Short Fault Research Articles

Step-Over and Bend Structures along the 1999 Duzce Earthquake Surface Rupture, North Anatolian Fault, Turkey

The 12 November 1999 Duzce earthquake (M w 7.1), which occurred on the Duzce fault of the North Anatolian Fault Zone, formed a 40-km-long surface rupture, which extended between Golyaka in the west and Kaynasli in the east. The earthquake nucleated close to the Beykoy step-over, a 0.8-km-wide and 1.8-km-long pressure ridge, with bilateral rupture propagation both to the west and the east. The Beykoy, Kaynasli, and Cevizlik step-overs, through which the 1999 Duzce rupture propagated, are less than 2.5 km wide. The Eften and Bakacak step-overs, where the rupture was arrested, are more than 4 km wide. These exceptional dimensions of step-overs associated with the 1999 Duzce rupture were investigated for their influ- ence on rupture propagation. The earthquake broke three distinct geometric segments, from west to east, the Eften, Dagdibi, and Kaynasli fault segments, separated by left-restraining step-overs at Beykoy and Kaynasli. To the west of the main shock, 3.5 m of average slip on the Eften fault segment propagated into the 2-km-wide Cevizlik releasing double bend, where it was largely arrested, with smaller (0.5 m) slip continuing westward on the Golyaka intervening segment, west of Lake Eften. This is similar to the ter- mination of slip observed on the Karadere fault segment in the 1999 Izmit earthquake, where 1.5 m of slip was largely terminated by a releasing double bend at the Golyaka intervening segment, with minor slip continuing eastward near Lake Eften. To the east of the main shock, 5 m of slip decreased along the Dagdibi fault segment to about 3.5 m at the 1-km-wide Kaynasli step-over. From here to the east, the 2.5 m of average slip on the Kaynasli fault segment continued to decrease, reaching zero at the releasing step-overs to the Elmalik fault. The terminations of the 1999 Duzce surface rupture are defined by distinct struc- tural complexities. The rupture was arrested in the west at the 4-km-wide Eften releasing double bend, where the eastern termination of the 1999 Izmit rupture also occurred. To the east, the rupture terminated at the 4- to 5-km-wide Bakacak releasing double step-overs. Both eastern and western ends of the Duzce rupture have short fault segments that experienced minor rupture during the 1999 Duzce earthquake. The Golyaka intervening segment experienced minor rupture, during both the 1999 Izmit and Duzce earthquakes. The Duzce rupture propagated across 0.8- to 2-km- wide step-overs, but it was arrested at step-overs 4 km wide or wider. These results agree with the observations on ratios between step-over width (in kilometers) and strike-slip displacement (in meters) collected along strike-slip faults worldwide (Let- tis et al., 2002).

Delay Testing Viability of Gate Oxide Short Defects

Gate Oxide Short (GOS) defects are becoming predominant as technology is scaling down. Boolean and IDDQ testing of this defect has been widely studied but there is no paper dedicated to delay testing of this defect. So, this paper studies the delay behavior of Gate Oxide Short faults due to pinhole in the gate oxide. The objective of this paper is to give a detailed analysis of the behavior of the GOS defect taking into account the random parameter of the defect such as the GOS resistance and the GOS location. Because an accurate analysis is desired, the bi-dimensional array will be used. Because a complete analysis is desired, we derive the dynamic characteristic of the GOS as a function of the GOS resistance and location. It is demonstrated that i) GOS has a significant impact on gate delay, ii) GOS located close to the source of the transistor and with small resistance has very high impact.

Fault characterization by seismic attributes and geomechanics in a Thamama oil field, United Arab Emirates

ABSTRACT Faults and fractures were interpreted using attributes that were extracted from a 3-D seismic data set recorded over a Lower Cretaceous Thamama oil field in offshore Abu Dhabi, United Arab Emirates. The Thamama reservoir has good matrix porosity (frequently exceeding 20%), but poor permeability (averaging 15 mD). Because of the low permeability, faults and fractures play an important role in fluid movement in the reservoir. The combination of the similarity and dip attributes gave clear images of small-displacement fault geometry, and the orientation of subseismic faults and fractures. The study better defined faults and fractures and improved geomechanical interpretations, thus reducing the uncertainty in the preferred fluid-flow direction. Two fault systems were recognized: (1) the main NW-trending fault system with mapped fault-length often exceeding 5 km; and (2) a secondary NNE-trending system with shorter faults. The secondary system is parallel to the long axis of the elliptical domal structure of the field. Some of the main faults appear to be composed of en-echelon segments with displacement transfer between the overlapping normal faults (relay faults with relay ramps). The fault systems recognized from the seismic attributes were correlated with well data and core observations. About 13 percent of the fractures seen in cores are non-mineralized. The development of the fault systems was studied by means of clay modeling, computer simulation, and a regional tectonics review. The existing fluid-flow characteristics of individual faults and fractures in the field can be modeled using the present-day stress regime, with the maximum horizontal stress oriented north-northeast. Slip-tendency and dilation-tendency analyses simulating present-day regional stress conditions are indicators of fault and fracture transmissibility. The NNE-striking secondary fault system is parallel to the present-day maximum horizontal stress and could act as a flow conduit in the reservoir.

Active faulting and seismicity of the Dasht-e-Bayaz region, eastern Iran

The Dasht-e-Bayaz left-lateral strike-slip fault system in NE Iran ruptured over a length of ca 120 km during two earthquakes in 1968 and 1979. We constrain source parameters of the 1968 August 31 (Dasht-e-Bayaz) and 1979 November 27 (Khuli-Buniabad) earthquakes by analysing long-period body wave seismograms. Both earthquakes involved complex rupture processes, with at least two subevents in each case. Coseismic surface ruptures and cumulative scarps in alluvium indicate fault segmentation on numerous short (ca 20 km long) strands with small pull-aparts between them. The earthquake subevents seen in the seismograms probably relate to this segmentation. The total, cumulative, offset on the fault system is estimated at ca 4–5 km. This is small compared to the total amount of Late Tertiary deformation expected in this part of Iran, and indicates that the Dasht-e-Bayaz fault may be relatively young. Distributed strike-slip faulting is widespread in the region and there are indications that the Dasht-e-Bayaz fault is evolving from several short faults that are coalescing. These results are important not only for understanding of the regional tectonics but for the development and evolution of strike-slip faults in general.

Thermal instability and current–voltage scaling in superconducting fault currentlimiters

We have developed a computer model for the simulation of resistive superconducting faultcurrent limiters in three dimensions. The program calculates the electromagnetic andthermal response of a superconductor to a time-dependent overload voltage, with differentpossible cooling conditions for the surfaces, and locally variable superconducting andthermal properties. We find that the cryogen boil-off parameters critically influence thestability of a limiter. The recovery time after a fault increases strongly with thickness.Above a critical thickness, the temperature is unstable even for a small applied AC voltage.The maximum voltage and maximum current during a short fault are correlated by asimple exponential law.

Nontree Routing for Reliability and Yield Improvement

We propose to introduce redundant interconnects for manufacturing yield and reliability improvement. By introducing redundant interconnects, the potential for open faults is reduced, at the cost of increased potential for short faults. Overall, manufacturing yield and fault tolerance can be improved. We focus on a postprocessing, tree-augmentation approach, which can be easily integrated in current physical design flows. Our contributions are as follows. 1) We formulate the problem as a variant of the classical two-edge-connectivity augmentation problem in which we take into account such practical issues as wirelength increase budget, routing obstacles, and the use of Steiner points. 2) We show that an optimum solution can always be found on the Hanan grid defined by the terminals and the corners of the feasible routing region. 3) We give a compact integer program formulation which is solved in practical runtime by the commercial optimization package CPLEX for nets with up to 100 terminals. 4) We give a well-scaling greedy algorithm which has a practical runtime up to 1000 terminals, and comes on the average within 1%-2% of the optimum computed by CPLEX. 5). We give a comprehensive experimental study comparing the solution quality and runtime of our methods with the best methods reported in the literature.

Adaptive algorithms for maximal diagnosis of wiring interconnects

We give two algorithms for maximal diagnosis of wiring networks without repair under a general fault model. Maximal diagnosis consists of identifying all diagnosable faults under the assumptions that each net can have multiple drivers and receivers and can be affected by any number of short and open faults. This process is equivalent to verifying all connections between inputs and outputs. Matrices represent the connections in fault-free and faulty networks. We present two new algorithms and discuss prior algorithms. All algorithms discussed are adaptive and have their tests divided into two phases. Our first new algorithm exploits a unique condition for verifying the connections; our second new algorithm maps the connection verification problem to a bipartite graph. All algorithms discussed use an independent test set for the first test phase. Simulation results show that the proposed algorithms outperform previous algorithms for maximal diagnosis in terms of the number of tests. The total time complexity for computing the test sequences and analyzing the output response is polynomial.

Characterization of coil faults in an axial flux variable reluctance PM motor

In recent years, variable reluctance (VR) and switch reluctance (SR) motors have been proposed for use in applications requiring a degree of fault tolerance. A range of topologies of brushless SR and VR permanent magnet (PM) motors are not susceptible to some types of faults, such as phase-to-phase shorts, and can often continue to function in the presence of other faults. In particular, coil winding faults in a single stator coil may have relatively little effect on motor performance, but may affect overall motor reliability, availability, and longevity. It is important to distinguish between, and characterize, various winding faults for maintenance and diagnostic purposes. These fault characterization and analysis results are a necessary first step in the process of motor fault detection and diagnosis for this motor topology. This paper examines rotor velocity damping due to stator winding turn-to-turn short faults in a fault-tolerant axial flux variable reluctance PM motor. In this type of motor, turn-to-turn shorts due to insulation failures have similar I-V characteristics to coil faults resulting from other problems, such as faulty maintenance or damage due to impact. In order to investigate the effects of such coil faults, a prototype axial flux variable reluctance PM motor was constructed. The motor was equipped with experimental fault simulation stator windings capable of simulating these and other types of stator winding faults. This paper will focus on two common types of winding faults and their effects on rotor velocity in this type of motor.

Seismic-reflection profiles of the central part of the Clarendon–Linden fault system of western New York in relation to regional seismicity

Geological and geophysical research in upstate New York, with few exceptions, has not definitively associated seismicity with specific Proterozoic basement or Paleozoic bedrock structures. The central part of the Clarendon–Linden fault system (CLFS) between Batavia and Dale, NY is one of those exceptions where seismicity has been studied and has been spatially associated with structure. The CLFS is either a complex system of long faults with associated shorter branches and parallel segments, or a region of many short faults aligned north–south from the Lake Ontario shore southward to Allegany County, NY. Interpretation of 38 km of Vibroseis and approximately 56 km of conventional seismic-reflection data along 13 lines suggests that the CLFS is a broad zone of small faults with small displacements in the lower Paleozoic bedrock section that is at least 77 km long and 7–17 km wide and spatially coincident with a north-trending geophysical (combined aeromagnetic and gravity) lineament within the basement. The relative offset across the faults of the system is more than 91 m near Attica, NY. The CLFS is the expression of tectonic crustal adjustments within the Paleozoic rock above the boundary of two basement megablocks of differing petrologic provinces and differing earthquake characteristics that forms the eastern side of the Elzevir–Frontenac boundary zone. Deep seismic-reflection profiles display concave-eastward listric faults that probably merge at depth near the mid-crustal boundary layer. An interpretive vertical section provides the setting for refined definitions of the CLFS, its extensions at depth and its relation to seismicity. Most modern seismicity in western New York and the Niagara Peninsula of Ontario occurs in apparent patterns of randomly dispersed activity. The sole exception is a line of seven epicenters of small earthquakes that trend east from Attica, NY into the Rochester basement megablock. Earthquakes may be triggered at the intersections of north- and east-trending brittle faults within the Niagara basement megablock. Current interpretations of the mechanisms for earthquake generation in western New York and the Niagara Peninsula of Ontario require conservative estimates of seismic hazards that assume that an earthquake the size of the 1929 Attica, NY, event ( M b=5.2) or larger could occur anywhere in the Eastern Great Lakes Basin (EGLB). The broad zone of small-displacement faults that marks the CLFS in the lower Paleozoic sedimentary section and the uppermost basement may not provide the structural environment for generation of earthquakes in western New York. If this interpretation is correct, most seismicity is generated within the Niagara basement megablock beneath or west of the CLFS. Consequently, we may have to look to the deeper tectonic regime of basement megablocks to understand the distribution of modern seismicity in the EGLB.

Characterization of Coil Faults in an Axial Flux Variable Reluctance PM Motor

In recent years, variable reluctance (VR) and switch reluctance (SR) motors have been proposed for use in applications requiring a degree of fault tolerance. A range of topologies of brushless SR and VR permanent magnet (PM) motors are not susceptible to some types of faults, such as phase-to-phase shorts, and can often continue to function in the presence of other faults. In particular, coil winding faults in a single stator coil may have relatively little effect on motor performance, but may affect overall motor reliability, availability, and longevity. It is important to distinguish between, and characterize, various winding faults for maintenance and diagnostic purposes. These fault characterization and analysis results are a necessary first step in the process of motor fault detection and diagnosis for this motor topology. This paper examines rotor velocity damping due to stator winding turn-to-turn short faults in a fault-tolerant axial flux variable reluctance PM motor. In this type of motor, turn-to-turn shorts due to insulation failures have similar I-V characteristics to coil faults resulting from other problems, such as faulty maintenance or damage due to impact. In order to investigate the effects of such coil faults, a prototype axial flux variable reluctance PM motor was constructed. The motor was equipped with experimental fault simulation stator windings capable of simulating these and other types of stator winding faults. This paper will focus on two common types of winding faults and their effects on rotor velocity in this type of motor.

The Earthquake of 1509 in the Sea of Marmara, Turkey, Revisited

This article is interdisciplinary in nature, relevant to the fields of both earth sciences and historiography, which come together in the investigation of long-term earthquake hazard. Taking here as an example the earthquake of 10 September 1509, which was associated with an inferred 70- ± 30-km-long offshore fault break in the Sea of Marmara ( M W 7.2 ± 0.3) and with widespread damage in Istanbul and the adjacent region, this article emphasizes the need for systematic and consistent analysis of historical earthquake data and sets an example for such a task. The re-examination of this earthquake, in the context of the long-term seismicity of the region over the last 2000 yr and in comparison with larger historic and modern events in the region, shows no macroseismic, and to some extent, no tectonic evidence that the 1509 earthquake was a catastrophic event. It is one of the damaging shocks in the 17-century-long history of Istanbul, of a magnitude that was smaller than the large events that can occur further east in the Anatolian Fault Zone. This is consistent with the evidence from seismic reflection surveys in the Sea of Marmara, which shows that faults are generally less continuous offshore than onshore, as well as from the long-term seismicity of the region, which is an implication of the opening up of the Sea of Marmara earthquakes and its association with relatively short faults compared with ruptures of great lengths in the Anatolian Fault Zone further east, which is dominated by strike slip.

Low-voltage, low-power current monitor for deep-submicron testing

An on-chip low-power circuit for both quiescent current I ddq and transient current I ddt monitoring is presented. The current monitor performs faster and is significantly smaller than those reported previously. The monitor is designed for low-voltage digital CMOS circuits (1.5V). The same design can be used in the testing of analogue and mixed signal circuits. The effect on the circuit under test performance is negligible. Testing speeds of up to 25MHz can be achieved (including the 4-bit A/D converter, 100MHz without the converter). The monitor has been implemented in 0.5μm and 0.35μm CMOS technology and tested successfully on parallel chains of inverters as circuit under test. Two types of fault (an open fault and a short fault) have been observed. Simulation and experimental results are included and analysed.

Neural Network–Based Fault Direction Discrimination for High-Speed Transmission Line Protection

Detection of the direction of a fault on a transmission line is essential to the proper performance of a power system. W ith the advent of large generating stations and highly interconnected power systems, shorter fault clearing times are becoming necessary. To classify forward and backward faults on a given line rapidly, a neural network's abilities in pattern recognition and classification could be considered as a solution. To demonstrate the applicability of this solution, neural network technique is employed to design two different fault direction discrimination modules. Results of performance studies with the proposed networks are presented in this paper. Results obtained indicate that the direction of fault on a transmission line can be identified rapidly and correctly by the proposed approaches.

Quaternary intra-arc extension in the central Trans-Mexican volcanic belt

The Trans-Mexican volcanic belt is an active volcanic arc related to subduction along the Middle America trench and characterized by shallow seismicity and synvolcanic to postvolcanic extensional arc-parallel faulting. Major intra-arc basins within the central part of the belt (between long 998W and 1028W) are (from west to east) the Cuitzeo and Acambay grabens, the Aljibes half-graben, and the Mezquital graben. In this region, ;100 eastwest2striking, .2 km long, steeply dipping normal faults, expressed by pronounced multi-event fault scarps, have been mapped. Of the 100 faults, ;65 displace rocks of known Quaternary age (younger than 1.6 Ma), and 22 cut rocks with a documented age younger than 750 ka. Known historical surface ruptures are limited to faults of the Acambay graben. Overall, the faults cause north-south to north-northwest2south-southeast2oriented extension of ,1 km, which is distributed over a 30250-km-wide zone that has 5210 faults in cross section and a relative extension of ,3%. Quaternary vertical slip rates, estimated for 13 of the faults, have a mean of 0.07 mm/yr. They are highest at the southern margin of the Cuitzeo graben, the northern margin of the Acambay graben, and in the Aljibes half-graben, where they measure between 0.16 and 0.18 mm/yr. The north-south to north-northwest2south-southeast2oriented Quaternary bulk extension rate of the system is likely to be 0.2 6 0.05 mm/yr. This fault system is in an initial stage of coalescence. Its western and eastern parts consist mostly of isolated fault segments, whereas in the central part deformation is localized onto a few through-going faults. The longest of these are the Venta de Bravo fault (45 km) and the Acambay-Tixmadeje fault (34 km). The short fault traces have a simple structure, whereas the longer ones are commonly composed of two or more segments. There is no obvious migratory pattern of Quaternary fault activity, which suggests that the entire region is tectonically active.

Transient analysis of proposed Indian MHD channel

The gas dynamics of the channel is affected by the load variation, which is responsible for shock wave formation. They (i.e. the shock wave), on the one hand, help in increasing the electrical conductivity of the fluid, whereas on the other hand, they disturb the fluid flow causing nonuniformity. These effects are studied at 45° slant angle for a diagonal generator at subsonic flow. It has been shown that no severe disturbance is induced by a short fault in the low interaction diagonal generator.

An efficient structural approach to board interconnect diagnosis

In this paper we present an efficient structural approach for diagnosing board interconnects using boundary-scan. Whereas existing diagnosis approaches assume only wired-AND or wired-OR bridging fault model, we consider a more complex bridging short fault model in a CMOS circuit environment. The diagnostic test set is generated on the basis of graph theoretic technique and the adjacency fault model is adopted. By using the structural information of the wiring layout, the test length can be reduced. Both one-step and two-step diagnosis algorithms are given. They guarantee the complete diagnosis of multiple interconnect faults with no aliasing or confounding. The algorithms have been evaluated by simulation on several benchmark layouts and randomly generated layouts. Simulation results show that more than 50% reduction in the number of tests can be achieved for two-step diagnosis when the fault rate is very small, such as in a matured product line. This can significantly save the diagnosis cost for boundary-scan testing.

Geoelectric structure of inland area of the Gökova rift, southwest Anatolia and its tectonic implications

A geoelectrical survey using vertical electrical sounding was carried out to identify the geoelectric model of graben structure within the Gökova rift, since it can provide further useful information on the north–south extension in the western Anatolia. Over 60 Schlumberger electrical soundings were made in the inland area of the rift, using current electrode spacings up to 1500 m. The geoelectrical models are obtained from two-dimensional resistivity inversion based on observed apparent resistivities, since one-dimensional stratified earth models cause several errors due to lateral resistivity changes. The resistivity maps and the two-dimensional geoelectric models indicate that the tectonic structure is comparatively complex, and that the structural pattern is disturbed by numerous fault zones. Interpretation of geoelectrical structure suggests that the inland area of the Gökova rift has an asymmetric graben structure as observed in both the Gediz and Büyük Menderes grabens of western Anatolia. The strong lateral variations in resistivity values at the northern and southern margins of the area indicate the edges of the basin. Abrupt variations in lateral resistivity across the profiles reflect the signature of east–west-trending faults in southern and northern margins of the Gökova graben. A conducting anomaly that is well depicted in all resistivity maps and the two-dimensional geoelectric structure show that the Plio-Quaternary deposit in the eastern part of the area is thicker (up to 140–150 m) and the basement is deeper. The irregular development of sedimentaries in the basin and the short faults trending northwest–southeast identified from two-dimensional geoelectrical models, suggest the cross-cutting relationship between the Gökova and Yatağan–Muğla rifts.

Catastrophic Short and Open Fault Detection in Bipolar CML Circuits: A Case Study

The detection of catastrophic short and open faults in bipolar current mode logic (CML) circuits is studied. The non-intrusive tests considered include functional (logic) tests, an Idd test, and a common-mode test. A 622 Mbps SONET SIPO (Serial-In/Parallel-Out) and a PISO (Parallel-In/Serial-Out) circuit form the basis of this case study.

Compaction of IDDQ test sequence using reassignment method

IDDQ testing is an effective method for detecting short faults of CMOS circuits. Since IDDQ testing requires the measurement of current, the testing time of IDDQ testing is longer than that of logical testing. In this paper, we propose an IDDQ test compaction method for internal short faults of gates in sequential circuits by using the reassignment method of signal values. Experimental results show that test sequences generated by weighted random vectors can be reduced to short sequences with less computation time.

Fault pattern of Nisyros Island volcano (Aegean Sea, Greece): structural, coastal and archaeological evidence

Abstract There has been much debate about the fault pattern of Nisyros Island at the southeastern edge of the Aegean volcanic arc. The small active volcanic island, less than 200–100 ka old, is dominated by a well-developed caldera and by post-caldera domes that are less than 25 ka old and up to 600 m high. Detailed mapping of the tectono-volcanic features of Nisyros have revealed that faults have a clear radial pattern, and they are more abundant in the northwest of the island, where volcanic domes are also concentrated. In contrast to previous speculations that certain major faults control the tectono-volcanic development of Nisyros, this paper argues that the radial fracture pattern is expected where faulting is a secondary effect of volcanic doming. Structural, coastal and archaeological evidence supports this contention. Most faults have a short fault length and a ‘scissors-type’ geometry typical of magma or salt ascent dynamics, and variable throws that are too high to reflect simply tectonic effects. Elevated coastal marine fossils (vermetids) in the northwest of the island indicate rates of uplift too high to be explained solely by differential fault movements. In the same area, a fault that borders the fortifications of a fourth-century BC castle is inferred to be the source of seismic damage effects observed in its ramparts and responsible for the near-total destruction of its westernmost fortifications. Together, the evidence suggests that localized high rates of uplift, faulting and tilting reflect tectonvolcanic deformation effects, and remind us that associated fault activity is likely to have constituted a major threat for the island since antiquity.