pairs using the double-difference earthquake algorithm and the program HypoDD. The double-difference algorithm minimizes the residuals between observed and calculated travel time difference for pairs of earthquakes at common stations by iteratively adjusting the vector difference between the hypocenters. We show the recognized spatial seismic clusters identifying the most active and hazarding sectors of the structure, their geometry and depth. Finally, in order to clarify the geodynamic framework of the area, we associate these results with calculated focal mechanisms for the most energetic earthquakes.

The continuation of the Kazerun fault system across the Sanandaj-Sirjan zone (Iran)

NASA Astrophysics Data System (ADS)

Safaei, Homayon

2009-08-01

The Kazerun (or Kazerun-Qatar) fault system is a north-trending dextral strike-slip fault zone in the Zagros mountain belt of Iran. It probably originated as a structure in the Panafrican basement. This fault system played an important role in the sedimentation and deformation of the Phanerozoic cover sequence and is still seismically active. No previous studies have reported the continuation of this important and ancient fault system northward across the Sanandaj-Sirjan zone. The Isfahan fault system is a north-trending dextral strike-slip fault across the Sanandaj-Sirjan zone that passes west of Isfahan city and is here recognized for the first time. This important fault system is about 220 km long and is seismically active in the basement as well as the sedimentary cover sequence. This fault system terminates to the south near the Main Zagros Thrust and to the north at the southern boundary of the Urumieh-Dokhtar zone. The Isfahan fault system is the boundary between the northern and southern parts of Sanandaj-Sirjan zone, which have fundamentally different stratigraphy, petrology, geomorphology, and geodynamic histories. Similarities in the orientations, kinematics, and geologic histories of the Isfahan and Kazerun faults and the way they affect the magnetic basement suggest that they are related. In fact, the Isfahan fault is a continuation of the Kazerun fault across the Sanandaj-Sirjan zone that has been offset by about 50 km of dextral strike-slip displacement along the Main Zagros Thrust.

Strain-dependent permeability of volcanic rocks.

NASA Astrophysics Data System (ADS)

Farquharson, Jamie; Heap, Michael; Baud, Patrick

2016-04-01

We explore permeability evolution during deformation of volcanic materials using a suite of rocks with varying compositions and physical properties (such as porosity ϕ). 40 mm × 20 mm cylindrical samples were made from a range of extrusive rocks, including andesites from Colima, Mexico (ϕ˜0.08; 0.18; 0.21), Kumamoto, Japan (ϕ˜0.13), and Ruapehu, New Zealand (ϕ˜0.15), and basalt from Mt Etna, Italy (ϕ˜0.04). Gas permeability of each sample was measured before and after triaxial deformation using a steady-state benchtop permeameter. To study the strain-dependence of permeability in volcanic rocks, we deformed samples to 2, 3, 4, 6, and 12 % axial strain at a constant strain rate of 10-5 s-1. Further, the influence of failure mode - dilatant or compactant - on permeability was assessed by repeating experiments at different confining pressures. During triaxial deformation, porosity change of the samples was monitored by a servo-controlled pore fluid pump. Below an initial porosity of ˜0.18, and at low confining pressures (≤ 20 MPa), we observe a dilatant failure mode (shear fracture formation). With increasing axial strain, stress is accommodated by fault sliding and the generation of ash-sized gouge between the fracture planes. In higher-porosity samples, or at relatively higher confining pressures (≥ 60 MPa), we observe compactant deformation characterised by a monotonous decrease in porosity with increasing axial strain. The relative permeability k' is given by the change in permeability divided by the initial reference state. When behaviour is dilatant, k' tends to be positive: permeability increases with progressive deformation. However, results suggest that after a threshold amount of strain, k' can decrease. k' always is negative (permeability decreases during deformation) when compaction is the dominant behaviour. Our results show that - in the absence of a sealing or healing process - the efficiency of a fault to transmit fluids is correlated to the degree of strain to which is subjected. Volcanic processes such as dome extrusion, which involve progressive strain on complex fault systems, have been seen to cause fault sliding and the prolific generation of fault gouge. Our results indicate that the permeability of these faults will tend to remain constant or increase during continued extrusion, allowing magmatic gases to readily outgas through permeable fault architectures despite the generation and accumulation of gouge. On the other hand, deeper regions of the edifice that will typically be compacting due to the relatively higher confining pressures, will exhibit a continuous decrease in permeability. The interplay between permeability-increasing and permeability-decreasing processes within the edifice is likely to influence outgassing and eruptive cycles at active volcanoes.

Application Research of Fault Tree Analysis in Grid Communication System Corrective Maintenance

NASA Astrophysics Data System (ADS)

Wang, Jian; Yang, Zhenwei; Kang, Mei

2018-01-01

This paper attempts to apply the fault tree analysis method to the corrective maintenance field of grid communication system. Through the establishment of the fault tree model of typical system and the engineering experience, the fault tree analysis theory is used to analyze the fault tree model, which contains the field of structural function, probability importance and so on. The results show that the fault tree analysis can realize fast positioning and well repairing of the system. Meanwhile, it finds that the analysis method of fault tree has some guiding significance to the reliability researching and upgrading f the system.

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.

Fault tolerant filtering and fault detection for quantum systems driven by fields in single photon states

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

Gao, Qing, E-mail: qing.gao.chance@gmail.com; Dong, Daoyi, E-mail: daoyidong@gmail.com; Petersen, Ian R., E-mail: i.r.petersen@gmai.com

The purpose of this paper is to solve the fault tolerant filtering and fault detection problem for a class of open quantum systems driven by a continuous-mode bosonic input field in single photon states when the systems are subject to stochastic faults. Optimal estimates of both the system observables and the fault process are simultaneously calculated and characterized by a set of coupled recursive quantum stochastic differential equations.

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).

Expert System Detects Power-Distribution Faults

NASA Technical Reports Server (NTRS)

Walters, Jerry L.; Quinn, Todd M.

1994-01-01

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

Results of an electrical power system fault study (CDDF)

NASA Technical Reports Server (NTRS)

Dugal-Whitehead, N. R.; Johnson, Y. B.

1993-01-01

This report gives the results of an electrical power system fault study which has been conducted over the last 2 and one-half years. First, the results of the literature search into electrical power system faults in space and terrestrial power system applications are reported. A description of the intended implementations of the power system faults into the Large Autonomous Spacecraft Electrical Power System (LASEPS) breadboard is then presented. Then, the actual implementation of the faults into the breadboard is discussed along with a discussion describing the LASEPS breadboard. Finally, the results of the injected faults and breadboard failures are discussed.

Multiple Fault Isolation in Redundant Systems

NASA Technical Reports Server (NTRS)

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

1997-01-01

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

Multiple Fault Isolation in Redundant Systems

NASA Technical Reports Server (NTRS)

Pattipati, Krishna R.

1997-01-01

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

Multiplex APLP System for High-Resolution Haplogrouping of Extremely Degraded East-Asian Mitochondrial DNAs

PubMed Central

Kakuda, Tsuneo; Shojo, Hideki; Tanaka, Mayumi; Nambiar, Phrabhakaran; Minaguchi, Kiyoshi; Umetsu, Kazuo; Adachi, Noboru

2016-01-01

Mitochondrial DNA (mtDNA) serves as a powerful tool for exploring matrilineal phylogeographic ancestry, as well as for analyzing highly degraded samples, because of its polymorphic nature and high copy numbers per cell. The recent advent of complete mitochondrial genome sequencing has led to improved techniques for phylogenetic analyses based on mtDNA, and many multiplex genotyping methods have been developed for the hierarchical analysis of phylogenetically important mutations. However, few high-resolution multiplex genotyping systems for analyzing East-Asian mtDNA can be applied to extremely degraded samples. Here, we present a multiplex system for analyzing mitochondrial single nucleotide polymorphisms (mtSNPs), which relies on a novel amplified product-length polymorphisms (APLP) method that uses inosine-flapped primers and is specifically designed for the detailed haplogrouping of extremely degraded East-Asian mtDNAs. We used fourteen 6-plex polymerase chain reactions (PCRs) and subsequent electrophoresis to examine 81 haplogroup-defining SNPs and 3 insertion/deletion sites, and we were able to securely assign the studied mtDNAs to relevant haplogroups. Our system requires only 1×10−13 g (100 fg) of crude DNA to obtain a full profile. Owing to its small amplicon size (<110 bp), this new APLP system was successfully applied to extremely degraded samples for which direct sequencing of hypervariable segments using mini-primer sets was unsuccessful, and proved to be more robust than conventional APLP analysis. Thus, our new APLP system is effective for retrieving reliable data from extremely degraded East-Asian mtDNAs. PMID:27355212

Multiplex APLP System for High-Resolution Haplogrouping of Extremely Degraded East-Asian Mitochondrial DNAs.

PubMed

Kakuda, Tsuneo; Shojo, Hideki; Tanaka, Mayumi; Nambiar, Phrabhakaran; Minaguchi, Kiyoshi; Umetsu, Kazuo; Adachi, Noboru

2016-01-01

Mitochondrial DNA (mtDNA) serves as a powerful tool for exploring matrilineal phylogeographic ancestry, as well as for analyzing highly degraded samples, because of its polymorphic nature and high copy numbers per cell. The recent advent of complete mitochondrial genome sequencing has led to improved techniques for phylogenetic analyses based on mtDNA, and many multiplex genotyping methods have been developed for the hierarchical analysis of phylogenetically important mutations. However, few high-resolution multiplex genotyping systems for analyzing East-Asian mtDNA can be applied to extremely degraded samples. Here, we present a multiplex system for analyzing mitochondrial single nucleotide polymorphisms (mtSNPs), which relies on a novel amplified product-length polymorphisms (APLP) method that uses inosine-flapped primers and is specifically designed for the detailed haplogrouping of extremely degraded East-Asian mtDNAs. We used fourteen 6-plex polymerase chain reactions (PCRs) and subsequent electrophoresis to examine 81 haplogroup-defining SNPs and 3 insertion/deletion sites, and we were able to securely assign the studied mtDNAs to relevant haplogroups. Our system requires only 1×10-13 g (100 fg) of crude DNA to obtain a full profile. Owing to its small amplicon size (<110 bp), this new APLP system was successfully applied to extremely degraded samples for which direct sequencing of hypervariable segments using mini-primer sets was unsuccessful, and proved to be more robust than conventional APLP analysis. Thus, our new APLP system is effective for retrieving reliable data from extremely degraded East-Asian mtDNAs.

Simultaneous Sensor and Process Fault Diagnostics for Propellant Feed System

NASA Technical Reports Server (NTRS)

Cao, J.; Kwan, C.; Figueroa, F.; Xu, R.

2006-01-01

The main objective of this research is to extract fault features from sensor faults and process faults by using advanced fault detection and isolation (FDI) algorithms. A tank system that has some common characteristics to a NASA testbed at Stennis Space Center was used to verify our proposed algorithms. First, a generic tank system was modeled. Second, a mathematical model suitable for FDI has been derived for the tank system. Third, a new and general FDI procedure has been designed to distinguish process faults and sensor faults. Extensive simulations clearly demonstrated the advantages of the new design.

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

NASA Technical Reports Server (NTRS)

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

1985-01-01

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

How fault evolution changes strain partitioning and fault slip rates in Southern California: Results from geodynamic modeling

NASA Astrophysics Data System (ADS)

Ye, Jiyang; Liu, Mian

2017-08-01

In Southern California, the Pacific-North America relative plate motion is accommodated by the complex southern San Andreas Fault system that includes many young faults (<2 Ma). The initiation of these young faults and their impact on strain partitioning and fault slip rates are important for understanding the evolution of this plate boundary zone and assessing earthquake hazard in Southern California. Using a three-dimensional viscoelastoplastic finite element model, we have investigated how this plate boundary fault system has evolved to accommodate the relative plate motion in Southern California. Our results show that when the plate boundary faults are not optimally configured to accommodate the relative plate motion, strain is localized in places where new faults would initiate to improve the mechanical efficiency of the fault system. In particular, the Eastern California Shear Zone, the San Jacinto Fault, the Elsinore Fault, and the offshore dextral faults all developed in places of highly localized strain. These younger faults compensate for the reduced fault slip on the San Andreas Fault proper because of the Big Bend, a major restraining bend. The evolution of the fault system changes the apportionment of fault slip rates over time, which may explain some of the slip rate discrepancy between geological and geodetic measurements in Southern California. For the present fault configuration, our model predicts localized strain in western Transverse Ranges and along the dextral faults across the Mojave Desert, where numerous damaging earthquakes occurred in recent years.

Advanced information processing system: Fault injection study and results

NASA Technical Reports Server (NTRS)

Burkhardt, Laura F.; Masotto, Thomas K.; Lala, Jaynarayan H.

1992-01-01

The objective of the AIPS program is to achieve a validated fault tolerant distributed computer system. The goals of the AIPS fault injection study were: (1) to present the fault injection study components addressing the AIPS validation objective; (2) to obtain feedback for fault removal from the design implementation; (3) to obtain statistical data regarding fault detection, isolation, and reconfiguration responses; and (4) to obtain data regarding the effects of faults on system performance. The parameters are described that must be varied to create a comprehensive set of fault injection tests, the subset of test cases selected, the test case measurements, and the test case execution. Both pin level hardware faults using a hardware fault injector and software injected memory mutations were used to test the system. An overview is provided of the hardware fault injector and the associated software used to carry out the experiments. Detailed specifications are given of fault and test results for the I/O Network and the AIPS Fault Tolerant Processor, respectively. The results are summarized and conclusions are given.

Sensor fault diagnosis of singular delayed LPV systems with inexact parameters: an uncertain system approach

NASA Astrophysics Data System (ADS)

Hassanabadi, Amir Hossein; Shafiee, Masoud; Puig, Vicenc

2018-01-01

In this paper, sensor fault diagnosis of a singular delayed linear parameter varying (LPV) system is considered. In the considered system, the model matrices are dependent on some parameters which are real-time measurable. The case of inexact parameter measurements is considered which is close to real situations. Fault diagnosis in this system is achieved via fault estimation. For this purpose, an augmented system is created by including sensor faults as additional system states. Then, an unknown input observer (UIO) is designed which estimates both the system states and the faults in the presence of measurement noise, disturbances and uncertainty induced by inexact measured parameters. Error dynamics and the original system constitute an uncertain system due to inconsistencies between real and measured values of the parameters. Then, the robust estimation of the system states and the faults are achieved with H∞ performance and formulated with a set of linear matrix inequalities (LMIs). The designed UIO is also applicable for fault diagnosis of singular delayed LPV systems with unmeasurable scheduling variables. The efficiency of the proposed approach is illustrated with an example.

Hierarchical Simulation to Assess Hardware and Software Dependability

NASA Technical Reports Server (NTRS)

Ries, Gregory Lawrence

1997-01-01

This thesis presents a method for conducting hierarchical simulations to assess system hardware and software dependability. The method is intended to model embedded microprocessor systems. A key contribution of the thesis is the idea of using fault dictionaries to propagate fault effects upward from the level of abstraction where a fault model is assumed to the system level where the ultimate impact of the fault is observed. A second important contribution is the analysis of the software behavior under faults as well as the hardware behavior. The simulation method is demonstrated and validated in four case studies analyzing Myrinet, a commercial, high-speed networking system. One key result from the case studies shows that the simulation method predicts the same fault impact 87.5% of the time as is obtained by similar fault injections into a real Myrinet system. Reasons for the remaining discrepancy are examined in the thesis. A second key result shows the reduction in the number of simulations needed due to the fault dictionary method. In one case study, 500 faults were injected at the chip level, but only 255 propagated to the system level. Of these 255 faults, 110 shared identical fault dictionary entries at the system level and so did not need to be resimulated. The necessary number of system-level simulations was therefore reduced from 500 to 145. Finally, the case studies show how the simulation method can be used to improve the dependability of the target system. The simulation analysis was used to add recovery to the target software for the most common fault propagation mechanisms that would cause the software to hang. After the modification, the number of hangs was reduced by 60% for fault injections into the real system.

Character and Significance of Surface Rupture Near the Intersection of the Denali and Totschunda Faults, M7.9 Denali Fault Earthquake, Alaska, November 3, 2002

NASA Astrophysics Data System (ADS)

Wallace, W. K.; Sherrod, B. L.; Dawson, T. E.

2002-12-01

Preliminary observations suggest that right-lateral strike-slip on the Denali fault is transferred to the Totschunda fault via an extensional bend in the Little Tok River valley. Most of the surface rupture during the Denali fault earthquake was along an east- to east-southeast striking, gently curved segment of the Denali fault. However, in the Little Tok River valley, rupture transferred to the southeast-striking Totschunda fault and continued to the southeast for another 75 km. West of the Little Tok River valley, 5-7 m of right-lateral slip and up to 2 m of vertical offset occurred on the main strand of the Denali fault, but no apparent displacement occurred on the Denali fault east of the valley. Rupture west of the intersection also occurred on multiple discontinuous strands parallel to and south of the main strand of the Denali fault. In the Little Tok River valley, the northern part of the Totschunda fault system consists of multiple discontinuous southeast-striking strands that are connected locally by south-striking stepover faults. Faults of the northern Totschunda system display 0-2.5 m of right-lateral slip and 0-2.75 m of vertical offset, with the largest vertical offset on a dominantly extensional stepover fault. The strands of the Totschunda system converge southeastward to a single strand that had up to 2 m of slip. Complex and discontinuous faulting may reflect in part the immaturity of the northern Totschunda system, which is known to be younger and have much less total slip than the Denali. The Totschunda fault forms an extensional bend relative to the dominantly right-lateral Denali fault to the west. The fault geometry and displacements at the intersection suggest that slip on the Denali fault during the earthquake was accommodated largely by extension in the northern Totschunda fault system, allowing a significant decrease in strike-slip relative to the Denali fault. Strands to the southwest in the area of the bend may represent shortcut faults that have reduced the curvature at the intersection of the two fault systems.

Comparative study of superconducting fault current limiter both for LCC-HVDC and VSC-HVDC systems

NASA Astrophysics Data System (ADS)

Lee, Jong-Geon; Khan, Umer Amir; Lim, Sung-Woo; Shin, Woo-ju; Seo, In-Jin; Lee, Bang-Wook

2015-11-01

High Voltage Direct Current (HVDC) system has been evaluated as the optimum solution for the renewable energy transmission and long-distance power grid connections. In spite of the various advantages of HVDC system, it still has been regarded as an unreliable system compared to AC system due to its vulnerable characteristics on the power system fault. Furthermore, unlike AC system, optimum protection and switching device has not been fully developed yet. Therefore, in order to enhance the reliability of the HVDC systems mitigation of power system fault and reliable fault current limiting and switching devices should be developed. In this paper, in order to mitigate HVDC fault, both for Line Commutated Converter HVDC (LCC-HVDC) and Voltage Source Converter HVDC (VSC-HVDC) system, an application of resistive superconducting fault current limiter which has been known as optimum solution to cope with the power system fault was considered. Firstly, simulation models for two types of LCC-HVDC and VSC-HVDC system which has point to point connection model were developed. From the designed model, fault current characteristics of faulty condition were analyzed. Second, application of SFCL on each types of HVDC system and comparative study of modified fault current characteristics were analyzed. Consequently, it was deduced that an application of AC-SFCL on LCC-HVDC system with point to point connection was desirable solution to mitigate the fault current stresses and to prevent commutation failure in HVDC electric power system interconnected with AC grid.

Intermittent/transient fault phenomena in digital systems

NASA Technical Reports Server (NTRS)

Masson, G. M.

1977-01-01

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

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

PubMed

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

2016-05-03

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

76 FR 19281 - Proposed Amendment of Class E Airspace; Bozeman, MT

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-07

... Instrument Landing System (ILS) Localizer (LOC) standard instrument approach procedures at the airport. The... extending upward from 700 feet or more above the surface of the earth. * * * * * ANM MT E5 Bozeman, MT...

Subduction zone and crustal dynamics of western Washington; a tectonic model for earthquake hazards evaluation

USGS Publications Warehouse

Stanley, Dal; Villaseñor, Antonio; Benz, Harley

1999-01-01

The Cascadia subduction zone is extremely complex in the western Washington region, involving local deformation of the subducting Juan de Fuca plate and complicated block structures in the crust. It has been postulated that the Cascadia subduction zone could be the source for a large thrust earthquake, possibly as large as M9.0. Large intraplate earthquakes from within the subducting Juan de Fuca plate beneath the Puget Sound region have accounted for most of the energy release in this century and future such large earthquakes are expected. Added to these possible hazards is clear evidence for strong crustal deformation events in the Puget Sound region near faults such as the Seattle fault, which passes through the southern Seattle metropolitan area. In order to understand the nature of these individual earthquake sources and their possible interrelationship, we have conducted an extensive seismotectonic study of the region. We have employed P-wave velocity models developed using local earthquake tomography as a key tool in this research. Other information utilized includes geological, paleoseismic, gravity, magnetic, magnetotelluric, deformation, seismicity, focal mechanism and geodetic data. Neotectonic concepts were tested and augmented through use of anelastic (creep) deformation models based on thin-plate, finite-element techniques developed by Peter Bird, UCLA. These programs model anelastic strain rate, stress, and velocity fields for given rheological parameters, variable crust and lithosphere thicknesses, heat flow, and elevation. Known faults in western Washington and the main Cascadia subduction thrust were incorporated in the modeling process. Significant results from the velocity models include delineation of a previously studied arch in the subducting Juan de Fuca plate. The axis of the arch is oriented in the direction of current subduction and asymmetrically deformed due to the effects of a northern buttress mapped in the velocity models. This buttress occurs under the North Cascades region of Washington and under southern Vancouver Island. We find that regional faults zones such as the Devils Mt. and Darrington zones follow the margin of this buttress and the Olympic-Wallowa lineament forms its southern boundary east of the Puget Lowland. Thick, high-velocity, lower-crustal rocks are interpreted to be a mafic/ultramafic wedge occuring just above the subduction thrust. This mafic wedge appears to be jointly deformed with the arch, suggesting strong coupling between the subducting plate and upper plate crust in the Puget Sound region at depths >30 km. Such tectonic coupling is possible if brittle-ductile transition temperatures for mafic/ultramafic rocks on both sides of the thrust are assumed. The deformation models show that dominant north-south compression in the coast ranges of Washington and Oregon is controlled by a highly mafic crust and low heat flow, allowing efficient transmission of margin-parallel shear from Pacific plate interaction with North America. Complex stress patterns which curve around the Puget Sound region require a concentration of northwest-directed shear in the North Cascades of Washington. The preferred model shows that greatest horizontal shortening occurs across the Devils Mt. fault zone and the east end of the Seattle fault.

Do moderate magnitude earthquakes generate seismically induced ground effects? The case study of the M w = 5.16, 29th December 2013 Matese earthquake (southern Apennines, Italy)

NASA Astrophysics Data System (ADS)

Valente, Ettore; Ascione, A.; Ciotoli, G.; Cozzolino, M.; Porfido, S.; Sciarra, A.

2018-03-01

Seismically induced ground effects characterize moderate to high magnitude seismic events, whereas they are not so common during seismic sequences of low to moderate magnitude. A low to moderate magnitude seismic sequence with a M w = 5.16 ± 0.07 main event occurred from December 2013 to February 2014 in the Matese ridge area, in the southern Apennines mountain chain. In the epicentral area of the M w = 5.16 main event, which happened on December 29th 2013 in the southeastern part of the Matese ridge, field surveys combined with information from local people and reports allowed the recognition of several earthquake-induced ground effects. Such ground effects include landslides, hydrological variations in local springs, gas flux, and a flame that was observed around the main shock epicentre. A coseismic rupture was identified in the SW fault scarp of a small-sized intermontane basin (Mt. Airola basin). To detect the nature of the coseismic rupture, detail scale geological and geomorphological investigations, combined with geoelectrical and soil gas prospections, were carried out. Such a multidisciplinary study, besides allowing reconstruction of the surface and subsurface architecture of the Mt. Airola basin, and suggesting the occurrence of an active fault at the SW boundary of such basin, points to the gravitational nature of the coseismic ground rupture. Based on typology and spatial distribution of the ground effects, an intensity I = VII-VIII is estimated for the M w = 5.16 earthquake according to the ESI-07 scale, which affected an area of at least 90 km2.

Endurance exercise rescues progeroid aging and induces systemic mitochondrial rejuvenation in mtDNA mutator mice

PubMed Central

Safdar, Adeel; Bourgeois, Jacqueline M.; Ogborn, Daniel I.; Little, Jonathan P.; Hettinga, Bart P.; Akhtar, Mahmood; Thompson, James E.; Melov, Simon; Mocellin, Nicholas J.; Kujoth, Gregory C.; Prolla, Tomas A.; Tarnopolsky, Mark A.

2011-01-01

A causal role for mitochondrial DNA (mtDNA) mutagenesis in mammalian aging is supported by recent studies demonstrating that the mtDNA mutator mouse, harboring a defect in the proofreading-exonuclease activity of mitochondrial polymerase gamma, exhibits accelerated aging phenotypes characteristic of human aging, systemic mitochondrial dysfunction, multisystem pathology, and reduced lifespan. Epidemiologic studies in humans have demonstrated that endurance training reduces the risk of chronic diseases and extends life expectancy. Whether endurance exercise can attenuate the cumulative systemic decline observed in aging remains elusive. Here we show that 5 mo of endurance exercise induced systemic mitochondrial biogenesis, prevented mtDNA depletion and mutations, increased mitochondrial oxidative capacity and respiratory chain assembly, restored mitochondrial morphology, and blunted pathological levels of apoptosis in multiple tissues of mtDNA mutator mice. These adaptations conferred complete phenotypic protection, reduced multisystem pathology, and prevented premature mortality in these mice. The systemic mitochondrial rejuvenation through endurance exercise promises to be an effective therapeutic approach to mitigating mitochondrial dysfunction in aging and related comorbidities. PMID:21368114

Smart intimation and location of faults in distribution system

NASA Astrophysics Data System (ADS)

Hari Krishna, K.; Srinivasa Rao, B.

2018-04-01

Location of faults in the distribution system is one of the most complicated problems that we are facing today. Identification of fault location and severity of fault within a short time is required to provide continuous power supply but fault identification and information transfer to the operator is the biggest challenge in the distribution network. This paper proposes a fault location method in the distribution system based on Arduino nano and GSM module with flame sensor. The main idea is to locate the fault in the distribution transformer by sensing the arc coming out from the fuse element. The biggest challenge in the distribution network is to identify the location and the severity of faults under different conditions. Well operated transmission and distribution systems will play a key role for uninterrupted power supply. Whenever fault occurs in the distribution system the time taken to locate and eliminate the fault has to be reduced. The proposed design was achieved with flame sensor and GSM module. Under faulty condition, the system will automatically send an alert message to the operator in the distribution system, about the abnormal conditions near the transformer, site code and its exact location for possible power restoration.

Seismic interpretation of the deep structure of the Wabash Valley Fault System

USGS Publications Warehouse

Bear, G.W.; Rupp, J.A.; Rudman, A.J.

1997-01-01

Interpretations of newly available seismic reflection profiles near the center of the Illinois Basin indicate that the Wabash Valley Fault System is rooted in a series of basement-penetrating faults. The fault system is composed predominantly of north-northeast-trending high-angle normal faults. The largest faults in the system bound the 22-km wide 40-km long Grayville Graben. Structure contour maps drawn on the base of the Mount Simon Sandstone (Cambrian System) and a deeper pre-Mount Simon horizon show dip-slip displacements totaling at least 600 meters across the New Harmony fault. In contrast to previous interpretations, the N-S extent of significant fault offsets is restricted to a region north of 38?? latitude and south of 38.35?? latitude. This suggests that the graben is not a NE extension of the structural complex composed of the Rough Creek Fault System and the Reelfoot Rift as previously interpreted. Structural complexity on the graben floor also decreases to the south. Structural trends north of 38?? latitude are offset laterally across several large faults, indicating strike-slip motions of 2 to 4 km. Some of the major faults are interpreted to penetrate to depths of 7 km or more. Correlation of these faults with steep potential field gradients suggests that the fault positions are controlled by major lithologic contacts within the basement and that the faults may extend into the depth range where earthquakes are generated, revealing a potential link between specific faults and recently observed low-level seismicity in the area.

Six years of atmospheric CO2 observations at Mt. Fuji recorded with a battery-powered measurement system

NASA Astrophysics Data System (ADS)

Nomura, Shohei; Mukai, Hitoshi; Terao, Yukio; Machida, Toshinobu; Nojiri, Yukihiro

2017-03-01

We developed a battery-powered carbon dioxide (CO2) measurement system for monitoring at the summit of Mt. Fuji (3776 m a.s.l.), which experiences very low temperatures (below -20 °C) and severe environmental conditions without access to gridded electricity for 10 months (from September to June). Our measurement system used 100 batteries to run the measurement unit during these months. These batteries were charged during the 2-month summer season when gridded electricity was available, using a specially designed automatic battery-charging system. We installed this system in summer 2009 at the Mt. Fuji weather station; observations of atmospheric CO2 concentration were taken through December 2015. Measurements were never interrupted by a lack of battery power except for two cases in which lightning damaged a control board. Thus we obtained CO2 data during about 94 % of the 6-year period. Analytical performances (stability and accuracy) were better than 0.1 ppm, as tested by checking working standards and comparisons with flask sampling.Observational results showed that CO2 mole fractions at Mt. Fuji demonstrated clear seasonal variation. The trend and the variability of the CO2 growth rate observed at Mt. Fuji were very similar to those of the Mauna Loa Observatory (MLO). Seasonally, the concentration at Mt. Fuji was 2-10 ppm lower in summer and 2-12 ppm higher in winter than those at MLO. The lower concentrations at Mt. Fuji in summer are mainly attributed to episodes of air mass transport from Siberia or China, where CO2 is taken up by the terrestrial biosphere. On the other hand, the relatively higher concentrations in winter seem to reflect the high percentage of air masses originating from China or Southeast Asia during this period, which carry increased anthropogenic carbon dioxide. These results show that Mt. Fuji is not very influenced by local sources but rather by the sources and sinks over a very large region.Thus we conclude that, as this system could provide stable measurement data with relatively easy operation for 6 years at Mt. Fuji, it could be a useful monitoring technique for remote background sites elsewhere.

Advanced Ground Systems Maintenance Functional Fault Models For Fault Isolation Project

NASA Technical Reports Server (NTRS)

Perotti, Jose M. (Compiler)

2014-01-01

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

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.

Molecular, dynamic, and structural origin of inhomogeneous magnetization transfer in lipid membranes.

PubMed

Swanson, Scott D; Malyarenko, Dariya I; Fabiilli, Mario L; Welsh, Robert C; Nielsen, Jon-Fredrik; Srinivasan, Ashok

2017-03-01

To elucidate the dynamic, structural, and molecular properties that create inhomogeneous magnetization transfer (ihMT) contrast. Amphiphilic lipids, lamellar phospholipids with cholesterol, and bovine spinal cord (BSC) specimens were examined along with nonlipid systems. Magnetization transfer (MT), enhanced MT (eMT, obtained with double-sided radiofrequency saturation), ihMT (MT - eMT), and dipolar relaxation, T 1D , were measured at 2.0 and 11.7 T. The amplitude of ihMT ratio (ihMTR) is positively correlated with T 1D values. Both ihMTR and T 1D increase with increasing temperature in BSC white matter and in phospholipids and decrease with temperature in other lipids. Changes in ihMTR with temperature arise primarily from alterations in MT rather than eMT. Spectral width of MT, eMT, and ihMT increases with increasing carbon chain length. Concerted motions of phospholipids in white matter decrease proton spin diffusion leading to increased proton T 1D times and increased ihMT amplitudes, consistent with decoupling of Zeeman and dipolar spin reservoirs. Molecular specificity and dynamic sensitivity of ihMT contrast make it a suitable candidate for probing myelin membrane disorders. Magn Reson Med 77:1318-1328, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Fault management for data systems

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

The stress shadow effect: a mechanical analysis of the evenly-spaced parallel strike-slip faults in the San Andreas fault system

NASA Astrophysics Data System (ADS)

Zuza, A. V.; Yin, A.; Lin, J. C.

2015-12-01

Parallel evenly-spaced strike-slip faults are prominent in the southern San Andreas fault system, as well as other settings along plate boundaries (e.g., the Alpine fault) and within continental interiors (e.g., the North Anatolian, central Asian, and northern Tibetan faults). In southern California, the parallel San Jacinto, Elsinore, Rose Canyon, and San Clemente faults to the west of the San Andreas are regularly spaced at ~40 km. In the Eastern California Shear Zone, east of the San Andreas, faults are spaced at ~15 km. These characteristic spacings provide unique mechanical constraints on how the faults interact. Despite the common occurrence of parallel strike-slip faults, the fundamental questions of how and why these fault systems form remain unanswered. We address this issue by using the stress shadow concept of Lachenbruch (1961)—developed to explain extensional joints by using the stress-free condition on the crack surface—to present a mechanical analysis of the formation of parallel strike-slip faults that relates fault spacing and brittle-crust thickness to fault strength, crustal strength, and the crustal stress state. We discuss three independent models: (1) a fracture mechanics model, (2) an empirical stress-rise function model embedded in a plastic medium, and (3) an elastic-plate model. The assumptions and predictions of these models are quantitatively tested using scaled analogue sandbox experiments that show that strike-slip fault spacing is linearly related to the brittle-crust thickness. We derive constraints on the mechanical properties of the southern San Andreas strike-slip faults and fault-bounded crust (e.g., local fault strength and crustal/regional stress) given the observed fault spacing and brittle-crust thickness, which is obtained by defining the base of the seismogenic zone with high-resolution earthquake data. Our models allow direct comparison of the parallel faults in the southern San Andreas system with other similar strike-slip fault systems, both on Earth and throughout the solar system (e.g., the Tiger Stripe Fractures on Enceladus).

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.

Software-implemented fault insertion: An FTMP example

NASA Technical Reports Server (NTRS)

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

1987-01-01

This report presents a model for fault insertion through software; describes its implementation on a fault-tolerant computer, FTMP; presents a summary of fault detection, identification, and reconfiguration data collected with software-implemented fault insertion; and compares the results to hardware fault insertion data. Experimental results show detection time to be a function of time of insertion and system workload. For the fault detection time, there is no correlation between software-inserted faults and hardware-inserted faults; this is because hardware-inserted faults must manifest as errors before detection, whereas software-inserted faults immediately exercise the error detection mechanisms. In summary, the software-implemented fault insertion is able to be used as an evaluation technique for the fault-handling capabilities of a system in fault detection, identification and recovery. Although the software-inserted faults do not map directly to hardware-inserted faults, experiments show software-implemented fault insertion is capable of emulating hardware fault insertion, with greater ease and automation.

Abstractions for Fault-Tolerant Distributed System Verification

NASA Technical Reports Server (NTRS)

Pike, Lee S.; Maddalon, Jeffrey M.; Miner, Paul S.; Geser, Alfons

2004-01-01

Four kinds of abstraction for the design and analysis of fault tolerant distributed systems are discussed. These abstractions concern system messages, faults, fault masking voting, and communication. The abstractions are formalized in higher order logic, and are intended to facilitate specifying and verifying such systems in higher order theorem provers.

An information transfer based novel framework for fault root cause tracing of complex electromechanical systems in the processing industry

NASA Astrophysics Data System (ADS)

Wang, Rongxi; Gao, Xu; Gao, Jianmin; Gao, Zhiyong; Kang, Jiani

2018-02-01

As one of the most important approaches for analyzing the mechanism of fault pervasion, fault root cause tracing is a powerful and useful tool for detecting the fundamental causes of faults so as to prevent any further propagation and amplification. Focused on the problems arising from the lack of systematic and comprehensive integration, an information transfer-based novel data-driven framework for fault root cause tracing of complex electromechanical systems in the processing industry was proposed, taking into consideration the experience and qualitative analysis of conventional fault root cause tracing methods. Firstly, an improved symbolic transfer entropy method was presented to construct a directed-weighted information model for a specific complex electromechanical system based on the information flow. Secondly, considering the feedback mechanisms in the complex electromechanical systems, a method for determining the threshold values of weights was developed to explore the disciplines of fault propagation. Lastly, an iterative method was introduced to identify the fault development process. The fault root cause was traced by analyzing the changes in information transfer between the nodes along with the fault propagation pathway. An actual fault root cause tracing application of a complex electromechanical system is used to verify the effectiveness of the proposed framework. A unique fault root cause is obtained regardless of the choice of the initial variable. Thus, the proposed framework can be flexibly and effectively used in fault root cause tracing for complex electromechanical systems in the processing industry, and formulate the foundation of system vulnerability analysis and condition prediction, as well as other engineering applications.

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

Clustering of GPS velocities in the Mojave Block, southeastern California

USGS Publications Warehouse

Savage, James C.; Simpson, Robert W.

2013-01-01

We find subdivisions within the Mojave Block using cluster analysis to identify groupings in the velocities observed at GPS stations there. The clusters are represented on a fault map by symbols located at the positions of the GPS stations, each symbol representing the cluster to which the velocity of that GPS station belongs. Fault systems that separate the clusters are readily identified on such a map. The most significant representation as judged by the gap test involves 4 clusters within the Mojave Block. The fault systems bounding the clusters from east to west are 1) the faults defining the eastern boundary of the Northeast Mojave Domain extended southward to connect to the Hector Mine rupture, 2) the Calico-Paradise fault system, 3) the Landers-Blackwater fault system, and 4) the Helendale-Lockhart fault system. This division of the Mojave Block is very similar to that proposed by Meade and Hager. However, no cluster boundary coincides with the Garlock Fault, the northern boundary of the Mojave Block. Rather, the clusters appear to continue without interruption from the Mojave Block north into the southern Walker Lane Belt, similar to the continuity across the Garlock Fault of the shear zone along the Blackwater-Little Lake fault system observed by Peltzer et al. Mapped traces of individual faults in the Mojave Block terminate within the block and do not continue across the Garlock Fault [Dokka and Travis, ].

Active Thrusting Offshore Mount Lebanon: Source of the Tsunamigenic A.D. 551 Beirut-Tripoli Earthquake

NASA Astrophysics Data System (ADS)

Tapponnier, P.; Elias, A.; Singh, S.; King, G.; Briais, A.; Daeron, M.; Carton, H.; Sursock, A.; Jacques, E.; Jomaa, R.; Klinger, Y.

2007-12-01

On July 9, AD 551, a large earthquake, followed by a tsunami destroyed most of the coastal cities of Phoenicia (modern-day Lebanon). This was arguably one of the most devastating historical submarine earthquakes in the eastern Mediterranean. Geophysical data from the Shalimar survey unveils the source of this Mw=7.5 event: rupture of the offshore, hitherto unknown, 100?150 km-long, active, east-dipping Mount Lebanon Thrust (MLT). Deep-towed sonar swaths along the base of prominent bathymetric escarpments reveal fresh, west facing seismic scarps that cut the sediment-smoothed seafloor. The MLT trace comes closest (~ 8 km) to the coast between Beirut and Enfeh, where as 13 radiocarbon-calibrated ages indicate, a shoreline-fringing Vermetid bench suddenly emerged by ~ 80 cm in the 6th century AD. At Tabarja, the regular vertical separation (~ 1 m) of higher fossil benches, suggests uplift by 3 more comparable-size earthquakes since the Holocene sea-level reached a maximum ca. 7-6 ka, implying a 1500?1750 yr recurrence time. Unabated thrusting on the MLT likely orchestrated the growth of Mt. Lebanon since the late Miocene. The newly discovered MLT has been the missing piece in the Dead Sea Transform and eastern Mediterranean tectonic scheme. Identifying the source of the AD 551 event thus ends a complete reassessment of the sources of the major historical earthquakes on the various faults of the Lebanese Restraining Bend of the Levant Fault System (or Dead Sea Transform).

Active Thrusting Offshore Mount Lebanon: Source of the Tsunamigenic A.D. 551 Beirut-Tripoli Earthquake

NASA Astrophysics Data System (ADS)

Tapponnier, P.; Elias, A.; Singh, S.; King, G.; Briais, A.; Daeron, M.; Carton, H.; Sursock, A.; Jacques, E.; Jomaa, R.; Klinger, Y.

2004-12-01

On July 9, AD 551, a large earthquake, followed by a tsunami destroyed most of the coastal cities of Phoenicia (modern-day Lebanon). This was arguably one of the most devastating historical submarine earthquakes in the eastern Mediterranean. Geophysical data from the Shalimar survey unveils the source of this Mw=7.5 event: rupture of the offshore, hitherto unknown, 100?150 km-long, active, east-dipping Mount Lebanon Thrust (MLT). Deep-towed sonar swaths along the base of prominent bathymetric escarpments reveal fresh, west facing seismic scarps that cut the sediment-smoothed seafloor. The MLT trace comes closest (~ 8 km) to the coast between Beirut and Enfeh, where as 13 radiocarbon-calibrated ages indicate, a shoreline-fringing Vermetid bench suddenly emerged by ~ 80 cm in the 6th century AD. At Tabarja, the regular vertical separation (~ 1 m) of higher fossil benches, suggests uplift by 3 more comparable-size earthquakes since the Holocene sea-level reached a maximum ca. 7-6 ka, implying a 1500?1750 yr recurrence time. Unabated thrusting on the MLT likely orchestrated the growth of Mt. Lebanon since the late Miocene. The newly discovered MLT has been the missing piece in the Dead Sea Transform and eastern Mediterranean tectonic scheme. Identifying the source of the AD 551 event thus ends a complete reassessment of the sources of the major historical earthquakes on the various faults of the Lebanese Restraining Bend of the Levant Fault System (or Dead Sea Transform).

Improving Multiple Fault Diagnosability using Possible Conflicts

NASA Technical Reports Server (NTRS)

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

2012-01-01

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

Geophysical Characterization of the Hilton Creek Fault System

NASA Astrophysics Data System (ADS)

Lacy, A. K.; Macy, K. P.; De Cristofaro, J. L.; Polet, J.

2016-12-01

The Long Valley Caldera straddles the eastern edge of the Sierra Nevada Batholith and the western edge of the Basin and Range Province, and represents one of the largest caldera complexes on Earth. The caldera is intersected by numerous fault systems, including the Hartley Springs Fault System, the Round Valley Fault System, the Long Valley Ring Fault System, and the Hilton Creek Fault System, which is our main region of interest. The Hilton Creek Fault System appears as a single NW-striking fault, dipping to the NE, from Davis Lake in the south to the southern rim of the Long Valley Caldera. Inside the caldera, it splays into numerous parallel faults that extend toward the resurgent dome. Seismicity in the area increased significantly in May 1980, following a series of large earthquakes in the vicinity of the caldera and a subsequent large earthquake swarm which has been suggested to be the result of magma migration. A large portion of the earthquake swarms in the Long Valley Caldera occurs on or around the Hilton Creek Fault splays. We are conducting an interdisciplinary geophysical study of the Hilton Creek Fault System from just south of the onset of splay faulting, to its extension into the dome of the caldera. Our investigation includes ground-based magnetic field measurements, high-resolution total station elevation profiles, Structure-From-Motion derived topography and an analysis of earthquake focal mechanisms and statistics. Preliminary analysis of topographic profiles, of approximately 1 km in length, reveals the presence of at least three distinct fault splays within the caldera with vertical offsets of 0.5 to 1.0 meters. More detailed topographic mapping is expected to highlight smaller structures. We are also generating maps of the variation in b-value along different portions of the Hilton Creek system to determine whether we can detect any transition to more swarm-like behavior towards the North. We will show maps of magnetic anomalies, topography, various models of the Hilton Creek Fault System and cross-sections through focal mechanism and earthquake catalogs, and will attempt to integrate these observations into a single fault geometry model.

Salton Seismic Imaging Project Line 6: San Andreas Fault and Northern Coachella Valley Structure, Riverside and San Bernardino Counties, California

NASA Astrophysics Data System (ADS)

Catchings, R. D.; Fuis, G.; Rymer, M. J.; Goldman, M.; Tarnowski, J. M.; Hole, J. A.; Stock, J. M.; Matti, J. C.

2012-12-01

The Salton Seismic Imaging Project (SSIP) is a large-scale, active- and passive-source seismic project designed to image the San Andreas fault (SAF) and adjacent basins (Imperial and Coachella Valleys) in southernmost California. Data and preliminary results from many of the seismic profiles are reported elsewhere (including Fuis et al., Rymer et al., Goldman et al., Langenheim et al., this meeting). Here, we focus on SSIP Line 6, one of four 2-D seismic profiles that were acquired across the Coachella Valley. The 44-km-long, SSIP-Line-6 seismic profile extended from the east flank of Mt. San Jacinto northwest of Palm Springs to the Little San Bernardino Mountains and crossed the SAF (Mission Creek (MCF), Banning (BF), and Garnet Hill (GHF) strands) roughly normal to strike. Data were generated by 10 downhole explosive sources (most spaced about 3 to 5 km apart) and were recorded by approximately 347 Texan seismographs (average spacing 126 m). We used first-arrival refractions to develop a P-wave refraction tomography velocity image of the upper crust along the seismic profile. The seismic data were also stacked and migrated to develop low-fold reflection images of the crust. From the surface to about 7 km depth, P-wave velocities range from about 2.5 km/s to about 7.2 km/s, with the lowest velocities within an ~2-km-deep, ~20-km-wide basin, and the highest velocities below the transition zone from the Coachella Valley to Mt. San Jacinto and within the Little San Bernardino Mountains. The BF and GHF strands bound a shallow sub-basin on the southwestern side of the Coachella Valley, but the underlying shallow-depth (~4 km) basement rocks are P-wave high in velocity (~7.2 km/s). The lack of a low-velocity zone beneath BF and GHF suggests that both faults dip northeastward. In a similar manner, high-velocity basement rocks beneath the Little San Bernardino Mountains suggest that the MCF dips vertically or southwestward. However, there is a pronounced low-velocity zone in basement rocks between about 2 and 7 km depth beneath and southwest of the MCF, suggesting a vertical or slightly southwest-dipping MCF. The apparent northeast dip of the BF and the apparent vertical or southwest dip of the MCF suggests that the two main strands of the SAF (MCF and BF) merge at about 10 km depth. A plot of double-difference earthquake hypocenters (Hauksson, 2000) along the seismic profile shows events that occurred between 1980-2000 (excluding those in 1992, prior to and after the Joshua Tree and Landers earthquakes) are largely confined to the vicinity of the basement low-velocity zone between the MCF and BF. However, a separate alignment of hypocenters occurs southwest of the BF and projects toward the surface beneath Mt. San Jacinto. Collectively, the velocity images and the seismicity data suggest the BF strand of the SAF dips to the northeast at about 50 degrees in the upper 10 km, and the MCF strand is either vertical or dips southwestward about 80 degrees, with both strands merging at about 10 km depth and forming a near-vertical zone of faults to at least 15 km depth. The SSIP Line 6 data are consistent with structures interpreted by Catchings et al. (2009).

Active faulting, earthquakes, and restraining bend development near Kerman city in southeastern Iran

NASA Astrophysics Data System (ADS)

Walker, Richard Thomas; Talebian, Morteza; Saiffori, Sohei; Sloan, Robert Alastair; Rasheedi, Ali; MacBean, Natasha; Ghassemi, Abbas

2010-08-01

We provide descriptions of strike-slip and reverse faulting, active within the late Quaternary, in the vicinity of Kerman city in southeastern Iran. The faults accommodate north-south, right-lateral, shear between central Iran and the Dasht-e-Lut depression. The regions that we describe have been subject to numerous earthquakes in the historical and instrumental periods, and many of the faults that are documented in this paper constitute hazards for local populations, including the city of Kerman itself (population ˜200,000). Faults to the north and east of Kerman are associated with the transfer of slip from the Gowk to the Kuh Banan right-lateral faults across a 40 km-wide restraining bend. Faults south and west of the city are associated with oblique slip on the Mahan and Jorjafk systems. The patterns of faulting observed along the Mahan-Jorjafk system, the Gowk-Kuh Banan system, and also the Rafsanjan-Rayen system further to the south, appear to preserve different stages in the development of these oblique-slip fault systems. We suggest that the faulting evolves through time. Topography is initially generated on oblique slip faults (as is seen on the Jorjafk fault). The shortening component then migrates to reverse faults situated away from the high topography whereas strike-slip continues to be accommodated in the high, mountainous, regions (as is seen, for example, on the Rafsanjan fault). The reverse faults may then link together and eventually evolve into new, through-going, strike-slip faults in a process that appears to be occurring, at present, in the bend between the Gowk and Kuh Banan faults.

A rapid identification system for metallothionein proteins using expert system

PubMed Central

Praveen, Bhoopathi; Vincent, Savariar; Murty, Upadhyayula Suryanarayana; Krishna, Amirapu Radha; Jamil, Kaiser

2005-01-01

Metallothioneins (MT) are low molecular weight proteins mostly rich in cysteine residues with high metal content. Generally, MT proteins are responsible for regulating the intracellular supply of biologically essential metal ions and they protect cells from the deleterious effects of non-essential polarizable transition and post-transition metal ions. Due to their biological importance, proper characterization of MT is necessary. Here we describe a computer program (ID3 algorithm, a part of Artificial Intelligence) developed using available data for the rapid identification of MT. Tissue samples contains several low molecular weight proteins with different physical, chemical and biological characteristics. The described software solution proposes to categorize MT proteins without aromatic amino acids and high metal content. The proposed solution can be expanded to other types of proteins with specific known characteristics. PMID:17597844

AGSM Functional Fault Models for Fault Isolation Project

NASA Technical Reports Server (NTRS)

Harp, Janicce Leshay

2014-01-01

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

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

PubMed

Xie, Chun-Hua; Yang, Guang-Hong

2016-09-01

This paper investigates the fault-tolerant control (FTC) problem for unknown nonlinear systems with actuator faults including stuck, outage, bias and loss of effectiveness. The upper bounds of stuck faults, bias faults and loss of effectiveness faults are unknown. A new data-based FTC scheme is proposed. It consists of the online estimations of the bounds and a state-dependent function. The estimations are adjusted online to compensate automatically the actuator faults. The state-dependent function solved by using real system data helps to stabilize the system. Furthermore, all signals in the resulting closed-loop system are uniformly bounded and the states converge asymptotically to zero. Compared with the existing results, the proposed approach is data-based. Finally, two simulation examples are provided to show the effectiveness of the proposed approach. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Validation techniques for fault emulation of SRAM-based FPGAs

DOE PAGES

Quinn, Heather; Wirthlin, Michael

2015-08-07

A variety of fault emulation systems have been created to study the effect of single-event effects (SEEs) in static random access memory (SRAM) based field-programmable gate arrays (FPGAs). These systems are useful for augmenting radiation-hardness assurance (RHA) methodologies for verifying the effectiveness for mitigation techniques; understanding error signatures and failure modes in FPGAs; and failure rate estimation. For radiation effects researchers, it is important that these systems properly emulate how SEEs manifest in FPGAs. If the fault emulation systems does not mimic the radiation environment, the system will generate erroneous data and incorrect predictions of behavior of the FPGA inmore » a radiation environment. Validation determines whether the emulated faults are reasonable analogs to the radiation-induced faults. In this study we present methods for validating fault emulation systems and provide several examples of validated FPGA fault emulation systems.« less

Fault-tolerant cooperative output regulation for multi-vehicle systems with sensor faults

NASA Astrophysics Data System (ADS)

Qin, Liguo; He, Xiao; Zhou, D. H.

2017-10-01

This paper presents a unified framework of fault diagnosis and fault-tolerant cooperative output regulation (FTCOR) for a linear discrete-time multi-vehicle system with sensor faults. The FTCOR control law is designed through three steps. A cooperative output regulation (COR) controller is designed based on the internal mode principle when there are no sensor faults. A sufficient condition on the existence of the COR controller is given based on the discrete-time algebraic Riccati equation (DARE). Then, a decentralised fault diagnosis scheme is designed to cope with sensor faults occurring in followers. A residual generator is developed to detect sensor faults of each follower, and a bank of fault-matching estimators are proposed to isolate and estimate sensor faults of each follower. Unlike the current distributed fault diagnosis for multi-vehicle systems, the presented decentralised fault diagnosis scheme in each vehicle reduces the communication and computation load by only using the information of the vehicle. By combing the sensor fault estimation and the COR control law, an FTCOR controller is proposed. Finally, the simulation results demonstrate the effectiveness of the FTCOR controller.

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

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

Perincek, D.

1988-08-01

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

Magma-tectonic Interaction at Laguna del Maule, Chile

NASA Astrophysics Data System (ADS)

Keranen, K. M.; Peterson, D. E.; Miller, C. A.; Garibaldi, N.; Tikoff, B.; Williams-Jones, G.

2016-12-01

The Laguna del Maule Volcanic Field (LdM), Chile, the largest concentration of rhyolite <20 kyr globally, exhibits crustal deformation at rates higher than any non-erupting volcano. The interaction of large magmatic systems with faulting is poorly understood, however, the Chaitén rhyolitic system demonstrated that faults can serve as magma pathways during an eruption. We present a complex fault system at LdM in close proximity to the magma reservoir. In March 2016, 18 CHIRP seismic reflection lines were acquired at LdM to identify faults and analyze potential spatial and temporal impacts of the fault system on volcanic activity. We mapped three key horizons on each line, bounding sediment packages between Holocene onset, 870 ybp, and the present date. Faults were mapped on each line and offset was calculated across key horizons. Our results indicate a system of normal-component faults in the northern lake sector, striking subparallel to the mapped Troncoso Fault SW of the lake. These faults correlate to prominent magnetic lineations mapped by boat magnetic data acquired February 2016 which are interpreted as dykes intruding along faults. We also imaged a vertical fault, interpreted as a strike-slip fault, and a series of normal faults in the SW lake sector near the center of magmatic inflation. Isochron and fault offset maps illuminate areas of growth strata and indicate migration and increase of fault activity from south to north through time. We identify a domal structure in the SW lake sector, coincident with an area of low magnetization, in the region of maximum deformation from InSAR results. The dome experienced 10 ms TWT ( 10 meters) of uplift throughout the past 16 kybp, which we interpret as magmatic inflation in a shallow magma reservoir. This inflation is isolated to a 1.5 km diameter region in the hanging wall of the primary normal fault system, indicating possible fault-facilitated inflation.

Evolution of the Rodgers Creek–Maacama right-lateral fault system and associated basins east of the northward-migrating Mendocino Triple Junction, northern California

USGS Publications Warehouse

McLaughlin, Robert J.; Sarna-Wojcicki, Andrei M.; Wagner, David L.; Fleck, Robert J.; Langenheim, V.E.; Jachens, Robert C.; Clahan, Kevin; Allen, James R.

2012-01-01

The Rodgers Creek–Maacama fault system in the northern California Coast Ranges (United States) takes up substantial right-lateral motion within the wide transform boundary between the Pacific and North American plates, over a slab window that has opened northward beneath the Coast Ranges. The fault system evolved in several right steps and splays preceded and accompanied by extension, volcanism, and strike-slip basin development. Fault and basin geometries have changed with time, in places with younger basins and faults overprinting older structures. Along-strike and successional changes in fault and basin geometry at the southern end of the fault system probably are adjustments to frequent fault zone reorganizations in response to Mendocino Triple Junction migration and northward transit of a major releasing bend in the northern San Andreas fault. The earliest Rodgers Creek fault zone displacement is interpreted to have occurred ca. 7 Ma along extensional basin-forming faults that splayed northwest from a west-northwest proto-Hayward fault zone, opening a transtensional basin west of Santa Rosa. After ca. 5 Ma, the early transtensional basin was compressed and extensional faults were reactivated as thrusts that uplifted the northeast side of the basin. After ca. 2.78 Ma, the Rodgers Creek fault zone again splayed from the earlier extensional and thrust faults to steeper dipping faults with more north-northwest orientations. In conjunction with the changes in orientation and slip mode, the Rodgers Creek fault zone dextral slip rate increased from ∼2–4 mm/yr 7–3 Ma, to 5–8 mm/yr after 3 Ma. The Maacama fault zone is shown from several data sets to have initiated ca. 3.2 Ma and has slipped right-laterally at ∼5–8 mm/yr since its initiation. The initial Maacama fault zone splayed northeastward from the south end of the Rodgers Creek fault zone, accompanied by the opening of several strike-slip basins, some of which were later uplifted and compressed during late-stage fault zone reorganization. The Santa Rosa pull-apart basin formed ca. 1 Ma, during the reorganization of the right stepover geometry of the Rodgers Creek–Maacama fault system, when the maturely evolved overlapping geometry of the northern Rodgers Creek and Maacama fault zones was overprinted by a less evolved, non-overlapping stepover geometry. The Rodgers Creek–Maacama fault system has contributed at least 44–53 km of right-lateral displacement to the East Bay fault system south of San Pablo Bay since 7 Ma, at a minimum rate of 6.1–7.8 mm/yr.

Structural styles of Paleozoic intracratonic fault reactivation: A case study of the Grays Point fault zone in southeastern Missouri, USA

USGS Publications Warehouse

Clendenin, C.W.; Diehl, S.F.

1999-01-01

A pronounced, subparallel set of northeast-striking faults occurs in southeastern Missouri, but little is known about these faults because of poor exposure. The Commerce fault system is the southernmost exposed fault system in this set and has an ancestry related to Reelfoot rift extension. Recent published work indicates that this fault system has a long history of reactivation. The northeast-striking Grays Point fault zone is a segment of the Commerce fault system and is well exposed along the southeast rim of an inactive quarry. Our mapping shows that the Grays Point fault zone also has a complex history of polyphase reactivation, involving three periods of Paleozoic reactivation that occurred in Late Ordovician, Devonian, and post-Mississippian. Each period is characterized by divergent, right-lateral oblique-slip faulting. Petrographic examination of sidwall rip-out clasts in calcite-filled faults associated with the Grays Point fault zone supports a minimum of three periods of right-lateral oblique-slip. The reported observations imply that a genetic link exists between intracratonic fault reactivation and strain produced by Paleozoic orogenies affecting the eastern margin of Laurentia (North America). Interpretation of this link indicate that right-lateral oblique-slip has occurred on all of the northeast-striking faults in southeastern Missouri as a result of strain influenced by the convergence directions of the different Paleozoic orogenies.

East Asian mtDNA haplogroup determination in Koreans: haplogroup-level coding region SNP analysis and subhaplogroup-level control region sequence analysis.

PubMed

Lee, Hwan Young; Yoo, Ji-Eun; Park, Myung Jin; Chung, Ukhee; Kim, Chong-Youl; Shin, Kyoung-Jin

2006-11-01

The present study analyzed 21 coding region SNP markers and one deletion motif for the determination of East Asian mitochondrial DNA (mtDNA) haplogroups by designing three multiplex systems which apply single base extension methods. Using two multiplex systems, all 593 Korean mtDNAs were allocated into 15 haplogroups: M, D, D4, D5, G, M7, M8, M9, M10, M11, R, R9, B, A, and N9. As the D4 haplotypes occurred most frequently in Koreans, the third multiplex system was used to further define D4 subhaplogroups: D4a, D4b, D4e, D4g, D4h, and D4j. This method allowed the complementation of coding region information with control region mutation motifs and the resultant findings also suggest reliable control region mutation motifs for the assignment of East Asian mtDNA haplogroups. These three multiplex systems produce good results in degraded samples as they contain small PCR products (101-154 bp) for single base extension reactions. SNP scoring was performed in 101 old skeletal remains using these three systems to prove their utility in degraded samples. The sequence analysis of mtDNA control region with high incidence of haplogroup-specific mutations and the selective scoring of highly informative coding region SNPs using the three multiplex systems are useful tools for most applications involving East Asian mtDNA haplogroup determination and haplogroup-directed stringent quality control.

Integrity of the yeast mitochondrial genome, but not its distribution and inheritance, relies on mitochondrial fission and fusion

PubMed Central

Osman, Christof; Noriega, Thomas R.; Okreglak, Voytek; Fung, Jennifer C.; Walter, Peter

2015-01-01

Mitochondrial DNA (mtDNA) is essential for mitochondrial and cellular function. In Saccharomyces cerevisiae, mtDNA is organized in nucleoprotein structures termed nucleoids, which are distributed throughout the mitochondrial network and are faithfully inherited during the cell cycle. How the cell distributes and inherits mtDNA is incompletely understood although an involvement of mitochondrial fission and fusion has been suggested. We developed a LacO-LacI system to noninvasively image mtDNA dynamics in living cells. Using this system, we found that nucleoids are nonrandomly spaced within the mitochondrial network and observed the spatiotemporal events involved in mtDNA inheritance. Surprisingly, cells deficient in mitochondrial fusion and fission distributed and inherited mtDNA normally, pointing to alternative pathways involved in these processes. We identified such a mechanism, where we observed fission-independent, but F-actin–dependent, tip generation that was linked to the positioning of mtDNA to the newly generated tip. Although mitochondrial fusion and fission were dispensable for mtDNA distribution and inheritance, we show through a combination of genetics and next-generation sequencing that their absence leads to an accumulation of mitochondrial genomes harboring deleterious structural variations that cluster at the origins of mtDNA replication, thus revealing crucial roles for mitochondrial fusion and fission in maintaining the integrity of the mitochondrial genome. PMID:25730886

Managing Space System Faults: Coalescing NASA's Views

NASA Technical Reports Server (NTRS)

Muirhead, Brian; Fesq, Lorraine

2012-01-01

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

Provable Transient Recovery for Frame-Based, Fault-Tolerant Computing Systems

NASA Technical Reports Server (NTRS)

DiVito, Ben L.; Butler, Ricky W.

1992-01-01

We present a formal verification of the transient fault recovery aspects of the Reliable Computing Platform (RCP), a fault-tolerant computing system architecture for digital flight control applications. The RCP uses NMR-style redundancy to mask faults and internal majority voting to purge the effects of transient faults. The system design has been formally specified and verified using the EHDM verification system. Our formalization accommodates a wide variety of voting schemes for purging the effects of transients.

Automatic Detection of Electric Power Troubles (ADEPT)

NASA Technical Reports Server (NTRS)

Wang, Caroline; Zeanah, Hugh; Anderson, Audie; Patrick, Clint; Brady, Mike; Ford, Donnie

1988-01-01

ADEPT is an expert system that integrates knowledge from three different suppliers to offer an advanced fault-detection system, and is designed for two modes of operation: real-time fault isolation and simulated modeling. Real time fault isolation of components is accomplished on a power system breadboard through the Fault Isolation Expert System (FIES II) interface with a rule system developed in-house. Faults are quickly detected and displayed and the rules and chain of reasoning optionally provided on a Laser printer. This system consists of a simulated Space Station power module using direct-current power supplies for Solar arrays on three power busses. For tests of the system's ability to locate faults inserted via switches, loads are configured by an INTEL microcomputer and the Symbolics artificial intelligence development system. As these loads are resistive in nature, Ohm's Law is used as the basis for rules by which faults are located. The three-bus system can correct faults automatically where there is a surplus of power available on any of the three busses. Techniques developed and used can be applied readily to other control systems requiring rapid intelligent decisions. Simulated modelling, used for theoretical studies, is implemented using a modified version of Kennedy Space Center's KATE (Knowledge-Based Automatic Test Equipment), FIES II windowing, and an ADEPT knowledge base. A load scheduler and a fault recovery system are currently under development to support both modes of operation.

Tectono-metallogenetic evolution of the Fe-Cu deposit of Dominga, northern Chile

NASA Astrophysics Data System (ADS)

Veloso, E.; Cembrano, J.; Arancibia, G.; Heuser, G.; Neira, S.; Siña, A.; Garrido, I.; Vermeesch, P.; Selby, D.

2017-04-01

The Dominga district in northern Chile (2082 Mt at 23.3 % Fe, 0.07 % Cu) shows a spatial and genetic affinity among distinctive structural elements and Fe-Cu-rich paragenetic mineral assemblages. Deep seated, NE-to-E striking structural elements form a right-lateral duplex-like structural system (early structural system, ESS) that cuts a regionally extensive alteration (stage I) zone. The EES system served as a locus and as path for the emplacement of biotite-magnetite alteration/mineralization (stage IIa) as veins and Fe-bearing layers following altered volcano sedimentary strata. NW-striking actinolite-magnetite hydrothermal breccias, coeval with and part of the ESS, include apatite (stage IIb) crystallized at 127 ± 15 Ma (U-Pb, 2σ). The ESS was also the locus of subsequent alteration/mineralization represented by K-feldspar, epidote, and albite (stage IIIa) and Fe-Cu-rich (vermiculite-anhydrite-chalcopyrite, stage IIIb) mineral associations. Shallowly developed, NNE-striking, left-lateral structural elements defining the El Tofo Structural System (ETSS)—probably part of the Atacama Fault System—clearly crosscut the ESS. Minerals associated with alteration/mineralization stage IIIb also occur as veins and as part of hydrothermal breccias of the ETSS, marking the transition from the ESS to ETSS. Molybdenite associated with alteration/mineralization stage IIIb yielded a Re-Os age of 127.1 ± 0.7 Ma (2σ). Both the ESS and ETSS were cut by left-lateral, NW- to E-striking shallowly developed structural elements (Intermediate Structural System, ISS) on which a hematite-calcite assemblage (stage IV) occurs mostly as infill material of veins and fault veins. The ISS is cut by N-striking, left-lateral, and shallowly developed structural elements (Late Structural System, LSS) showing no evidence of alteration/mineralization. Estimated strain and stress fields indicate an overall NW-trending shortening/compression and NE-trending stretching/tension strike-slip regime probably due to oblique subduction during the Mesozoic. However, the orientations of the stress and strain fields calculated for each structural system suggest a back-and-forth rotation pattern during transition from one structural system to the other—as they change between transtension and transpression—and between alteration/mineralization stages.

Integrated Fault Diagnosis Algorithm for Motor Sensors of In-Wheel Independent Drive Electric Vehicles.

PubMed

Jeon, Namju; Lee, Hyeongcheol

2016-12-12

An integrated fault-diagnosis algorithm for a motor sensor of in-wheel independent drive electric vehicles is presented. This paper proposes a method that integrates the high- and low-level fault diagnoses to improve the robustness and performance of the system. For the high-level fault diagnosis of vehicle dynamics, a planar two-track non-linear model is first selected, and the longitudinal and lateral forces are calculated. To ensure redundancy of the system, correlation between the sensor and residual in the vehicle dynamics is analyzed to detect and separate the fault of the drive motor system of each wheel. To diagnose the motor system for low-level faults, the state equation of an interior permanent magnet synchronous motor is developed, and a parity equation is used to diagnose the fault of the electric current and position sensors. The validity of the high-level fault-diagnosis algorithm is verified using Carsim and Matlab/Simulink co-simulation. The low-level fault diagnosis is verified through Matlab/Simulink simulation and experiments. Finally, according to the residuals of the high- and low-level fault diagnoses, fault-detection flags are defined. On the basis of this information, an integrated fault-diagnosis strategy is proposed.

Neotectonics of interior Alaska and the late Quaternary slip rate along the Denali fault system

USGS Publications Warehouse

Haeussler, Peter J.; Matmon, Ari; Schwartz, David P.; Seitz, Gordon G.

2017-01-01

The neotectonics of southern Alaska (USA) are characterized by a several hundred kilometers–wide zone of dextral transpressional that spans the Alaska Range. The Denali fault system is the largest active strike-slip fault system in interior Alaska, and it produced a Mw 7.9 earthquake in 2002. To evaluate the late Quaternary slip rate on the Denali fault system, we collected samples for cosmogenic surface exposure dating from surfaces offset by the fault system. This study includes data from 107 samples at 19 sites, including 7 sites we previously reported, as well as an estimated slip rate at another site. We utilize the interpreted surface ages to provide estimated slip rates. These new slip rate data confirm that the highest late Quaternary slip rate is ∼13 mm/yr on the central Denali fault near its intersection with the eastern Denali and the Totschunda faults, with decreasing slip rate both to the east and west. The slip rate decreases westward along the central and western parts of the Denali fault system to 5 mm/yr over a length of ∼575 km. An additional site on the eastern Denali fault near Kluane Lake, Yukon, implies a slip rate of ∼2 mm/yr, based on geological considerations. The Totschunda fault has a maximum slip rate of ∼9 mm/yr. The Denali fault system is transpressional and there are active thrust faults on both the north and south sides of it. We explore four geometric models for southern Alaska tectonics to explain the slip rates along the Denali fault system and the active fault geometries: rotation, indentation, extrusion, and a combination of the three. We conclude that all three end-member models have strengths and shortcomings, and a combination of rotation, indentation, and extrusion best explains the slip rate observations.

Geometry and kinematics of the eastern Lake Mead fault system in the Virgin Mountains, Nevada and Arizona

USGS Publications Warehouse

Beard, Sue; Campagna, David J.; Anderson, R. Ernest

2010-01-01

The Lake Mead fault system is a northeast-striking, 130-km-long zone of left-slip in the southeast Great Basin, active from before 16 Ma to Quaternary time. The northeast end of the Lake Mead fault system in the Virgin Mountains of southeast Nevada and northwest Arizona forms a partitioned strain field comprising kinematically linked northeast-striking left-lateral faults, north-striking normal faults, and northwest-striking right-lateral faults. Major faults bound large structural blocks whose internal strain reflects their position within a left step-over of the left-lateral faults. Two north-striking large-displacement normal faults, the Lakeside Mine segment of the South Virgin–White Hills detachment fault and the Piedmont fault, intersect the left step-over from the southwest and northeast, respectively. The left step-over in the Lake Mead fault system therefore corresponds to a right-step in the regional normal fault system.Within the left step-over, displacement transfer between the left-lateral faults and linked normal faults occurs near their junctions, where the left-lateral faults become oblique and normal fault displacement decreases away from the junction. Southward from the center of the step-over in the Virgin Mountains, down-to-the-west normal faults splay northward from left-lateral faults, whereas north and east of the center, down-to-the-east normal faults splay southward from left-lateral faults. Minimum slip is thus in the central part of the left step-over, between east-directed slip to the north and west-directed slip to the south. Attenuation faults parallel or subparallel to bedding cut Lower Paleozoic rocks and are inferred to be early structures that accommodated footwall uplift during the initial stages of extension.Fault-slip data indicate oblique extensional strain within the left step-over in the South Virgin Mountains, manifested as east-west extension; shortening is partitioned between vertical for extension-dominated structural blocks and south-directed for strike-slip faults. Strike-slip faults are oblique to the extension direction due to structural inheritance from NE-striking fabrics in Proterozoic crystalline basement rocks.We hypothesize that (1) during early phases of deformation oblique extension was partitioned to form east-west–extended domains bounded by left-lateral faults of the Lake Mead fault system, from ca. 16 to 14 Ma. (2) Beginning ca. 13 Ma, increased south-directed shortening impinged on the Virgin Mountains and forced uplift, faulting, and overturning along the north and west side of the Virgin Mountains. (3) By ca. 10 Ma, initiation of the younger Hen Spring to Hamblin Bay fault segment of the Lake Mead fault system accommodated westward tectonic escape, and the focus of south-directed shortening transferred to the western Lake Mead region. The shift from early partitioned oblique extension to south-directed shortening may have resulted from initiation of right-lateral shear of the eastern Walker Lane to the west coupled with left-lateral shear along the eastern margin of the Great Basin.

Multi scale modeling of 2450MHz electric field effects on microtubule mechanical properties.

PubMed

Setayandeh, S S; Lohrasebi, A

2016-11-01

Microtubule (MT) rigidity and response to 2450MHz electric fields were investigated, via multi scale modeling approach. For this purpose, six systems were designed and simulated to consider all types of feasible interactions between α and β monomers in MT, by using all atom molecular dynamics method. Subsequently, coarse grain modeling was used to design different lengths of MT. Investigation of effects of external 2450MHz electric field on MT showed MT less rigidity in the presence of such field, which may perturb its functions. Moreover, an additional computational setup was designed to study effects of 2450MHz field on MT response to AFM tip. It was found, more tip velocity led to MT faster transformation and less time was required to change MT elastic response to plastic one, applying constant radius. Moreover it was observed smaller tip caused to increase required time to change MT elastic response to plastic one, considering constant velocity. Furthermore, exposing MT to 2450MHz field led to no significant changes in MT response to AFM tip, but quick change in MT elastic response to plastic one. Copyright © 2016 Elsevier Inc. All rights reserved.

Evaluating use and outcomes of mobility technology: a multiple stakeholder analysis.

PubMed

Hammel, Joy; Southall, Kenneth; Jutai, Jeffrey; Finlayson, Marcia; Kashindi, Gabriel; Fok, Daniel

2013-07-01

This qualitative, multi-site study compared and contrasted the outcomes of mobility technology (MT) and the factors influencing these outcomes from the perspective of MT users, caregivers, and professionals involved in MT service delivery. Qualitative focus groups were held in the USA and Canada with multiple stakeholder groups (consumer: n = 45, caregiver: n = 10, service provider: n = 10). Data were analyzed thematically. MT outcomes were conceptualized by participants as a match between expectations for MT and the actual outcomes experienced. Several factors influenced the match including a) MT features, b) environmental factors (e.g. built/physical environment, societal context of acceptance, MT delivery systems/policies), and c) the ability to self-manage the interaction across person, technology and environment, which involved constant negotiation and strategizing. Stakeholders identified MT outcomes that corresponded to ICF levels including body structure and function, activity, and participation across environments; however, varied on their importance and influence on MT impact. The conceptual fit model and factors related to self-management of MT represent new knowledge and provide a framework for stakeholder-based evaluation of MT outcomes. Implications for MT assessment, service delivery, outcomes research, and interventions are discussed.

Slip distribution, strain accumulation and aseismic slip on the Chaman Fault system

NASA Astrophysics Data System (ADS)

Amelug, F.

2015-12-01

The Chaman fault system is a transcurrent fault system developed due to the oblique convergence of the India and Eurasia plates in the western boundary of the India plate. To evaluate the contemporary rates of strain accumulation along and across the Chaman Fault system, we use 2003-2011 Envisat SAR imagery and InSAR time-series methods to obtain a ground velocity field in radar line-of-sight (LOS) direction. We correct the InSAR data for different sources of systematic biases including the phase unwrapping errors, local oscillator drift, topographic residuals and stratified tropospheric delay and evaluate the uncertainty due to the residual delay using time-series of MODIS observations of precipitable water vapor. The InSAR velocity field and modeling demonstrates the distribution of deformation across the Chaman fault system. In the central Chaman fault system, the InSAR velocity shows clear strain localization on the Chaman and Ghazaband faults and modeling suggests a total slip rate of ~24 mm/yr distributed on the two faults with rates of 8 and 16 mm/yr, respectively corresponding to the 80% of the total ~3 cm/yr plate motion between India and Eurasia at these latitudes and consistent with the kinematic models which have predicted a slip rate of ~17-24 mm/yr for the Chaman Fault. In the northern Chaman fault system (north of 30.5N), ~6 mm/yr of the relative plate motion is accommodated across Chaman fault. North of 30.5 N where the topographic expression of the Ghazaband fault vanishes, its slip does not transfer to the Chaman fault but rather distributes among different faults in the Kirthar range and Sulaiman lobe. Observed surface creep on the southern Chaman fault between Nushki and north of City of Chaman, indicates that the fault is partially locked, consistent with the recorded M<7 earthquakes in last century on this segment. The Chaman fault between north of the City of Chaman to North of Kabul, does not show an increase in the rate of strain accumulation. However, lack of seismicity on this segment, presents a significant hazard on Kabul. The high rate of strain accumulation on the Ghazaband fault and lack of evidence for the rupture of the fault during the 1935 Quetta earthquake, present a growing earthquake hazard to the Balochistan and the populated areas such as the city of Quetta.

Extended phase graph formalism for systems with magnetization transfer and exchange

PubMed Central

Teixeira, Rui Pedro A.G.; Hajnal, Joseph V.

2017-01-01

Purpose An extended phase graph framework (EPG‐X) for modeling systems with exchange or magnetization transfer (MT) is proposed. Theory EPG‐X models coupled two‐compartment systems by describing each compartment with separate phase graphs that exchange during evolution periods. There are two variants: EPG‐X(BM) for systems governed by the Bloch‐McConnell equations, and EPG‐X(MT) for the pulsed MT formalism. For the MT case, the “bound” protons have no transverse components, so their phase graph consists of only longitudinal states. Methods The EPG‐X model was validated against steady‐state solutions and isochromat‐based simulation of gradient‐echo sequences. Three additional test cases were investigated: (i) MT effects in multislice turbo spin‐echo; (ii) variable flip angle gradient‐echo imaging of the type used for MR fingerprinting; and (iii) water exchange in multi‐echo spin‐echo T2 relaxometry. Results EPG‐X was validated successfully against isochromat based transient simulations and known steady‐state solutions. EPG‐X(MT) simulations matched in‐vivo measurements of signal attenuation in white matter in multislice turbo spin‐echo images. Magnetic resonance fingerprinting–style experiments with a bovine serum albumin (MT) phantom showed that the data were not consistent with a single‐pool model, but EPG‐X(MT) could be used to fit the data well. The EPG‐X(BM) simulations of multi‐echo spin‐echo T2 relaxometry suggest that exchange could lead to an underestimation of the myelin‐water fraction. Conclusions The EPG‐X framework can be used for modeling both steady‐state and transient signal response of systems exhibiting exchange or MT. This may be particularly beneficial for relaxometry approaches that rely on characterizing transient rather than steady‐state sequences. Magn Reson Med 80:767–779, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:29243295

The mid-Miocene structural conversion within the NE Tibetan Plateau from new proof of the interaction between two conflicting fault systems in the western Qaidam Basin

NASA Astrophysics Data System (ADS)

Zhao, H.; Wu, L.; Xiao, A.

2016-12-01

We present a detailed structural analysis on the fault geometry and Cenozoic development in the Dongping area, northwestern Qaidam Basin, based on the precise 3-D seismic interpretation, remote sensing images and seismic attribute analysis. Two conflicting fault systems distributed in different orientations ( EW-striking and NNW-striking) with opposing senses of shear are recognized and discussed, and the interaction between them provides new insights to the intracontinental deformation of the Qaidam Basin within the NE Tibetan Plateau. The EW-striking fault system constitutes the south part of the Altyn left-slip positive flower structure. Faulting on the EW-striking faults dominated the northwestern Qaidam since 40 Ma in respond to the inception of the Altyn Tagh fault system as a ductile shear zone, tilting the south slope of the Altyn Tagh. Whereas the NNW-striking fault system became the dominant structures since the mid-Miocene ( 15 Ma), induced by the large scale strike-slip of the Altyn Tagh fault which leads to the NE-SW directed compression of the Qaidam Basin. Thus it evidently implies a structural conversion taking place within the NE Tibetan Plateau since the mid-Miocece ( 15 Ma). Interestingly, the preexisting faults possibly restrained the development of the later period faults, while the latter tended to track and link to the former fault traces. Taken the large scale sinistral striking-slip East Kunlun fault system into account, the late Cenozoic intracontinental deformation in the Qaidam Basin showing the dextral transpressional attribute is suggested to be the consequence of the combined effect of its two border sinistral strike-slip faults, which furthermore favors a continuous and lateral-extrusion mechanism of the growth of the NE Tibetan Plateau.

Clustering of GPS velocities in the Mojave Block, southeastern California

NASA Astrophysics Data System (ADS)

Savage, J. C.; Simpson, R. W.

2013-04-01

find subdivisions within the Mojave Block using cluster analysis to identify groupings in the velocities observed at GPS stations there. The clusters are represented on a fault map by symbols located at the positions of the GPS stations, each symbol representing the cluster to which the velocity of that GPS station belongs. Fault systems that separate the clusters are readily identified on such a map. The most significant representation as judged by the gap test involves 4 clusters within the Mojave Block. The fault systems bounding the clusters from east to west are 1) the faults defining the eastern boundary of the Northeast Mojave Domain extended southward to connect to the Hector Mine rupture, 2) the Calico-Paradise fault system, 3) the Landers-Blackwater fault system, and 4) the Helendale-Lockhart fault system. This division of the Mojave Block is very similar to that proposed by Meade and Hager []. However, no cluster boundary coincides with the Garlock Fault, the northern boundary of the Mojave Block. Rather, the clusters appear to continue without interruption from the Mojave Block north into the southern Walker Lane Belt, similar to the continuity across the Garlock Fault of the shear zone along the Blackwater-Little Lake fault system observed by Peltzer et al. []. Mapped traces of individual faults in the Mojave Block terminate within the block and do not continue across the Garlock Fault [Dokka and Travis, ].

Population genetics inside a cell: Mutations and mitochondrial genome maintenance

NASA Astrophysics Data System (ADS)

Goyal, Sidhartha; Shraiman, Boris; Gottschling, Dan

2012-02-01

In realistic ecological and evolutionary systems natural selection acts on multiple levels, i.e. it acts on individuals as well as on collection of individuals. An understanding of evolutionary dynamics of such systems is limited in large part due to the lack of experimental systems that can challenge theoretical models. Mitochondrial genomes (mtDNA) are subjected to selection acting on cellular as well as organelle levels. It is well accepted that mtDNA in yeast Saccharomyces cerevisiae is unstable and can degrade over time scales comparable to yeast cell division time. We utilize a recent technology designed in Gottschling lab to extract DNA from populations of aged yeast cells and deep sequencing to characterize mtDNA variation in a population of young and old cells. In tandem, we developed a stochastic model that includes the essential features of mitochondrial biology that provides a null model for expected mtDNA variation. Overall, we find approximately 2% of the polymorphic loci that show significant increase in frequency as cells age providing direct evidence for organelle level selection. Such quantitative study of mtDNA dynamics is absolutely essential to understand the propagation of mtDNA mutations linked to a spectrum of age-related diseases in humans.

Timing of activity of two fault systems on Mercury

NASA Astrophysics Data System (ADS)

Galluzzi, V.; Guzzetta, L.; Giacomini, L.; Ferranti, L.; Massironi, M.; Palumbo, P.

2015-10-01

Here we discuss about two fault systems found in the Victoria and Shakespeare quadrangles of Mercury. The two fault sets intersect each other and show probable evidence for two stages of deformation. The most prominent system is N-S oriented and encompasses several tens to hundreds of kilometers long and easily recognizable fault segments. The other system strikes NE- SW and encompasses mostly degraded and short fault segments. The structural framework of the studied area and the morphological appearance of the faults suggest that the second system is older than the first one. We intend to apply the buffered crater counting technique on both systems to make a quantitative study of their timing of activity that could confirm the already clear morphological evidence.

The Lithospheric Structure of the Solonker Suture Zone and Adjacent Areas: Crustal Structure Revealed by a High-Resolution Magnetotelluric Study

NASA Astrophysics Data System (ADS)

Ye, Gaofeng; Jin, Sheng; Wei, Wenbo; Jing, Jian'en

2017-04-01

The closure of the Paleo-Asian Ocean along the Solonker Suture Zone (SSZ) during the Late Permian and Triassic represented the final stage in the formation of the Central Asian Orogenic Belt between the Siberian Craton and the North China Craton. In order to better understand the structure and formation of this ancient subduction zone, a high-resolution magnetotelluric (MT) profile was collected with both broadband and long-period MT data. The high resolution mapping of the lithosphere achieved in this study is due to the closely spaced MT stations (2-3 km). With the 2-D resistivity model, a south-dipping conductor was detected and extends through the entire crust. The geometry of this feature provides evidence that a southward directed subduction zone formed the Solonker suture. The enhanced conductivity was interpreted to subducted sulfide-bearing graphitic sediments. The resistive body beneath the northern margin of the North China Craton indicates a thickened lithosphere caused by the southward subduction at this region, and the resistive body beneath the Solonker Suture Zone indicates the subducted oceanic lithosphere. North-dipping low resistivity features were also detected in the crust of both the North China Craton and Central Asian Orogenic Belt, and were interpreted as post-collisional thrust faults. Strong anisotropy was found beneath the suture zone, and can be explained if the high strain rate has rotated the fold axes into the dip direction.

Magnetotelluric images of deep crustal structure of the Rehai geothermal field near Tengchong, southern China

NASA Astrophysics Data System (ADS)

Bai, Denghai; Meju, Maxwell A.; Liao, Zhijie

2001-12-01

Broadband (0.004-4096s) magnetotelluric (MT) soundings have been applied to the determination of the deep structure across the Rehai geothermal field in a Quaternary volcanic area near the Indo-Eurasian collisional margin. Tensorial analysis of the data show evidence of weak to strong 3-D effects but for approximate 2-D imaging, we obtained dual-mode MT responses for an assumed strike direction coincident with the trend of the regional-scale faults and with the principal impedance azimuth at long periods. The data were subsequently inverted using different approaches. The rapid relaxation inversion models are comparable to the sections constructed from depth-converted invariant impedance phase data. The results from full-domain 2-D conjugate-gradient inversion with different initial models are concordant and evoke a picture of a dome-like structure consisting of a conductive (<10 Ωm) core zone, c . 2km wide, and a resistive (>50-1000 Ωm) cap which is about 5-6km thick in the central part of the known geothermal field and thickens outwards to about 15-20km. The anomalous structure rests on a mid-crustal zone of 20-30 Ωm resistivity extending down to about 25km depth where there appears to be a moderately resistive (>30 Ωm) substratum. The MT images are shown to be in accord with published geological, isotopic and geochemical results that suggested the presence of a magma body underneath the area of study.

Role, structure and effects of medical tourism in Africa: a systematic scoping review protocol.

PubMed

Mogaka, John Jo; Tsoka-Gwegweni, Joyce M; Mupara, Lucia M; Mashamba-Thompson, Tivani

2017-06-23

Some patients travel out of, while others come into Africa for medical care through a growing global phenomenon referred to as medical tourism (MT): the travel in search of medical care that is either unavailable, unaffordable or proscribed at home healthcare systems. While some castigate MT as promoting healthcare inequity, others endorse it as a revenue generator, promising local healthcare system strengthening. Currently, however, the understanding of this component of healthcare in Africa is inadequate. This study seeks to determine the level of knowledge on the role, structure and effect of MT in Africa as it relates to healthcare systems in the region. Conduct a systematic scoping review to outline the role, structure and effect of MT in Africa. Databases: Academic Search Complete, Business Source Complete. Studies mapped in two stages: (1) mapping the studies based on the relevance of their titles and subject descriptors; (2) applying further inclusion criteria on studies from stage 1. Two reviewers will independently assess study quality and abstract data. Both quantitative and qualitative data analysis will be performed, using STATA V.13 and NVIVO, respectively. The study results will be disseminated by publication in peer-reviewed journals and findings presented at academic and industry conferences related to MT, public health, health systems strengthening and tourism. MT spurs cutting-edge medical technologies, techniques and best practices in healthcare delivery. The two-tier healthcare landscape in Africa, however, presents an exceptionally unique context in which to situate this study. Much has been written about MT globally, but not much is known about the phenomenon in Africa; hence the appropriateness of this scientific assessment of MT in the region. By elucidating the role, structure and effect of this phenomenon, this study hopes to contribute to health systems strengthening in Africa. CRD42016039745. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Role, structure and effects of medical tourism in Africa: a systematic scoping review protocol

PubMed Central

Mogaka, John JO; Tsoka-Gwegweni, Joyce M; Mupara, Lucia M; Mashamba-Thompson, Tivani

2017-01-01

Introduction Some patients travel out of, while others come into Africa for medical care through a growing global phenomenon referred to as medical tourism (MT): the travel in search of medical care that is either unavailable, unaffordable or proscribed at home healthcare systems. While some castigate MT as promoting healthcare inequity, others endorse it as a revenue generator, promising local healthcare system strengthening. Currently, however, the understanding of this component of healthcare in Africa is inadequate. This study seeks to determine the level of knowledge on the role, structure and effect of MT in Africa as it relates to healthcare systems in the region. Methods Conduct a systematic scoping review to outline the role, structure and effect of MT in Africa. Databases: Academic Search Complete, Business Source Complete. Studies mapped in two stages: (1) mapping the studies based on the relevance of their titles and subject descriptors; (2) applying further inclusion criteria on studies from stage 1. Two reviewers will independently assess study quality and abstract data. Both quantitative and qualitative data analysis will be performed, using STATA V.13 and NVIVO, respectively. Ethics and dissemination The study results will be disseminated by publication in peer-reviewed journals and findings presented at academic and industry conferences related to MT, public health, health systems strengthening and tourism. Discussion MT spurs cutting-edge medical technologies, techniques and best practices in healthcare delivery. The two-tier healthcare landscape in Africa, however, presents an exceptionally unique context in which to situate this study. Much has been written about MT globally, but not much is known about the phenomenon in Africa; hence the appropriateness of this scientific assessment of MT in the region. By elucidating the role, structure and effect of this phenomenon, this study hopes to contribute to health systems strengthening in Africa. PROSPERO registration number CRD42016039745. PMID:28645947

Modeling and Fault Simulation of Propellant Filling System

NASA Astrophysics Data System (ADS)

Jiang, Yunchun; Liu, Weidong; Hou, Xiaobo

2012-05-01

Propellant filling system is one of the key ground plants in launching site of rocket that use liquid propellant. There is an urgent demand for ensuring and improving its reliability and safety, and there is no doubt that Failure Mode Effect Analysis (FMEA) is a good approach to meet it. Driven by the request to get more fault information for FMEA, and because of the high expense of propellant filling, in this paper, the working process of the propellant filling system in fault condition was studied by simulating based on AMESim. Firstly, based on analyzing its structure and function, the filling system was modular decomposed, and the mathematic models of every module were given, based on which the whole filling system was modeled in AMESim. Secondly, a general method of fault injecting into dynamic system was proposed, and as an example, two typical faults - leakage and blockage - were injected into the model of filling system, based on which one can get two fault models in AMESim. After that, fault simulation was processed and the dynamic characteristics of several key parameters were analyzed under fault conditions. The results show that the model can simulate effectively the two faults, and can be used to provide guidance for the filling system maintain and amelioration.

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.

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.

Spatial and Temporal Variations in Slip Partitioning During Oblique Convergence Experiments

NASA Astrophysics Data System (ADS)

Beyer, J. L.; Cooke, M. L.; Toeneboehn, K.

2017-12-01

Physical experiments of oblique convergence in wet kaolin demonstrate the development of slip partitioning, where two faults accommodate strain via different slip vectors. In these experiments, the second fault forms after the development of the first fault. As one strain component is relieved by one fault, the local stress field then favors the development of a second fault with different slip sense. A suite of physical experiments reveals three styles of slip partitioning development controlled by the convergence angle and presence of a pre-existing fault. In experiments with low convergence angles, strike-slip faults grow prior to reverse faults (Type 1) regardless of whether the fault is precut or not. In experiments with moderate convergence angles, slip partitioning is dominantly controlled by the presence of a pre-existing fault. In all experiments, the primarily reverse fault forms first. Slip partitioning then develops with the initiation of strike-slip along the precut fault (Type 2) or growth of a secondary reverse fault where the first fault is steepest. Subsequently, the slip on the first fault transitions to primarily strike-slip (Type 3). Slip rates and rakes along the slip partitioned faults for both precut and uncut experiments vary temporally, suggesting that faults in these slip-partitioned systems are constantly adapting to the conditions produced by slip along nearby faults in the system. While physical experiments show the evolution of slip partitioning, numerical simulations of the experiments provide information about both the stress and strain fields, which can be used to compute the full work budget, providing insight into the mechanisms that drive slip partitioning. Preliminary simulations of precut experiments show that strain energy density (internal work) can be used to predict fault growth, highlighting where fault growth can reduce off-fault deformation in the physical experiments. In numerical simulations of uncut experiments with a first non-planar oblique slip fault, strain energy density is greatest where the first fault is steepest, as less convergence is accommodated along this portion of the fault. The addition of a second slip-partitioning fault to the system decreases external work indicating that these faults increase the mechanical efficiency of the system.

Late Quaternary faulting along the Death Valley-Furnace Creek fault system, California and Nevada

USGS Publications Warehouse

Brogan, George E.; Kellogg, Karl; Slemmons, D. Burton; Terhune, Christina L.

1991-01-01

The Death Valley-Furnace Creek fault system, in California and Nevada, has a variety of impressive late Quaternary neotectonic features that record a long history of recurrent earthquake-induced faulting. Although no neotectonic features of unequivocal historical age are known, paleoseismic features from multiple late Quaternary events of surface faulting are well developed throughout the length of the system. Comparison of scarp heights to amount of horizontal offset of stream channels and the relationships of both scarps and channels to the ages of different geomorphic surfaces demonstrate that Quaternary faulting along the northwest-trending Furnace Creek fault zone is predominantly right lateral, whereas that along the north-trending Death Valley fault zone is predominantly normal. These observations are compatible with tectonic models of Death Valley as a northwest-trending pull-apart basin. The largest late Quaternary scarps along the Furnace Creek fault zone, with vertical separation of late Pleistocene surfaces of as much as 64 m (meters), are in Fish Lake Valley. Despite the predominance of normal faulting along the Death Valley fault zone, vertical offset of late Pleistocene surfaces along the Death Valley fault zone apparently does not exceed about 15 m. Evidence for four to six separate late Holocene faulting events along the Furnace Creek fault zone and three or more late Holocene events along the Death Valley fault zone are indicated by rupturing of Q1B (about 200-2,000 years old) geomorphic surfaces. Probably the youngest neotectonic feature observed along the Death Valley-Furnace Creek fault system, possibly historic in age, is vegetation lineaments in southernmost Fish Lake Valley. Near-historic faulting in Death Valley, within several kilometers south of Furnace Creek Ranch, is represented by (1) a 2,000-year-old lake shoreline that is cut by sinuous scarps, and (2) a system of young scarps with free-faceted faces (representing several faulting events) that cuts Q1B surfaces.

The physical mechanism of "inhomogeneous" magnetization transfer MRI

NASA Astrophysics Data System (ADS)

Manning, Alan P.; Chang, Kimberley L.; MacKay, Alex L.; Michal, Carl A.

2017-01-01

Inhomogeneous MT (ihMT) is a new magnetic resonance imaging technique that shows promise for myelin selectivity. Materials with a high proportion of lipids, such as white matter tissue, show a reduced intensity in magnetic resonance images acquired with selective prepulses at positive and negative offsets simultaneously compared to images with a single positive or negative offset prepulse of the same power. This effect was initially explained on the basis of hole-burning in inhomogeneously broadened lines of the lipid proton spin system. Our results contradict this explanation. ihMT in lipids can be understood with a simple spin-1 model of a coupled methylene proton pair. More generally, Provotorov theory can be used to consider the evolution of dipolar order in the non-aqueous spins during the prepulses. We show that the flip-angle dependence of the proton spectrum of a model lipid system (Prolipid-161) following dipolar order generation is in quantitative agreement with the model. In addition, we directly observe dipolar order and ihMT signals in the non-aqueous components of Prolipid-161 and homogeneously-broadened systems (hair, wood, and tendon) following ihMT prepulses. The observation of ihMT signals in tendon suggests that the technique may not be as specific to myelin as previously thought. Our work shows that ihMT occurs because of dipolar couplings alone, not from a specific type of spectral line broadening as its name suggests.

Simultaneous Event-Triggered Fault Detection and Estimation for Stochastic Systems Subject to Deception Attacks.

PubMed

Li, Yunji; Wu, QingE; Peng, Li

2018-01-23

In this paper, a synthesized design of fault-detection filter and fault estimator is considered for a class of discrete-time stochastic systems in the framework of event-triggered transmission scheme subject to unknown disturbances and deception attacks. A random variable obeying the Bernoulli distribution is employed to characterize the phenomena of the randomly occurring deception attacks. To achieve a fault-detection residual is only sensitive to faults while robust to disturbances, a coordinate transformation approach is exploited. This approach can transform the considered system into two subsystems and the unknown disturbances are removed from one of the subsystems. The gain of fault-detection filter is derived by minimizing an upper bound of filter error covariance. Meanwhile, system faults can be reconstructed by the remote fault estimator. An recursive approach is developed to obtain fault estimator gains as well as guarantee the fault estimator performance. Furthermore, the corresponding event-triggered sensor data transmission scheme is also presented for improving working-life of the wireless sensor node when measurement information are aperiodically transmitted. Finally, a scaled version of an industrial system consisting of local PC, remote estimator and wireless sensor node is used to experimentally evaluate the proposed theoretical results. In particular, a novel fault-alarming strategy is proposed so that the real-time capacity of fault-detection is guaranteed when the event condition is triggered.

Evaluation of an Enhanced Bank of Kalman Filters for In-Flight Aircraft Engine Sensor Fault Diagnostics

NASA Technical Reports Server (NTRS)

Kobayashi, Takahisa; Simon, Donald L.

2004-01-01

In this paper, an approach for in-flight fault detection and isolation (FDI) of aircraft engine sensors based on a bank of Kalman filters is developed. This approach utilizes multiple Kalman filters, each of which is designed based on a specific fault hypothesis. When the propulsion system experiences a fault, only one Kalman filter with the correct hypothesis is able to maintain the nominal estimation performance. Based on this knowledge, the isolation of faults is achieved. Since the propulsion system may experience component and actuator faults as well, a sensor FDI system must be robust in terms of avoiding misclassifications of any anomalies. The proposed approach utilizes a bank of (m+1) Kalman filters where m is the number of sensors being monitored. One Kalman filter is used for the detection of component and actuator faults while each of the other m filters detects a fault in a specific sensor. With this setup, the overall robustness of the sensor FDI system to anomalies is enhanced. Moreover, numerous component fault events can be accounted for by the FDI system. The sensor FDI system is applied to a commercial aircraft engine simulation, and its performance is evaluated at multiple power settings at a cruise operating point using various fault scenarios.

Faults Discovery By Using Mined Data

NASA Technical Reports Server (NTRS)

Lee, Charles

2005-01-01

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

First Results from a Forward, 3-Dimensional Regional Model of a Transpressional San Andreas Fault System

NASA Astrophysics Data System (ADS)

Fitzenz, D. D.; Miller, S. A.

2001-12-01

We present preliminary results from a 3-dimensional fault interaction model, with the fault system specified by the geometry and tectonics of the San Andreas Fault (SAF) system. We use the forward model for earthquake generation on interacting faults of Fitzenz and Miller [2001] that incorporates the analytical solutions of Okada [85,92], GPS-constrained tectonic loading, creep compaction and frictional dilatancy [Sleep and Blanpied, 1994, Sleep, 1995], and undrained poro-elasticity. The model fault system is centered at the Big Bend, and includes three large strike-slip faults (each discretized into multiple subfaults); 1) a 300km, right-lateral segment of the SAF to the North, 2) a 200km-long left-lateral segment of the Garlock fault to the East, and 3) a 100km-long right-lateral segment of the SAF to the South. In the initial configuration, three shallow-dipping faults are also included that correspond to the thrust belt sub-parallel to the SAF. Tectonic loading is decomposed into basal shear drag parallel to the plate boundary with a 35mm yr-1 plate velocity, and East-West compression approximated by a vertical dislocation surface applied at the far-field boundary resulting in fault-normal compression rates in the model space about 4mm yr-1. Our aim is to study the long-term seismicity characteristics, tectonic evolution, and fault interaction of this system. We find that overpressured faults through creep compaction are a necessary consequence of the tectonic loading, specifically where high normal stress acts on long straight fault segments. The optimal orientation of thrust faults is a function of the strike-slip behavior, and therefore results in a complex stress state in the elastic body. This stress state is then used to generate new fault surfaces, and preliminary results of dynamically generated faults will also be presented. Our long-term aim is to target measurable properties in or around fault zones, (e.g. pore pressures, hydrofractures, seismicity catalogs, stress orientation, surface strain, triggering, etc.), which may allow inferences on the stress state of fault systems.

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.

Implementation of a model based fault detection and diagnosis for actuation faults of the Space Shuttle main engine

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Robust Fault Detection and Isolation for Stochastic Systems

NASA Technical Reports Server (NTRS)

George, Jemin; Gregory, Irene M.

2010-01-01

This paper outlines the formulation of a robust fault detection and isolation scheme that can precisely detect and isolate simultaneous actuator and sensor faults for uncertain linear stochastic systems. The given robust fault detection scheme based on the discontinuous robust observer approach would be able to distinguish between model uncertainties and actuator failures and therefore eliminate the problem of false alarms. Since the proposed approach involves precise reconstruction of sensor faults, it can also be used for sensor fault identification and the reconstruction of true outputs from faulty sensor outputs. Simulation results presented here validate the effectiveness of the robust fault detection and isolation system.

Sliding Mode Observer-Based Current Sensor Fault Reconstruction and Unknown Load Disturbance Estimation for PMSM Driven System.

PubMed

Zhao, Kaihui; Li, Peng; Zhang, Changfan; Li, Xiangfei; He, Jing; Lin, Yuliang

2017-12-06

This paper proposes a new scheme of reconstructing current sensor faults and estimating unknown load disturbance for a permanent magnet synchronous motor (PMSM)-driven system. First, the original PMSM system is transformed into two subsystems; the first subsystem has unknown system load disturbances, which are unrelated to sensor faults, and the second subsystem has sensor faults, but is free from unknown load disturbances. Introducing a new state variable, the augmented subsystem that has sensor faults can be transformed into having actuator faults. Second, two sliding mode observers (SMOs) are designed: the unknown load disturbance is estimated by the first SMO in the subsystem, which has unknown load disturbance, and the sensor faults can be reconstructed using the second SMO in the augmented subsystem, which has sensor faults. The gains of the proposed SMOs and their stability analysis are developed via the solution of linear matrix inequality (LMI). Finally, the effectiveness of the proposed scheme was verified by simulations and experiments. The results demonstrate that the proposed scheme can reconstruct current sensor faults and estimate unknown load disturbance for the PMSM-driven system.

Kinematics of shallow backthrusts in the Seattle fault zone, Washington State

USGS Publications Warehouse

Pratt, Thomas L.; Troost, K.G.; Odum, Jackson K.; Stephenson, William J.

2015-01-01

Near-surface thrust fault splays and antithetic backthrusts at the tips of major thrust fault systems can distribute slip across multiple shallow fault strands, complicating earthquake hazard analyses based on studies of surface faulting. The shallow expression of the fault strands forming the Seattle fault zone of Washington State shows the structural relationships and interactions between such fault strands. Paleoseismic studies document an ∼7000 yr history of earthquakes on multiple faults within the Seattle fault zone, with some backthrusts inferred to rupture in small (M ∼5.5–6.0) earthquakes at times other than during earthquakes on the main thrust faults. We interpret seismic-reflection profiles to show three main thrust faults, one of which is a blind thrust fault directly beneath downtown Seattle, and four small backthrusts within the Seattle fault zone. We then model fault slip, constrained by shallow deformation, to show that the Seattle fault forms a fault propagation fold rather than the alternatively proposed roof thrust system. Fault slip modeling shows that back-thrust ruptures driven by moderate (M ∼6.5–6.7) earthquakes on the main thrust faults are consistent with the paleoseismic data. The results indicate that paleoseismic data from the back-thrust ruptures reveal the times of moderate earthquakes on the main fault system, rather than indicating smaller (M ∼5.5–6.0) earthquakes involving only the backthrusts. Estimates of cumulative shortening during known Seattle fault zone earthquakes support the inference that the Seattle fault has been the major seismic hazard in the northern Cascadia forearc in the late Holocene.

Development, Interaction and Linkage of Normal Fault Segments along the 100-km Bilila-Mtakataka Fault, Malawi

NASA Astrophysics Data System (ADS)

Fagereng, A.; Hodge, M.; Biggs, J.; Mdala, H. S.; Goda, K.

2016-12-01

Faults grow through the interaction and linkage of isolated fault segments. Continuous fault systems are those where segments interact, link and may slip synchronously, whereas non-continuous fault systems comprise isolated faults. As seismic moment is related to fault length (Wells and Coppersmith, 1994), understanding whether a fault system is continuous or not is critical in evaluating seismic hazard. Maturity may be a control on fault continuity: immature, low displacement faults are typically assumed to be non-continuous. Here, we study two overlapping, 20 km long, normal fault segments of the N-S striking Bilila-Mtakataka fault, Malawi, in the southern section of the East African Rift System. Despite its relative immaturity, previous studies concluded the Bilila-Mtakataka fault is continuous for its entire 100 km length, with the most recent event equating to an Mw8.0 earthquake (Jackson and Blenkinsop, 1997). We explore whether segment geometry and relationship to pre-existing high-grade metamorphic foliation has influenced segment interaction and fault development. Fault geometry and scarp height is constrained by DEMs derived from SRTM, Pleiades and `Structure from Motion' photogrammetry using a UAV, alongside direct field observations. The segment strikes differ on average by 10°, but up to 55° at their adjacent tips. The southern segment is sub-parallel to the foliation, whereas the northern segment is highly oblique to the foliation. Geometrical surface discontinuities suggest two isolated faults; however, displacement-length profiles and Coulomb stress change models suggest segment interaction, with potential for linkage at depth. Further work must be undertaken on other segments to assess the continuity of the entire fault, concluding whether an earthquake greater than that of the maximum instrumentally recorded (1910 M7.4 Rukwa) is possible.

MT3DMS: Model use, calibration, and validation

USGS Publications Warehouse

Zheng, C.; Hill, Mary C.; Cao, G.; Ma, R.

2012-01-01

MT3DMS is a three-dimensional multi-species solute transport model for solving advection, dispersion, and chemical reactions of contaminants in saturated groundwater flow systems. MT3DMS interfaces directly with the U.S. Geological Survey finite-difference groundwater flow model MODFLOW for the flow solution and supports the hydrologic and discretization features of MODFLOW. MT3DMS contains multiple transport solution techniques in one code, which can often be important, including in model calibration. Since its first release in 1990 as MT3D for single-species mass transport modeling, MT3DMS has been widely used in research projects and practical field applications. This article provides a brief introduction to MT3DMS and presents recommendations about calibration and validation procedures for field applications of MT3DMS. The examples presented suggest the need to consider alternative processes as models are calibrated and suggest opportunities and difficulties associated with using groundwater age in transport model calibration.

Verification of an IGBT Fusing Switch for Over-current Protection of the SNS HVCM

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

Benwell, Andrew; Kemp, Mark; Burkhart, Craig

2010-06-11

An IGBT based over-current protection system has been developed to detect faults and limit the damage caused by faults in high voltage converter modulators. During normal operation, an IGBT enables energy to be transferred from storage capacitors to a H-bridge. When a fault occurs, the over-current protection system detects the fault, limits the fault current and opens the IGBT to isolate the remaining stored energy from the fault. This paper presents an experimental verification of the over-current protection system under applicable conditions.

Discrete Wavelet Transform for Fault Locations in Underground Distribution System

NASA Astrophysics Data System (ADS)

Apisit, C.; Ngaopitakkul, A.

2010-10-01

In this paper, a technique for detecting faults in underground distribution system is presented. Discrete Wavelet Transform (DWT) based on traveling wave is employed in order to detect the high frequency components and to identify fault locations in the underground distribution system. The first peak time obtained from the faulty bus is employed for calculating the distance of fault from sending end. The validity of the proposed technique is tested with various fault inception angles, fault locations and faulty phases. The result is found that the proposed technique provides satisfactory result and will be very useful in the development of power systems protection scheme.

Dynamic characteristics of a 20 kHz resonant power system - Fault identification and fault recovery

NASA Technical Reports Server (NTRS)

Wasynczuk, O.

1988-01-01

A detailed simulation of a dc inductor resonant driver and receiver is used to demonstrate the transient characteristics of a 20 kHz resonant power system during fault and overload conditions. The simulated system consists of a dc inductor resonant inverter (driver), a 50-meter transmission cable, and a dc inductor resonant receiver load. Of particular interest are the driver and receiver performance during fault and overload conditions and on the recovery characteristics following removal of the fault. The information gained from these studies sets the stage for further work in fault identification and autonomous power system control.

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.

Jurassic faults of southwest Alabama and offshore areas

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

Mink, R.M.; Tew, B.H.; Bearden, B.L.

1991-03-01

Four fault groups affecting Jurassic strata occur in the southwest and offshore Alabama areas. They include the regional basement rift trend, the regional peripheral fault trend, the Mobile graben fault system, and the Lower Mobile Bay fault system. The regional basement system rift and regional peripheral fault trends are distinct and rim the inner margin of the eastern Gulf Coastal Plain. The regional basement rift trend is genetically related to the breakup of Pangea and the opening of the Gulf of Mexico in the Late Triassic-Early Jurassic. This fault trend is thought to have formed contemporaneously with deposition of Latemore » Triassic-Early Jurassic Eagle Mills Formation and to displace pre-Mesozoic rocks. The regional peripheral fault trend consists of a group of en echelon extensional faults that are parallel or subparallel to regional strike of Gulf Coastal Plain strata and correspond to the approximate updip limit of thick Louann Salt. Nondiapiric salt features are associated with the trend and maximum structural development is exhibited in the Haynesville-Smackover section. No hydrocarbon accumulations have been documented in the pre-Jurassic strata of southwest and offshore Alabama. Productive hydrocarbon reservoirs occur in Jurassic strata along the trends of the fault groups, suggesting a significant relationship between structural development in the Jurassic and hydrocarbon accumulation. Hydrocarbon traps are generally structural or contain a major structural component and include salt anticlines, faulted salt anticlines, and extensional fault traps. All of the major hydrocarbon accumulations are associated with movement of the Louann Salt along the regional peripheral fault trend, the Mobile graben fault system, or the Lower Mobile Bay fault system.« less

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

Structural controls on a geothermal system in the Tarutung Basin, north central Sumatra

NASA Astrophysics Data System (ADS)

Nukman, Mochamad; Moeck, Inga

2013-09-01

The Sumatra Fault System provides a unique geologic setting to evaluate the influence of structural controls on geothermal activity. Whereas most of the geothermal systems in Indonesia are controlled by volcanic activity, geothermal systems at the Sumatra Fault System might be controlled by faults and fractures. Exploration strategies for these geothermal systems need to be verified because the typical pattern of heat source and alteration clays are missing so that conventional exploration with magnetotelluric surveys might not provide sufficient data to delineate favorable settings for drilling. We present field geological, structural and geomorphological evidence combined with mapping of geothermal manifestations to allow constraints between fault dynamics and geothermal activity in the Tarutung Basin in north central Sumatra. Our results indicate that the fault pattern in the Tarutung Basin is generated by a compressional stress direction acting at a high angle to the right-lateral Sumatra Fault System. NW-SE striking normal faults possibly related to negative flower structures and NNW-SSE to NNE-SSW oriented dilative Riedel shears are preferential fluid pathways whereas ENE-WSW striking faults act as barriers in this system. The dominant of geothermal manifestations at the eastern part of the basin indicates local extension due to clockwise block rotation in the Sumatra Fault System. Our results support the effort to integrate detailed field geological surveys to refined exploration strategies even in tropical areas where outcrops are limited.

The Trans-Rocky Mountain Fault System - A Fundamental Precambrian Strike-Slip System

USGS Publications Warehouse

Sims, P.K.

2009-01-01

Recognition of a major Precambrian continental-scale, two-stage conjugate strike-slip fault system - here designated as the Trans-Rocky Mountain fault system - provides new insights into the architecture of the North American continent. The fault system consists chiefly of steep linear to curvilinear, en echelon, braided and branching ductile-brittle shears and faults, and local coeval en echelon folds of northwest strike, that cut indiscriminately across both Proterozoic and Archean cratonic elements. The fault system formed during late stages of two distinct tectonic episodes: Neoarchean and Paleoproterozoic orogenies at about 2.70 and 1.70 billion years (Ga). In the Archean Superior province, the fault system formed (about 2.70-2.65 Ga) during a late stage of the main deformation that involved oblique shortening (dextral transpression) across the region and progressed from crystal-plastic to ductile-brittle deformation. In Paleoproterozoic terranes, the fault system formed about 1.70 Ga, shortly following amalgamation of Paleoproterozoic and Archean terranes and the main Paleoproterozoic plastic-fabric-producing events in the protocontinent, chiefly during sinistral transpression. The postulated driving force for the fault system is subcontinental mantle deformation, the bottom-driven deformation of previous investigators. This model, based on seismic anisotropy, invokes mechanical coupling and subsequent shear between the lithosphere and the asthenosphere such that a major driving force for plate motion is deep-mantle flow.

Automatic Fault Characterization via Abnormality-Enhanced Classification

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

Bronevetsky, G; Laguna, I; de Supinski, B R

Enterprise and high-performance computing systems are growing extremely large and complex, employing hundreds to hundreds of thousands of processors and software/hardware stacks built by many people across many organizations. As the growing scale of these machines increases the frequency of faults, system complexity makes these faults difficult to detect and to diagnose. Current system management techniques, which focus primarily on efficient data access and query mechanisms, require system administrators to examine the behavior of various system services manually. Growing system complexity is making this manual process unmanageable: administrators require more effective management tools that can detect faults and help tomore » identify their root causes. System administrators need timely notification when a fault is manifested that includes the type of fault, the time period in which it occurred and the processor on which it originated. Statistical modeling approaches can accurately characterize system behavior. However, the complex effects of system faults make these tools difficult to apply effectively. This paper investigates the application of classification and clustering algorithms to fault detection and characterization. We show experimentally that naively applying these methods achieves poor accuracy. Further, we design novel techniques that combine classification algorithms with information on the abnormality of application behavior to improve detection and characterization accuracy. Our experiments demonstrate that these techniques can detect and characterize faults with 65% accuracy, compared to just 5% accuracy for naive approaches.« less

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.

Fault Modeling of Extreme Scale Applications Using Machine Learning

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

Vishnu, Abhinav; Dam, Hubertus van; Tallent, Nathan R.

Faults are commonplace in large scale systems. These systems experience a variety of faults such as transient, permanent and intermittent. Multi-bit faults are typically not corrected by the hardware resulting in an error. Here, this paper attempts to answer an important question: Given a multi-bit fault in main memory, will it result in an application error — and hence a recovery algorithm should be invoked — or can it be safely ignored? We propose an application fault modeling methodology to answer this question. Given a fault signature (a set of attributes comprising of system and application state), we use machinemore » learning to create a model which predicts whether a multibit permanent/transient main memory fault will likely result in error. We present the design elements such as the fault injection methodology for covering important data structures, the application and system attributes which should be used for learning the model, the supervised learning algorithms (and potentially ensembles), and important metrics. Lastly, we use three applications — NWChem, LULESH and SVM — as examples for demonstrating the effectiveness of the proposed fault modeling methodology.« less

Fault Modeling of Extreme Scale Applications Using Machine Learning

DOE PAGES

Vishnu, Abhinav; Dam, Hubertus van; Tallent, Nathan R.; ...

2016-05-01

Faults are commonplace in large scale systems. These systems experience a variety of faults such as transient, permanent and intermittent. Multi-bit faults are typically not corrected by the hardware resulting in an error. Here, this paper attempts to answer an important question: Given a multi-bit fault in main memory, will it result in an application error — and hence a recovery algorithm should be invoked — or can it be safely ignored? We propose an application fault modeling methodology to answer this question. Given a fault signature (a set of attributes comprising of system and application state), we use machinemore » learning to create a model which predicts whether a multibit permanent/transient main memory fault will likely result in error. We present the design elements such as the fault injection methodology for covering important data structures, the application and system attributes which should be used for learning the model, the supervised learning algorithms (and potentially ensembles), and important metrics. Lastly, we use three applications — NWChem, LULESH and SVM — as examples for demonstrating the effectiveness of the proposed fault modeling methodology.« less

A comparative study of sensor fault diagnosis methods based on observer for ECAS system

NASA Astrophysics Data System (ADS)

Xu, Xing; Wang, Wei; Zou, Nannan; Chen, Long; Cui, Xiaoli

2017-03-01

The performance and practicality of electronically controlled air suspension (ECAS) system are highly dependent on the state information supplied by kinds of sensors, but faults of sensors occur frequently. Based on a non-linearized 3-DOF 1/4 vehicle model, different methods of fault detection and isolation (FDI) are used to diagnose the sensor faults for ECAS system. The considered approaches include an extended Kalman filter (EKF) with concise algorithm, a strong tracking filter (STF) with robust tracking ability, and the cubature Kalman filter (CKF) with numerical precision. We propose three filters of EKF, STF, and CKF to design a state observer of ECAS system under typical sensor faults and noise. Results show that three approaches can successfully detect and isolate faults respectively despite of the existence of environmental noise, FDI time delay and fault sensitivity of different algorithms are different, meanwhile, compared with EKF and STF, CKF method has best performing FDI of sensor faults for ECAS system.

Hardware fault insertion and instrumentation system: Mechanization and validation

NASA Technical Reports Server (NTRS)

Benson, J. W.

1987-01-01

Automated test capability for extensive low-level hardware fault insertion testing is developed. The test capability is used to calibrate fault detection coverage and associated latency times as relevant to projecting overall system reliability. Described are modifications made to the NASA Ames Reconfigurable Flight Control System (RDFCS) Facility to fully automate the total test loop involving the Draper Laboratories' Fault Injector Unit. The automated capability provided included the application of sequences of simulated low-level hardware faults, the precise measurement of fault latency times, the identification of fault symptoms, and bulk storage of test case results. A PDP-11/60 served as a test coordinator, and a PDP-11/04 as an instrumentation device. The fault injector was controlled by applications test software in the PDP-11/60, rather than by manual commands from a terminal keyboard. The time base was especially developed for this application to use a variety of signal sources in the system simulator.

The weakest t-norm based intuitionistic fuzzy fault-tree analysis to evaluate system reliability.

PubMed

Kumar, Mohit; Yadav, Shiv Prasad

2012-07-01

In this paper, a new approach of intuitionistic fuzzy fault-tree analysis is proposed to evaluate system reliability and to find the most critical system component that affects the system reliability. Here weakest t-norm based intuitionistic fuzzy fault tree analysis is presented to calculate fault interval of system components from integrating expert's knowledge and experience in terms of providing the possibility of failure of bottom events. It applies fault-tree analysis, α-cut of intuitionistic fuzzy set and T(ω) (the weakest t-norm) based arithmetic operations on triangular intuitionistic fuzzy sets to obtain fault interval and reliability interval of the system. This paper also modifies Tanaka et al.'s fuzzy fault-tree definition. In numerical verification, a malfunction of weapon system "automatic gun" is presented as a numerical example. The result of the proposed method is compared with the listing approaches of reliability analysis methods. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

Linking numerical models of lithospheric deformation and magnetotelluric images

NASA Astrophysics Data System (ADS)

Sobolev, S. V.

2012-12-01

Efficient modeling of geodynamic processes requires constraints from different fields of geosciences. Frequently used are data on crustal structure and composition and their evolution constrained by seismic, gravity and petrological/geochemical studies. However, links between geodynamic modeling and rapidly developing field of magnetotelluric (MT) studies are still insufficient. I'll consider two recent examples of MT observations and geodynamic modeling demonstrating that joint analyses of thermomechanical models of lithospheric deformation and MT images may be useful to understand geodynamic processes. One set of observations is MT data for San Andreas Fault (SAF) in the region close to the SAFOD Site (Becken et al., 2011) that shows high conductivity anomalies in the mantle, that are interpreted as fluid flow feeding creeping part of SAF south of the SAFOD Site. Interestingly, zones of high conductivity do not coincide with the expected zones of the recent active deformation (SAF), but are located to the west of it. Based on thermomechanical model of the evolution of the SAFS in Central and Northern California during the last 20 Mln. years (Popov et al., 2012), I'll demonstrate that high conductivity anomalies precisely coincide with the expected zones of the highest accumulated shear strain. Possible interpretation of this coincidence is that strong preferred orientation of olivine crystals in the highly deformed mantle shear zone causes high permeability of fluids. Another set of observations is MT data showing high conductivity anomalies in the crust of Tibet (Unsworh et al., 2005, Bai et al., 2010) and Pamirs (Sass et al., 2011) that are often interpreted as an evidence for the widely spread partially molten crust. Using 2D thermomechanical models of the collision between India and Eurasia, I'll demonstrate that such structures in the crust cannot appear without delamination of the mantle lithosphere during tectonic shortening. Internal heating of the thickened felsic crust due to radiogenic heat production and shear heating is not sufficient to produce such structures. The key triggering factor for the delamination is gabbro-eclogite transformation in the lower crust. Delamination of the lower crust and mantle lithosphere is followed by the partial melting and internal convection in the thickened upper-middle crust.

Multiplex genotyping system for efficient inference of matrilineal genetic ancestry with continental resolution

PubMed Central

2011-01-01

Background In recent years, phylogeographic studies have produced detailed knowledge on the worldwide distribution of mitochondrial DNA (mtDNA) variants, linking specific clades of the mtDNA phylogeny with certain geographic areas. However, a multiplex genotyping system for the detection of the mtDNA haplogroups of major continental distribution that would be desirable for efficient DNA-based bio-geographic ancestry testing in various applications is still missing. Results Three multiplex genotyping assays, based on single-base primer extension technology, were developed targeting a total of 36 coding-region mtDNA variants that together differentiate 43 matrilineal haplo-/paragroups. These include the major diagnostic haplogroups for Africa, Western Eurasia, Eastern Eurasia and Native America. The assays show high sensitivity with respect to the amount of template DNA: successful amplification could still be obtained when using as little as 4 pg of genomic DNA and the technology is suitable for medium-throughput analyses. Conclusions We introduce an efficient and sensitive multiplex genotyping system for bio-geographic ancestry inference from mtDNA that provides resolution on the continental level. The method can be applied in forensics, to aid tracing unknown suspects, as well as in population studies, genealogy and personal ancestry testing. For more complete inferences of overall bio-geographic ancestry from DNA, the mtDNA system provided here can be combined with multiplex systems for suitable autosomal and, in the case of males, Y-chromosomal ancestry-sensitive DNA markers. PMID:21429198

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.

The CAFE Experiment: A Joint Seismic and MT Investigation of the Cascadia Subduction System

DTIC Science & Technology

2013-02-01

In this thesis we present results from inversion of data using dense arrays of collocated seismic and magnetotelluric stations located in the Cascadia...implicit in the standard MT inversion provides tools that enable us to generate a more accurate MT model. This final MT model clearly demonstrates...references within, Hacker, 2008) have given us the tools to better interpret geophysical evidence. Improvements in the thermal modeling of subduction zones

Integrated Fault Diagnosis Algorithm for Motor Sensors of In-Wheel Independent Drive Electric Vehicles

PubMed Central

Jeon, Namju; Lee, Hyeongcheol

2016-01-01

An integrated fault-diagnosis algorithm for a motor sensor of in-wheel independent drive electric vehicles is presented. This paper proposes a method that integrates the high- and low-level fault diagnoses to improve the robustness and performance of the system. For the high-level fault diagnosis of vehicle dynamics, a planar two-track non-linear model is first selected, and the longitudinal and lateral forces are calculated. To ensure redundancy of the system, correlation between the sensor and residual in the vehicle dynamics is analyzed to detect and separate the fault of the drive motor system of each wheel. To diagnose the motor system for low-level faults, the state equation of an interior permanent magnet synchronous motor is developed, and a parity equation is used to diagnose the fault of the electric current and position sensors. The validity of the high-level fault-diagnosis algorithm is verified using Carsim and Matlab/Simulink co-simulation. The low-level fault diagnosis is verified through Matlab/Simulink simulation and experiments. Finally, according to the residuals of the high- and low-level fault diagnoses, fault-detection flags are defined. On the basis of this information, an integrated fault-diagnosis strategy is proposed. PMID:27973431

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

USGS Publications Warehouse

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

1999-01-01

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

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

Quinn, Heather; Wirthlin, Michael

A variety of fault emulation systems have been created to study the effect of single-event effects (SEEs) in static random access memory (SRAM) based field-programmable gate arrays (FPGAs). These systems are useful for augmenting radiation-hardness assurance (RHA) methodologies for verifying the effectiveness for mitigation techniques; understanding error signatures and failure modes in FPGAs; and failure rate estimation. For radiation effects researchers, it is important that these systems properly emulate how SEEs manifest in FPGAs. If the fault emulation systems does not mimic the radiation environment, the system will generate erroneous data and incorrect predictions of behavior of the FPGA inmore » a radiation environment. Validation determines whether the emulated faults are reasonable analogs to the radiation-induced faults. In this study we present methods for validating fault emulation systems and provide several examples of validated FPGA fault emulation systems.« less

In-flight Fault Detection and Isolation in Aircraft Flight Control Systems

NASA Technical Reports Server (NTRS)

Azam, Mohammad; Pattipati, Krishna; Allanach, Jeffrey; Poll, Scott; Patterson-Hine, Ann

2005-01-01

In this paper we consider the problem of test design for real-time fault detection and isolation (FDI) in the flight control system of fixed-wing aircraft. We focus on the faults that are manifested in the control surface elements (e.g., aileron, elevator, rudder and stabilizer) of an aircraft. For demonstration purposes, we restrict our focus on the faults belonging to nine basic fault classes. The diagnostic tests are performed on the features extracted from fifty monitored system parameters. The proposed tests are able to uniquely isolate each of the faults at almost all severity levels. A neural network-based flight control simulator, FLTZ(Registered TradeMark), is used for the simulation of various faults in fixed-wing aircraft flight control systems for the purpose of FDI.

New features of mitochondrial DNA replication system in yeast and man.

PubMed

Lecrenier, N; Foury, F

2000-04-04

In this review, we sum up the research carried out over two decades on mitochondrial DNA (mtDNA) replication, primarily by comparing this system in Saccharomyces cerevisiae and Homo sapiens. Brief incursions into systems of other organisms have also been achieved when they provide new information.S. cerevisiae and H. sapiens mitochondrial DNA (mtDNA) have been thought for a long time to share closely related architecture and replication mechanisms. However, recent studies suggest that mitochondrial genome of S. cerevisiae may be formed, at least partially, from linear multimeric molecules, while human mtDNA is circular. Although several proteins involved in the replication of these two genomes are very similar, divergences are also now increasingly evident. As an example, the recently cloned human mitochondrial DNA polymerase beta-subunit has no counterpart in yeast. Yet, yeast Abf2p and human mtTFA are probably not as closely functionally related as thought previously. Some mtDNA metabolism factors, like DNA ligases, were until recently largely uncharacterized, and have been found to be derived from alternative nuclear products. Many factors involved in the metabolism of mitochondrial DNA are linked through genetic or biochemical interconnections. These links are presented on a map. Finally, we discuss recent studies suggesting that the yeast mtDNA replication system diverges from that observed in man, and may involve recombination, possibly coupled to alternative replication mechanisms like rolling circle replication.

78 FR 67299 - Modification of Class E Airspace; Cut Bank, MT

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-12

...-0664; Airspace Docket No. 13-ANM-22] Modification of Class E Airspace; Cut Bank, MT AGENCY: Federal... Cut Bank, MT, to accommodate new Area Navigation (RNAV) Global Positioning System (GPS) standard instrument approach procedures at Cut Bank Municipal Airport. This improves the safety and management of...

Heteromeric MT1/MT2 Melatonin Receptors Modulate Photoreceptor Function

PubMed Central

Baba, Kenkichi; Benleulmi-Chaachoua, Abla; Journé, Anne-Sophie; Kamal, Maud; Guillaume, Jean-Luc; Dussaud, Sébastien; Gbahou, Florence; Yettou, Katia; Liu, Cuimei; Contreras-Alcantara, Susana; Jockers, Ralf; Tosini, Gianluca

2013-01-01

The formation of G protein-coupled receptor (GPCR) heteromers elicits signaling diversification and holds great promise for improved drug selectivity. Most studies have been conducted in heterologous expression systems; however, in vivo validation is missing from most cases thus questioning the physiological significance of GPCR heteromerization. Melatonin MT1 and MT2 receptors have been shown to exist as homo- and heteromers in vitro. We show here that the effect of melatonin on rod photoreceptor light sensitivity is mediated by melatonin MT1/MT2 receptor heteromers. This effect involves activation of the heteromer-specific PLC/PKC pathway and is abolished in MT1−/− and MT2−/− mice as well as in mice overexpressing a non-functional MT2 receptor mutant that competes with the formation of functional MT1/MT2 heteromers in photoreceptor cells. This study establishes the essential role of melatonin receptor heteromers in retinal function and supports the physiological importance of GPCR heteromerization. Finally, our work may have important therapeutic implications, as the heteromer complex may provide a unique pharmacological target to improve photoreceptor functioning and to extend the viability of photoreceptors during aging. PMID:24106342

From experiment to design -- Fault characterization and detection in parallel computer systems using computational accelerators

NASA Astrophysics Data System (ADS)

Yim, Keun Soo

This dissertation summarizes experimental validation and co-design studies conducted to optimize the fault detection capabilities and overheads in hybrid computer systems (e.g., using CPUs and Graphics Processing Units, or GPUs), and consequently to improve the scalability of parallel computer systems using computational accelerators. The experimental validation studies were conducted to help us understand the failure characteristics of CPU-GPU hybrid computer systems under various types of hardware faults. The main characterization targets were faults that are difficult to detect and/or recover from, e.g., faults that cause long latency failures (Ch. 3), faults in dynamically allocated resources (Ch. 4), faults in GPUs (Ch. 5), faults in MPI programs (Ch. 6), and microarchitecture-level faults with specific timing features (Ch. 7). The co-design studies were based on the characterization results. One of the co-designed systems has a set of source-to-source translators that customize and strategically place error detectors in the source code of target GPU programs (Ch. 5). Another co-designed system uses an extension card to learn the normal behavioral and semantic execution patterns of message-passing processes executing on CPUs, and to detect abnormal behaviors of those parallel processes (Ch. 6). The third co-designed system is a co-processor that has a set of new instructions in order to support software-implemented fault detection techniques (Ch. 7). The work described in this dissertation gains more importance because heterogeneous processors have become an essential component of state-of-the-art supercomputers. GPUs were used in three of the five fastest supercomputers that were operating in 2011. Our work included comprehensive fault characterization studies in CPU-GPU hybrid computers. In CPUs, we monitored the target systems for a long period of time after injecting faults (a temporally comprehensive experiment), and injected faults into various types of program states that included dynamically allocated memory (to be spatially comprehensive). In GPUs, we used fault injection studies to demonstrate the importance of detecting silent data corruption (SDC) errors that are mainly due to the lack of fine-grained protections and the massive use of fault-insensitive data. This dissertation also presents transparent fault tolerance frameworks and techniques that are directly applicable to hybrid computers built using only commercial off-the-shelf hardware components. This dissertation shows that by developing understanding of the failure characteristics and error propagation paths of target programs, we were able to create fault tolerance frameworks and techniques that can quickly detect and recover from hardware faults with low performance and hardware overheads.

Did the Middlesboro, Kentucky, bolide impact event influence coal rank?

USGS Publications Warehouse

Hower, J.C.; Greb, S.F.; Kuehn, K.W.; Eble, C.F.

2009-01-01

The Middlesboro Basin, southeastern Kentucky, occurs on the Cumberland Overthrust Sheet and includes a ca. 5.5-km diameter impact structure. The Lower and Middle Pennsylvanian coal-bearing strata are faulted, with some evidence for shock metamorphism. The event post-dated the latest-Pennsylvanian-early-Permian thrusting and was likely prior to late-Mesozoic entrenchment of drainages. The impact of a 0.5-km meteor traveling at ca. 60,000??km/h would release about 1??EJ, the approximate equivalent of the instantaneous combustion of 30??Mt of coal. The coal rank, while increased slightly above the regional level, still is within the upper portion of the high volatile A bituminous rank range. This helps to constrain the depth of burial at the time of the impact. The coal would have had to have been at a depth of a few kilometers to have avoided a more substantial rank increase. In addition, it is possible that some of the coal rank increase might be attributable to movements along the cross-cutting Rocky Face fault, unrelated to the impact. ?? 2009 Elsevier B.V. All rights reserved.

Palaeopermeability structure within fault-damage zones: A snap-shot from microfracture analyses in a strike-slip system

NASA Astrophysics Data System (ADS)

Gomila, Rodrigo; Arancibia, Gloria; Mitchell, Thomas M.; Cembrano, Jose M.; Faulkner, Daniel R.

2016-02-01

Understanding fault zone permeability and its spatial distribution allows the assessment of fluid-migration leading to precipitation of hydrothermal minerals. This work is aimed at unraveling the conditions and distribution of fluid transport properties in fault zones based on hydrothermally filled microfractures, which reflect the ''frozen-in'' instantaneous advective hydrothermal activity and record palaeopermeability conditions of the fault-fracture system. We studied the Jorgillo Fault, an exposed 20 km long, left-lateral strike-slip fault, which juxtaposes Jurassic gabbro against metadiorite belonging to the Atacama Fault System in northern Chile. Tracings of microfracture networks of 19 oriented thin sections from a 400 m long transect across the main fault trace was carried out to estimate the hydraulic properties of the low-strain fault damagezone, adjacent to the high-strain fault core, by assuming penny-shaped microfractures of constant radius and aperture within an anisotropic fracture system. Palaeopermeability values of 9.1*10-11 to 3.2*10-13 m2 in the gabbro and of 5.0*10-10 to 1.2*10-13 m2 in the metadiorite were determined, both decreasing perpendicularly away from the fault core. Fracture porosity values range from 40.00% to 0.28%. The Jorgillo Fault has acted as a left-lateral dilational fault-bend, generating large-scale dilation sites north of the JF during co-seismic activity.

Evaluation of reliability modeling tools for advanced fault tolerant systems

NASA Technical Reports Server (NTRS)

Baker, Robert; Scheper, Charlotte

1986-01-01

The Computer Aided Reliability Estimation (CARE III) and Automated Reliability Interactice Estimation System (ARIES 82) reliability tools for application to advanced fault tolerance aerospace systems were evaluated. To determine reliability modeling requirements, the evaluation focused on the Draper Laboratories' Advanced Information Processing System (AIPS) architecture as an example architecture for fault tolerance aerospace systems. Advantages and limitations were identified for each reliability evaluation tool. The CARE III program was designed primarily for analyzing ultrareliable flight control systems. The ARIES 82 program's primary use was to support university research and teaching. Both CARE III and ARIES 82 were not suited for determining the reliability of complex nodal networks of the type used to interconnect processing sites in the AIPS architecture. It was concluded that ARIES was not suitable for modeling advanced fault tolerant systems. It was further concluded that subject to some limitations (the difficulty in modeling systems with unpowered spare modules, systems where equipment maintenance must be considered, systems where failure depends on the sequence in which faults occurred, and systems where multiple faults greater than a double near coincident faults must be considered), CARE III is best suited for evaluating the reliability of advanced tolerant systems for air transport.

Slab narrowing in the Central Mediterranean: the Calabro-Ionian subduction zone as imaged by high resolution seismic tomography.

PubMed

Scarfì, L; Barberi, G; Barreca, G; Cannavò, F; Koulakov, I; Patanè, D

2018-03-26

A detailed 3D image of the Calabro-Ionian subduction system in the central Mediterranean was obtained by means of a seismic tomography, exploiting a large dataset of local earthquakes and computing algorithms able to build a dense grid of measure nodes. Results show that the slab is continuous below the southern sector of the Calabro-Peloritan Arc, but the deformation processes developing at its edges are leading to its progressive narrowing, influencing tectonics and magmatism at the surface, and with possible stress concentration in the tip zones. In the southwest, the deformation occurring at a free slab edge lead to propagation of a vertical lithospheric tear in the overriding plate, which extends along a NW-SE fault system (Aeolian-Tindari-Letojanni) up to about 30 km into the Ionian Sea; further southeast, the lithosphere appears only flexed and not broken yet. In the northeast, the slab seems to break progressively, parallel to the trench. Finally, northwest of Mt. Etna, the tomography highlights low V P that can be related to an upwelling of deep mantle material likely flowing laterally through a window opened by the complete slab detachment.

Expert systems for real-time monitoring and fault diagnosis

NASA Technical Reports Server (NTRS)

Edwards, S. J.; Caglayan, A. K.

1989-01-01

Methods for building real-time onboard expert systems were investigated, and the use of expert systems technology was demonstrated in improving the performance of current real-time onboard monitoring and fault diagnosis applications. The potential applications of the proposed research include an expert system environment allowing the integration of expert systems into conventional time-critical application solutions, a grammar for describing the discrete event behavior of monitoring and fault diagnosis systems, and their applications to new real-time hardware fault diagnosis and monitoring systems for aircraft.

Ultrareliable fault-tolerant control systems

NASA Technical Reports Server (NTRS)

Webster, L. D.; Slykhouse, R. A.; Booth, L. A., Jr.; Carson, T. M.; Davis, G. J.; Howard, J. C.

1984-01-01

It is demonstrated that fault-tolerant computer systems, such as on the Shuttles, based on redundant, independent operation are a viable alternative in fault tolerant system designs. The ultrareliable fault-tolerant control system (UFTCS) was developed and tested in laboratory simulations of an UH-1H helicopter. UFTCS includes asymptotically stable independent control elements in a parallel, cross-linked system environment. Static redundancy provides the fault tolerance. A polling is performed among the computers, with results allowing for time-delay channel variations with tight bounds. When compared with the laboratory and actual flight data for the helicopter, the probability of a fault was, for the first 10 hr of flight given a quintuple computer redundancy, found to be 1 in 290 billion. Two weeks of untended Space Station operations would experience a fault probability of 1 in 24 million. Techniques for avoiding channel divergence problems are identified.

Award ER25750: Coordinated Infrastructure for Fault Tolerance Systems Indiana University Final Report

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

Lumsdaine, Andrew

2013-03-08

The main purpose of the Coordinated Infrastructure for Fault Tolerance in Systems initiative has been to conduct research with a goal of providing end-to-end fault tolerance on a systemwide basis for applications and other system software. While fault tolerance has been an integral part of most high-performance computing (HPC) system software developed over the past decade, it has been treated mostly as a collection of isolated stovepipes. Visibility and response to faults has typically been limited to the particular hardware and software subsystems in which they are initially observed. Little fault information is shared across subsystems, allowing little flexibility ormore » control on a system-wide basis, making it practically impossible to provide cohesive end-to-end fault tolerance in support of scientific applications. As an example, consider faults such as communication link failures that can be seen by a network library but are not directly visible to the job scheduler, or consider faults related to node failures that can be detected by system monitoring software but are not inherently visible to the resource manager. If information about such faults could be shared by the network libraries or monitoring software, then other system software, such as a resource manager or job scheduler, could ensure that failed nodes or failed network links were excluded from further job allocations and that further diagnosis could be performed. As a founding member and one of the lead developers of the Open MPI project, our efforts over the course of this project have been focused on making Open MPI more robust to failures by supporting various fault tolerance techniques, and using fault information exchange and coordination between MPI and the HPC system software stack from the application, numeric libraries, and programming language runtime to other common system components such as jobs schedulers, resource managers, and monitoring tools.« less

Fault tolerant operation of switched reluctance machine

NASA Astrophysics Data System (ADS)

Wang, Wei

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

In vivo conformation of mitochondrial DNA revealed by pulsed-field gel electrophoresis in the true slime mold, Physarum polycephalum.

PubMed

Sakurai, R; Sasaki, N; Takano, H; Abe, T; Kawano, S

2000-04-28

Pulsed-field gel electrophoresis (PFGE) was used to examine the in vivo and in vitro conformations of Physarum polycephalum mitochondrial DNA (mtDNA). We used plugs containing isolated mitochondria, isolated mitochondrial nucleoids (mt-nuclei), and isolated mtDNA, in addition to whole cells. The mtDNA contained in the myxamoebae, plasmodia, isolated mitochondria, and isolated mt-nuclei was circular, but most of the isolated mtDNA had been site-specifically fragmented and linearized during DNA preparation and storage under low ionic strength conditions. Restriction mapping of Physarum mtDNA by the direct digestion of the isolated mt-nuclei from two different strains, DP89 x AI16 and KM88 x AI16, resulted in the circular form. A linear mitochondrial plasmid, mF, is known to promote mitochondrial fusion and integration of itself into the mtDNA in Physarum. Linearization of mtDNA by the integration of the mF plasmid was demonstrated when we used PFGE to analyze isolated mitochondria from the plasmodial strain DP89 x NG7 carrying the mF plasmid (mF+). The PFGE system can be used not only to determine whether the form of mtDNA is linear or circular but also to analyze the dynamic conformational changes of mtDNA.

Design of on-board Bluetooth wireless network system based on fault-tolerant technology

NASA Astrophysics Data System (ADS)

You, Zheng; Zhang, Xiangqi; Yu, Shijie; Tian, Hexiang

2007-11-01

In this paper, the Bluetooth wireless data transmission technology is applied in on-board computer system, to realize wireless data transmission between peripherals of the micro-satellite integrating electronic system, and in view of the high demand of reliability of a micro-satellite, a design of Bluetooth wireless network based on fault-tolerant technology is introduced. The reliability of two fault-tolerant systems is estimated firstly using Markov model, then the structural design of this fault-tolerant system is introduced; several protocols are established to make the system operate correctly, some related problems are listed and analyzed, with emphasis on Fault Auto-diagnosis System, Active-standby switch design and Data-Integrity process.

Slip accumulation and lateral propagation of active normal faults in Afar

NASA Astrophysics Data System (ADS)

Manighetti, I.; King, G. C. P.; Gaudemer, Y.; Scholz, C. H.; Doubre, C.

2001-01-01

We investigate fault growth in Afar, where normal fault systems are known to be currently growing fast and most are propagating to the northwest. Using digital elevation models, we have examined the cumulative slip distribution along 255 faults with lengths ranging from 0.3 to 60 km. Faults exhibiting the elliptical or "bell-shaped" slip profiles predicted by simple linear elastic fracture mechanics or elastic-plastic theories are rare. Most slip profiles are roughly linear for more than half of their length, with overall slopes always <0.035. For the dominant population of NW striking faults and fault systems longer than 2 km, the slip profiles are asymmetric, with slip being maximum near the eastern ends of the profiles where it drops abruptly to zero, whereas slip decreases roughly linearly and tapers in the direction of overall Aden rift propagation. At a more detailed level, most faults appear to be composed of distinct, shorter subfaults or segments, whose slip profiles, while different from one to the next, combine to produce the roughly linear overall slip decrease along the entire fault. On a larger scale, faults cluster into kinematically coupled systems, along which the slip on any scale individual fault or fault system complements that of its neighbors, so that the total slip of the whole system is roughly linearly related to its length, with an average slope again <0.035. We discuss the origin of these quasilinear, asymmetric profiles in terms of "initiation points" where slip starts, and "barriers" where fault propagation is arrested. In the absence of a barrier, slip apparently extends with a roughly linear profile, tapered in the direction of fault propagation.

Comparing Different Fault Identification Algorithms in Distributed Power System

NASA Astrophysics Data System (ADS)

Alkaabi, Salim

A power system is a huge complex system that delivers the electrical power from the generation units to the consumers. As the demand for electrical power increases, distributed power generation was introduced to the power system. Faults may occur in the power system at any time in different locations. These faults cause a huge damage to the system as they might lead to full failure of the power system. Using distributed generation in the power system made it even harder to identify the location of the faults in the system. The main objective of this work is to test the different fault location identification algorithms while tested on a power system with the different amount of power injected using distributed generators. As faults may lead the system to full failure, this is an important area for research. In this thesis different fault location identification algorithms have been tested and compared while the different amount of power is injected from distributed generators. The algorithms were tested on IEEE 34 node test feeder using MATLAB and the results were compared to find when these algorithms might fail and the reliability of these methods.

Automatic translation of digraph to fault-tree models

NASA Technical Reports Server (NTRS)

Iverson, David L.

1992-01-01

The author presents a technique for converting digraph models, including those models containing cycles, to a fault-tree format. A computer program which automatically performs this translation using an object-oriented representation of the models has been developed. The fault-trees resulting from translations can be used for fault-tree analysis and diagnosis. Programs to calculate fault-tree and digraph cut sets and perform diagnosis with fault-tree models have also been developed. The digraph to fault-tree translation system has been successfully tested on several digraphs of varying size and complexity. Details of some representative translation problems are presented. Most of the computation performed by the program is dedicated to finding minimal cut sets for digraph nodes in order to break cycles in the digraph. Fault-trees produced by the translator have been successfully used with NASA's Fault-Tree Diagnosis System (FTDS) to produce automated diagnostic systems.

Fault tolerant architectures for integrated aircraft electronics systems, task 2

NASA Technical Reports Server (NTRS)

Levitt, K. N.; Melliar-Smith, P. M.; Schwartz, R. L.

1984-01-01

The architectural basis for an advanced fault tolerant on-board computer to succeed the current generation of fault tolerant computers is examined. The network error tolerant system architecture is studied with particular attention to intercluster configurations and communication protocols, and to refined reliability estimates. The diagnosis of faults, so that appropriate choices for reconfiguration can be made is discussed. The analysis relates particularly to the recognition of transient faults in a system with tasks at many levels of priority. The demand driven data-flow architecture, which appears to have possible application in fault tolerant systems is described and work investigating the feasibility of automatic generation of aircraft flight control programs from abstract specifications is reported.

Nonlinear dynamic failure process of tunnel-fault system in response to strong seismic event

NASA Astrophysics Data System (ADS)

Yang, Zhihua; Lan, Hengxing; Zhang, Yongshuang; Gao, Xing; Li, Langping

2013-03-01

Strong earthquakes and faults have significant effect on the stability capability of underground tunnel structures. This study used a 3-Dimensional Discrete Element model and the real records of ground motion in the Wenchuan earthquake to investigate the dynamic response of tunnel-fault system. The typical tunnel-fault system was composed of one planned railway tunnel and one seismically active fault. The discrete numerical model was prudentially calibrated by means of the comparison between the field survey and numerical results of ground motion. It was then used to examine the detailed quantitative information on the dynamic response characteristics of tunnel-fault system, including stress distribution, strain, vibration velocity and tunnel failure process. The intensive tunnel-fault interaction during seismic loading induces the dramatic stress redistribution and stress concentration in the intersection of tunnel and fault. The tunnel-fault system behavior is characterized by the complicated nonlinear dynamic failure process in response to a real strong seismic event. It can be qualitatively divided into 5 main stages in terms of its stress, strain and rupturing behaviors: (1) strain localization, (2) rupture initiation, (3) rupture acceleration, (4) spontaneous rupture growth and (5) stabilization. This study provides the insight into the further stability estimation of underground tunnel structures under the combined effect of strong earthquakes and faults.

Orion GN&C Fault Management System Verification: Scope And Methodology

NASA Technical Reports Server (NTRS)

Brown, Denise; Weiler, David; Flanary, Ronald

2016-01-01

In order to ensure long-term ability to meet mission goals and to provide for the safety of the public, ground personnel, and any crew members, nearly all spacecraft include a fault management (FM) system. For a manned vehicle such as Orion, the safety of the crew is of paramount importance. The goal of the Orion Guidance, Navigation and Control (GN&C) fault management system is to detect, isolate, and respond to faults before they can result in harm to the human crew or loss of the spacecraft. Verification of fault management/fault protection capability is challenging due to the large number of possible faults in a complex spacecraft, the inherent unpredictability of faults, the complexity of interactions among the various spacecraft components, and the inability to easily quantify human reactions to failure scenarios. The Orion GN&C Fault Detection, Isolation, and Recovery (FDIR) team has developed a methodology for bounding the scope of FM system verification while ensuring sufficient coverage of the failure space and providing high confidence that the fault management system meets all safety requirements. The methodology utilizes a swarm search algorithm to identify failure cases that can result in catastrophic loss of the crew or the vehicle and rare event sequential Monte Carlo to verify safety and FDIR performance requirements.

Evidence for Phanerozoic reactivation of the Najd Fault System in AVHRR, TM, and SPOT images of central Arabia

NASA Technical Reports Server (NTRS)

Andre, Constance G.

1989-01-01

SPOT stereoscopic and TM multispectral images support evidence in AVHRR thermal-IR images of a major unmapped shear zone in Phanerozoic cover rocks southeast of the ancient Najd Fault System in the Arabian Shield. This shear zone and faults of the Najd share a common alignment, orientation, and sinistral sense of movement. These similarities suggest a 200-km extension of the Najd Fault System and reactivation since it formed in the late Precambrian. Topographic and lithologic features in the TM and SPOT data along one of three faults inferred from the AVHRR data indicate sinistral offsets up to 2.5 km, en echelon folds and secondary faults like those predicted by models of left-lateral strike-slip faulting. The age of the affected outcrops indicates reactivation of Najd faults in the Cretaceous, judging from TM and SPOT data or in the Tertiary, based on AVHRR data. The total length of the system visible at the surface measures 1300 km. If the Najd Fault System is extrapolated beneath sands of the Empty Quarter to faults of a similar trend in South Yemen, the shear zone would span the Arabian Plate. Furthermore, if extensions into the Arabian Sea bed and into Egypt proposed by others are considered, it would exceed 3000 km.

A fault diagnosis system for PV power station based on global partitioned gradually approximation method

NASA Astrophysics Data System (ADS)

Wang, S.; Zhang, X. N.; Gao, D. D.; Liu, H. X.; Ye, J.; Li, L. R.

2016-08-01

As the solar photovoltaic (PV) power is applied extensively, more attentions are paid to the maintenance and fault diagnosis of PV power plants. Based on analysis of the structure of PV power station, the global partitioned gradually approximation method is proposed as a fault diagnosis algorithm to determine and locate the fault of PV panels. The PV array is divided into 16x16 blocks and numbered. On the basis of modularly processing of the PV array, the current values of each block are analyzed. The mean current value of each block is used for calculating the fault weigh factor. The fault threshold is defined to determine the fault, and the shade is considered to reduce the probability of misjudgments. A fault diagnosis system is designed and implemented with LabVIEW. And it has some functions including the data realtime display, online check, statistics, real-time prediction and fault diagnosis. Through the data from PV plants, the algorithm is verified. The results show that the fault diagnosis results are accurate, and the system works well. The validity and the possibility of the system are verified by the results as well. The developed system will be benefit for the maintenance and management of large scale PV array.

A Study on Management Standards and Manual of Water supply system for the response of Mt. Baekdu Volcanic Eruption in South Korea

NASA Astrophysics Data System (ADS)

Lee, G.; Jee, Y.; Kim, J.

2013-12-01

Korea is regarded as a safety area from the volcanic disaster, however, the countermeasures for Mt. Baekdu volcanic eruption has been discussed because the possibility of the volcanic eruption had been heightened and various experimental results show risk of Mt. Baekdu volcanic eruption. The purpose of study is to establish management standards and manual for water supply system through the analysis of the volcanic ash effect to the water supply systems. In this study, similar case study for the water supply system to the volcanic ash damage had been investigated. Present status of water supply system and response manual for water supply systems also had been investigated. And then problems of present response manual using had been estimated. As the result, damage according to Mt. Baekdu volcanic eruption on the water supply system could be forecasted. And the direction of management standard and response manual has been established. Acknowledgments This research was supported by a grant [NEMA-BAEKDUSAN-2012-2-2] from the Volcanic Disaster Preparedness Research Center sponsored by National Emergency Management Agency of Korea.

Software fault tolerance in computer operating systems

NASA Technical Reports Server (NTRS)

Iyer, Ravishankar K.; Lee, Inhwan

1994-01-01

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

Possible strand of the North Anatolian fault in the Thrace basin, Turkey - An interpretation

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

Perincek, D.

1991-02-01

This study focuses on the presence of a major strike-slip fault system in the Thrace basin. This new discovery is important for the geology of the Thrace basin and also brings a new perspective to petroleum exploration. The wrench fault system is named the Thrace strike-slip fault system (Perincek, 1988). Similarities with the North Anatolian fault zone prompted an investigation of the relationship between these two fault system.s The study area covers most of the Thrace region of Turkey. The purposes of this paper are (1) to outline the geometry of the Thrace fault system, (2) to demonstrate its tectonicmore » relation with other major structures of the region, (3) to define the age of its inception, and (4) to discuss possible magnitudes of the lateral displacement. The interpretation is based mainly on seismic data consisting of 180 seismic reflection profiles that have a total cumulative length of 2,800 km. Seismic data are complemented with subsurface control from 54 wells.« less

Critical fault patterns determination in fault-tolerant computer systems

NASA Technical Reports Server (NTRS)

Mccluskey, E. J.; Losq, J.

1978-01-01

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

Practical Methods for Estimating Software Systems Fault Content and Location

NASA Technical Reports Server (NTRS)

Nikora, A.; Schneidewind, N.; Munson, J.

1999-01-01

Over the past several years, we have developed techniques to discriminate between fault-prone software modules and those that are not, to estimate a software system's residual fault content, to identify those portions of a software system having the highest estimated number of faults, and to estimate the effects of requirements changes on software quality.

Fault diagnosis

NASA Technical Reports Server (NTRS)

Abbott, Kathy

1990-01-01

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

cost and benefits optimization model for fault-tolerant aircraft electronic systems

NASA Technical Reports Server (NTRS)

1983-01-01

The factors involved in economic assessment of fault tolerant systems (FTS) and fault tolerant flight control systems (FTFCS) are discussed. Algorithms for optimization and economic analysis of FTFCS are documented.

Mitochondrial transcription: Lessons from mouse models

PubMed Central

Peralta, Susana; Wang, Xiao; Moraes, Carlos T.

2012-01-01

Mammalian mitochondrial DNA (mtDNA) is a circular double-stranded DNA genome of ∼ 16.5 kilobase pairs (kb) that encodes 13 catalytic proteins of the ATP-producing oxidative phosphorylation system (OXPHOS), and the rRNAs and tRNAs required for the translation of the mtDNA transcripts. All the components needed for transcription and replication of the mtDNA are, therefore, encoded in the nuclear genome, as are the remaining components of the OXPHOS system and the mitochondrial translation machinery. Regulation of mtDNA gene expression is very important for modulating the OXPHOS capacity in response to metabolic requirements and in pathological processes. The combination of in vitro and in vivo studies has allowed the identification of the core machinery required for basal mtDNA transcription in mammals and a few proteins that regulate mtDNA transcription. Specifically, the generation of knockout mouse strains in the last several years, has been key to understanding the basis of mtDNA transcription in vivo. However, it is well accepted that many components of the transcription machinery are still unknown and little is known about mtDNA gene expression regulation under different metabolic requirements or disease processes. In this review we will focus on how the creation of knockout mouse models and the study of their phenotypes have contributed to the understanding of mitochondrial transcription in mammals. PMID:22120174

Mt. Elgon, Africa, Shaded Relief and Colored Height

NASA Technical Reports Server (NTRS)

2004-01-01

The striking contrast of geologic structures in Africa is shown in this shaded relief image of Mt. Elgon on the left and a section of the Great Rift Valley on the right.

Mt. Elgon is a solitary extinct volcano straddling the border between Uganda and Kenya, and at 4,321 meters (14,178 feet) tall is the eighth highest mountain in Africa. It is positioned on the Pre-Cambriam bedrock of the Trans Nzoia Plateau, and is similar to other such volcanoes in East Africa in that it is associated with the formation of the Rift Valley. However one thing that sets Mt. Elgon apart is its age.

Although there is no verifiable evidence of its earliest volcanic activity, Mt. Elgon is estimated to be at least 24 million years old, making it the oldest extinct volcano in East Africa. This presents a striking comparison to Mt. Kilimanjaro, the highest mountain in Africa at 5,895 meters (19,341 feet), which is just over one million years old. Judging by the diameter of its base, it is a common belief among geological experts that Mt. Elgon was once the highest mountains in Africa, however erosion has played a significant role in reducing the height to its present value.

Juxtaposed with this impressive mountain is a section of the Great Rift Valley, a geological fault system that extends for about 4,830 kilometers (2,995 miles) from Syria to central Mozambique. Erosion has concealed some sections, but in some sections like that shown here, there are sheer cliffs several thousand feet high. The present configuration of the valley, which dates from the mid-Pleistocene epoch, results from a rifting process associated with thermal currents in the Earth's mantle.

Two visualization methods were combined to produce the image: shading and color coding of topographic height. The shade image was derived by computing topographic slope in the northwest-southeast direction, so that northwest slopes appear bright and southeast slopes appear dark. Color coding is directly related to topographic height, with green at the lower elevations, rising through yellow and tan, to white at the highest elevations.

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

Location: 1 degree north latitude, 35 degrees east longitude Orientation: North toward the top, Mercator projection Size: 223 by 223 kilometers (138 by 138 miles) Image Data: shaded and colored SRTM elevation model Date Acquired: February 2000

Role of the Precambrian Mughese Shear Zone on Cenozoic faulting along the Rukwa-Malawi Rift segment of the East African Rift System

NASA Astrophysics Data System (ADS)

Heilman, E.; Kolawole, F.; Mayle, M.; Atekwana, E. A.; Abdelsalam, M. G.

2017-12-01

We address the longstanding question of the role of long-lived basement structures in strain accommodation within active rift systems. Studies have highlighted the influence of pre-existing zones of lithospheric weakness in modulating faulting and fault kinematics. Here, we investigate the role of the Neoproterozoic Mughese Shear Zone (MSZ) in Cenozoic rifting along the Rukwa-Malawi rift segment of the East African Rift System (EARS). Detailed analyses of Shuttle Radar Topography Mission (SRTM) DEM and filtered aeromagnetic data allowed us to determine the relationship between rift-related basement-rooted normal faults and the MSZ fabric extending along the southern boundary of the Rukwa-Malawi Rift North Basin. Our results show that the magnetic lineaments defining the MSZ coincide with the collinear Rukwa Rift border fault (Ufipa Fault), a dextral strike-slip fault (Mughese Fault), and the North Basin hinge-zone fault (Mbiri Fault). Fault-scarp and minimum fault-throw analyses reveal that within the Rukwa Rift, the Ufipa Border Fault has been accommodating significant displacement relative to the Lupa Border Fault, which represents the northeastern border fault of the Rukwa Rift. Our analysis also shows that within the North Basin half-graben, the Mbiri Fault has accommodated the most vertical displacement relative to other faults along the half-graben hinge zone. We propose that the Cenozoic reactivation along the MSZ facilitated significant normal slip displacement along the Ufipa Border Fault and the Mbiri Fault, and minor dextral strike-slip between the two faults. We suggest that the fault kinematics along the Rukwa-Malawi Rift is the result of reactivation of the MSZ through regional oblique extension.

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

NASA Technical Reports Server (NTRS)

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

1988-01-01

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

Sliding Mode Observer-Based Current Sensor Fault Reconstruction and Unknown Load Disturbance Estimation for PMSM Driven System

PubMed Central

Li, Xiangfei; Lin, Yuliang

2017-01-01

This paper proposes a new scheme of reconstructing current sensor faults and estimating unknown load disturbance for a permanent magnet synchronous motor (PMSM)-driven system. First, the original PMSM system is transformed into two subsystems; the first subsystem has unknown system load disturbances, which are unrelated to sensor faults, and the second subsystem has sensor faults, but is free from unknown load disturbances. Introducing a new state variable, the augmented subsystem that has sensor faults can be transformed into having actuator faults. Second, two sliding mode observers (SMOs) are designed: the unknown load disturbance is estimated by the first SMO in the subsystem, which has unknown load disturbance, and the sensor faults can be reconstructed using the second SMO in the augmented subsystem, which has sensor faults. The gains of the proposed SMOs and their stability analysis are developed via the solution of linear matrix inequality (LMI). Finally, the effectiveness of the proposed scheme was verified by simulations and experiments. The results demonstrate that the proposed scheme can reconstruct current sensor faults and estimate unknown load disturbance for the PMSM-driven system. PMID:29211017

Model-Based Diagnostics for Propellant Loading Systems

NASA Technical Reports Server (NTRS)

Daigle, Matthew John; Foygel, Michael; Smelyanskiy, Vadim N.

2011-01-01

The loading of spacecraft propellants is a complex, risky operation. Therefore, diagnostic solutions are necessary to quickly identify when a fault occurs, so that recovery actions can be taken or an abort procedure can be initiated. Model-based diagnosis solutions, established using an in-depth analysis and understanding of the underlying physical processes, offer the advanced capability to quickly detect and isolate faults, identify their severity, and predict their effects on system performance. We develop a physics-based model of a cryogenic propellant loading system, which describes the complex dynamics of liquid hydrogen filling from a storage tank to an external vehicle tank, as well as the influence of different faults on this process. The model takes into account the main physical processes such as highly nonequilibrium condensation and evaporation of the hydrogen vapor, pressurization, and also the dynamics of liquid hydrogen and vapor flows inside the system in the presence of helium gas. Since the model incorporates multiple faults in the system, it provides a suitable framework for model-based diagnostics and prognostics algorithms. Using this model, we analyze the effects of faults on the system, derive symbolic fault signatures for the purposes of fault isolation, and perform fault identification using a particle filter approach. We demonstrate the detection, isolation, and identification of a number of faults using simulation-based experiments.

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.

Exhumation at orogenic indentor corners under long-term glacial conditions: Example of the St. Elias orogen, Southern Alaska

NASA Astrophysics Data System (ADS)

Spotila, James A.; Berger, Aaron L.

2010-07-01

Syntaxial bends in convergent plate boundaries, or indentor corners, display some of the most intriguing deformation patterns on Earth and are type localities for "aneurysms" of coupled erosion, thermal weakening, and strain. The St. Elias orogen in Alaska is a small, young convergent system that has been dominated by a glacial climate for much of its history and exhibits two prominent indentor corners that are not well understood. We have added 40 new apatite (U-Th)/He ages to the already extensive dataset for the low-temperature cooling history of this orogen to constrain the pattern of exhumation in these indentor corners. Ages from the western syntaxis show minor variation across the structural hinge, suggesting that the bend has little effect on the pattern of exhumation and that structures, including the Bagley fault, connect smoothly from the orogen core to the subduction zone to the southwest. Rock uplift on the north flank of the range appears to increase steadily towards the eastern syntaxis, which represents the apex in the right-angle bend between a transform fault in the south and the collision zone in the west. Based on age-elevation relationships, zones of relative rock uplift can be defined in which the Mt. Logan massif, or the area just north of the eastern syntaxis, experienced ˜ 4.8 km greater rock uplift than background levels northwest of the western syntaxis. A bulge in relative rock uplift is symmetric about the hinge in the eastern indentor corner. However, rates of denudation in this bulge are not as rapid as the core of the fold and thrust belt and are lower than those implied by detrital cooling ages from beneath the Seward Glacier. This implies that a large bull's eye of ultra-rapid (˜ 5 mm/yr) exhumation does not occur and that the subpopulation of young detrital ages may be sourced from a narrow transpressional zone along the Fairweather fault. Unlike the Himalayan syntaxes, it thus appears that an aneurysm of coupled erosion-strain has not developed in either indentor corner of the St. Elias orogen. This may indicate a limit to the degree to which glacial erosion can partition strain in convergent orogens. Similarly, the likely existence of a through-going dextral fault, the Totschunda fault, through the eastern syntaxis implies that tectonics, rather than surface processes, exerts the main control on strain partitioning in these corners.

An Ontology for Identifying Cyber Intrusion Induced Faults in Process Control Systems

NASA Astrophysics Data System (ADS)

Hieb, Jeffrey; Graham, James; Guan, Jian

This paper presents an ontological framework that permits formal representations of process control systems, including elements of the process being controlled and the control system itself. A fault diagnosis algorithm based on the ontological model is also presented. The algorithm can identify traditional process elements as well as control system elements (e.g., IP network and SCADA protocol) as fault sources. When these elements are identified as a likely fault source, the possibility exists that the process fault is induced by a cyber intrusion. A laboratory-scale distillation column is used to illustrate the model and the algorithm. Coupled with a well-defined statistical process model, this fault diagnosis approach provides cyber security enhanced fault diagnosis information to plant operators and can help identify that a cyber attack is underway before a major process failure is experienced.

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.

Solar system fault detection

DOEpatents

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

1984-05-14

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

Solar system fault detection

DOEpatents

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

1986-01-01

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

Real-time fault diagnosis for propulsion systems

NASA Technical Reports Server (NTRS)

Merrill, Walter C.; Guo, Ten-Huei; Delaat, John C.; Duyar, Ahmet

1991-01-01

Current research toward real time fault diagnosis for propulsion systems at NASA-Lewis is described. The research is being applied to both air breathing and rocket propulsion systems. Topics include fault detection methods including neural networks, system modeling, and real time implementations.

The 2016 central Italy earthquake sequence: surface effects, fault model and triggering scenarios

NASA Astrophysics Data System (ADS)

Chatzipetros, Alexandros; Pavlides, Spyros; Papathanassiou, George; Sboras, Sotiris; Valkaniotis, Sotiris; Georgiadis, George

2017-04-01

The results of fieldwork performed during the 2016 earthquake sequence around the karstic basins of Norcia and La Piana di Castelluccio, at an altitude of 1400 m, on the Monte Vettore (altitude 2476 m) and Vettoretto, as well as the three mapped seismogenic faults, striking NNW-SSW, are presented in this paper. Surface co-seismic ruptures were observed in the Vettore and Vettoretto segment of the fault for several kilometres ( 7 km) in the August earthquakes at high altitudes, and were re-activated and expanded northwards during the October earthquakes. Coseismic ruptures and the neotectonic Mt. Vettore fault zone were modelled in detail using images acquired from specifically planned UAV (drone) flights. Ruptures, typically with displacement of up to 20 cm, were observed after the August event both in the scree and weathered mantle (elluvium), as well as the bedrock, consisting mainly of fragmented carbonate rocks with small tectonic surfaces. These fractures expanded and new ones formed during the October events, typically of displacements of up to 50 cm, although locally higher displacements of up to almost 2 m were observed. Hundreds of rock falls and landslides were mapped through satellite imagery, using pre- and post- earthquake Sentinel 2A images. Several of them were also verified in the field. Based on field mapping results and seismological information, the causative faults were modelled. The model consists of five seismogenic sources, each one associated with a strong event in the sequence. The visualisation of the seismogenic sources follows INGV's DISS standards for the Individual Seismogenic Sources (ISS) layer, while strike, dip and rake of the seismic sources are obtained from selected focal mechanisms. Based on this model, the ground deformation pattern was inferred, using Okada's dislocation solution formulae, which shows that the maximum calculated vertical displacement is 0.53 m. This is in good agreement with the statistical analysis of the observed surface rupture displacement. Stress transfer analysis was also performed in the five modelled seismogenic sources, using seismologically defined parameters. The resulting stress transfer pattern, based on the sequence of events, shows that the causative fault of each event was influenced by loading from the previous ones.

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.

Nearly frictionless faulting by unclamping in long-term interaction models

USGS Publications Warehouse

Parsons, T.

2002-01-01

In defiance of direct rock-friction observations, some transform faults appear to slide with little resistance. In this paper finite element models are used to show how strain energy is minimized by interacting faults that can cause long-term reduction in fault-normal stresses (unclamping). A model fault contained within a sheared elastic medium concentrates stress at its end points with increasing slip. If accommodating structures free up the ends, then the fault responds by rotating, lengthening, and unclamping. This concept is illustrated by a comparison between simple strike-slip faulting and a mid-ocean-ridge model with the same total transform length; calculations show that the more complex system unclapms the transforms and operates at lower energy. In another example, the overlapping San Andreas fault system in the San Francisco Bay region is modeled; this system is complicated by junctions and stepovers. A finite element model indicates that the normal stress along parts of the faults could be reduced to hydrostatic levels after ???60-100 k.y. of system-wide slip. If this process occurs in the earth, then parts of major transform fault zones could appear nearly frictionless.

Automatic Detection of Electric Power Troubles (ADEPT)

NASA Technical Reports Server (NTRS)

Wang, Caroline; Zeanah, Hugh; Anderson, Audie; Patrick, Clint; Brady, Mike; Ford, Donnie

1988-01-01

Automatic Detection of Electric Power Troubles (A DEPT) is an expert system that integrates knowledge from three different suppliers to offer an advanced fault-detection system. It is designed for two modes of operation: real time fault isolation and simulated modeling. Real time fault isolation of components is accomplished on a power system breadboard through the Fault Isolation Expert System (FIES II) interface with a rule system developed in-house. Faults are quickly detected and displayed and the rules and chain of reasoning optionally provided on a laser printer. This system consists of a simulated space station power module using direct-current power supplies for solar arrays on three power buses. For tests of the system's ablilty to locate faults inserted via switches, loads are configured by an INTEL microcomputer and the Symbolics artificial intelligence development system. As these loads are resistive in nature, Ohm's Law is used as the basis for rules by which faults are located. The three-bus system can correct faults automatically where there is a surplus of power available on any of the three buses. Techniques developed and used can be applied readily to other control systems requiring rapid intelligent decisions. Simulated modeling, used for theoretical studies, is implemented using a modified version of Kennedy Space Center's KATE (Knowledge-Based Automatic Test Equipment), FIES II windowing, and an ADEPT knowledge base.

Automatic Detection of Electric Power Troubles (ADEPT)

NASA Astrophysics Data System (ADS)

Wang, Caroline; Zeanah, Hugh; Anderson, Audie; Patrick, Clint; Brady, Mike; Ford, Donnie

1988-11-01

Automatic Detection of Electric Power Troubles (A DEPT) is an expert system that integrates knowledge from three different suppliers to offer an advanced fault-detection system. It is designed for two modes of operation: real time fault isolation and simulated modeling. Real time fault isolation of components is accomplished on a power system breadboard through the Fault Isolation Expert System (FIES II) interface with a rule system developed in-house. Faults are quickly detected and displayed and the rules and chain of reasoning optionally provided on a laser printer. This system consists of a simulated space station power module using direct-current power supplies for solar arrays on three power buses. For tests of the system's ablilty to locate faults inserted via switches, loads are configured by an INTEL microcomputer and the Symbolics artificial intelligence development system. As these loads are resistive in nature, Ohm's Law is used as the basis for rules by which faults are located. The three-bus system can correct faults automatically where there is a surplus of power available on any of the three buses. Techniques developed and used can be applied readily to other control systems requiring rapid intelligent decisions. Simulated modeling, used for theoretical studies, is implemented using a modified version of Kennedy Space Center's KATE (Knowledge-Based Automatic Test Equipment), FIES II windowing, and an ADEPT knowledge base.

76 FR 41725 - Proposed Amendment of Class E Airspace; Miles City, MT

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-15

... Class E Airspace; Miles City, MT AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of..., Miles City, MT, to accommodate aircraft using new Area Navigation (RNAV) Global Positioning System (GPS... airspace and Class E airspace extending upward from 700 feet above the surface at Frank Wiley Field, Miles...

Geology along the Fairweather-Queen Charlotte fault system off southeast Alaska and British Columbia from GLORIA images and seismic-reflection data

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

Bruns, T.R.; Carlson, P.R.; Stevenson, A.J.

1990-06-01

GLORIA images collected in 1989 along southeast Alaska and British Columbia strikingly show the active trace of the Fairweather-Queen Charlotte transform fault system beneath the outer shelf and slope; seismic-reflection data are used to track the fault system across the continental shelf where GLORIA data are not available. From Cross Sound to Chatham Strait, the fault system is comprised of two sets of subparallel fault traces separated by 3 to 6 km. The fault system crosses the shelf from Icy Point to south of Yakobi Valley, then follows the shelf edge to Chatham Strait. Between Chatham Strait and Dixon Entrance,more » a single, sharply defined active fault trace underlies the upper and middle slope. This fault segment is bounded on the seaward side by a high, midslope ridge and by lower slope Quaternary( ) anticlines up to 35 km wide. Southeast of Dixon Entrance, the active fault trace trends back onto the outer shelf until midway along the Queen Charlotte Islands, then cuts back to and stays at midslope to the Tuzo Wilson Knolls south of the Queen Charlotte Islands. The fault steps westward at Tuzo Wilson Knolls, which are likely part of a spreading ridge segment. Major deep-sea fans along southeast Alaska show a southeastward age progression from older to younger and record both point source deposition at Chatham Strait and Dixon Entrance and subsequent (Quaternary ) offset along the fault system. Subsidence of ocean plate now adjacent to the Chatham Strait-Dixon Entrance fault segment initiated development of both Mukluk and Horizon Channels.« less

Tutorial: Advanced fault tree applications using HARP

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

Adaptation of machine translation for multilingual information retrieval in the medical domain.

PubMed

Pecina, Pavel; Dušek, Ondřej; Goeuriot, Lorraine; Hajič, Jan; Hlaváčová, Jaroslava; Jones, Gareth J F; Kelly, Liadh; Leveling, Johannes; Mareček, David; Novák, Michal; Popel, Martin; Rosa, Rudolf; Tamchyna, Aleš; Urešová, Zdeňka

2014-07-01

We investigate machine translation (MT) of user search queries in the context of cross-lingual information retrieval (IR) in the medical domain. The main focus is on techniques to adapt MT to increase translation quality; however, we also explore MT adaptation to improve effectiveness of cross-lingual IR. Our MT system is Moses, a state-of-the-art phrase-based statistical machine translation system. The IR system is based on the BM25 retrieval model implemented in the Lucene search engine. The MT techniques employed in this work include in-domain training and tuning, intelligent training data selection, optimization of phrase table configuration, compound splitting, and exploiting synonyms as translation variants. The IR methods include morphological normalization and using multiple translation variants for query expansion. The experiments are performed and thoroughly evaluated on three language pairs: Czech-English, German-English, and French-English. MT quality is evaluated on data sets created within the Khresmoi project and IR effectiveness is tested on the CLEF eHealth 2013 data sets. The search query translation results achieved in our experiments are outstanding - our systems outperform not only our strong baselines, but also Google Translate and Microsoft Bing Translator in direct comparison carried out on all the language pairs. The baseline BLEU scores increased from 26.59 to 41.45 for Czech-English, from 23.03 to 40.82 for German-English, and from 32.67 to 40.82 for French-English. This is a 55% improvement on average. In terms of the IR performance on this particular test collection, a significant improvement over the baseline is achieved only for French-English. For Czech-English and German-English, the increased MT quality does not lead to better IR results. Most of the MT techniques employed in our experiments improve MT of medical search queries. Especially the intelligent training data selection proves to be very successful for domain adaptation of MT. Certain improvements are also obtained from German compound splitting on the source language side. Translation quality, however, does not appear to correlate with the IR performance - better translation does not necessarily yield better retrieval. We discuss in detail the contribution of the individual techniques and state-of-the-art features and provide future research directions. Copyright © 2014 Elsevier B.V. All rights reserved.

Deformation Styles Along the Southern Alaska Margin Constrained by GPS

NASA Astrophysics Data System (ADS)

Elliott, J.; Freymueller, J. T.; Larsen, C. F.

2009-12-01

The present-day deformation observed in southcentral and southeast Alaska and the adjacent region of Canada is controlled by two main factors: ~ 50 mm/yr relative motion between the Pacific plate and North America and the Yakutat block’s collision with and accretion to southern Alaska. Over 45 mm/yr of NW-SE directed convergence from the collision is currently accommodated within the St. Elias orogen. The Fairweather, St. Elias, and Chugach ranges show the spectacular consequences of the relative tectonic motions, but the details of the plate interactions have not been well understood. Here we present GPS data from a network of over 170 campaign sites across the region. We use the data to constrain block models and forward models that characterize the nature and extent of the tectonic deformation along the Pacific-Yakutat-North America boundary. Tectonics in southeast Alaska can be described by block motion, with the Pacific plate bounding the region to the west. The fastest block motions occur along the coastal regions. The Yakutat block has a velocity of 51 ± 2.7 mm/yr towards N22 ± 2.5 deg W relative to North America. This velocity has a magnitude almost identical to that of the Pacific plate, but the azimuth is more westerly. The northeastern edge of the Yaktuat block is deforming, represented in our model by two small blocks outboard of the Fairweather fault. East of that fault, the Fairweather block rotates clockwise relative to North America, resulting in transpression along the Duke River and Eastern Denali faults. There is a clear transfer of strain from the coastal region hundreds of kilometers eastward into the Northern Cordillera block, confirming earlier suggestions that the effects of the Yakutat collision are far-reaching along its eastern margin. In contrast, deformation along the leading edge of the Yakutat collision is relatively narrowly focused within the southern half of the St. Elias orogen. The current deformation front of the Yakutat block with southern Alaska is in the vicinity of Icy Bay, where strain rates approach -1 microstrain/yr. The Malaspina thrust likely forms the northern boundary of the Yakutat block. Between Icy Bay and the Mt. St. Elias area, the tectonics cannot easily be described by block motion. The GPS data require the relative convergence to be partitioned onto multiple N-NW dipping thrust faults, resulting in a 50-70-km wide zone of deformation. This zone continues around the western side of Icy Bay into the Yakataga fold and thrust belt. North of the Mt. St. Elias area and the Bagley ice valley, roughly 100 km from the deformation front, GPS velocities are consistent with predictions of the motion of the southern Alaska block.

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.

Stress concentrations at structural discontinuities in active fault zones in the western United States: Implications for permeability and fluid flow in geothermal fields

USGS Publications Warehouse

Siler, Drew; Hinz, Nicholas H.; Faulds, James E.

2018-01-01

Slip can induce concentration of stresses at discontinuities along fault systems. These structural discontinuities, i.e., fault terminations, fault step-overs, intersections, bends, and other fault interaction areas, are known to host fluid flow in ore deposition systems, oil and gas reservoirs, and geothermal systems. We modeled stress transfer associated with slip on faults with Holocene-to-historic slip histories at the Salt Wells and Bradys geothermal systems in western Nevada, United States. Results show discrete locations of stress perturbation within discontinuities along these fault systems. Well field data, surface geothermal manifestations, and subsurface temperature data, each a proxy for modern fluid circulation in the fields, indicate that geothermal fluid flow is focused in these same areas where stresses are most highly perturbed. These results suggest that submeter- to meter-scale slip on these fault systems generates stress perturbations that are sufficiently large to promote slip on an array of secondary structures spanning the footprint of the modern geothermal activity. Slip on these secondary faults and fractures generates permeability through kinematic deformation and allows for transmission of fluids. Still, mineralization is expected to seal permeability along faults and fractures over time scales that are generally shorter than either earthquake recurrence intervals or the estimated life span of geothermal fields. This suggests that though stress perturbations resulting from fault slip are broadly important for defining the location and spatial extent of enhanced permeability at structural discontinuities, continual generation and maintenance of flow conduits throughout these areas are probably dependent on the deformation mechanism(s) affecting individual structures.

Adaptive robust fault-tolerant control for linear MIMO systems with unmatched uncertainties

NASA Astrophysics Data System (ADS)

Zhang, Kangkang; Jiang, Bin; Yan, Xing-Gang; Mao, Zehui

2017-10-01

In this paper, two novel fault-tolerant control design approaches are proposed for linear MIMO systems with actuator additive faults, multiplicative faults and unmatched uncertainties. For time-varying multiplicative and additive faults, new adaptive laws and additive compensation functions are proposed. A set of conditions is developed such that the unmatched uncertainties are compensated by actuators in control. On the other hand, for unmatched uncertainties with their projection in unmatched space being not zero, based on a (vector) relative degree condition, additive functions are designed to compensate for the uncertainties from output channels in the presence of actuator faults. The developed fault-tolerant control schemes are applied to two aircraft systems to demonstrate the efficiency of the proposed approaches.

Publications - PIR 2015-5-2 | Alaska Division of Geological & Geophysical

Science.gov Websites

faults in the Bruin Bay fault system, Ursus Head, lower Cook Inlet Authors: Betka, P.M., and Gillis, R.J strike-slip and reverse-slip faults in the Bruin Bay fault system, Ursus Head, lower Cook Inlet, in

Formal Validation of Fault Management Design Solutions

NASA Technical Reports Server (NTRS)

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

2013-01-01

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

Identifiability of Additive, Time-Varying Actuator and Sensor Faults by State Augmentation

NASA Technical Reports Server (NTRS)

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

2014-01-01

Recent work has provided a set of necessary and sucient conditions for identifiability of additive step faults (e.g., lock-in-place actuator faults, constant bias in the sensors) using state augmentation. This paper extends these results to an important class of faults which may affect linear, time-invariant systems. In particular, the faults under consideration are those which vary with time and affect the system dynamics additively. Such faults may manifest themselves in aircraft as, for example, control surface oscillations, control surface runaway, and sensor drift. The set of necessary and sucient conditions presented in this paper are general, and apply when a class of time-varying faults affects arbitrary combinations of actuators and sensors. The results in the main theorems are illustrated by two case studies, which provide some insight into how the conditions may be used to check the theoretical identifiability of fault configurations of interest for a given system. It is shown that while state augmentation can be used to identify certain fault configurations, other fault configurations are theoretically impossible to identify using state augmentation, giving practitioners valuable insight into such situations. That is, the limitations of state augmentation for a given system and configuration of faults are made explicit. Another limitation of model-based methods is that there can be large numbers of fault configurations, thus making identification of all possible configurations impractical. However, the theoretical identifiability of known, credible fault configurations can be tested using the theorems presented in this paper, which can then assist the efforts of fault identification practitioners.

Designing Fault-Injection Experiments for the Reliability of Embedded Systems

NASA Technical Reports Server (NTRS)

White, Allan L.

2012-01-01

This paper considers the long-standing problem of conducting fault-injections experiments to establish the ultra-reliability of embedded systems. There have been extensive efforts in fault injection, and this paper offers a partial summary of the efforts, but these previous efforts have focused on realism and efficiency. Fault injections have been used to examine diagnostics and to test algorithms, but the literature does not contain any framework that says how to conduct fault-injection experiments to establish ultra-reliability. A solution to this problem integrates field-data, arguments-from-design, and fault-injection into a seamless whole. The solution in this paper is to derive a model reduction theorem for a class of semi-Markov models suitable for describing ultra-reliable embedded systems. The derivation shows that a tight upper bound on the probability of system failure can be obtained using only the means of system-recovery times, thus reducing the experimental effort to estimating a reasonable number of easily-observed parameters. The paper includes an example of a system subject to both permanent and transient faults. There is a discussion of integrating fault-injection with field-data and arguments-from-design.

Decreased Circulating mtDNA Levels in Professional Male Volleyball Players.

PubMed

Nasi, Milena; Cristani, Alessandro; Pinti, Marcello; Lamberti, Igor; Gibellini, Lara; De Biasi, Sara; Guazzaloca, Alessandro; Trenti, Tommaso; Cossarizza, Andrea

2016-01-01

Exercise exerts various effects on the immune system, and evidence is emerging on its anti-inflammatory effects; the mechanisms on the basis of these modifications are poorly understood. Mitochondrial DNA (mtDNA) released from damaged cells acts as a molecule containing the so-called damage-associated molecular patterns and can trigger sterile inflammation. Indeed, high plasma levels of mtDNA are associated to several inflammatory conditions and physiological aging and longevity. The authors evaluated plasma mtDNA in professional male volleyball players during seasonal training and the possible correlation between mtDNA levels and clinical parameters, body composition, and physical performance. Plasma mtDNA was quantified by real-time PCR every 2 mo in 12 professional volleyball players (PVPs) during 2 consecutive seasons. As comparison, 20 healthy nonathlete male volunteers (NAs) were analyzed. The authors found lower levels of mtDNA in plasma of PVPs than in NAs. However, PVPs showed a decrease of circulating mtDNA only in the first season, while no appreciable variations were observed during the second season. No correlation was observed among mtDNA, hematochemical, and anthropometric parameters. Regular physical activity appeared associated with lower levels of circulating mtDNA, further confirming the protective, anti-inflammatory effect of exercise.

Adjusting MtDNA Quantification in Whole Blood for Peripheral Blood Platelet and Leukocyte Counts.

PubMed

Hurtado-Roca, Yamilee; Ledesma, Marta; Gonzalez-Lazaro, Monica; Moreno-Loshuertos, Raquel; Fernandez-Silva, Patricio; Enriquez, Jose Antonio; Laclaustra, Martin

2016-01-01

Alterations of mitochondrial DNA copy number (mtDNAcn) in the blood (mitochondrial to nuclear DNA ratio) appear associated with several systemic diseases, including primary mitochondrial disorders, carcinogenesis, and hematologic diseases. Measuring mtDNAcn in DNA extracted from whole blood (WB) instead of from peripheral blood mononuclear cells or buffy coat may yield different results due to mitochondrial DNA present in platelets. The aim of this work is to quantify the contribution of platelets to mtDNAcn in whole blood [mtDNAcn(WB)] and to propose a correction formula to estimate leukocytes' mtDNAcn [mtDNAcn(L)] from mtDNAcn(WB). Blood samples from 10 healthy adults were combined with platelet-enriched plasma and saline solution to produce artificial blood preparations. Aliquots of each sample were combined with five different platelet concentrations. In 46 of these blood preparations, mtDNAcn was measured by qPCR. MtDNAcn(WB) increased 1.07 (95%CI 0.86, 1.29; p<0.001) per 1000 platelets present in the preparation. We proved that leukocyte count should also be taken into account as mtDNAcn(WB) was inversely associated with leukocyte count; it increased 1.10 (95%CI 0.95, 1.25, p<0.001) per unit increase of the ratio between platelet and leukocyte counts. If hematological measurements are available, subtracting 1.10 the platelets/leukocyte ratio from mtDNAcn(WB) may serve as an estimation for mtDNAcn(L). Both platelet and leukocyte counts in the sample are important sources of variation if comparing mtDNAcn among groups of patients when mtDNAcn is measured in DNA extracted from whole blood. Not taking the platelet/leukocyte ratio into account in whole blood measurements, may lead to overestimation and misclassification if interpreted as leukocytes' mtDNAcn.

Mitochondrial genome-maintaining activity of mouse mitochondrial transcription factor A and its transcript isoform in Saccharomyces cerevisiae.

PubMed

Yoon, Young Geol; Koob, Michael D; Yoo, Young Hyun

2011-09-15

Mitochondrial transcription factor A (Tfam) binds to and organizes mitochondrial DNA (mtDNA) genome into a mitochondrial nucleoid (mt-nucleoid) structure, which is necessary for mtDNA transcription and maintenance. Here, we demonstrate the mtDNA-organizing activity of mouse Tfam and its transcript isoform (Tfam(iso)), which has a smaller high-mobility group (HMG)-box1 domain, using a yeast model system that contains a deletion of the yeast homolog of mouse Tfam protein, Abf2p. When the mouse Tfam genes were introduced into the ABF2 locus of yeast genome, the corresponding mouse proteins, Tfam and Tfam(iso), can functionally replace the yeast Abf2p and support mtDNA maintenance and mitochondrial biogenesis in yeast. Growth properties, mtDNA content and mitochondrial protein levels of genes encoded in the mtDNA were comparable in the strains expressing mouse proteins and the wild-type yeast strain, indicating that the proteins have robust mtDNA-maintaining and -expressing function in yeast mitochondria. These results imply that the mtDNA-organizing activities of the mouse mt-nucleoid proteins are structurally and evolutionary conserved, thus they can maintain the mtDNA of distantly related and distinctively different species, such as yeast. Copyright © 2011 Elsevier B.V. All rights reserved.

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

Yokohira, Masanao; Arnold, Lora L.; Pennington, Karen L.

Arsenic (+ 3 oxidation state) methyltransferase (As3mt) catalyzes reactions which convert inorganic arsenic to methylated metabolites. This study determined whether the As3mt null genotype in the mouse modifies cytotoxic and proliferative effects seen in urinary bladders of wild type mice after exposure to inorganic arsenic. Female wild type C57BL/6 mice and As3mt KO mice were divided into 3 groups each (n = 8) with free access to a diet containing 0, 100 or 150 ppm of arsenic as arsenite (As{sup III}). During the first week of As{sup III} exposure, As3mt KO mice exhibited severe and lethal systemic toxicity. At termination,more » urinary bladders of both As3mt KO and wild type mice showed hyperplasia by light microscopy. As expected, arsenic-containing granules were found in the superficial urothelial layer of wild type mice. In As3mt KO mice these granules were present in all layers of the bladder epithelium and were more abundant and larger than in wild type mice. Scanning electron microscopy of the bladder urothelium of As3mt KO mice treated with 100 ppm As{sup III} showed extensive superficial necrosis and hyperplastic changes. In As3mt KO mice, livers showed severe acute inflammatory changes and spleen size and lymphoid areas were decreased compared with wild type mice. Thus, diminished arsenic methylation in As3mt KO mice exacerbates systemic toxicity and the effects of As{sup III} on the bladder epithelium, showing that altered kinetic and dynamic behavior of arsenic can affect its toxicity.« less

Formal Techniques for Synchronized Fault-Tolerant Systems

NASA Technical Reports Server (NTRS)

DiVito, Ben L.; Butler, Ricky W.

1992-01-01

We present the formal verification of synchronizing aspects of the Reliable Computing Platform (RCP), a fault-tolerant computing system for digital flight control applications. The RCP uses NMR-style redundancy to mask faults and internal majority voting to purge the effects of transient faults. The system design has been formally specified and verified using the EHDM verification system. Our formalization is based on an extended state machine model incorporating snapshots of local processors clocks.

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

USGS Publications Warehouse

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

2004-01-01

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

Alaska Crustal Deformation: Finite Element Modeling Constrained by Geologic and Very Long Baseline Interferometry Data

NASA Technical Reports Server (NTRS)

Lundgren, Paul; Saucier, Fraancois; Palmer, Randy; Langon, Marc

1995-01-01

We compute crustal motions in Alaska by calculating the finite element solution for an elastic spherical shell problem. The method we use allows the finite element mesh to include faults and very long baseline interferometry (VLBI) baseline rates of change. Boundary conditions include Pacific-North American (PA-NA) plate motions. The solution is constrained by the oblique orientation of the Fairweather-Queen Charlotte strike-slip faults relative to the PA-NA relative motion direction and the oblique orientation from normal convergence of the eastern Aleutian trench fault systems, as well as strike-shp motion along the Denali and Totschunda fault systems. We explore the effects that a range of fault slip constraints and weighting of VLBI rates of change has on the solution. This allows us to test the motion on faults, such as the Denali fault, where there are conflicting reports on its present-day slip rate. We find a pattern of displacements which produce fault motions generally consistent with geologic observations. The motion of the continuum has the general pattern of radial movement of crust to the NE away from the Fairweather-Queen Charlotte fault systems in SE Alaska and Canada. This pattern of crustal motion is absorbed across the Mackenzie Mountains in NW Canada, with strike-slip motion constrained along the Denali and Tintina fault systems. In south central Alaska and the Alaska forearc oblique convergence at the eastern Aleutian trench and the strike-shp motion of the Denali fault system produce a counterclockwise pattern of motion which is partially absorbed along the Contact and related fault systems in southern Alaska and is partially extruded into the Bering Sea and into the forearc parallel the Aleutian trench from the Alaska Peninsula westward. Rates of motion and fault slip are small in western and northern Alaska, but the motions we compute are consistent with the senses of strike-slip motion inferred geologically along the Kaltag, Kobuk Trench, and Thompson Creek faults and with the normal faulting observed in NW Alaska near Nome. The nonrigid behavior of our finite element solution produces patterns of motion that would not have been expected from rigid block models: strike-slip faults can exist in a continuum that has motion mostly perpendicular to their strikes, and faults can exhibit along-strike differences in magnitudes and directions.

Method and system for environmentally adaptive fault tolerant computing

NASA Technical Reports Server (NTRS)

Copenhaver, Jason L. (Inventor); Jeremy, Ramos (Inventor); Wolfe, Jeffrey M. (Inventor); Brenner, Dean (Inventor)

2010-01-01

A method and system for adapting fault tolerant computing. The method includes the steps of measuring an environmental condition representative of an environment. An on-board processing system's sensitivity to the measured environmental condition is measured. It is determined whether to reconfigure a fault tolerance of the on-board processing system based in part on the measured environmental condition. The fault tolerance of the on-board processing system may be reconfigured based in part on the measured environmental condition.

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.

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.

The emergence of asymmetric normal fault systems under symmetric boundary conditions

NASA Astrophysics Data System (ADS)

Schöpfer, Martin P. J.; Childs, Conrad; Manzocchi, Tom; Walsh, John J.; Nicol, Andrew; Grasemann, Bernhard

2017-11-01

Many normal fault systems and, on a smaller scale, fracture boudinage often exhibit asymmetry with one fault dip direction dominating. It is a common belief that the formation of domino and shear band boudinage with a monoclinic symmetry requires a component of layer parallel shearing. Moreover, domains of parallel faults are frequently used to infer the presence of a décollement. Using Distinct Element Method (DEM) modelling we show, that asymmetric fault systems can emerge under symmetric boundary conditions. A statistical analysis of DEM models suggests that the fault dip directions and system polarities can be explained using a random process if the strength contrast between the brittle layer and the surrounding material is high. The models indicate that domino and shear band boudinage are unreliable shear-sense indicators. Moreover, the presence of a décollement should not be inferred on the basis of a domain of parallel faults alone.

Indirect adaptive fuzzy fault-tolerant tracking control for MIMO nonlinear systems with actuator and sensor failures.

PubMed

Bounemeur, Abdelhamid; Chemachema, Mohamed; Essounbouli, Najib

2018-05-10

In this paper, an active fuzzy fault tolerant tracking control (AFFTTC) scheme is developed for a class of multi-input multi-output (MIMO) unknown nonlinear systems in the presence of unknown actuator faults, sensor failures and external disturbance. The developed control scheme deals with four kinds of faults for both sensors and actuators. The bias, drift, and loss of accuracy additive faults are considered along with the loss of effectiveness multiplicative fault. A fuzzy adaptive controller based on back-stepping design is developed to deal with actuator failures and unknown system dynamics. However, an additional robust control term is added to deal with sensor faults, approximation errors, and external disturbances. Lyapunov theory is used to prove the stability of the closed loop system. Numerical simulations on a quadrotor are presented to show the effectiveness of the proposed approach. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Model-based development of a fault signature matrix to improve solid oxide fuel cell systems on-site diagnosis

NASA Astrophysics Data System (ADS)

Polverino, Pierpaolo; Pianese, Cesare; Sorrentino, Marco; Marra, Dario

2015-04-01

The paper focuses on the design of a procedure for the development of an on-field diagnostic algorithm for solid oxide fuel cell (SOFC) systems. The diagnosis design phase relies on an in-deep analysis of the mutual interactions among all system components by exploiting the physical knowledge of the SOFC system as a whole. This phase consists of the Fault Tree Analysis (FTA), which identifies the correlations among possible faults and their corresponding symptoms at system components level. The main outcome of the FTA is an inferential isolation tool (Fault Signature Matrix - FSM), which univocally links the faults to the symptoms detected during the system monitoring. In this work the FTA is considered as a starting point to develop an improved FSM. Making use of a model-based investigation, a fault-to-symptoms dependency study is performed. To this purpose a dynamic model, previously developed by the authors, is exploited to simulate the system under faulty conditions. Five faults are simulated, one for the stack and four occurring at BOP level. Moreover, the robustness of the FSM design is increased by exploiting symptom thresholds defined for the investigation of the quantitative effects of the simulated faults on the affected variables.

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.

Evidence of Quaternary and recent activity along the Kyaukkyan Fault, Myanmar

NASA Astrophysics Data System (ADS)

Crosetto, Silvia; Watkinson, Ian M.; Soe Min; Gori, Stefano; Falcucci, Emanuela; Nwai Le Ngal

2018-05-01

Cenozoic right-lateral shear between the eastern Indian margin and Eurasia is expressed by numerous N-S trending fault systems inboard of the Sunda trench, including the Sagaing Fault. The most easterly of these fault systems is the prominent ∼500 km long Kyaukkyan Fault, on the Shan Plateau. Myanmar's largest recorded earthquake, Mw 7.7 on 23rd May 1912, focused near Maymyo, has been attributed to the Kyaukkyan Fault, but the area has experienced little significant seismicity since then. Despite its demonstrated seismic potential and remarkable topographic expression, questions remain about the Kyaukkyan Fault's neotectonic history.

A distributed fault-tolerant signal processor /FTSP/

NASA Astrophysics Data System (ADS)

Bonneau, R. J.; Evett, R. C.; Young, M. J.

1980-01-01

A digital fault-tolerant signal processor (FTSP), an example of a self-repairing programmable system is analyzed. The design configuration is discussed in terms of fault tolerance, system-level fault detection, isolation and common memory. Special attention is given to the FDIR (fault detection isolation and reconfiguration) logic, noting that the reconfiguration decisions are based on configuration, summary status, end-around tests, and north marker/synchro data. Several mechanisms of fault detection are described which initiate reconfiguration at different levels. It is concluded that the reliability of a signal processor can be significantly enhanced by the use of fault-tolerant techniques.

Advanced power system protection and incipient fault detection and protection of spaceborne power systems

NASA Technical Reports Server (NTRS)

Russell, B. Don

1989-01-01

This research concentrated on the application of advanced signal processing, expert system, and digital technologies for the detection and control of low grade, incipient faults on spaceborne power systems. The researchers have considerable experience in the application of advanced digital technologies and the protection of terrestrial power systems. This experience was used in the current contracts to develop new approaches for protecting the electrical distribution system in spaceborne applications. The project was divided into three distinct areas: (1) investigate the applicability of fault detection algorithms developed for terrestrial power systems to the detection of faults in spaceborne systems; (2) investigate the digital hardware and architectures required to monitor and control spaceborne power systems with full capability to implement new detection and diagnostic algorithms; and (3) develop a real-time expert operating system for implementing diagnostic and protection algorithms. Significant progress has been made in each of the above areas. Several terrestrial fault detection algorithms were modified to better adapt to spaceborne power system environments. Several digital architectures were developed and evaluated in light of the fault detection algorithms.

On-board fault management for autonomous spacecraft

NASA Technical Reports Server (NTRS)

Fesq, Lorraine M.; Stephan, Amy; Doyle, Susan C.; Martin, Eric; Sellers, Suzanne

1991-01-01

The dynamic nature of the Cargo Transfer Vehicle's (CTV) mission and the high level of autonomy required mandate a complete fault management system capable of operating under uncertain conditions. Such a fault management system must take into account the current mission phase and the environment (including the target vehicle), as well as the CTV's state of health. This level of capability is beyond the scope of current on-board fault management systems. This presentation will discuss work in progress at TRW to apply artificial intelligence to the problem of on-board fault management. The goal of this work is to develop fault management systems. This presentation will discuss work in progress at TRW to apply artificial intelligence to the problem of on-board fault management. The goal of this work is to develop fault management systems that can meet the needs of spacecraft that have long-range autonomy requirements. We have implemented a model-based approach to fault detection and isolation that does not require explicit characterization of failures prior to launch. It is thus able to detect failures that were not considered in the failure and effects analysis. We have applied this technique to several different subsystems and tested our approach against both simulations and an electrical power system hardware testbed. We present findings from simulation and hardware tests which demonstrate the ability of our model-based system to detect and isolate failures, and describe our work in porting the Ada version of this system to a flight-qualified processor. We also discuss current research aimed at expanding our system to monitor the entire spacecraft.

Early Tertiary transtension-related deformation and magmatism along the Tintina fault system, Alaska

USGS Publications Warehouse

Till, A.B.; Roeske, S.M.; Bradley, D.C.; Friedman, R.; Layer, P.W.

2007-01-01

Transtensional deformation was concentrated in a zone adjacent to the Tintina strike-slip fault system in Alaska during the early Tertiary. The deformation occurred along the Victoria Creek fault, the trace of the Tintina system that connects it with the Kaltag fault; together the Tintina and Kaltag fault systems girdle Alaska from east to west. Over an area of ???25 by 70 km between the Victoria Creek and Tozitna faults, bimodal volcanics erupted; lacustrine and fluvial rocks were deposited; plutons were emplaced and deformed; and metamorphic rocks cooled, all at about the same time. Plutonic and volcanic rocks in this zone yield U-Pb zircon ages of ca. 60 Ma; 40Ar/ 39Ar cooling ages from those plutons and adjacent metamorphic rocks are also ca. 60 Ma. Although early Tertiary magmatism occurred over a broad area in central Alaska, meta- morphism and ductile deformation accompanied that magmatism in this one zone only. Within the zone of deformation, pluton aureoles and metamorphic rocks display consistent NE-SW-stretching lineations parallel to the Victoria Creek fault, suggesting that deformation processes involved subhorizontal elongation of the package. The most deeply buried metamorphic rocks, kyanite-bearing metapelites, occur as lenses adjacent to the fault, which cuts the crust to the Moho (Beaudoin et al., 1997). Geochronologic data and field relationships suggest that the amount of early Tertiary exhumation was greatest adjacent to the Victoria Creek fault. The early Tertiary crustal-scale events that may have operated to produce transtension in this area are (1) increased heat flux and related bimodal within-plate magmatism, (2) movement on a releasing stepover within the Tintina fault system or on a regional scale involving both the Tintina and the Kobuk fault systems, and (3) oroclinal bending of the Tintina-Kaltag fault system with counterclockwise rotation of western Alaska. ?? 2007 The Geological Society of America. All rights reserved.

Robust fault detection of wind energy conversion systems based on dynamic neural networks.

PubMed

Talebi, Nasser; Sadrnia, Mohammad Ali; Darabi, Ahmad

2014-01-01

Occurrence of faults in wind energy conversion systems (WECSs) is inevitable. In order to detect the occurred faults at the appropriate time, avoid heavy economic losses, ensure safe system operation, prevent damage to adjacent relevant systems, and facilitate timely repair of failed components; a fault detection system (FDS) is required. Recurrent neural networks (RNNs) have gained a noticeable position in FDSs and they have been widely used for modeling of complex dynamical systems. One method for designing an FDS is to prepare a dynamic neural model emulating the normal system behavior. By comparing the outputs of the real system and neural model, incidence of the faults can be identified. In this paper, by utilizing a comprehensive dynamic model which contains both mechanical and electrical components of the WECS, an FDS is suggested using dynamic RNNs. The presented FDS detects faults of the generator's angular velocity sensor, pitch angle sensors, and pitch actuators. Robustness of the FDS is achieved by employing an adaptive threshold. Simulation results show that the proposed scheme is capable to detect the faults shortly and it has very low false and missed alarms rate.

Robust Fault Detection of Wind Energy Conversion Systems Based on Dynamic Neural Networks

PubMed Central

Talebi, Nasser; Sadrnia, Mohammad Ali; Darabi, Ahmad

2014-01-01

Occurrence of faults in wind energy conversion systems (WECSs) is inevitable. In order to detect the occurred faults at the appropriate time, avoid heavy economic losses, ensure safe system operation, prevent damage to adjacent relevant systems, and facilitate timely repair of failed components; a fault detection system (FDS) is required. Recurrent neural networks (RNNs) have gained a noticeable position in FDSs and they have been widely used for modeling of complex dynamical systems. One method for designing an FDS is to prepare a dynamic neural model emulating the normal system behavior. By comparing the outputs of the real system and neural model, incidence of the faults can be identified. In this paper, by utilizing a comprehensive dynamic model which contains both mechanical and electrical components of the WECS, an FDS is suggested using dynamic RNNs. The presented FDS detects faults of the generator's angular velocity sensor, pitch angle sensors, and pitch actuators. Robustness of the FDS is achieved by employing an adaptive threshold. Simulation results show that the proposed scheme is capable to detect the faults shortly and it has very low false and missed alarms rate. PMID:24744774

Quasi-dynamic earthquake fault systems with rheological heterogeneity

NASA Astrophysics Data System (ADS)

Brietzke, G. B.; Hainzl, S.; Zoeller, G.; Holschneider, M.

2009-12-01

Seismic risk and hazard estimates mostly use pure empirical, stochastic models of earthquake fault systems tuned specifically to the vulnerable areas of interest. Although such models allow for reasonable risk estimates, such models cannot allow for physical statements of the described seismicity. In contrary such empirical stochastic models, physics based earthquake fault systems models allow for a physical reasoning and interpretation of the produced seismicity and system dynamics. Recently different fault system earthquake simulators based on frictional stick-slip behavior have been used to study effects of stress heterogeneity, rheological heterogeneity, or geometrical complexity on earthquake occurrence, spatial and temporal clustering of earthquakes, and system dynamics. Here we present a comparison of characteristics of synthetic earthquake catalogs produced by two different formulations of quasi-dynamic fault system earthquake simulators. Both models are based on discretized frictional faults embedded in an elastic half-space. While one (1) is governed by rate- and state-dependent friction with allowing three evolutionary stages of independent fault patches, the other (2) is governed by instantaneous frictional weakening with scheduled (and therefore causal) stress transfer. We analyze spatial and temporal clustering of events and characteristics of system dynamics by means of physical parameters of the two approaches.

Metallothionein blocks oxidative DNA damage induced by acute inorganic arsenic exposure

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

Qu, Wei, E-mail: qu@niehs.nih.gov; Waalkes, Michael P.

We studied how protein metallothionein (MT) impacts arsenic-induced oxidative DNA damage (ODD) using cells that poorly express MT (MT-I/II double knockout embryonic cells; called MT-null cells) and wild-type (WT) MT competent cells. Arsenic (as NaAsO{sub 2}) was less cytolethal over 24 h in WT cells (LC{sub 50} = 11.0 ± 1.3 μM; mean ± SEM) than in MT-null cells (LC{sub 50} = 5.6 ± 1.2 μM). ODD was measured by the immuno-spin trapping method. Arsenic (1 or 5 μM; 24 h) induced much less ODD in WT cells (121% and 141% of control, respectively) than in MT-null cells (202% andmore » 260%). In WT cells arsenic caused concentration-dependent increases in MT expression (transcript and protein), and in the metal-responsive transcription factor-1 (MTF-1), which is required to induce the MT gene. In contrast, basal MT levels were not detectable in MT-null cells and unaltered by arsenic exposure. Transfection of MT-I gene into the MT-null cells markedly reduced arsenic-induced ODD levels. The transport genes, Abcc1 and Abcc2 were increased by arsenic in WT cells but either showed no or very limited increases in MT-null cells. Arsenic caused increases in oxidant stress defense genes HO-1 and GSTα2 in both WT and MT-null cells, but to much higher levels in WT cells. WT cells appear more adept at activating metal transport systems and oxidant response genes, although the role of MT in these responses is unclear. Overall, MT protects against arsenic-induced ODD in MT competent cells by potential sequestration of scavenging oxidant radicals and/or arsenic. - Highlights: • Metallothionein blocks arsenic toxicity. • Metallothionein reduces arsenic-induced DNA damage. • Metallothionein may bind arsenic or radicals produced by arsenic.« less

Extent and architecture of major fault systems between northern Victoria Land and the eastern margin of the Wilkes Subglacial Basin (East Antarctica)

NASA Astrophysics Data System (ADS)

Armadillo, E.; Ferraccioli, F.; Balbi, P.; Bozzo, E.

2013-12-01

Terrane bounding and intra-terrane faults of the Ross Orogen in East Antarctica are linked to several phases of Cambrian to Ordovician age subduction and accretion along the active paleo-Pacific margin of Gondwana. Here we compile and analyse new enhanced aeromagnetic anomaly images over the Northern Victoria Land (NVL) segment of the Ross Orogen and the eastern margin of the Wilkes Subglacial Basin (WSB) that help constrain the extent and structural architecture of these fault systems and enable us re-assess their tectonic evolution. Long-wavelength magnetic lows and residual Bouguer gravity highs are modelled as several-km thick inverted sedimentary basins of early Cambrian(?) age. Tectonic inversion occurred along major thrust faults during the late stages of the Ross Orogen, forming a major high-grade pop-up structure within the central Wilson Terrane, flanked by lower grade rocks. The Prince Albert Fault System can now be recongnised as being located to the west of the Exiles Thrust fault system rather than representing its southern continuation. Relatively thin sheets of mylonitic sheared granitoids and possible ultramafic lenses are associated with the late-Ross (ca 480 Ma) Exiles Thrust fault system, while significantly larger and thicker batholiths were emplaced along the Prince Albert Fault System. Recent zircon U-Pb dating over small exposures of gabbro-diorites within the Prince Albert Mountains to the south lead us to propose that this part of the magmatic arc was emplaced during an earlier phase of subduction (~520 Ma or older?), compared to the late-Ross intrusions to the east. Whether the Prince Albert Fault System was indeed a major cryptic suture in early Cambrian times (Ferraccioli et al., 2002, GRL) remains speculative, but possible. Our aeromagnetic interpretation leads us to conclude that these inherited terrane bounding and intra-terrane fault systems of the Ross Orogen exerted a key influence on Cenozoic tectonic blocks and faults of the Transantarctic Mountains, and that the eastern margin of the WSB adjacent to NVL was also strongly controlled by a complex array of major intraplate strike-slip fault systems.

Multi-faults decoupling on turbo-expander using differential-based ensemble empirical mode decomposition

NASA Astrophysics Data System (ADS)

Li, Hongguang; Li, Ming; Li, Cheng; Li, Fucai; Meng, Guang

2017-09-01

This paper dedicates on the multi-faults decoupling of turbo-expander rotor system using Differential-based Ensemble Empirical Mode Decomposition (DEEMD). DEEMD is an improved version of DEMD to resolve the imperfection of mode mixing. The nonlinear behaviors of the turbo-expander considering temperature gradient with crack, rub-impact and pedestal looseness faults are investigated respectively, so that the baseline for the multi-faults decoupling can be established. DEEMD is then utilized on the vibration signals of the rotor system with coupling faults acquired by numerical simulation, and the results indicate that DEEMD can successfully decouple the coupling faults, which is more efficient than EEMD. DEEMD is also applied on the vibration signal of the misalignment coupling with rub-impact fault obtained during the adjustment of the experimental system. The conclusion shows that DEEMD can decompose the practical multi-faults signal and the industrial prospect of DEEMD is verified as well.

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.

Functional requirements for an intelligent RPC. [remote power controller for spaceborne electrical distribution system

NASA Technical Reports Server (NTRS)

Aucoin, B. M.; Heller, R. P.

1990-01-01

An intelligent remote power controller (RPC) based on microcomputer technology can implement advanced functions for the accurate and secure detection of all types of faults on a spaceborne electrical distribution system. The intelligent RPC will implement conventional protection functions such as overcurrent, under-voltage, and ground fault protection. Advanced functions for the detection of soft faults, which cannot presently be detected, can also be implemented. Adaptive overcurrent protection changes overcurrent settings based on connected load. Incipient and high-impedance fault detection provides early detection of arcing conditions to prevent fires, and to clear and reconfigure circuits before soft faults progress to a hard-fault condition. Power electronics techniques can be used to implement fault current limiting to prevent voltage dips during hard faults. It is concluded that these techniques will enhance the overall safety and reliability of the distribution system.

SignMT: An Alternative Language Learning Tool

ERIC Educational Resources Information Center

Ditcharoen, Nadh; Naruedomkul, Kanlaya; Cercone, Nick

2010-01-01

Learning a second language is very difficult, especially, for the disabled; the disability may be a barrier to learn and to utilize information written in text form. We present the SignMT, Thai sign to Thai machine translation system, which is able to translate from Thai sign language into Thai text. In the translation process, SignMT takes into…

Software fault tolerance for real-time avionics systems

NASA Technical Reports Server (NTRS)

Anderson, T.; Knight, J. C.

1983-01-01

Avionics systems have very high reliability requirements and are therefore prime candidates for the inclusion of fault tolerance techniques. In order to provide tolerance to software faults, some form of state restoration is usually advocated as a means of recovery. State restoration can be very expensive for systems which utilize concurrent processes. The concurrency present in most avionics systems and the further difficulties introduced by timing constraints imply that providing tolerance for software faults may be inordinately expensive or complex. A straightforward pragmatic approach to software fault tolerance which is believed to be applicable to many real-time avionics systems is proposed. A classification system for software errors is presented together with approaches to recovery and continued service for each error type.

Airborne Advanced Reconfigurable Computer System (ARCS)

NASA Technical Reports Server (NTRS)

Bjurman, B. E.; Jenkins, G. M.; Masreliez, C. J.; Mcclellan, K. L.; Templeman, J. E.

1976-01-01

A digital computer subsystem fault-tolerant concept was defined, and the potential benefits and costs of such a subsystem were assessed when used as the central element of a new transport's flight control system. The derived advanced reconfigurable computer system (ARCS) is a triple-redundant computer subsystem that automatically reconfigures, under multiple fault conditions, from triplex to duplex to simplex operation, with redundancy recovery if the fault condition is transient. The study included criteria development covering factors at the aircraft's operation level that would influence the design of a fault-tolerant system for commercial airline use. A new reliability analysis tool was developed for evaluating redundant, fault-tolerant system availability and survivability; and a stringent digital system software design methodology was used to achieve design/implementation visibility.

Intelligent classifier for dynamic fault patterns based on hidden Markov model

NASA Astrophysics Data System (ADS)

Xu, Bo; Feng, Yuguang; Yu, Jinsong

2006-11-01

It's difficult to build precise mathematical models for complex engineering systems because of the complexity of the structure and dynamics characteristics. Intelligent fault diagnosis introduces artificial intelligence and works in a different way without building the analytical mathematical model of a diagnostic object, so it's a practical approach to solve diagnostic problems of complex systems. This paper presents an intelligent fault diagnosis method, an integrated fault-pattern classifier based on Hidden Markov Model (HMM). This classifier consists of dynamic time warping (DTW) algorithm, self-organizing feature mapping (SOFM) network and Hidden Markov Model. First, after dynamic observation vector in measuring space is processed by DTW, the error vector including the fault feature of being tested system is obtained. Then a SOFM network is used as a feature extractor and vector quantization processor. Finally, fault diagnosis is realized by fault patterns classifying with the Hidden Markov Model classifier. The importing of dynamic time warping solves the problem of feature extracting from dynamic process vectors of complex system such as aeroengine, and makes it come true to diagnose complex system by utilizing dynamic process information. Simulating experiments show that the diagnosis model is easy to extend, and the fault pattern classifier is efficient and is convenient to the detecting and diagnosing of new faults.

Fault Deformation and Segmentation of the Newport-Inglewood Rose Canyon, and San Onofre Trend Fault Systems from New High-Resolution 3D Seismic Imagery

NASA Astrophysics Data System (ADS)

Holmes, J. J.; Driscoll, N. W.; Kent, G. M.

2016-12-01

The Inner California Borderlands (ICB) is situated off the coast of southern California and northern Baja. The structural and geomorphic characteristics of the area record a middle Oligocene transition from subduction to microplate capture along the California coast. Marine stratigraphic evidence shows large-scale extension and rotation overprinted by modern strike-slip deformation. Geodetic and geologic observations indicate that approximately 6-8 mm/yr of Pacific-North American relative plate motion is accommodated by offshore strike-slip faulting in the ICB. The farthest inshore fault system, the Newport-Inglewood Rose Canyon (NIRC) Fault is a dextral strike-slip system that is primarily offshore for approximately 120 km from San Diego to the San Joaquin Hills near Newport Beach, California. Based on trenching and well data, the NIRC Fault Holocene slip rate is 1.5-2.0 mm/yr to the south and 0.5-1.0 mm/yr along its northern extent. An earthquake rupturing the entire length of the system could produce an Mw 7.0 earthquake or larger. West of the main segments of the NIRC Fault is the San Onofre Trend (SOT) along the continental slope. Previous work concluded that this is part of a strike-slip system that eventually merges with the NIRC Fault. Others have interpreted this system as deformation associated with the Oceanside Blind Thrust fault purported to underlie most of the region. In late 2013, we acquired the first high-resolution 3D Parallel Cable (P-Cable) seismic surveys of the NIRC and SOT faults as part of the Southern California Regional Fault Mapping project aboard the R/V New Horizon. Analysis of these data volumes provides important new insights and constraints on the fault segmentation and transfer of deformation. Based on this new data, we've mapped several small fault strands associated with the SOT that appear to link up with a westward jog in right-lateral fault splays of the NIRC Fault on the shelf and then narrowly radiate southwards. Our observations are that these strands are strike-slip features associated with a dying splay of the NIRC system rather than compressional features associated with a regional thrust.

Sliding Mode Fault Tolerant Control with Adaptive Diagnosis for Aircraft Engines

NASA Astrophysics Data System (ADS)

Xiao, Lingfei; Du, Yanbin; Hu, Jixiang; Jiang, Bin

2018-03-01

In this paper, a novel sliding mode fault tolerant control method is presented for aircraft engine systems with uncertainties and disturbances on the basis of adaptive diagnostic observer. By taking both sensors faults and actuators faults into account, the general model of aircraft engine control systems which is subjected to uncertainties and disturbances, is considered. Then, the corresponding augmented dynamic model is established in order to facilitate the fault diagnosis and fault tolerant controller design. Next, a suitable detection observer is designed to detect the faults effectively. Through creating an adaptive diagnostic observer and based on sliding mode strategy, the sliding mode fault tolerant controller is constructed. Robust stabilization is discussed and the closed-loop system can be stabilized robustly. It is also proven that the adaptive diagnostic observer output errors and the estimations of faults converge to a set exponentially, and the converge rate greater than some value which can be adjusted by choosing designable parameters properly. The simulation on a twin-shaft aircraft engine verifies the applicability of the proposed fault tolerant control method.

Geometric-kinematic characteristics of the main faults in the W-SW of the Lut Block (SE Iran)

NASA Astrophysics Data System (ADS)

Rashidi Boshrabadi, Ahmad; Khatib, Mohamad Mahdi; Raeesi, Mohamad; Mousavi, Seyed Morteza; Djamour, Yahya

2018-03-01

The area to the W-SW of the Lut Block in Iran has experienced numerous historical and recent destructive earthquakes. We examined a number of faults in this area that have high potential for generating destructive earthquakes. In this study a number of faults are introduced and named for the first time. These new faults are Takdar, Dehno, Suru, Hojat Abad, North Faryab, North Kahnoj, Heydarabad, Khatun Abad and South Faryab. For a group of previously known faults, their mechanism and geological offsets are investigated for the first time. This group of faults include East Nayband, West Nayband, Sardueiyeh, Dalfard, Khordum, South Jabal-e-Barez, and North Jabal-e-Barez. The N-S fault systems of Sabzevaran, Gowk, and Nayband induce slip on the E-W, NE-SW and NW-SE fault systems. The faulting patterns appear to preserve different stages of fault development. We investigated the distribution of active faults and the role that they play in accommodating tectonic strain in the SW-Lut. In the study area, the fault systems with en-echelon arrangement create structures such as restraining and releasing stepover, fault bend and pullapart basin. The main mechanism for fault growth in the region seems to be 'segment linkage of preexisting weaknesses' and also for a limited area through 'process zone'. Estimations are made for the likely magnitudes of separate or combined failure of the fault segments. Such magnitudes are used in hazard analysis of the region.

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.

Fault Management Techniques in Human Spaceflight Operations

NASA Technical Reports Server (NTRS)

O'Hagan, Brian; Crocker, Alan

2006-01-01

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

Structural setting and kinematics of Nubian fault system, SE Western Desert, Egypt: An example of multi-reactivated intraplate strike-slip faults

NASA Astrophysics Data System (ADS)

Sakran, Shawky; Said, Said Mohamed

2018-02-01

Detailed surface geological mapping and subsurface seismic interpretation have been integrated to unravel the structural style and kinematic history of the Nubian Fault System (NFS). The NFS consists of several E-W Principal Deformation Zones (PDZs) (e.g. Kalabsha fault). Each PDZ is defined by spectacular E-W, WNW and ENE dextral strike-slip faults, NNE sinistral strike-slip faults, NE to ENE folds, and NNW normal faults. Each fault zone has typical self-similar strike-slip architecture comprising multi-scale fault segments. Several multi-scale uplifts and basins were developed at the step-over zones between parallel strike-slip fault segments as a result of local extension or contraction. The NNE faults consist of right-stepping sinistral strike-slip fault segments (e.g. Sin El Kiddab fault). The NNE sinistral faults extend for long distances ranging from 30 to 100 kms and cut one or two E-W PDZs. Two nearly perpendicular strike-slip tectonic regimes are recognized in the NFS; an inactive E-W Late Cretaceous - Early Cenozoic dextral transpression and an active NNE sinistral shear.

Paleoseismology of Sinistral-Slip Fault System, Focusing on the Mae Chan Fault, on the Shan Plateau, SE Asia.

NASA Astrophysics Data System (ADS)

Curtiss, E. R.; Weldon, R. J.; Wiwegwin, W.; Weldon, E. M.

2017-12-01

The Shan Plateau, which includes portions of Myanmar, China, Thailand, Laos, and Vietnam lies between the dextral NS-trending Sagaing and SE-trending Red River faults and contains 14 active E-W sinistral-slip faults, including the Mae Chan Fault (MCF) in northern Thailand. The last ground-rupturing earthquake to occur on the broader sinistral fault system was the M6.8 Tarlay earthquake in Myanmar in March 2011 on the Nam Ma fault immediately north of the MCF the last earthquake to occur on the MCF was a M4.0 in the 5th century that destroyed the entire city of Wiang Yonok (Morley et al., 2011). We report on a trenching study of the MCF, which is part of a broader study to create a regional seismic hazard map of the entire Shan Plateau. By studying the MCF, which appears to be representative of the sinistral faults, and easy to work on, we hope to characterize both it and the other unstudied faults in the system. As part of a paleoseismology training course we dug two trenches at the Pa Tueng site on the MCF, within an offset river channel and the trenches exposed young sediment with abundant charcoal (in process of dating), cultural artifacts, and evidence for the last two (or three) ground-rupturing earthquakes on the fault. We hope to use the data from this site to narrow the recurrence interval, which is currently to be 2,000-4,000 years and the slip rate of 1-2 mm/year, being developed at other sites on the fault. By extrapolating the data of the MCF to the other faults we will have a better understanding of the whole fault system. Once we have characterized the MCF, we plan to use geomorphic offsets and strain rates from regional GPS to relatively estimate the activity of the other faults in this sinistral system.

Tectonics and soil edaphics as controls on animal migrations and early human inhabitance in the Kenya Rift

NASA Astrophysics Data System (ADS)

Kübler, Simon; Rucina, Stephen; Reynolds, Sally; Fürgut, Felix; Bailey, Geoffrey; King, Geoffrey

2017-04-01

Animal movements in the tectonically active East African Rift Valley today are influenced by a combination of topography and soil nutrient distribution (soil edaphics). These patterns would have been the same in the past when hominins inhabited the area. Our study in the Kenya Rift shows that soil edaphics and active rift structures play a key role in present day animal movements as well as the for the location of early hominin sites. We carried out field analysis at Olorgesailie and Kariandusi, two key hominin sites in the southern and central Kenya Rift, respectiveley. Based on studying the relationship between the geology, tectonics and soil development we identified 'good' and 'bad' regions both in terms of edaphics and accessibility for grazing animals. We further sampled a large number of soils that developed on the volcanic bedrock and sediments of the region and interviewed the local Maasai shepherds to learn about present-day good and bad grazing sites. Ultimately, we created palaeoenvironmental and spatio-temporal reconstructions for interpreting human land use and exploitation of large mammals in the Kenya Rift for the relevant time frame of approximately 1 Ma BP. At Olorgesailie the hominin site is located in lacustrine sediments at the southern edge of a playa that extends north and northwest of Mt. Olorgesailie. The lakebeds are now tilted and eroded by motion on two north-south striking faults. The lake was trapped by volcanic flows and alluvial fans from Mt. Olorgesailie and was released by the fault motion leading to deep river incision and exposure of the site. To the west and the north steep fault scarps bound the playa forming a natural barrier for animals. Field observations and information from local shepherds suggest that the abundant trachytes at the valley floor produce poor soils whereas the soils developed on lacustrine and alluvial sediments close to the hominin site provide much more attractive grazing sites for present-day animals. This is supported by our soil analysis. With a lake in the past the Olorgesailie site represents an key example of how early hominins may have used the landscape for their strategic advantage. At Kariandusi site we investigated the tectonic and volcanic history of the region, and the system of lakes that have undergone periodic expansion and contraction during the Pleistocene in response to climatic and tectonic controls. We used this information to reconstruct topographic features as they would have existed at different periods of the past and their likely influence on patterns of large-mammal movements, and linked this with information from soil analysis. Our results show that Kariandusi occupied a unique window of opportunity in place and time for trapping mammals constrained to move through a narrowly defined topographic bottleneck between edaphically-rich areas during the lake highstand 1 Ma BP. Results of our study suggests that both Olorgesailie and Kariandusi sites were used for a simple form of ambush hunting.

Mitochondrial genome maintenance: roles for nuclear nonhomologous end-joining proteins in Saccharomyces cerevisiae.

PubMed

Kalifa, Lidza; Quintana, Daniel F; Schiraldi, Laura K; Phadnis, Naina; Coles, Garry L; Sia, Rey A; Sia, Elaine A

2012-03-01

Mitochondrial DNA (mtDNA) deletions are associated with sporadic and inherited diseases and age-associated neurodegenerative disorders. Approximately 85% of mtDNA deletions identified in humans are flanked by short directly repeated sequences; however, mechanisms by which these deletions arise are unknown. A limitation in deciphering these mechanisms is the essential nature of the mitochondrial genome in most living cells. One exception is budding yeast, which are facultative anaerobes and one of the few organisms for which directed mtDNA manipulation is possible. Using this model system, we have developed a system to simultaneously monitor spontaneous direct-repeat-mediated deletions (DRMDs) in the nuclear and mitochondrial genomes. In addition, the mitochondrial DRMD reporter contains a unique KpnI restriction endonuclease recognition site that is not present in otherwise wild-type (WT) mtDNA. We have expressed KpnI fused to a mitochondrial localization signal to induce a specific mitochondrial double-strand break (mtDSB). Here we report that loss of the MRX (Mre11p, Rad50p, Xrs2p) and Ku70/80 (Ku70p, Ku80p) complexes significantly impacts the rate of spontaneous deletion events in mtDNA, and these proteins contribute to the repair of induced mtDSBs. Furthermore, our data support homologous recombination (HR) as the predominant pathway by which mtDNA deletions arise in yeast, and suggest that the MRX and Ku70/80 complexes are partially redundant in mitochondria.

Mitochondrial Genome Maintenance: Roles for Nuclear Nonhomologous End-Joining Proteins in Saccharomyces cerevisiae

PubMed Central

Kalifa, Lidza; Quintana, Daniel F.; Schiraldi, Laura K.; Phadnis, Naina; Coles, Garry L.; Sia, Rey A.; Sia, Elaine A.

2012-01-01

Mitochondrial DNA (mtDNA) deletions are associated with sporadic and inherited diseases and age-associated neurodegenerative disorders. Approximately 85% of mtDNA deletions identified in humans are flanked by short directly repeated sequences; however, mechanisms by which these deletions arise are unknown. A limitation in deciphering these mechanisms is the essential nature of the mitochondrial genome in most living cells. One exception is budding yeast, which are facultative anaerobes and one of the few organisms for which directed mtDNA manipulation is possible. Using this model system, we have developed a system to simultaneously monitor spontaneous direct-repeat–mediated deletions (DRMDs) in the nuclear and mitochondrial genomes. In addition, the mitochondrial DRMD reporter contains a unique KpnI restriction endonuclease recognition site that is not present in otherwise wild-type (WT) mtDNA. We have expressed KpnI fused to a mitochondrial localization signal to induce a specific mitochondrial double-strand break (mtDSB). Here we report that loss of the MRX (Mre11p, Rad50p, Xrs2p) and Ku70/80 (Ku70p, Ku80p) complexes significantly impacts the rate of spontaneous deletion events in mtDNA, and these proteins contribute to the repair of induced mtDSBs. Furthermore, our data support homologous recombination (HR) as the predominant pathway by which mtDNA deletions arise in yeast, and suggest that the MRX and Ku70/80 complexes are partially redundant in mitochondria. PMID:22214610

Estimation of Faults in DC Electrical Power System

NASA Technical Reports Server (NTRS)

Gorinevsky, Dimitry; Boyd, Stephen; Poll, Scott

2009-01-01

This paper demonstrates a novel optimization-based approach to estimating fault states in a DC power system. Potential faults changing the circuit topology are included along with faulty measurements. Our approach can be considered as a relaxation of the mixed estimation problem. We develop a linear model of the circuit and pose a convex problem for estimating the faults and other hidden states. A sparse fault vector solution is computed by using 11 regularization. The solution is computed reliably and efficiently, and gives accurate diagnostics on the faults. We demonstrate a real-time implementation of the approach for an instrumented electrical power system testbed, the ADAPT testbed at NASA ARC. The estimates are computed in milliseconds on a PC. The approach performs well despite unmodeled transients and other modeling uncertainties present in the system.

Survivable algorithms and redundancy management in NASA's distributed computing systems

NASA Technical Reports Server (NTRS)

Malek, Miroslaw

1992-01-01

The design of survivable algorithms requires a solid foundation for executing them. While hardware techniques for fault-tolerant computing are relatively well understood, fault-tolerant operating systems, as well as fault-tolerant applications (survivable algorithms), are, by contrast, little understood, and much more work in this field is required. We outline some of our work that contributes to the foundation of ultrareliable operating systems and fault-tolerant algorithm design. We introduce our consensus-based framework for fault-tolerant system design. This is followed by a description of a hierarchical partitioning method for efficient consensus. A scheduler for redundancy management is introduced, and application-specific fault tolerance is described. We give an overview of our hybrid algorithm technique, which is an alternative to the formal approach given.

Effects of Strike-Slip Fault Segmentation on Earthquake Energy and Seismic Hazard

NASA Astrophysics Data System (ADS)

Madden, E. H.; Cooke, M. L.; Savage, H. M.; McBeck, J.

2014-12-01

Many major strike-slip faults are segmented along strike, including those along plate boundaries in California and Turkey. Failure of distinct fault segments at depth may be the source of multiple pulses of seismic radiation observed for single earthquakes. However, how and when segmentation affects fault behavior and energy release is the basis of many outstanding questions related to the physics of faulting and seismic hazard. These include the probability for a single earthquake to rupture multiple fault segments and the effects of segmentation on earthquake magnitude, radiated seismic energy, and ground motions. Using numerical models, we quantify components of the earthquake energy budget, including the tectonic work acting externally on the system, the energy of internal rock strain, the energy required to overcome fault strength and initiate slip, the energy required to overcome frictional resistance during slip, and the radiated seismic energy. We compare the energy budgets of systems of two en echelon fault segments with various spacing that include both releasing and restraining steps. First, we allow the fault segments to fail simultaneously and capture the effects of segmentation geometry on the earthquake energy budget and on the efficiency with which applied displacement is accommodated. Assuming that higher efficiency correlates with higher probability for a single, larger earthquake, this approach has utility for assessing the seismic hazard of segmented faults. Second, we nucleate slip along a weak portion of one fault segment and let the quasi-static rupture propagate across the system. Allowing fractures to form near faults in these models shows that damage develops within releasing steps and promotes slip along the second fault, while damage develops outside of restraining steps and can prohibit slip along the second fault. Work is consumed in both the propagation of and frictional slip along these new fractures, impacting the energy available for further slip and for subsequent earthquakes. This suite of models reveals that efficiency may be a useful tool for determining the relative seismic hazard of different segmented fault systems, while accounting for coseismic damage zone production is critical in assessing fault interactions and the associated energy budgets of specific systems.

Origin and tectonic implications of the Zhaxikang Pb-Zn-Sb-Ag deposit in northern Himalaya: evidence from structures, Re-Os-Pb-S isotopes, and fluid inclusions

NASA Astrophysics Data System (ADS)

Zhou, Qing; Li, Wenchang; Qing, Chengshi; Lai, Yang; Li, Yingxu; Liao, Zhenwen; Wu, Jianyang; Wang, Shengwei; Dong, Lei; Tian, Enyuan

2018-04-01

The Zhaxikang Pb-Zn-Sb-Ag-(Au) deposits, located in the eastern part of northern Himalaya, totally contain more than 1.146 million tonnes (Mt) of Pb, 1.407 Mt of Zn, 0.345 Mt of Sb, and 3 kilotonnes (kt) of Ag. Our field observations suggest that these deposits are controlled by N-S trending and west- and steep-dipping normal faults, suggesting a hydrothermal rather than a syngenetic sedimentary origin. The Pb-Zn-Sb-Ag-(Cu-Au) mineralization formed in the Eocene as indicated by a Re-Os isochron age of 43.1 ± 2.5 Ma. Sulfide minerals have varying initial Pb isotopic compositions, with (206Pb/204Pb)i of 19.04-19.68, (207Pb/204Pb)i of 15.75-15.88, and (208Pb/204Pb)i of 39.66-40.31. Sulfur isotopic values display a narrow δ34S interval of +7.8-+12.2‰. These Pb-S isotopic data suggest that the Zhaxikang sources of Pb and S should be mainly from the coeval felsic magmas and partly from the surrounding Mesozoic strata including metasedimentary rocks and layered felsic volcanic rocks. Fluid inclusion studies indicate that the hydrothermal fluids have medium temperatures (200-336 °C) but varying salinities (1.40-18.25 wt.% NaCl equiv.) with densities of 0.75-0.95 g/cm3, possibly suggesting an evolution mixing between a high salinity fluid, perhaps of magmatic origin, with meteoric water.

A Unified Nonlinear Adaptive Approach for Detection and Isolation of Engine Faults

NASA Technical Reports Server (NTRS)

Tang, Liang; DeCastro, Jonathan A.; Zhang, Xiaodong; Farfan-Ramos, Luis; Simon, Donald L.

2010-01-01

A challenging problem in aircraft engine health management (EHM) system development is to detect and isolate faults in system components (i.e., compressor, turbine), actuators, and sensors. Existing nonlinear EHM methods often deal with component faults, actuator faults, and sensor faults separately, which may potentially lead to incorrect diagnostic decisions and unnecessary maintenance. Therefore, it would be ideal to address sensor faults, actuator faults, and component faults under one unified framework. This paper presents a systematic and unified nonlinear adaptive framework for detecting and isolating sensor faults, actuator faults, and component faults for aircraft engines. The fault detection and isolation (FDI) architecture consists of a parallel bank of nonlinear adaptive estimators. Adaptive thresholds are appropriately designed such that, in the presence of a particular fault, all components of the residual generated by the adaptive estimator corresponding to the actual fault type remain below their thresholds. If the faults are sufficiently different, then at least one component of the residual generated by each remaining adaptive estimator should exceed its threshold. Therefore, based on the specific response of the residuals, sensor faults, actuator faults, and component faults can be isolated. The effectiveness of the approach was evaluated using the NASA C-MAPSS turbofan engine model, and simulation results are presented.

Bedrock morphology and structure, upper Santa Cruz Basin, south-central Arizona, with transient electromagnetic survey data

USGS Publications Warehouse

Bultman, Mark W.; Page, William R.

2016-10-31

The upper Santa Cruz Basin is an important groundwater basin containing the regional aquifer for the city of Nogales, Arizona. This report provides data and interpretations of data aimed at better understanding the bedrock morphology and structure of the upper Santa Cruz Basin study area which encompasses the Rio Rico and Nogales 1:24,000-scale U.S. Geological Survey quadrangles. Data used in this report include the Arizona Aeromagnetic and Gravity Maps and Data referred to here as the 1996 Patagonia Aeromagnetic survey, Bouguer gravity anomaly data, and conductivity-depth transforms (CDTs) from the 1998 Santa Cruz transient electromagnetic survey (whose data are included in appendixes 1 and 2 of this report).Analyses based on magnetic gradients worked well to identify the range-front faults along the Mt. Benedict horst block, the location of possibly fault-controlled canyons to the west of Mt. Benedict, the edges of buried lava flows, and numerous other concealed faults and contacts. Applying the 1996 Patagonia aeromagnetic survey data using the horizontal gradient method produced results that were most closely correlated with the observed geology.The 1996 Patagonia aeromagnetic survey was used to estimate depth to bedrock in the upper Santa Cruz Basin study area. Three different depth estimation methods were applied to the data: Euler deconvolution, horizontal gradient magnitude, and analytic signal. The final depth to bedrock map was produced by choosing the maximum depth from each of the three methods at a given location and combining all maximum depths. In locations of rocks with a known reversed natural remanent magnetic field, gravity based depth estimates from Gettings and Houser (1997) were used.The depth to bedrock map was supported by modeling aeromagnetic anomaly data along six profiles. These cross sectional models demonstrated that by using the depth to bedrock map generated in this study, known and concealed faults, measured and estimated magnetic susceptibilities of rocks found in the study area, and estimated natural remanent magnetic intensities and directions, reasonable geologic models can be built. This indicates that the depth to bedrock map is reason-able and geologically possible.Finally, CDTs derived from the 1998 Santa Cruz Basin transient electromagnetic survey were used to help identify basin structure and some physical properties of the basin fill in the study area. The CDTs also helped to confirm depth to bedrock estimates in the Santa Cruz Basin, in particular a region of elevated bedrock in the area of Potrero Canyon, and a deep basin in the location of the Arizona State Highway 82 microbasin. The CDTs identified many concealed faults in the study area and possibly indicate deep water-saturated clay-rich sediments in the west-central portion of the study area. These sediments grade to more sand-rich saturated sediments to the south with relatively thick, possibly unsaturated, sediments at the surface. Also, the CDTs may indicate deep saturated clay-rich sediments in the Highway 82 microbasin and in the Mount Benedict horst block from Proto Canyon south to the international border.

Structural control on fluid flow at the Dominga IOCG deposit in Northern Chile: insights from microtextural analysis

NASA Astrophysics Data System (ADS)

Heuser, G.; Arancibia, G.; Veloso, E. A.; Reich, M.; Morales, H.

2017-12-01

The Fe-Cu paragenetic assemblages at the Cretaceous Dominga IOCG deposit in northern Chile (2082 Mt at 23% Fe, 0.07% Cu) show a spatial and genetic affinity with major structural systems in the district: the Early Structural System (ESS), El Tofo Structural System (ETSS) and Intermediate Structural System (ISS), developed under different tectonic regimes, from transtension (ESS) to transpression (ETSS, ISS). The ESS is a NE-ENE-trending right-lateral strike slip duplex related to the formation of biotite-magnetite mineralization in Fe-rich bands parallel to bedding (stage I), and magnetite-apatite-actinolite-quartz hydrothermal breccia (stage II). The ETSS is a NNE left-lateral fault breccia related to K-feldspar veins and anhydrite-chalcopyrite hydrothermal breccia (stage III). The ISS is a NW-WNW left lateral strike slip duplex composed of calcite veins (stage IV). However, an understanding of fault-driven fluid flow mechanisms and their impact on the studied Fe-Cu deposit is still lacking. We analyzed representative textures from veins and hydrothermal breccias of stages II, III and IV. Microstructural analysis was made in thin/polished sections normal and parallel to the vein wall using optical and scanning electron microscopy techniques. Stage II shows euhedral magnetite with ilmenite lamellae exsolution textures and intergrowths between magnetite and anhedral mosaic quartz. Hydrothermal breccias contain euhedral quartz with double-terminated crystal shapes and concentric growth zoning surrounded by plumose quartz. Stage III exhibits zoned K-feldspar veins, banded plumose quartz veins, and mosaic subhedral anhydrite. Stage IV is characterized by banded veins of plumose and rhombic calcite, and dilational jogs with rhombic calcite. The observed microtextures suggest slow cooling of high temperature Fe-Cu-rich fluid, suspension in aqueous fluid during crystal growth, and boiling. Despite the different tectonic regimes, the paleo-fluids at the Dominga IOCG deposit were emplaced under similar conditions during the main activity of each structural system, i.e., 1) development of veins related to fluid overpressure and 2) episodic boiling triggered by abrupt pressure drop. Acknowledgements: CONICYT Ph.D. Scholarship, Millennium Nucleus for Metal Tracing Along Subduction NC 130065.

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.

Audio-frequency magnetotelluric imaging of the Hijima fault, Yamasaki fault system, southwest Japan

NASA Astrophysics Data System (ADS)

Yamaguchi, S.; Ogawa, Y.; Fuji-Ta, K.; Ujihara, N.; Inokuchi, H.; Oshiman, N.

2010-04-01

An audio-frequency magnetotelluric (AMT) survey was undertaken at ten sites along a transect across the Hijima fault, a major segment of the Yamasaki fault system, Japan. The data were subjected to dimensionality analysis, following which two-dimensional inversions for the TE and TM modes were carried out. This model is characterized by (1) a clear resistivity boundary that coincides with the downward projection of the surface trace of the Hijima fault, (2) a resistive zone (>500 Ω m) that corresponds to Mesozoic sediment, and (3) shallow and deep two highly conductive zones (30-40 Ω m) along the fault. The shallow conductive zone is a common feature of the Yamasaki fault system, whereas the deep conductor is a newly discovered feature at depths of 800-1,800 m to the southwest of the fault. The conductor is truncated by the Hijima fault to the northeast, and its upper boundary is the resistive zone. Both conductors are interpreted to represent a combination of clay minerals and a fluid network within a fault-related fracture zone. In terms of the development of the fluid networks, the fault core of the Hijima fault and the highly resistive zone may play important roles as barriers to fluid flow on the northeast and upper sides of the conductive zones, respectively.

Along-strike variations of the partitioning of convergence across the Haiyuan fault system detected by InSAR

NASA Astrophysics Data System (ADS)

Daout, S.; Jolivet, R.; Lasserre, C.; Doin, M.-P.; Barbot, S.; Tapponnier, P.; Peltzer, G.; Socquet, A.; Sun, J.

2016-04-01

Oblique convergence across Tibet leads to slip partitioning with the coexistence of strike-slip, normal and thrust motion on major fault systems. A key point is to understand and model how faults interact and accumulate strain at depth. Here, we extract ground deformation across the Haiyuan Fault restraining bend, at the northeastern boundary of the Tibetan plateau, from Envisat radar data spanning the 2001-2011 period. We show that the complexity of the surface displacement field can be explained by the partitioning of a uniform deep-seated convergence. Mountains and sand dunes in the study area make the radar data processing challenging and require the latest developments in processing procedures for Synthetic Aperture Radar interferometry. The processing strategy is based on a small baseline approach. Before unwrapping, we correct for atmospheric phase delays from global atmospheric models and digital elevation model errors. A series of filtering steps is applied to improve the signal-to-noise ratio across high ranges of the Tibetan plateau and the phase unwrapping capability across the fault, required for reliable estimate of fault movement. We then jointly invert our InSAR time-series together with published GPS displacements to test a proposed long-term slip-partitioning model between the Haiyuan and Gulang left-lateral Faults and the Qilian Shan thrusts. We explore the geometry of the fault system at depth and associated slip rates using a Bayesian approach and test the consistency of present-day geodetic surface displacements with a long-term tectonic model. We determine a uniform convergence rate of 10 [8.6-11.5] mm yr-1 with an N89 [81-97]°E across the whole fault system, with a variable partitioning west and east of a major extensional fault-jog (the Tianzhu pull-apart basin). Our 2-D model of two profiles perpendicular to the fault system gives a quantitative understanding of how crustal deformation is accommodated by the various branches of this thrust/strike-slip fault system and demonstrates how the geometry of the Haiyuan fault system controls the partitioning of the deep secular motion.

Implementation of an experimental fault-tolerant memory system

NASA Technical Reports Server (NTRS)

Carter, W. C.; Mccarthy, C. E.

1976-01-01

The experimental fault-tolerant memory system described in this paper has been designed to enable the modular addition of spares, to validate the theoretical fault-secure and self-testing properties of the translator/corrector, to provide a basis for experiments using the new testing and correction processes for recovery, and to determine the practicality of such systems. The hardware design and implementation are described, together with methods of fault insertion. The hardware/software interface, including a restricted single error correction/double error detection (SEC/DED) code, is specified. Procedures are carefully described which, (1) test for specified physical faults, (2) ensure that single error corrections are not miscorrections due to triple faults, and (3) enable recovery from double errors.

Measurement and analysis of workload effects on fault latency in real-time systems

NASA Technical Reports Server (NTRS)

Woodbury, Michael H.; Shin, Kang G.

1990-01-01

The authors demonstrate the need to address fault latency in highly reliable real-time control computer systems. It is noted that the effectiveness of all known recovery mechanisms is greatly reduced in the presence of multiple latent faults. The presence of multiple latent faults increases the possibility of multiple errors, which could result in coverage failure. The authors present experimental evidence indicating that the duration of fault latency is dependent on workload. A synthetic workload generator is used to vary the workload, and a hardware fault injector is applied to inject transient faults of varying durations. This method makes it possible to derive the distribution of fault latency duration. Experimental results obtained from the fault-tolerant multiprocessor at the NASA Airlab are presented and discussed.

Structural Data for the Columbus Salt Marsh Geothermal Area - GIS Data

DOE Data Explorer

Faulds, James E.

2011-12-31

Shapefiles and spreadsheets of structural data, including attitudes of faults and strata and slip orientations of faults. - Detailed geologic mapping of ~30 km2 was completed in the vicinity of the Columbus Marsh geothermal field to obtain critical structural data that would elucidate the structural controls of this field. - Documenting E‐ to ENE‐striking left lateral faults and N‐ to NNE‐striking normal faults. - Some faults cut Quaternary basalts. - This field appears to occupy a displacement transfer zone near the eastern end of a system of left‐lateral faults. ENE‐striking sinistral faults diffuse into a system of N‐ to NNE‐striking normal faults within the displacement transfer zone. - Columbus Marsh therefore corresponds to an area of enhanced extension and contains a nexus of fault intersections, both conducive for geothermal activity.

PSR J2032+4127/MT91 213 on approach to periastron: X-ray & optical monitoring

NASA Astrophysics Data System (ADS)

Coe, M. J.; Steele, I. A.; Ho, W. C. G.; Stappers, B.; Lyne, A. G.; Halpern, J. P.; Ray, P. S.; Johnson, T. L.; Ng, C.-Y.; Kerr, M.

2017-11-01

Swift XRT monitoring of the 50 year binary system PSR J2032+4127/MT91 213 shows a dramatic decrease in the X-ray flux as the system is in the final stages of approach to periastron (13 November 2017).

An autonomous fault detection, isolation, and recovery system for a 20-kHz electric power distribution test bed

NASA Technical Reports Server (NTRS)

Quinn, Todd M.; Walters, Jerry L.

1991-01-01

Future space explorations will require long term human presence in space. Space environments that provide working and living quarters for manned missions are becoming increasingly larger and more sophisticated. Monitor and control of the space environment subsystems by expert system software, which emulate human reasoning processes, could maintain the health of the subsystems and help reduce the human workload. The autonomous power expert (APEX) system was developed to emulate a human expert's reasoning processes used to diagnose fault conditions in the domain of space power distribution. APEX is a fault detection, isolation, and recovery (FDIR) system, capable of autonomous monitoring and control of the power distribution system. APEX consists of a knowledge base, a data base, an inference engine, and various support and interface software. APEX provides the user with an easy-to-use interactive interface. When a fault is detected, APEX will inform the user of the detection. The user can direct APEX to isolate the probable cause of the fault. Once a fault has been isolated, the user can ask APEX to justify its fault isolation and to recommend actions to correct the fault. APEX implementation and capabilities are discussed.

Launch vehicle tracking enhancement through Global Positioning System Metric Tracking

NASA Astrophysics Data System (ADS)

Moore, T. C.; Li, Hanchu; Gray, T.; Doran, A.

United Launch Alliance (ULA) initiated operational flights of both the Atlas V and Delta IV launch vehicle families in 2002. The Atlas V and Delta IV launch vehicles were developed jointly with the US Air Force (USAF) as part of the Evolved Expendable Launch Vehicle (EELV) program. Both Launch Vehicle (LV) families have provided 100% mission success since their respective inaugural launches and demonstrated launch capability from both Vandenberg Air Force Base (VAFB) on the Western Test Range and Cape Canaveral Air Force Station (CCAFS) on the Eastern Test Range. However, the current EELV fleet communications, tracking, & control architecture & technology, which date back to the origins of the space launch business, require support by a large and high cost ground footprint. The USAF has embarked on an initiative known as Future Flight Safety System (FFSS) that will significantly reduce Test Range Operations and Maintenance (O& M) cost by closing facilities and decommissioning ground assets. In support of the FFSS, a Global Positioning System Metric Tracking (GPS MT) System based on the Global Positioning System (GPS) satellite constellation has been developed for EELV which will allow both Ranges to divest some of their radar assets. The Air Force, ULA and Space Vector have flown the first 2 Atlas Certification vehicles demonstrating the successful operation of the GPS MT System. The first Atlas V certification flight was completed in February 2012 from CCAFS, the second Atlas V certification flight from VAFB was completed in September 2012 and the third certification flight on a Delta IV was completed October 2012 from CCAFS. The GPS MT System will provide precise LV position, velocity and timing information that can replace ground radar tracking resource functionality. The GPS MT system will provide an independent position/velocity S-Band telemetry downlink to support the current man-in-the-loop ground-based commanded destruct of an anomalous flight- The system utilizes a 50 channel digital receiver capable of navigating in high dynamic environments and high altitudes fed by antennas mounted diametrically opposed on the second stage airframe skin. To enhance cost effectiveness, the GPS MT System design implemented existing commercial parts and common environmental and interface requirements for both EELVs. The EELV GPS MT System design is complete, successfully qualified and has demonstrated that the system performs as simulated. This paper summarizes the current development status, system cost comparison, and performance capabilities of the EELV GPS MT System.

Shortening accommodated by extension-parallel folding of detachment faults during oblique rifting in the Gulf of California

NASA Astrophysics Data System (ADS)

Seiler, Christian; Fletcher, John

2013-04-01

Large-scale fault corrugations or megamullions are a common feature of detachment faults and form either as original fault grooves, displacement-gradient folds or constrictional folds parallel to the extension direction. In highly oblique extensional settings such as the Gulf of California, horizontal shortening perpendicular to the extension direction is an inherent part of the regional stress field and likely forms a key factor during the development of extension-parallel fault corrugations. However, the amount of horizontal shortening absorbed by megamullions is difficult to quantify, and constrictional folding is not normally thought to accommodate significant strike-slip deformation. The Las Cuevitas and Santa Rosa detachments are two low-angle normal fault systems exposed on the Gulf of California rifted margin in northeastern Baja California, Mexico. The two detachments accommodate between ~7-9km of SE-directed extension and represent the next significant set of faults in direction of transport from the rift breakaway fault. Fault kinematics are highly complex, but suggest integrated normal, oblique- and strike-slip faulting, with kinematics controlled by the orientation of faults with respect to the regional transtensional stress field. Both fault systems are strongly corrugated, with megamullion amplitudes of ~4-7km and half wavelenghts of between ~15 to 20km. Differential folding of the syntectonic basin-fill of the supradetachment basins strongly suggest that the observed megamullions formed largely, though not exclusively, due to constrictional folding associated with the transtensional stress regime of the plate boundary. This is consistent with basin-scale facies variations that record differential uplift and subsidence in antiformal and synformal megamullion domains, respectively. Compared to the two detachments, the San Pedro Martir fault - the master fault of the rift system at this latitude - shows more subtle fault corrugations with amplitudes of <3km. Unlike the Las Cuevitas and Santa Rosa detachments, though, there is no evidence for constrictional folding on the San Pedro Martir fault. Instead, the observed corrugations likely represent original grooves of the fault plane, formed as adjacent fault nuclei joined along-strike during fault growth. Comparison between the sinuosity of the San Pedro Martir fault (1.08), attributed entirely to original fault asperities, with the sinuosity of the two detachment systems (Las Cuevitas detachment: 1.17, Santa Rosa detachment: 1.22), suggests that about 10% of shortening occurred on each of the two detachments due to synextensional constrictional folding. This corresponds to a combined total of ~8km of N-S shortening, or ~10km of dextral shear resolved in direction of the relative plate motion, and occurs in addition to ~21km of right-lateral strain accommodated by clockwise vertical-axis block rotations. Thus, strain in this part of the rift system was partitioned between discrete extensional faulting on the two detachment systems, and significant right-lateral shear accommodated by distributed volume deformation.

Precisely determined the surface displacement by the ionospheric mitigation using the L-band SAR Interferometry over Mt.Baekdu

NASA Astrophysics Data System (ADS)

Lee, Won-Jin; Jung, Hyung-Sup; Park, Sun-Cheon; Lee, Duk Kee

2016-04-01

Mt. Baekdu (Changbaishan in Chinese) is located on the border between China and North Korea. It has recently attracted the attention of volcanic unrest during 2002-2005. Many researchers have applied geophysical approaches to detect magma system of beneath Mt.Baekdu such as leveling, Global Positioning System (GPS), gases analysis, seismic analysis, etc. Among them, deformation measuring instruments are important tool to evaluate for volcanism. In contrast to GPS or other deformation measuring instruments, Synthetic Aperture Radar Interferometry (InSAR) has provided high resolution of 2-D surface displacement from remote sensed data. However, Mt. Baekdu area has disturbed by decorrelation on interferogram because of wide vegetation coverage. To overcome this limitation, L-band system of long wavelength is more effective to detect surface deformation. In spite of this advantage, L-band can surfer from more severe ionospheric phase distortions than X- or C- band system because ionospheric phase distortions are inverse proportion to the radar frequency. Recently, Multiple Aperture Interferometry (MAI) based ionospheric phase distortions mitigation method have proposed and investigated. We have applied this technique to the Mt.Baekdu area to measure surface deformation precisely using L-band Advanced Land Observing Satellite-1(ALOS-1) Phased Array type L-band Synthetic Aperture Radar(PALSAR) data acquiring from 2006 to 2011.

3D Constraints On Fault Architecture and Strain Distribution of the Newport-Inglewood Rose Canyon and San Onofre Trend Fault Systems

NASA Astrophysics Data System (ADS)

Holmes, J. J.; Driscoll, N. W.; Kent, G. M.

2017-12-01

The Inner California Borderlands (ICB) is situated off the coast of southern California and northern Baja. The structural and geomorphic characteristics of the area record a middle Oligocene transition from subduction to microplate capture along the California coast. Marine stratigraphic evidence shows large-scale extension and rotation overprinted by modern strike-slip deformation. Geodetic and geologic observations indicate that approximately 6-8 mm/yr of Pacific-North American relative plate motion is accommodated by offshore strike-slip faulting in the ICB. The farthest inshore fault system, the Newport-Inglewood Rose Canyon (NIRC) Fault is a dextral strike-slip system that is primarily offshore for approximately 120 km from San Diego to the San Joaquin Hills near Newport Beach, California. Based on trenching and well data, the NIRC Fault Holocene slip rate is 1.5-2.0 mm/yr to the south and 0.5-1.0 mm/yr along its northern extent. An earthquake rupturing the entire length of the system could produce an Mw 7.0 earthquake or larger. West of the main segments of the NIRC Fault is the San Onofre Trend (SOT) along the continental slope. Previous work concluded that this is part of a strike-slip system that eventually merges with the NIRC Fault. Others have interpreted this system as deformation associated with the Oceanside Blind Thrust Fault purported to underlie most of the region. In late 2013, we acquired the first high-resolution 3D Parallel Cable (P-Cable) seismic surveys of the NIRC and SOT faults as part of the Southern California Regional Fault Mapping project. Analysis of stratigraphy and 3D mapping of this new data has yielded a new kinematic fault model of the area that provides new insight on deformation caused by interactions in both compressional and extensional regimes. For the first time, we can reconstruct fault interaction and investigate how strain is distributed through time along a typical strike-slip margin using 3D constraints on fault architecture.

A fault-tolerant intelligent robotic control system

NASA Technical Reports Server (NTRS)

Marzwell, Neville I.; Tso, Kam Sing

1993-01-01

This paper describes the concept, design, and features of a fault-tolerant intelligent robotic control system being developed for space and commercial applications that require high dependability. The comprehensive strategy integrates system level hardware/software fault tolerance with task level handling of uncertainties and unexpected events for robotic control. The underlying architecture for system level fault tolerance is the distributed recovery block which protects against application software, system software, hardware, and network failures. Task level fault tolerance provisions are implemented in a knowledge-based system which utilizes advanced automation techniques such as rule-based and model-based reasoning to monitor, diagnose, and recover from unexpected events. The two level design provides tolerance of two or more faults occurring serially at any level of command, control, sensing, or actuation. The potential benefits of such a fault tolerant robotic control system include: (1) a minimized potential for damage to humans, the work site, and the robot itself; (2) continuous operation with a minimum of uncommanded motion in the presence of failures; and (3) more reliable autonomous operation providing increased efficiency in the execution of robotic tasks and decreased demand on human operators for controlling and monitoring the robotic servicing routines.

Fault-tolerant Control of a Cyber-physical System

NASA Astrophysics Data System (ADS)

Roxana, Rusu-Both; Eva-Henrietta, Dulf

2017-10-01

Cyber-physical systems represent a new emerging field in automatic control. The fault system is a key component, because modern, large scale processes must meet high standards of performance, reliability and safety. Fault propagation in large scale chemical processes can lead to loss of production, energy, raw materials and even environmental hazard. The present paper develops a multi-agent fault-tolerant control architecture using robust fractional order controllers for a (13C) cryogenic separation column cascade. The JADE (Java Agent DEvelopment Framework) platform was used to implement the multi-agent fault tolerant control system while the operational model of the process was implemented in Matlab/SIMULINK environment. MACSimJX (Multiagent Control Using Simulink with Jade Extension) toolbox was used to link the control system and the process model. In order to verify the performance and to prove the feasibility of the proposed control architecture several fault simulation scenarios were performed.

The Nitrate Transporter MtNPF6.8 (MtNRT1.3) Transports Abscisic Acid and Mediates Nitrate Regulation of Primary Root Growth in Medicago truncatula1[W

PubMed Central

Pellizzaro, Anthoni; Clochard, Thibault; Cukier, Caroline; Bourdin, Céline; Juchaux, Marjorie; Montrichard, Françoise; Thany, Steeve; Raymond, Valérie; Planchet, Elisabeth; Morère-Le Paven, Marie-Christine

2014-01-01

Elongation of the primary root during postgermination of Medicago truncatula seedlings is a multigenic trait that is responsive to exogenous nitrate. A quantitative genetic approach suggested the involvement of the nitrate transporter MtNPF6.8 (for Medicago truncatula NITRATE TRANSPORTER1/PEPTIDE TRANSPORTER Family6.8) in the inhibition of primary root elongation by high exogenous nitrate. In this study, the inhibitory effect of nitrate on primary root elongation, via inhibition of elongation of root cortical cells, was abolished in npf6.8 knockdown lines. Accordingly, we propose that MtNPF6.8 mediates nitrate inhibitory effects on primary root growth in M. truncatula. pMtNPF6.8:GUS promoter-reporter gene fusion in Agrobacterium rhizogenes-generated transgenic roots showed the expression of MtNPF6.8 in the pericycle region of primary roots and lateral roots, and in lateral root primordia and tips. MtNPF6.8 expression was insensitive to auxin and was stimulated by abscisic acid (ABA), which restored the inhibitory effect of nitrate in npf6.8 knockdown lines. It is then proposed that ABA acts downstream of MtNPF6.8 in this nitrate signaling pathway. Furthermore, MtNPF6.8 was shown to transport ABA in Xenopus spp. oocytes, suggesting an additional role of MtNPF6.8 in ABA root-to-shoot translocation. 15NO3−-influx experiments showed that only the inducible component of the low-affinity transport system was affected in npf6.8 knockdown lines. This indicates that MtNPF6.8 is a major contributor to the inducible component of the low-affinity transport system. The short-term induction by nitrate of the expression of Nitrate Reductase1 (NR1) and NR2 (genes that encode two nitrate reductase isoforms) was greatly reduced in the npf6.8 knockdown lines, supporting a role of MtNPF6.8 in the primary nitrate response in M. truncatula. PMID:25367858

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.

Detection of faults and software reliability analysis

NASA Technical Reports Server (NTRS)

Knight, J. C.

1986-01-01

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

Publications - PIR 2014-5 | Alaska Division of Geological & Geophysical

Science.gov Websites

the Iniskin Peninsula: Implications for the kinematic history of the Bruin Bay fault system, lower Iniskin Peninsula: Implications for the kinematic history of the Bruin Bay fault system, lower Cook Inlet (3.0 M) Keywords Bruin Bay Fault; Chinitna Bay; Faults; Folds; Forearc Basin; Geologic Map; Iniskin Bay