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1

Imaging the 3D geometry of pseudotachylyte-bearing faults  

NASA Astrophysics Data System (ADS)

Dynamic friction experiments in granitoid or gabbroic rocks that achieve earthquake slip velocities reveal significant weakening by melt-lubrication of the sliding surfaces. Extrapolation of these experimental results to seismic source depths (> 7 km) suggests that the slip weakening distance (Dw) over which this transition occurs is < 10 cm. The physics of this lubrication in the presence of a fluid (melt) is controlled by surface micro-topography. In order to characterize fault surface microroughness and its evolution during dynamic slip events on natural faults, we have undertaken an analysis of three-dimensional (3D) fault surface microtopography and its causes on a suite of pseudotachylyte-bearing fault strands from the Gole Larghe fault zone, Italy. The solidification of frictional melt soon after seismic slip ceases "freezes in" earthquake source geometries, however it also precludes the development of extensive fault surface exposures that have enabled direct studies of fault surface roughness. We have overcome this difficulty by imaging the intact 3D geometry of the fault using high-resolution X-ray computed tomography (CT). We collected a suite of 2-3.5 cm diameter cores (2-8 cm long) from individual faults within the Gole Larghe fault zone with a range of orientations (+/- 45 degrees from average strike) and slip magnitudes (0-1 m). Samples were scanned at the University of Texas High Resolution X-ray CT Facility, using an Xradia MicroCT scanner with a 70 kV X-ray source. Individual voxels (3D pixels) are ~36 ?m across. Fault geometry is thus imaged over ~4 orders of magnitude from the micron scale up to ~Dw. Pseudotachylyte-bearing fault zones are imaged as tabular bodies of intermediate X-ray attenuation crosscutting high attenuation biotite and low attenuation quartz and feldspar of the surrounding tonalite. We extract the fault surfaces (contact between the pseudotachylyte bearing fault zone and the wall rock) using integrated manual mapping, automated edge detection, and statistical evaluation. This approach results in a digital elevation model for each side of the fault zone that we use to quantify melt thickness and volume as well as surface microroughness and explore the relationship between these properties and the geometry, slip magnitude, and wall rock mineralogy of the fault.

Resor, Phil; Shervais, Katherine

2013-04-01

2

3-D geometry and physical property of the Mega-Splay Fault in Nankai trough  

NASA Astrophysics Data System (ADS)

The Nankai trough is a subduction zone, where the Philippine Sea plate is being subducted beneath southwest Japan at a rate of ~4-6.5 cm/y at an azimuth of ~300°-315°. A lot of operations have been done in Nankai, such as three-dimensional seismic reflection surveys and Deep Sea Drilling Project (DSDP), Ocean Drilling Program (ODP), Integrated Ocean Drilling Program (IODP). They revealed that there is a large splay fault, referred to as 'Mega-Splay'. The Mega-Splay Fault has caused a series of catastrophic earthquakes and submarine landslides, which may have led to TSUNAMI. Since fault development history may have affected the geometry of the Mega-Splay Fault and physical property within the fault zone, they need to be examined in detail. In this research, we used 3-D pre-stack depth migration (PSDM), 3-D pre-stack time migration (PSTM) and P-wave velocity in C0004B well (Logging data), in order to interpret 3-D structure of Mega-Splay Fault. The analysis in this research is basically divided into two parts. One is structural interpretation of Splay Fault, based on the high amplitude reflection surface on seismic profiles. The other part is acoustic impedance inversion (AI inversion), in which we inverted seismic waveform into physical property (in this study, acoustic impedance), with the P-wave velocity data at C0004B near Mega-Splay Fault. The 3-D PSDM (or PSTM) clearly images details of Splay Fault, with good continuity of reflections along the fault. It is possible on each seismic profile to trace the high amplitude lines, where rock-properties significantly change. Since Mega-Splay Fault has 45-59m width along the wells, we interpreted the upper limit and the lower limit of the Mega-Splay Fault, based on the high amplitude surfaces along 3-D PSDM. Our interpretation shows that the width of Mega-Splay Fault has variation along the fault, and the plan geometry of the fault toe has a salient at the middle of the 3D box area, suggesting the fault could be divided into two segments: the eastern part and western part. In AI inversion, the 3-D PSTM and P-wave velocity at C0004B were used to build a physical property model around Mega-Splay Fault. AI Inversion is a methodology to invert seismic waveforms with physical property data, into acoustic impedance. Acoustic Impedance governs the ability of a rock to allow the passage of an acoustic wave. In this analysis, we used Hampson-Russell STRATA to perform post-stack seismic inversion. Our results show that there is a low acoustic impedance layer in the upper zone of Splay Fault. 3-D distribution of the low acoustic impedance layer in the fault zone has a variation in the width, similar to the 3-D interpretation of the geometry. This suggests that there are a relationship between structural geometry and physical property along the Mega-Splay Fault.

Masui, R.; Tsuji, T.; Yamada, Y.; Environmental Resource; System Engineering laboratory

2011-12-01

3

Segmentation of the Calaveras-Hayward Fault System Based on 3-D Geometry and Geology at Large-Earthquake Depth  

Microsoft Academic Search

For the purpose of estimating seismic hazard, the Calaveras and Hayward Faults have been considered as separate structures and analyzed and segmented based largely on their surface-trace geometry and the extent of the 1868 Hayward Fault earthquake. Recent relocations of earthquakes and 3-D geologic mapping have shown, however, that at depths associated with large earthquakes (>5 km) the fault geology

R. W. Graymer; R. W. Simpson; R. C. Jachens; D. A. Ponce; G. A. Phelps; J. T. Watt; C. M. Wentworth

2007-01-01

4

3-D Geometry of Active Deformation East of the San Andreas Fault Near Parkfield, California  

NASA Astrophysics Data System (ADS)

The thrust-and-fold belt east of the San Andreas fault that extends from the Diablo Range to the Temblor Range has been studied in detail mostly at its toe, where a large amount of data is available from oil exploration. We focus more on the part of the belt closer to the San Andreas fault (SAF). We use earthquake data for the period 1980-2006 coupled with surface geology to examine the 3-D geometry of faults in the southernmost Diablo Range, in particular the SAF from just north of Parkfield to the end of the creeping section, and the faults immediately to the east of the SAF. We then combine the results of our study with existing detailed studies and recent earthquake data of the eastern part of the belt to produce a consistent structural model all the way to the San Joaquin basin. We identify from earthquake data an active reverse fault just east of the SAF that abuts the SAF near the bottom of the seismogenic crust (~15 km depth). This fault strikes parallel to the mountain ridge above it, diverges from the SAF from north to south just like the ridge does, and it steepens close to the surface in its southern half. It also matches a major mapped fault trace at the surface. The presence of this fault would explain why this particular ridge has significantly higher structural relief than the surrounding areas, with the Franciscan brought to the surface. At the western margin of the San Joaquin basin, earthquakes indicate the presence of faulting to at least 18 km depth, deeper than can be inferred from oil data alone. The 3-D shape of some of these structures is also illuminated by earthquakes. For example, the aftershocks associated with the 1985 Kettleman Hills earthquake delineate a ramp-flat structure that is clearly different and separate from the structure associated with the 1983 Coalinga event. In general, structures east of the SAF near Parkfield are west-rooting, steeply- dipping thrust faults oriented perpendicular to the regional compression. From double-difference relocated earthquakes we recognize joint-like structures forming a "sliced-bread" pattern in the SAF near Parkfield. These structures are at the resolution limit, but their orientation matches exactly the one predicted from the orientation of the stress field in this region and agrees with the early SAFOD results.

Carena, S.

2006-12-01

5

Active Fault Geometry and Crustal Deformation Along the San Andreas Fault System Through San Gorgonio Pass, California: The View in 3D From Seismicity  

NASA Astrophysics Data System (ADS)

Understanding the 3D geometry and deformation style of the San Andreas fault (SAF) is critical to accurate dynamic rupture and ground motion prediction models. We use 3D alignments of hypocenter and focal mechanism nodal planes within a relocated earthquake catalog (1981-2011) [Hauksson et al., 2012] to develop improved 3D fault models for active strands of the SAF and adjacent secondary structures. Through San Gorgonio Pass (SGP), earthquakes define a mechanically layered crust with predominantly high-angle strike-slip faults in the upper ~10 km, while at greater depth, intersecting sets of strike-slip, oblique slip and low-angle thrust faults define a wedge-shaped volume deformation of the lower crust. In some places, this interface between upper and lower crustal deformation may be an active detachment fault, and may have controlled the down-dip extent of recent fault rupture. Alignments of hypocenters and nodal planes define multiple principal slip surfaces through SGP, including a through-going steeply-dipping predominantly strike-slip Banning fault strand at depth that upward truncates a more moderately dipping (40°-50°) blind, oblique North Palm Springs fault. The North Palm Springs fault may be the active down-dip extension of the San Gorgonio Pass thrust offset at depth by the principal, through-going Banning strand. In the northern Coachella Valley, seismicity indicates that the Garnet Hill and Banning fault strands are most likely sub-parallel and steeply dipping (~70°NE) to depths of 8-10 km, where they intersect and merge with a stack of moderately dipping to low-angle oblique thrust faults. Gravity and water well data confirm that these faults are sub-parallel and near vertical in the upper 2-3 km. Although the dense wedge of deep seismicity below SGP and largely south of the SAF contains multiple secondary fault sets of different orientations, the predominant fault set appears to be a series of en echelon NW-striking oblique strike-slip faults that dip 55°-60°NE and strike slightly oblique to the SAF. Together with the multiple active fault strands of the SAF, these deeper, mostly blind faults also help accommodate plate boundary strain through SGP. The improved complex 3D fault models allow for multiple pathways of dynamic rupture along the SAF to propagate in the northern Coachella Valley and into SGP, implying that large earthquake ruptures at depth through SGP are indeed possible.

Nicholson, C.; Hauksson, E.; Plesch, A.

2012-12-01

6

3-D Drawing and Geometry  

NSDL National Science Digital Library

A Math Forum Summer 1998 Institute project that uses examples of paintings, architecture, etc. to analyze different types of 3-D drawings, and teaches students how to create them. Careers in 3-D drawing that use these techniques, from architecture to movies, are also illustrated. Types include isometric, oblique, and perspective drawings. A drawing project for students is outlined and submissions are invited.

Forum, Math; Sanders, Cathi

2001-01-01

7

Tool 3D geometry measurement system  

NASA Astrophysics Data System (ADS)

A new non-contact tool 3D geometry measurement system based on machine vision is described. In this system, analytical and optimization methods are used respectively to achieve system calibration, which can determine the rotation center of the drill. The data merging method is fully studied which can translate the scattered different groups of raw data in sensor coordinates into drill coordinates and get 3-D topography of the drill body. Corresponding data processing methods for drill geometry are also studied. Statistical methods are used to remove the outliers. Laplacian of Gaussian operator are used to detect the boundary on drill cross-section and drill tip profile. The arithmetic method for calculating the parameters is introduced. The initial measurement results are presented. The cross-section profile, drill tips geometry are shown. Pictures of drill wear on drill tip are given. Parameters extracted from the cross-section are listed. Compared with the measurement results using CMM, the difference between this drill geometry measurement system and CMM is, Radius of drill: 0.020mm, Helix angle: 1.310, Web thickness: 0.034mm.

Zhao, Huijie; Ni, Jun; Sun, Yi; Lin, Xuewen

2001-10-01

8

Imaging fault zones using 3D seismic image processing techniques  

NASA Astrophysics Data System (ADS)

Significant advances in structural analysis of deep water structure, salt tectonic and extensional rift basin come from the descriptions of fault system geometries imaged in 3D seismic data. However, even where seismic data are excellent, in most cases the trajectory of thrust faults is highly conjectural and still significant uncertainty exists as to the patterns of deformation that develop between the main faults segments, and even of the fault architectures themselves. Moreover structural interpretations that conventionally define faults by breaks and apparent offsets of seismic reflectors are commonly conditioned by a narrow range of theoretical models of fault behavior. For example, almost all interpretations of thrust geometries on seismic data rely on theoretical "end-member" behaviors where concepts as strain localization or multilayer mechanics are simply avoided. Yet analogue outcrop studies confirm that such descriptions are commonly unsatisfactory and incomplete. In order to fill these gaps and improve the 3D visualization of deformation in the subsurface, seismic attribute methods are developed here in conjunction with conventional mapping of reflector amplitudes (Marfurt & Chopra, 2007)). These signal processing techniques recently developed and applied especially by the oil industry use variations in the amplitude and phase of the seismic wavelet. These seismic attributes improve the signal interpretation and are calculated and applied to the entire 3D seismic dataset. In this contribution we will show 3D seismic examples of fault structures from gravity-driven deep-water thrust structures and extensional basin systems to indicate how 3D seismic image processing methods can not only build better the geometrical interpretations of the faults but also begin to map both strain and damage through amplitude/phase properties of the seismic signal. This is done by quantifying and delineating the short-range anomalies on the intensity of reflector amplitudes and collecting these into "disturbance geobodies". These seismic image processing methods represents a first efficient step toward a construction of a robust technique to investigate sub-seismic strain, mapping noisy deformed zones and displacement within subsurface geology (Dutzer et al.,2011; Iacopini et al.,2012). In all these cases, accurate fault interpretation is critical in applied geology to building a robust and reliable reservoir model, and is essential for further study of fault seal behavior, and reservoir compartmentalization. They are also fundamental for understanding how deformation localizes within sedimentary basins, including the processes associated with active seismogenetic faults and mega-thrust systems in subduction zones. Dutzer, JF, Basford., H., Purves., S. 2009, Investigating fault sealing potential through fault relative seismic volume analysis. Petroleum Geology Conference series 2010, 7:509-515; doi:10.1144/0070509 Marfurt, K.J., Chopra, S., 2007, Seismic attributes for prospect identification and reservoir characterization. SEG Geophysical development Iacopini, D., Butler, RWH. & Purves, S. (2012). 'Seismic imaging of thrust faults and structural damage: a visualization workflow for deepwater thrust belts'. First Break, vol 5, no. 30, pp. 39-46.

Iacopini, David; Butler, Rob; Purves, Steve

2013-04-01

9

A parametric method to model 3D displacements around faults with volumetric vector fields  

NASA Astrophysics Data System (ADS)

This paper presents a 3D parametric fault representation for modeling the displacement field associated with faults in accordance with their geometry. The displacements are modeled in a canonical fault space where the near-field displacement is defined by a small set of parameters consisting of the maximum displacement amplitude and the profiles of attenuation in the surrounding space. The particular geometry and the orientation of the slip of each fault are then taken into account by mapping the actual fault onto its canonical representation. This mapping is obtained with the help of a curvilinear frame aligned both on the fault surface and slip direction. This formulation helps us to include more geological concepts in quantitative subsurface models during 3D structural modeling tasks. Its applicability is demonstrated in the framework of forward modeling and stochastic sequential fault simulations, and the results of our model are compared to observations of natural objects described in the literature.

Laurent, Gautier; Caumon, Guillaume; Bouziat, Antoine; Jessell, Mark

2013-04-01

10

Kinematic Indicators of strike-slip faults in 3D seismic data: Implications for fault propagation  

NASA Astrophysics Data System (ADS)

A kinematic indicator is a geological structure or feature that can be used to identify both direction and magnitude of translation, in this case providing measurable piercing points for strike-slip fault offsets. We document for the first time a set of stratigraphic and structural kinematic indicators based on three-dimensional (3D) seismic reflection data. Stratigraphic types include any uniquely recognizable sedimentary feature such as meandering deepwater channels, and large intact blocks within internally disaggregated mass transport deposits. Structural indicators include the systematic offset of older intersecting faults, and thrust-propagation folds. The examples presented here come from the deepwater Levant Basin located in the Eastern Mediterranean. This area reveals a complex network of conjugate strike-slip faults that propagated in the last two million years due to gravity driven salt tectonics. The faults are part of a contractional structural assemblage in the down-dip toe domain of the gravity linked system and detach at the Messinian evaporites. Using seismic attributes such as coherency, dip, and amplitude, the plan view geometry of these strike-slip faults is spectacularly revealed across a c. 2km thick clastic overburden overlying the Messinian evaporites. This provides a unique opportunity to map kinematic indicators at points not only along strike of the faults but in depth as well, resulting in a full 3D visualisation of the fault. The use of these varied kinematic indicators signifies a potential to map displacement distributions of strike-slip faults and subsequently reconstruct their 4D growth history, similar to recent studies of normal and thrust fault propagation. We are thus able to analyse the evolution of these conjugate systems and the relationship between precursor structures (R shears and en echelon normal faults) and the main through-going strike slip fault zone as a function of increasing displacement accumulation. These examples open a novel analytical technique for the wider investigation of this important class of structure.

Wild, C. E.; Cartwright, J. A.

2011-12-01

11

3-D GPR IMAGING OF THE NEODANI FAULT, CENTRAL JAPAN  

Microsoft Academic Search

GPR data collected across a segment of the Neodani Fault in the Tokai region of central Japan represents the first 3-D GPR data successfully collected across a major seismogenic fault in Japan. Despite the inherent difficulty of GPR to significantly penetrate wet, clay-rich soils, a 3 meter bedrock offset across the fault was imaged through 3-6 meters of saturated unconsolidated

Ernest C. Hauser; Daiei Inoue

12

Using 3D Geometric Models to Teach Spatial Geometry Concepts.  

ERIC Educational Resources Information Center

An explanation of 3-D Computer Aided Design (CAD) usage to teach spatial geometry concepts using nontraditional techniques is presented. The software packages CADKEY and AutoCAD are described as well as their usefulness in solving space geometry problems. (KR)

Bertoline, Gary R.

1991-01-01

13

Micro-Geometry of 3-D Braided Tubular Preform  

Microsoft Academic Search

The micro-geometry of three-dimensional (3-D) braided tubular preform is more complex than that of rectangular one, and it is more difficult to analyze its architecture and mechanical properties theoretically as well. Through the advantage of digital element approach for textile technology, 3-D circular braiding process could be simulated dynamically using different parameters like yarn tension, yarn properties, the size of

Xuekun Sun

2004-01-01

14

Automatic visualization of 3-D geometry contained in online databases  

NASA Astrophysics Data System (ADS)

In this paper, the application of the Virtual Reality Modeling Language (VRML) for efficient database visualization is analyzed. With the help of JAVA programming, three examples of automatic visualization from a database containing 3-D Geometry are given. The first example is used to create basic geometries. The second example is used to create cylinders with a defined start point and end point. The third example is used to processs data from an old copper mine complex in Cheshire, United Kingdom. Interactive 3-D visualization of all geometric data in an online database is achieved with JSP technology.

Zhang, Jie; John, Nigel W.

2003-04-01

15

Wavelet-based multiple description coding of 3-D geometry  

NASA Astrophysics Data System (ADS)

In this work, we present a multiple description coding (MDC) scheme for reliable transmission of compressed three dimensional (3-D) meshes. It trades off reconstruction quality for error resilience to provide the best expected reconstruction of 3-D mesh at the decoder side. The proposed scheme is based on multiresolution geometry compression achieved by using wavelet transform and modified SPIHT algorithm. The trees of wavelet coefficients are divided into sets. Each description contains the coarsest level mesh and a number of tree sets coded with different rates. The original 3-D geometry can be reconstructed with acceptable quality from any received description. More descriptions provide better reconstruction quality. The proposed algorithm provides flexible number of descriptions and is optimized for varying packet loss rates (PLR) and channel bandwidth.

Norkin, Andrey; Bici, M. Oguz; Bozdagi Akar, Gozde; Gotchev, Atanas; Astola, Jaakko

2007-01-01

16

3D Simulations of Dynamic Rupture on Rough Faults  

NASA Astrophysics Data System (ADS)

Natural faults during their evolution stages manifest varying degrees of geometric complexities over a broad range of scales spanning from larger-scale features such as branching and segmentation to smaller-scale features such as topographic variations on the slip surface. At a microscopic scale, surface roughness affects the frictional properties through its role in the distribution and evolution of contact areas of the sliding surface. At a larger scale, the geometric irregularities of the fault affects the inter-seismic and post-seismic static stress distribution that is responsible for earthquake nucleation. Our study, however, focuses on the fundamental role that surface roughness plays in the dynamic processes of earthquake rupture propagation and resultant ground motion using numerical simulations of 3D dynamic rupture. As have been shown in several previous 2D numerical studies, dynamic ruptures propagating along rough fault surface can excite high-frequency radiation as they accelerate and decelerate from interaction with geometric irregularities. Also perturbation of local dynamic stress due to roughness contributes to the heterogeneous distributions of slip rate and slip over the entire fault. With the goal of producing more realistic physics-based dynamic ground motion, we perform 3D numerical simulations of dynamic rupture along faults with self-similar roughness distribution of wavelength scales spanning three orders of magnitude (10^2 -10^5 m). We examine the influence of fault roughness characteristics (shortest wavelength and amplitude-to-wavelength ratio) on the rupture behavior, the resultant ground motion pattern and the final slip pattern. The fault is governed by a rate-and-state friction with strongly velocity-weakening feature and the inelastic yielding of off-fault bulk material is subject to Drucker-Prager viscoplasticity. Initial investigations clearly indicate that the amount of high-frequency radiation generated and rupture properties are heavily influenced by the roughness properties. Detailed analyses of our simulation results will be presented at the conference.

Shi, Z.; Day, S. M.

2011-12-01

17

Thermal 3D modeling system based on 3-view geometry  

NASA Astrophysics Data System (ADS)

In this paper, we propose a novel thermal three-dimensional (3D) modeling system that includes 3D shape, visual, and thermal infrared information and solves a registration problem among these three types of information. The proposed system consists of a projector, a visual camera and, a thermal camera (PVT). To generate 3D shape information, we use a structured light technique, which consists of a visual camera and a projector. A thermal camera is added to the structured light system in order to provide thermal information. To solve the correspondence problem between the three sensors, we use three-view geometry. Finally, we obtain registered PVT data, which includes visual, thermal, and 3D shape information. Among various potential applications such as industrial measurements, biological experiments, military usage, and so on, we have adapted the proposed method to biometrics, particularly for face recognition. With the proposed method, we obtain multi-modal 3D face data that includes not only textural information but also data regarding head pose, 3D shape, and thermal information. Experimental results show that the performance of the proposed face recognition system is not limited by head pose variation which is a serious problem in face recognition.

Yu, Sunjin; Kim, Joongrock; Lee, Sangyoun

2012-11-01

18

Dynamic 3D simulations of earthquakes on en echelon faults  

USGS Publications Warehouse

One of the mysteries of earthquake mechanics is why earthquakes stop. This process determines the difference between small and devastating ruptures. One possibility is that fault geometry controls earthquake size. We test this hypothesis using a numerical algorithm that simulates spontaneous rupture propagation in a three-dimensional medium and apply our knowledge to two California fault zones. We find that the size difference between the 1934 and 1966 Parkfield, California, earthquakes may be the product of a stepover at the southern end of the 1934 earthquake and show how the 1992 Landers, California, earthquake followed physically reasonable expectations when it jumped across en echelon faults to become a large event. If there are no linking structures, such as transfer faults, then strike-slip earthquakes are unlikely to propagate through stepovers >5 km wide. Copyright 1999 by the American Geophysical Union.

Harris, R. A.; Day, S. M.

1999-01-01

19

Dynamic Source Rupture Simulation of Dipping Faults With a 3D Finite-Difference Method  

NASA Astrophysics Data System (ADS)

The finite-difference method (FDM) has been widely used for numerical modeling of seismic source problems, including investigation on the dynamic source processes. Owing to both conceptual and computational constraints of FDM, fault models have largely been limited to the cases that the fault planes are parallel to the FDM grid. However, recent observation and kinematic inversion results discover that more complex fault geometry models, such as bending faults or curved faults, are needed to explain some earthquake phenomena. Thus, we need to develop an approach of FDM to treat a fault planes slanted with respect to the FDM grid. In this study, we propose a method to analyze the dynamic source problems of nonvertical faults, using a 3D FDM with nonuniform grid spacing (Pitarka, 1999). This approach does not require aligning the fault plane to the FDM grid for implementation of FDM. We estimate the shear stress on the nonvertical fault plane from the six stress components obtained in FDM calculation with respect to the force balance condition and the coordination transformation. This method can be used to deal with a more realistically complex fault geometry model. We validate our method by studying two cases of the dynamic source problems which have been analyzed by Madariaga et al. (1998). One is the instantaneous rupture model of a circular fault embedded in a homogeneous elastic medium; another is the spontaneous rupture model of a rectangular fault which starts from a local circular asperity on the fault plane. We analyze the inclined fault models against the space grid coordination for both of the rupture problems and compare our simulations with previous results obtained by Madariaga et al. (1998) using the horizontal fault plane model. Our simulations gave similar results with those of Madariaga et al. (1998). Thus, our method can be used to analyze the dynamic rupture processes of dipping fault models. This implementation was used to compute the dynamic source problems of the 1999 Chi-Chi, Taiwan, earthquake by Zhang et al. (2003, 2004). We found that the rupture process of this event is more complex than that described in the kinematic model. Our dynamic model revealed that for a large earthquake such as the Chi-Chi earthquake, the rupture propagation can be discontinuous, as suggested by some numerical simulations (Das and Aki, 1977; Day, 1982). In this study, we apply the proposed method to analyze the dynamics of the 2003 Tokachi-Oki, Japan, earthquake. The fault model of this earthquake is a dipping fault with a dip angle of 18 degree. We rebuild the dynamic rupture process of this event and simulate the near source ground motions based on the dynamic source model.

Zhang, W.; Iwata, T.

2004-12-01

20

3D Fault Network of the Murchison Domain, Yilgarn Craton  

NASA Astrophysics Data System (ADS)

The architecture of Archean granite-greenstone terranes is often controlled by networks of 10 km to 100 km-scale shear zones that record displacement under amphibolite facies to greenschist facies metamorphic conditions. The geometry of such crustal scale 'fault networks' has been shown to be highly relevant to understand the tectonic and metamorphic history of granite-greenstone terranes, as well as the availability of structural controlled fluid pathways related to magmatic and hydrothermal mineralization. The Neoarchean Yilgarn Craton and the Proterozoic orogens around its margins constitute one of Earth's greatest mineral treasure troves, including iron, gold, copper and nickel mineral deposits. Whereas the Yilgarn Craton is one of the best studied Archean cratons, its enormous size and limited outcrop are detrimental to the better understanding of what controls the distribution of these vast resources and what geodynamic processes were involved the tectonic assembly of this part of the Australian continent. Here we present a network of the major faults of the NW Yilgarn Craton between the Yalgar Fault, Murchison's NW contact with the Narryer Terrane to the Ida Fault, its boundary with the Eastern Goldfields Superterrane. The model has been constructed from various geophysical and geological data, including potential field grids, Geological Survey of Western Australia map sheets, seismic reflection surveys and magnetotelluric traverses. The northern extremity of the modelled area is bounded by the Proterozoic cover and the southern limit has been arbitrarily chosen to include various greenstone belts. In the west, the major faults in the upper crust, such as the Carbar and Chundaloo Shear Zones, dip steeply towards the west and then flatten off at depth. They form complex branching fault systems that bound the greenstone belts in a series of stacked faults. East of the Ida, the far east of the model, the faults have been integrated with Geoscience Australia's pmd*CRC Eastern Goldfields model. In the central portion, the major faults such as the Youanmi and Wattle Creek, dip to the east and can be followed into the fabric of the Yarraquin Seismic Province. The Wattle Creek Shear Zone in particular can be traced on all three of the Youanmi seismic lines. The greenstones are cradled between these major faults and antithetic westward dipping subsidiary faults such as the Edale Shear Zone. While the Ida Fault cannot be located with great confidence, the slight drop in Moho depth toward the east and the overall change of seismic texture delineate the Youanmi-Eastern Goldfields boundary. The Lawler's Anticline, presumably located in the hanging wall of the Ida Fault, again changes the style of faulting with the Lawler's tonalite forming the core of a 10 km-scale antiform. The fault network presented here is a milestone to a craton-wide integrated structural model and will hopefully contribute to provide a better spatial context for geological, geochemical and geophysical data in our quest to understand the tectonics and mineral potential of the Yilgarn craton.

Murdie, Ruth; Gessner, Klaus

2014-05-01

21

Magma rheology from 3D geometry of martian lava flows  

NASA Astrophysics Data System (ADS)

Volcanism is an important geologic agent which has been recently active at the surface of Mars. The composition of individual lava flows is difficult to infer from spectroscopic data because of the absence of crystallized minerals and the possible cover of the flows by dust. The 3D geometry of lava flows provides an interesting alternative to infer the chemical composition of lavas and effusion rates. Indeed, chemical composition exerts a strong control on the viscosity and yield strength of the magma and global geometry of lava flow reflects its emplacement rate. Until recently, these studies where realized from 2D data. The third dimension, which is a key parameter, was deduced or supposed from local shadow measurements on MGS Themis IR images with an uncertainty of more than 500%. Recent CTX data (MRO mission) allow to compute Digital Elevation Model at a resolution of 1 or 2 pixels (5 to 10 m) with the help of Isis and the Ames Stereo Pipeline pipe line. The CTX images are first transformed in format readable by Isis. The external geometric parameters of the CTX camera are computed and added to the image header with Isis. During a correlation phase, the homologous pixels are searched on the pair of stereo images. Finally, the DEM is computed from the position of the homologous pixels and the geometrical parameters of the CTX camera. Twenty DEM have been computed from stereo images showing lava flows of various ages on the region of Cerberus, Elyseum, Daedalia and Amazonis planitia. The 3D parameters of the lava flows have been measured on the DEMs and tested against shadows measurement. These 3D parameters have been inverted to estimate the viscosity and the yield strength of the flow. The effusion rate has also been estimated. These parameters have been compared to those of similar lava flows of the East Pacific rise.

Allemand, P.; Deschamps, A.; Lesaout, M.; Delacourt, C.; Quantin, C.; Clenet, H.

2012-04-01

22

Impacts of Fault Geometry on Fault System Behaviors  

NASA Astrophysics Data System (ADS)

Complexity in earthquake populations arises primarily due to two components: friction and fault geometry. We present preliminary investigations into contributions to event population complexity due to fault geometry variation. In one key application, we investigate probabilities of events continuing along multiple, en echelon fault segments in both compressional and extensional regimes as a function of distance between the segments and segment overlap. These and other results are produced in the course of developing the extended finite element method, XFEM (e.g. [Dolbow, Moes, and Belytschko, 2001]), for static, quasistatic, and dynamic rupture problems on complicated fault networks. This method, part of a broader class of mesh-free methods, allow faults to be included nearly arbitrarily in a simulation, enabling many simulations with varying fault geometries to be conducted with minimal remeshing. We introduce the enforcement of failure criteria in dynamic rupture problems and test the method through a series of two-dimensional static and dynamic benchmarks. We also introduce a novel, ``two and a half-dimensional'' formulation, where two-dimensional plates intersect at faults that include a dip parameter which can vary along-strike. This enables us to model fault systems with strike-slip, thrust, normal, and mixed-mode faults. To demonstrate this capability, we examine fault systems composed of faults taken from the SCEC Community Fault Model Surface Traces. These results demonstrate the feasibility of the XFEM for both static and dynamic rupture problems. Furthermore, we demonstrate usage of the XFEM in studies with uncertain fault geometry, and enable new studies of fault system behaviors due to fault geometry.

Coon, E. T.; Shaw, B. E.; Spiegelman, M. W.

2009-12-01

23

3D Velocity Structure of Chukou Fault Area, Taiwan from Seismic Tomography  

NASA Astrophysics Data System (ADS)

In this study, we used the seismic data that recorded by the broadband stations which deployed around the Chukou fault area, Taiwan. We have chosen 1661 earthquake events with high quality records in this research. The waveform cross correlation technique is applied to calculate the 143086 pairs of waveform data. By combining with data from the seismic catalog, there are 342202 absolute travel-time pairs through the double difference tomography method to relocate the seismicity and invert the 3D velocity structures beneath the Chukou fault area. Due to Taiwan Island is located in an active boundary zone between the Eurasia continental and Philippine Sea plates, the violent collision between the two plates which causes a series of imbricate fold-thrust belts to form between the western foothills and the coastal plain. The Chukou fault is just the boundary between the fold-thrust belts and the coastal plain in the Chia-Nan area, Taiwan. The seismotectonic structure beneath this area is more complex. From many studies, velocity structure can be used as an indicator of the geometry of fault and the general aspect of tectonics. Therefore, the first goal of this research is to analyze the degree of correlation between the velocity structure and the characteristics of seismicity and the tectonic implications of the area. The second intention is to study the distribution of seismic events and its association with fault activities. Our results indicate that the variation of velocity structure beneath fault area is caused by local geological structures, complex fault crossing. We also find that most earthquakes occur in the area that has Vp/Vs gradient varying rapidly. Finally, both using catalog and cross-correlation data in the inversion procedure are not only exhibit better resolution, but also can obtain the detail 3D velocity structure beneath the fault zone.

Chen, C.; Chang, W.; Jian, W.

2009-12-01

24

Three-dimensional geometry and evolution of a salt-related growth-fault array: Eugene Island 330 field, offshore Louisiana, Gulf of Mexico  

Microsoft Academic Search

The geometry and evolution of a growth-fault array bounding the Eugene Island 330 Field were studied using 3-D seismic interpretation and analysis of displacement patterns. The 3-D geometry of the kinematically coherent fault array is complex and characterized by both lateral and vertical branching and linkage of individual fault segments, so that fault patterns and interactions very considerably between different

Mark G. Rowan; Bruce S. Hart; Steve Nelson; Peter B. Flemings; Bruce D. Trudgill

1998-01-01

25

Stochastic Modeling of Calcium in 3D Geometry  

PubMed Central

Release of inflammatory mediators by mast cells in type 1 immediate-hypersensitivity allergic reactions relies on antigen-dependent increases in cytosolic calcium. Here, we used a series of electron microscopy images to build a 3D reconstruction representing a slice through a rat tumor mast cell, which then served as a basis for stochastic modeling of inositol-trisphosphate-mediated calcium responses. The stochastic approach was verified by reaction-diffusion modeling within the same geometry. Local proximity of the endoplasmic reticulum to either the plasma membrane or mitochondria is predicted to differentially impact local inositol trisphosphate receptor transport. The explicit consideration of organelle spatial relationships represents an important step toward building a comprehensive, realistic model of cellular calcium dynamics.

Mazel, Tomas; Raymond, Rebecca; Raymond-Stintz, Mary; Jett, Stephen; Wilson, Bridget S.

2009-01-01

26

3-D mapping of segmented active faults in the Vienna Basin from integrated geophysical, geomorphological and geological data: building up an active fault database  

NASA Astrophysics Data System (ADS)

The Vienna Basin basin formed as a Miocene pull-apart basin along a sinistral transform system between the Eastern Alps and the Carpathians. Moderate seismicity in the southern Vienna Basin as well as thick Quaternary deposits in the center of the basin prove that part of the faults within the Miocene basin are active today. However, nearly no systematical data exist on the positions, segmentation, and geometry of active faults, which yield important input parameters for seismic hazard evaluations. Spatial mapping of active faults and kinematical analyses are based on 3-D reflection seismic data by OMV Austria, geomorphological features such as tilted Quaternary river terraces and fault scarps, the geometry of Quaternary basins, and published geodetic data. Interpretation of combined data sets are summarized in a map and an active fault catalog of for future seismic hazard evaluations. The map reveals two regions with different types of Quaternary and active faults. (A) The southern part of the Vienna Basin reveals a seismically active NE-striking sinistral strike-slip fault with a large negative flower structure. Recent activity of the flower structure is documented by the accumulation of up to 150 m thick Quaternary gravels. The Quaternary basin is limited by faults, depicted by 3-D seismics and near surface geophysics (Gegenleitner et al, 2003, this volume). At the surface, a prominent morphological scarp parallels the fault traces mapped from the 3-D seismic. (B) The western and central part of the Vienna Basin is characterized by major listric E-dipping normal faults branching off from the strike-slip fault system, which is localized in the seismically active area at the eastern border of the Basin. Deformation is partitioned on several normal faults via a common detachment horizon. These faults kinematically link up with the strike-slip fault system. At the surface normal faulting is documented by tilted Quaternary terraces of the Danube caused by the hangingwall collapse above listric faults. Major branch points are marked by changes in the geomorphological expression and Quaternary basin architecture, indicating a segmentation of the main fault along strike. We propose that at least one major mapped branch point coincide with a seismogenic segment-boundary at depth. This interpretation is supported by hypocenters clustering near the two adjacent fault segments mapped in the 3-D seismic survey. However, not all major branch points are presently defined well enough to allow an assessment of fault segment surfaces for the calculation of earthquake magnitudes.

Hinsch, R.; Decker, K.

2003-04-01

27

Intensity of joints associated with an extensional fault zone: an estimation by poly3d .  

NASA Astrophysics Data System (ADS)

The presence and frequency of joints in sedimentary rocks strongly affects the mechanical and fluid flow properties of the host layers. Joints intensity is evaluated by spacing, S, the distance between neighbouring fractures, or by density, D = 1/S. Joint spacing in layered rocks is often linearly related to layer thickness T, with typical values of 0.5 T < S < 2.0 T . On the other hand, some field cases display very tight joints with S << T and nonlinear relations between spacing and thickness , most of these cases are related to joint system “genetically” related to a nearby fault zone. The present study by using the code Poly3D (Rock Fracture Project at Stanford), numerically explores the effect of the stress distribution in the neighbour of an extensional fault zone with respect to the mapped intensity of joints both in the hanging wall and in the foot wall of it (WILLEMSE, E. J. M., 1997; MARTEL, S. J, AND BOGER, W. A,; 1998). Poly3D is a C language computer program that calculates the displacements, strains and stresses induced in an elastic whole or half-space by planar, polygonal-shaped elements of displacement discontinuity (WILLEMSE, E. J. M., POLLARD, D. D., 2000) Dislocations of varying shapes may be combined to yield complex three-dimensional surfaces well-suited for modeling fractures, faults, and cavities in the earth's crust. The algebraic expressions for the elastic fields around a polygonal element are derived by superposing the solution for an angular dislocation in an elastic half-space. The field data have been collected in a quarry located close to Noci town (Puglia) by using the scan line methodology. In this quarry a platform limestone with a regular bedding with very few shale or marly intercalations displaced by a normal fault are exposed. The comparison between the mapped joints intensity and the calculated stress around the fault displays a good agreement. Nevertheless the intrinsic limitations (isotropic medium and elastic behaviour) of this project encourages other application of Poly3d. References WILLEMSE, E. J. M., 1997, Segmented normal faults: Correspondence between three-dimensional mechanical models and field data: Journal of Geophysical Research, v. 102, p. 675-692. MARTEL, S. J, AND BOGER, W. A, 1998, Geometry and mechanics of secondary fracturing around small three-dimensional faults in granitic rock: Journal of Geophysical Research, v. 103, p. 21,299-21,314. WILLEMSE, E. J. M., POLLARD, D. D., 2000, Normal fault growth: evolution of tipline shapes and slip distribution: in Lehner, F.K. &Urai, J.L. (eds.), Aspects of Tectonic Faulting, Springer -Verlag , Berlin, p. 193-226.

Minelli, G.

2003-04-01

28

Preliminary Pseudo 3-D Imagery of the State Line Fault, Stewart Valley, Nevada Using Seismic Reflection Data  

NASA Astrophysics Data System (ADS)

The Pahrump Fault system is located in the central Basin and Range region and consists of three main fault zones: the Nopah range front fault zone, the State Line fault zone and the Spring Mountains range fault zone. The State Line fault zone is made up north-west trending dextral strike-slip faults that run parallel to the Nevada- California border. Previous geologic and geophysical studies conducted in and around Stewart Valley, located ~90 km from Las Vegas, Nevada, have constrained the location of the State Line fault zone to within a few kilometers. The goals of this project were to use seismic methods to definitively locate the northwestern most trace of the State Line fault and produce pseudo 3-D seismic cross-sections that can then be used to characterize the subsurface geometry and determine the slip of the State Line fault. During July 2007, four seismic lines were acquired in Stewart Valley: two normal and two parallel to the mapped traces of the State Line fault. Presented here are preliminary results from the two seismic lines acquired normal to the fault. These lines were acquired utilizing a 144-channel geode system with each of the 4.5 Hz vertical geophones set out at 5 m intervals to produce a 595 m long profile to the north and a 715 m long profile to the south. The vibroseis was programmed to produce an 8 s linear sweep from 20-160 Hz. These data returned excellent signal to noise and reveal subsurface lithology that will subsequently be used to resolve the subsurface geometry of the State Line fault. This knowledge will then enhance our understanding of the evolution of the State Line fault. Knowing how the State Line fault has evolved gives insight into the stick-slip fault evolution for the region and may improve understanding of how stress has been partitioned from larger strike-slip systems such as the San Andreas fault.

Saldaña, S. C.; Snelson, C. M.; Taylor, W. J.; Beachly, M.; Cox, C. M.; Davis, R.; Stropky, M.; Phillips, R.; Robins, C.; Cothrun, C.

2007-12-01

29

The COMET method in 3-D hexagonal geometry  

SciTech Connect

The hybrid stochastic-deterministic coarse mesh radiation transport (COMET) method developed at Georgia Tech now solves reactor core problems in 3-D hexagonal geometry. In this paper, the method is used to solve three preliminary test problems designed to challenge the method with steep flux gradients, high leakage, and strong asymmetry and heterogeneity in the core. The test problems are composed of blocks taken from a high temperature test reactor benchmark problem. As the method is still in development, these problems and their results are strictly preliminary. Results are compared to whole core Monte Carlo reference solutions in order to verify the method. Relative errors are on the order of 50 pcm in core eigenvalue, and mean relative error in pin fission density calculations is less than 1% in these difficult test cores. The method requires the one-time pre-computation of a response expansion coefficient library, which may be compiled in a comparable amount of time to a single whole core Monte Carlo calculation. After the library has been computed, COMET may solve any number of core configurations on the order of an hour, representing a significant gain in efficiency over other methods for whole core transport calculations. (authors)

Connolly, K. J.; Rahnema, F. [Nuclear and Radiological Engineering and Medical Physics Programs, George W. Woodruff School, Georgia Inst. of Technology, Atlanta, GA (United States)

2012-07-01

30

Indoor Modelling Benchmark for 3D Geometry Extraction  

NASA Astrophysics Data System (ADS)

A combination of faster, cheaper and more accurate hardware, more sophisticated software, and greater industry acceptance have all laid the foundations for an increased desire for accurate 3D parametric models of buildings. Pointclouds are the data source of choice currently with static terrestrial laser scanning the predominant tool for large, dense volume measurement. The current importance of pointclouds as the primary source of real world representation is endorsed by CAD software vendor acquisitions of pointcloud engines in 2011. Both the capture and modelling of indoor environments require great effort in time by the operator (and therefore cost). Automation is seen as a way to aid this by reducing the workload of the user and some commercial packages have appeared that provide automation to some degree. In the data capture phase, advances in indoor mobile mapping systems are speeding up the process, albeit currently with a reduction in accuracy. As a result this paper presents freely accessible pointcloud datasets of two typical areas of a building each captured with two different capture methods and each with an accurate wholly manually created model. These datasets are provided as a benchmark for the research community to gauge the performance and improvements of various techniques for indoor geometry extraction. With this in mind, non-proprietary, interoperable formats are provided such as E57 for the scans and IFC for the reference model. The datasets can be found at: http://indoor-bench.github.io/indoor-bench.

Thomson, C.; Boehm, J.

2014-06-01

31

3D Fault modeling of the active Chittagong-Myanmar fold belt, Bangladesh  

NASA Astrophysics Data System (ADS)

The Chittagong-Myanmar fold belt (CMFB), located in eastern Bangladesh, eastern India and western Myanmar, accommodates east-west shortening at the India-Burma plate boundary. Oblique subduction of the Indian Plate beneath the Burma Plate since the Eocene has led to the development of a large accretionary prism complex, creating a series of north-south trending folds. A continuous sediment record from ~55 Ma to the present has been deposited in the Bengal Basin by the Ganges-Brahmaputra-Meghna rivers, providing an opportunity to learn about the history of tectonic deformation and activity in this fold-and-thrust belt. Surface mapping indicates that the fold-and-thrust belt is characterized by extensive N-S-trending anticlines and synclines in a belt ~150-200 km wide. Seismic reflection profiles from the Chittagong and Chittagong Hill Tracts, Bangladesh, indicate that the anticlines mapped at the surface narrow with depth and extend to ~3.0 seconds TWTT (two-way travel time), or ~6.0 km. The folds of Chittagong and Chittagong Hill Tracts are characterized by doubly plunging box-shaped en-echelon anticlines separated by wide synclines. The seismic data suggest that some of these anticlines are cored by thrust fault ramps that extend to a large-scale décollement that dips gently to the east. Other anticlines may be the result of detachment folding from the same décollement. The décollement likely deepens to the east and intersects with the northerly-trending, oblique-slip Kaladan fault. The CMFB region is bounded to the north by the north-dipping Dauki fault and the Shillong Plateau. The tectonic transition from a wide band of E-W shortening in the south to a narrow zone of N-S shortening along the Dauki fault is poorly understood. We integrate surface and subsurface datasets, including topography, geological maps, seismicity, and industry seismic reflection profiles, into a 3D modeling environment and construct initial 3D surfaces of the major faults in this region. These models will further our understanding of fault geometry and history of the CMFB, allowing us to investigate the region's potential for geologic hazards. At least twenty-five percent of the country of Bangladesh sits on top of this actively deforming region, which is home to more than 28 million people. The CMFB also extends offshore, meaning that a major thrusting event could induce a regional tsunami with little warning. Understanding the geometry of the region's underlying detachment as well as the location and ages of specific thrust faults is critical to assessing seismic hazards for this heavily populated area.

Peterson, D. E.; Hubbard, J.; Akhter, S. H.; Shamim, N.

2013-12-01

32

Connecting multi-scale fault geometry with field observations: insights into fluid-fault rock relations  

NASA Astrophysics Data System (ADS)

Fault geometry along with heterogenities in fluid pressure locally influences the mechanical behavior of faulting and the type of fault rock damage generated. The Naukluft Nappe Complex in central Namibia, southwest Africa features a well exposed basal foreland thrust fault emplaced during the 550 Ma Damara Orogen. Using differential GPS we walked and mapped the kilometer-scale dolomitic basal fault at two localities, the East and West side of the nappe complex. 3D fault geometry and orientation over each locality was interpolated using the high resolution GPS maps. The interpolated 3D geometry was then correlated with field observations of fault rock damage including cataclastic injection systems, brecciation, and alteration in the fault rock. 2D cross-sections were rendered using the interpolated 3D geometries. The eastern flank of the nappe complex locally exhibits ramp geometries and a prevalent granular fault rock known as "gritty dolomite". Cataclastic injection systems of gritty dolomite are observed injecting upsection off the basal thrust through opening mode fractures and are generally subvertical to the fault plane. The injectites are centimeter to meter scale, sometimes reach tens of meters in vertical extent, the width tapered towards the injection tip. Laminae interpreted as flow banding are oriented subparallel to the injectite walls and is also present in the basal thrust subparallel to the fault plane. Neocrystallized dolomite, quartz, and fracture filling calcite is observed within injectite systems suggesting the presence of super-saturated fluid. Bending strains create localized extension as the hanging wall enters the ramp, facilitating Mode I fractures and the formation of injectites which are observed at the base, within, and at the upper flat of the ramp structure, recording progressive hanging wall transport. Fault dip increases in the northern area of the eastern locality where a unit of shales directly overlies footwall limestone. The dolomitic fault rock, typically directly overlying the footwall is observed upsection. Injections propagate downsection off the dolomitic source bed and create a complex, discontinuous network of minor dikes and sills within the shale beds, likely exploiting bedding weaknesses. The basal thrust in the western side of the nappe complex is of consistent shallow dip with no evidence of ramp structures. The footwall is primarily shales with some discontinuous calc-mylonite and limestone lenses. At the basal thrust a yellow, altered dolomite grades upsection into massive grey dolomite. The hanging wall is composed of imbricate listric faults and folds of dolomite, quartzite, and shale layers. The alteration zone, along with the presence of footwall shales injecting upsection into the altered zone suggests a relative high fluid pressure in the footwall, consistent with the requirement for low angle overthrust sliding. We hypothesize that differing fault damage structures between the eastern and western localities on the basal thrust is the result of the relationship between local fault geometry and fluid pressure. Where the eastern basal thrust contained fluid within the granular fault rock, brecciation and injectites are common, and where the western locale had pore fluid within the footwall, an alteration zone is present along the fault with minor footwall injections.

Sherry, T. J.; Melosh, B. L.; Rowe, C. D.

2012-12-01

33

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)

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.

Ercoli, Maurizio; Pauselli, Cristina; Frigeri, Alessandro; Forte, Emanuele; Federico, Costanzo

2014-07-01

34

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)

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.

Ercoli, Maurizio; Pauselli, Cristina; Frigeri, Alessandro; Forte, Emanuele; Federico, Costanzo

2014-05-01

35

An Interactive, 3D Fault Editor for VR Environments  

NASA Astrophysics Data System (ADS)

Digitial Fault Models (DFM) play a vital role in the study of earthquake dynamics, fault-earthquake interactions, and seismicity. DFMs serve as input for finite-element method (FEM) or other earthquake simulations such as Virtual California. Generally, digital fault models are generated by importing a digitized and georeferenced (2D) fault map and/or a hillshade image of the study area into a geographical information system (GIS) application, where individual fault lines are traced by the user. Data assimilation and creation of a DFM, or updating an existing DFM based on new observations, is a tedious and time-consuming process. In order to facilitate the creation process, we are developing an immersive virtual reality (VR) application to visualize and edit fault models. This program is designed to run in immersive environments such as a CAVE (walk-in VR environment), but also works in a wide range of other environments, including desktop systems and GeoWalls. It is being developed at the UC Davis W.M. Keck Center for Active Visualization in the Earth Sciences (KeckCAVES, http://www.keckcaves.org). Our program allows users to create new models or modify existing ones; for instance by repositioning individual fault-segments, by changing the dip angle, or by modifying (or assigning) the value of a property associated with a particular fault segment (i.e. slip rate). With the addition of high resolution Digital Elevation Models (DEM) , georeferenced active tectonic fault maps and earthquake hypocenters, the user can accurately add new segments to an existing model or create a fault model entirely from scratch. Interactively created or modified models can be written to XML files at any time; from there the data may easily be converted into various formats required by the analysis software or simulation. We believe that the ease of interaction provided by VR technology is ideally suited to the problem of creating and editing digital fault models. Our software provides the user with an intuitive environment for visualizing and editing fault model data. This translates not only into less time spent creating fault models, but also enables the researcher to easily generate and maintain any number of models for use in ensemble analysis.

van Aalsburg, J.; Yikilmaz, M. B.; Kreylos, O.; Kellogg, L. H.; Rundle, J. B.

2008-12-01

36

The 3D geometry of Dark Matter Halos  

Microsoft Academic Search

The thickness of the neutral hydrogen layer, coupled with the rotation curve, traces the outer dark matter potential. We estimate the amplitude of the flaring in spiral galaxies from a 3D model of the HI gas. Warps in particular are explicitly parametrized in the form of an harmonical density wave. Applying our method to the galaxy NGC 891, the only

J.-F. Becquaert; F. Combes

1997-01-01

37

Types of Reasoning in 3D Geometry Thinking and Their Relation with Spatial Ability  

ERIC Educational Resources Information Center

The aim of this study is to describe and analyse the structure of 3D geometry thinking by identifying different types of reasoning and to examine their relation with spatial ability. To achieve this goal, two tests were administered to students in grades 5 to 9. The results of the study showed that 3D geometry thinking could be described by four…

Pittalis, Marios; Christou, Constantinos

2010-01-01

38

A 3D Immersive Fault Visualizer and Editor  

NASA Astrophysics Data System (ADS)

Digital fault models are an important resource for the study of earthquake dynamics, fault-earthquake interactions and seismicity. Once digitized these fault models can be used in Finite Element Model (FEM) programs or earthquake simulations such as Virtual California (VC). However, these models are often difficult to create, requiring a substantial amount of time to generate the fault topology and compute the properties of the individual segments. To aid in the construction of such models we have developed an immersive virtual reality (VR) application to visualize and edit fault models. Our program is designed to run in a CAVE (walk-in VR environment), but also works in a wide range of other environments, including desktop systems and GeoWalls. It is being developed at the UC Davis W.M. Keck Center for Active Visualization in the Earth Sciences (KeckCAVES, http://www.keckcaves.org). Immersive VR environments are ideal for visualizing and manipulating three- dimensional data sets. Our program allows users to create new models or modify existing ones; for example by repositioning individual fault-segments, by changing the dip angle, or by modifying (or assigning) the value of a property associated with a particular fault segment (i.e. slip rate). With the addition of high resolution Digital Elevation Models (DEM) the user can accurately add new segments to an existing model or create a fault model entirely from scratch. Interactively created or modified models can be written to XML files at any time; from there the data may easily be converted into various formats required by the analysis software or simulation. We believe that the ease of interaction provided by VR technology is ideally suited to the problem of creating and editing digital fault models. Our software provides the user with an intuitive environment for visualizing and editing fault model data. This translates not only into less time spent creating fault models, but also enables the researcher to easily generate and maintain any number of models for use in ensemble analysis.

Yikilmaz, M. B.; van Aalsburg, J.; Kreylos, O.; Kellogg, L. H.; Rundle, J. B.

2007-12-01

39

Improved Scanning Geometry to Collect 3D-Geometry Data in Flat Samples  

SciTech Connect

3D integration through silicon technology of integrated circuits challenges non-destructive testing methods. 3D x-ray methods are the techniques of choice to localize defects in interconnects. The development of high-power x-ray sources enabled the use of x-ray microscopy in laboratory tools. Those devices are able to resolve features down to 40 nm in an acceptable measurement time. However, the field of view is very limited to 16 {mu}m in high-resolution mode and to 65 {mu}m in large-field-of-view mode. To record tomography data, the size of the samples must not exceed the field of view to circumvent specific artifacts. Semiconductor samples usually do not fulfill the condition mentioned above since they have the shape of flat sheets. Therefore limited-angle tomography is typically used. The missing angles cause typical capping artifacts and poor signal-to-noise ratio. We present a modified scanning geometry that overcomes some of the artifacts and yields a better image quality. The geometry and potential applications are presented in comparison to the traditional limited-angle tomography.

Krueger, P.; Niese, S.; Zschech, E. [Fraunhofer IZFP-D, Maria-Reiche-Str. 2, 01109 Dresden (Germany); Gelb, J.; Feser, M. [Xradia Inc., 5052 Commercial Circle, Concord, CA 94520 (United States)

2011-09-09

40

Four-Dimensional Descriptive Geometry Problems on 3-D Spaces.  

National Technical Information Service (NTIS)

The paper presents new solutions of five problems in four-dimensional descriptive geometry. These problems were briefly discussed in previous papers. The new solutions have already been used in papers preceding this one but were not fully examined. (Autho...

C. E. S. Lindgren

1965-01-01

41

Extension of the 3-D range migration algorithm to cylindrical and spherical scanning geometries  

Microsoft Academic Search

A near field three-dimensional (3-D) synthetic-aperture radar (SAR) algorithm specially tailored for cylindrical and spherical scanning geometries is presented. An imaging system with 3-D capability can be implemented by using a stepped-frequency radar which synthesizes a two-dimensional (2-D) aperture. Typical scanning geometries commonly used are planar, cylindrical, and spherical. The 3-D range migration algorithm (RMA) can be readily used with

Joaquim Fortuny-Guasch; Juan M. Lopez-Sanchez

2001-01-01

42

3D microstructural and microchemical characteristics of SAFOD fault gouge: implications for understanding fault creep  

NASA Astrophysics Data System (ADS)

Fault creep on the SAFOD section of the San Andreas Fault occurs along mechanically weak fault gouge characterized by high proportions of hydrous clay minerals, namely smectite, illite-smectite and chlorite-smectite phases. These minerals are concentrated along closely spaced, interconnected polished slip surfaces that give the gouge its characteristic scaly fabric. Although it is generally accepted that the creep behavior of the gouge relates to the concentration of these minerals, the precise mechanisms by which clay minerals weaken rock is currently a topic of debate. In this contribution we present the first results from a "slice-and-view" study of SAFOD gouge material by focused ion beam - scanning electron microscopy (Zeiss Auriga FIB/SEM), which allows the reconstruction of the microstructure and microchemistry of mineralized slip surfaces in 3D. The core and cuttings samples studied were selected from ca. 3297 m measured depth and represent some of the weakest materials yet recovered from the borehole, with a frictional coefficient of ca. 0.10 and a healing rate close to zero. This gouge contains abundant serpentine and smectite minerals, the latter of which was identified by X-ray diffraction to be saponite, after Mg- and glycol intercalation. Imaging and chemical analyses reveal nanometer scale thin alteration seams of saponite clay distributed throughout the ca. 50 micron thick sheared serpentinite layer that coats the slip surfaces. The base of this layer is defined by cataclastically deformed iron oxide minerals. The 3D fabric implies the orientation of the hydrated smectite minerals, which are interconnected and lie commonly sub parallel to the slip surface, are responsible for the gouge creep behavior in the laboratory. These minerals, and related interlayered varieties, are particularly weak due to their thin particle size and large quantities of adsorbed water, properties that are expected to persist down to mid-crustal depth (ca. 10 km). Creep of the San Andres Fault at Parkfield can therefore be adequately explained by the nature and abundance of smectite lattice layers that provide a nanometer-scale control on the mechanisms of fault behavior.

Warr, Laurence; Wojatschke, Jasmaria; Carpenter, Brett; Marone, Chris; Schleicher, Anja; van der Pluijm, Ben

2013-04-01

43

Thrust fault systems of the Nankai Trough accretionary wedge interpreted from 3-D seismic reflection images  

NASA Astrophysics Data System (ADS)

In 1999 we acquired a large volume of 3-D seismic reflection data to image the deformational structure of the Nankai Trough accretionary wedge that forms due to the subduction of the Philippine Sea plate beneath Japan. We imaged an 8 x 80 km2 area south of the Muroto Peninsula offshore Shikoku Island, southwestern Japan, from the trench across the seaward most 70 km of the accretionary wedge. These data have been processed with 3-D prestack time migration and in selected locations with 3-D prestack depth migration. The 3-D volume reveals complex thrust fault systems that have offset and displaced stratigraphic horizons at a range of scales from meters to kilometers. We identify four distinctive fault systems with increasing scale as: 1) small thrusts with lengths of 100 - 500 m and offsets of 10 - 100 m, many of these lie immediately adjacent and parallel to the primary accretionary wedge thrust system (#2 below) or are conjugate thrusts (backthrusts), 2) the primary thrusts of the accretionary wedge imbricate thrust system, which initiate at the deformation front and develop into 1 - 5 km long thrusts with displacements of 100 - 1000 m, 3) thrusts (out-of-sequence) that develop after the initial imbricate thrust system develops (#2 above), these are > 5 km long, have a shallower dip than the imbricate thrust system and intersect the imbricate thrust system, and 4) the main plate-boundary thrust, or décollement, that lies at the base of the accretionary wedge, which can be traced from its initiation at the trench to > 50 km down into the subduction zone. Each of these thrust systems controls the accretionary wedge tectonics and influences the structure of the accretionary wedge in both the dip and strike directions. We will present evidence to show how these fault systems affect wedge tectonics. We will also show that surprisingly, the wedge thrust activity reacts to the regional stress pattern created by recent seamount subduction, centered 50 km northeast of the survey area, as much or more than the localized stress conditions produced by changes in the geometry of the décollement or the top of the subducting oceanic crust.

Bangs, N. L.; Gulick, S. P.; Shipley, T. H.; Moore, G. F.

2004-12-01

44

High-resolution 3-D seismic reflection imaging of late Quaternary deformation in the shallow Alpine Fault Zone, New Zealand  

NASA Astrophysics Data System (ADS)

The Alpine Fault is a major continental transform fault that delineates the boundary of the Australian and Pacific plates across the South Island of New Zealand. Although the fault has not ruptured during the short ~ 200 yr history of European settlement, paleoseismic evidence shows it is capable of producing damaging (M > 7.5) earthquakes. To date, key physical and seismic properties of the fault, such as geometry, slip-rates, and dip, have been determined or inferred from surface outcrops, geomorphology, shallow boreholes, and/or trenches. High-resolution geophysical imaging at greater depths can extend and enhance interpretations of fault-zone structure and behaviour. We previously presented high-resolution 2-D and 3-D ground-penetrating radar images across a northern section of the fault that revealed multiple fault strands in the subsurface. We now describe the results of a high-resolution 3-D seismic survey to elucidate fault-zone structure to a depth of ~ 150 m. Careful tailored processing schemes were needed to address the following challenges presented by these data: i) significant static shifts caused by both topography and strong near-surface velocity heterogeneity, ii) substantial source-generated noise typical of very shallow seismic surveys, and iii) the imaging of complex, discontinuous, and dipping structures associated with the fault zone. We image a prominent reflection from the late Pleistocene basement surface that is juxtaposed on either side of the fault. Three-dimensional mapping of this surface reveals significant vertical offset (~ 35 m) across the main fault strand. In addition, distributed deformation within ~ 80 m of the main fault trace is evident in the form of normal fault drag on this surface. Joint interpretation of the GPR and seismic datasets allows the main fault strand and subsidiary faults within the overlying late Quaternary sediments to be traced from the near-surface to greater depth. The distribution of deformation across the shallow fault zone suggests greater slip at depth than that traditionally measured by offset of localised markers close to the surface.

Kaiser, A. E.; McClymont, A. F.; Green, A.; Horstmeyer, H.; Campbell, F. M.; Langridge, R. M.

2009-12-01

45

Using 3D Computer Graphics Multimedia to Motivate Preservice Teachers' Learning of Geometry and Pedagogy  

ERIC Educational Resources Information Center

This paper describes the genesis and purpose of our geometry methods course, focusing on a geometry-teaching technology we created using NVIDIA[R] Chameleon demonstration. This article presents examples from a sequence of lessons centered about a 3D computer graphics demonstration of the chameleon and its geometry. In addition, we present data…

Goodson-Espy, Tracy; Lynch-Davis, Kathleen; Schram, Pamela; Quickenton, Art

2010-01-01

46

Super Cooled Large Droplet Analysis of Several Geometries Using LEWICE3D Version 3  

NASA Technical Reports Server (NTRS)

Super Cooled Large Droplet (SLD) collection efficiency calculations were performed for several geometries using the LEWICE3D Version 3 software. The computations were performed using the NASA Glenn Research Center SLD splashing model which has been incorporated into the LEWICE3D Version 3 software. Comparisons to experiment were made where available. The geometries included two straight wings, a swept 64A008 wing tip, two high lift geometries, and the generic commercial transport DLR-F4 wing body configuration. In general the LEWICE3D Version 3 computations compared well with the 2D LEWICE 3.2.2 results and with experimental data where available.

Bidwell, Colin S.

2011-01-01

47

Modeling the effects of 3-D slab geometry and oblique subduction on subduction zone thermal structure  

NASA Astrophysics Data System (ADS)

In this study, we revisit the effects of along-strike variation in slab geometry and oblique subduction on subduction zone thermal structures. Along-strike variations in slab dip cause changes in the descending rate of the slab and generate trench-parallel pressure gradients that drive trench-parallel mantle flow (e.g., Kneller and van Keken, 2007). Oblique subduction also drives trench-parallel mantle flow. In this study, we use a finite element code PGCtherm3D and examine a range of generic subduction geometries and parameters to investigate the effects of the above two factors. This exercise is part of foundational work towards developing detailed 3-D thermal models for NE Japan, Nankai, and Cascadia to better constrain their 3-D thermal structures and to understand the role of temperature in controlling metamorphic, seismogenic, and volcanic processes. The 3-D geometry of the subducting slabs in the forearc and arc regions are well delineated at these three subduction zones. Further, relatively large compilations of surface heat flow data at these subduction zones make them excellent candidates for this study. At NE Japan, a megathrust earthquake occurred on March 11, 2011; at Nankai and Cascadia, there has been a great effort to constrain the scale of the next subduction thrust earthquake for the purpose of disaster prevention. Temperature influences the slip behavior of subduction faults by (1) affecting the rheology of the interface material and (2) controlling dehydration reactions, which can lead to elevated pore fluid pressure. Beyond the depths of subduction thrust earthquakes, the thermal structure is affected strongly by the pattern of mantle wedge flow. This flow is driven by viscous coupling between the subducting slab and the overriding mantle, and it brings in hot flowing mantle into the wedge. The trench-ward (up-dip) extent of the slab-mantle coupling is thus a key factor that controls the thermal structure. Slab-mantle decoupling at shallow depths causes mantle stagnation and a cool condition, which allows serpentinization to occur, whereas coupling at greater depths drives hot flowing mantle, providing the thermal condition required for melt generation in the mantle wedge. The flowing mantle also causes rapid heating of the subducting slab and affects the occurrence of intraslab earthquakes. In the generic model calculations in the study, we also investigate the effect of local fluctuations in the depth of decoupling-coupling transition on the 3-D mantle wedge flow pattern and thermal structure. Kneller, E.A., and P.E. van Keken (2008), Effect of three-dimensional slab geometry on deformation in the mantle wedge: Implications for shear wave anisotropy, Geochem. Geophys. Geosyst., 9, Q01003, doi:10.1029/2007GC001677.

Wada, I.; Wang, K.; He, J.

2013-12-01

48

On the geometry of an earthquake fault system  

Microsoft Academic Search

Invariants of a two-point correlation function of the seismic moment tensor were used to investigate an earthquake fault system. The geometry of the fault system is significantly different from the standard model of an earthquake fault, i.e. coherent rupture on a planar surface. Contrary to the `flat-fault' model, we see clear evidence for non-planarity of the fault system geometry, and

Y. Y. Kagan

1992-01-01

49

Automated geometry measurement of wheel rims based on optical 3D metrology  

Microsoft Academic Search

One of the economically most important branches is the automotive industry with their component suppliers. The high degree of automation in manufacturing processes, requires automated control and quality assurance equally. In this scope, we present a complex 3D measuring device, consisting of multiple optical 3D sensors, which is designed to capture the geometry of wheel rims. The principal challenge for

Christian Teutsch; Dirk Berndt; Nico Schmidt; Erik Trostmann

2006-01-01

50

Deformation around bends and stepovers of intracontinental strike-slip faults: Results of 3-D numerical modeling  

NASA Astrophysics Data System (ADS)

Bends and stepovers of strike slip faults are where transpressive mountain ranges or transtenstional basins are formed, and they are often the sites of termination, sometimes nucleation, of earthquake fault ruptures. Using a three-dimensional (3-D) visco-elasto-plastic finite element model, we are systematically investigating the 3-D stress fields and strain partitioning around bends and stopovers to better understand lithospheric deformation around these important geological features. We started with simplified stopovers and bends to illustrate the basic mechanics. For compressive stopovers, high shear stress is concentrated in the gap region, between the strike-slip faults. When the gap is wide (>75 km), plastic strain is localized in two narrow belts extending from the tips of the faults, indicating that the stepover may develop into subparallel faults. When the gap is narrow (<50 km), high plastic strain is localized between the gap, favoring formation of connecting faults and restraining bends. For dilatational stopovers, strain is localized in the gap region even when the gap is up to 100 km wide, hence wide releasing bends and pull-apart basins can be expected. When the connecting faults form to turn stopovers into bends, they generally enhance strain localization around the bends. The stress field and strain patterns around restraining bends and releasing bends vary with the geometry of the bends. In general, high shear stress is found in a broad band across the restraining bends, and strain is localized in two belts extending from the ends of the bend and sub-parallel to the strike-slip faults. For releasing bends, shear stress is generally low across the bends, strain can be localized within the bend with the effect of straightening the bends, and subsidence is often asymmetric. Applying these models to the Big Bend (a restraining bend) and the Salton Trough (a releasing bend), we show that the model results are generally consistent with observations.

Liu, M.; Wang, H.

2012-12-01

51

Polyscale, polymodal fault geometries: evolution and predictive capability  

NASA Astrophysics Data System (ADS)

The Late Permian Rangal coal measures on the edge of the Nebo synclinorium in the Bowen basin, NE Queensland, Australia, are cut by normal faults. Mining operations allow 13 faults to be mapped in some detail to depths of 200m. These faults cut Tertiary intrusions and a reverse fault as well as the coal seams, and show no obvious signs of reactivation. The steeply dipping faults are clustered into groups of two to four, separated by hundreds of meters. The faults trend ENE and NE; both trends of faults dip in both directions, defining a quadrimodal geometry. The odd axis construction for these faults suggests that vertical shortening was accompanied by horizontal extension along both principal directions of 153° and 063°. The mapped extents of the faults are limited by erosion and the depth to which the faults have been drilled, but displacement profiles along the lengths of the faults show maxima within the fault planes. The displacement profiles suggest that the currently mapped faults have similar lengths to the total preserved lengths of the faults, and that they will continue into the unmined ground to a limited, but predictable extent. The fault planes have a complex geometry, with segments of individual faults showing a similar variability in orientation to the ensemble of fault planes: the fault planes themselves are polymodal. Displacement profiles show a good correlation with segment orientation. An odd axis construction based on fault segments, rather than individual faults, gives principal extension directions within 4° of the above results. The variable orientation of fault segments, the correlation of the displacement profiles with fault orientation, and the similarity between the segment and ensemble fault kinematics suggest that the faults have evolved by propagation and linking of smaller polymodal faults in the same bulk strain field.ross section of polymodal fault at Hail Creek coal mine

Blenkinsop, T. G.; Carvell, J.; Clarke, G.; Tonelli, M.

2012-12-01

52

3-D Finite-Difference Simulation of Fault Zone Trapped Waves -Application to the Fault Zone Structure of the Mozumi-Sukenobu Fault, Central Japan-  

NASA Astrophysics Data System (ADS)

Fault zone trapped waves are thought to be a useful tool to reveal fine structure of the fault zone down to the seismogenic depth. 3D numerical simulation is necessary to determine the velocity and Q structures and geometry of the low velocity zone (LVZ) with relatively complex fault structure. In the present study, a program was coded for performing the 3D simulation of trapped waves. Then we computed the synthetics for fitting the real seismograms recorded by a linear seismometer array at the depth of 300m across the Mozumi-Sukenobu fault with explosion sources. We solved the equation of motion and stress-strain relation numerically in velocity-stress scheme by using the staggered-grid finite-difference method with a second-order approximation for the time derivative and fourth-order approximation for the spatial one. We used the free surface boundary condition for the earth_fs surface and absorbing boundary condition for the other model boundaries. The observations (Ito et al. 2001) were performed in the following two cases of the source location: (i) in the center of the LVZ and (ii) 100m outside from the boundary of the LVZ. The distances of sources and linear array were 2km and 4km for the both cases. The following features are noted from the observational results of the source distance 2km in the case (i): (a) Distinctive phases with a large amplitude appear about 0.2s after the first arrival especially for the fault zone-parallel component recorded in the LVZ. (b) Following the previous phase, wave trains with relative large amplitude can be clearly seen only for the seismograms in the LVZ. On the other hand, phase (a) and wave trains (b) are not clearly seen in the case (ii) where the source is outside the LVZ. To compare the observational results with the synthetics, we adopted a 200m-wide uniform LVZ with 40% velocity reduction comparing the P-waves of 4.5km/s and the S-waves of 2.7 km/s for the surrounding rock. For the case (i) in the fault zone-parallel component of synthetic seismograms in the LVZ, we could identify 3 major phases such as the fault zone head waves at the first arrival, direct P-wave arrival with large amplitude following the head waves, and then wave trains of the trapped waves with relative large amplitude. For the case (ii) the amplitudes of the direct P-wave and trapped waves become small compared with that for the case (i). These characteristics are sufficiently consistent with the observational results (a) and (b). This program is, thus, expected to be able to determine details of 3D complex fault zone structure.

Mamada, Y.; Kuwahara, Y.; Ito, H.; Takenaka, H.

2001-12-01

53

Restoration of original 3D sedimentary geometries in deformed basin fill supporting reservoir characterization  

NASA Astrophysics Data System (ADS)

A large progradational clastic system centred on Brunei Darussalam has been present on the NW Borneo margin since the early middle Miocene. This system has many sedimentary and structural similarities with major deltaic provinces such as the Niger and Nile. It differs from these systems by being affected in the hinterland by contemporaneous compressional tectonics. Uplift partially forced strong progradation of the clastic system, but also folded older deltaic units. Erosion and the exhumation of folded strata in the area of the Jerudong Anticline resulted in the exposure of large-scale prograding clinoforms and syn-sedimentary deltaic faults of middle Miocene age along a natural cross-section of several tens of kilometres in extent. Westward of the key outcrop sites on the Jerudong Anticline, the middle Miocene deltaic units are overlain by late Miocene, Pliocene and Quaternary clastics up to 3 kilometres thick. Both, the middle Miocene target units of this study as well as the late Miocene to recent overburden are recorded in the subsurface of the Belait Syncline on regional 2D seismic lines (total line length around 1400 km) and at 7 well locations. In this study, we integrate the available geophysical subsurface information with existing structural, sedimentological and geomorphological field data of the "classic" Jerudong Anticline exposures (e.g., Back et al. 2001, Morley et al. 2003, Back et al. 2005) into a static 3D surface-subsurface model that provides quantitative constraints on the structural and stratigraphic architecture of the Miocene Belait delta and the overlying units in three dimensions, supporting basin-scale as well as reservoir-scale analysis of the subsurface rock volume. Additionally, we use the static surface-subsurface model as input for a tectonic retro-deformation of the study area, in which the 3D paleo-relief of the middle Miocene Belait delta is restored by unfolding and fault balancing (Back et al. 2008). This kinematic reconstruction ultimately provides a detailed view into the stratal architecture of middle Miocene delta clinoforms, indicating a close relationship between delta-lobe activity, clinoform morphology, and the generation of slumps and turbidites. Literature BACK, S., MORLEY, C.K., SIMMONS, M.D. & LAMBIASE, J.J. (2001): Depositional environment and sequence stratigraphy of Miocene deltaic cycles exposed along the Jerudong anticline, Brunei Darussalam. - Journal of Sedimentary Research, 71: 915-923. BACK, S., TIOE HAK JING, TRAN XUAN THANG & MORLEY, C.K. (2005): Stratigraphic development of synkinematic deposits in a large growth-fault system, onshore Brunei Darussalam. - Journal of the Geological Society, London, 162: 243-258. BACK, S., STROZYK, F., KUKLA, P.A. & LAMBIASE, J.J. (2008): 3D restoration of original sedimentary geometries in deformed basin fill, onshore Brunei Darussalam, NW Borneo. Basin Research, 20: 99-117. MORLEY, C.K., BACK, S., VANRENSBERGEN, P., CREVELLO, P. & LAMBIASE, J.J. (2003): Characteristics of repeated, detached, Miocene -Pliocene tectonic inversion events, in a large delta province on an active margin, Brunei Darussalam, Borneo. - Journal of Structural Geology, 25: 1147-1169.

Back, S.

2009-04-01

54

Normal Fault-Related Surface Monoclines: 3-D Developmental Controls and Implications for Fault Evolution  

Microsoft Academic Search

Fault-related folds are usually described in sedimentary sequences but surface folds are also associated with normal faults in volcanic rocks erupted at divergent plate boundaries or in continental rift zones. At the active plate boundary in SW Iceland, normal fault traces in basalt lava flows are commonly marked at the surface by laterally continuous, narrow monoclinal flexures that formed above

N. D. Boersma; S. A. Kattenhorn

2006-01-01

55

KENO3D Visualization Tool for KENO V.a and KENO-VI Geometry Models  

SciTech Connect

Criticality safety analyses often require detailed modeling of complex geometries. Effective visualization tools can enhance checking the accuracy of these models. This report describes the KENO3D visualization tool developed at the Oak Ridge National Laboratory (ORNL) to provide visualization of KENO V.a and KENO-VI criticality safety models. The development of KENO3D is part of the current efforts to enhance the SCALE (Standardized Computer Analyses for Licensing Evaluations) computer software system.

Horwedel, J.E.; Bowman, S.M.

2000-06-01

56

3D radiation transport benchmark problems and results for simple geometries with void region  

Microsoft Academic Search

Three-dimensional (3D) transport benchmark problems for simple geometries with void region were proposed at the OECD\\/NEA in order to check the accuracy of deterministic 3D transport programs. The exact total fluxes by the analytical method are given for the pure absorber cases, and Monte Carlo values are given for the 50% scattering cases as the reference values. The total fluxes

Yasunobu Nagaya; Naoki Sugimura

2001-01-01

57

Constraints on 3D fault and fracture distribution in layered volcanic- volcaniclastic sequences from terrestrial LIDAR datasets: Faroe Islands  

NASA Astrophysics Data System (ADS)

Hydrocarbon reservoirs commonly contain an array of fine-scale structures that control fluid flow in the subsurface, such as polyphase fracture networks and small-scale fault zones. These structures are unresolvable using seismic imaging and therefore outcrop-based studies have been used as analogues to characterize fault and fracture networks and assess their impact on fluid flow in the subsurface. To maximize recovery and enhance production, it is essential to understand the geometry, physical properties, and distribution of these structures in 3D. Here we present field data and terrestrial LIDAR-derived 3D, photo-realistic virtual outcrops of fault zones at a range of displacement scales (0.001- 4.5 m) within a volcaniclastic sand- and basaltic lava unit sequence in the Faroe Islands. Detailed field observations were used to constrain the virtual outcrop dataset, and a workflow has been developed to build a discrete fracture network (DFN) models in GOCAD® from these datasets. Model construction involves three main stages: (1) Georeferencing and processing of LIDAR datasets; (2) Structural interpretation to discriminate between faults, fractures, veins, and joint planes using CAD software and RiSCAN Pro; and (3) Building a 3D DFN in GOCAD®. To test the validity of this workflow, we focus here on a 4.5 m displacement strike-slip fault zone that displays a complex polymodal fracture network in the inter-layered basalt-volcaniclastic sequence, which is well-constrained by field study. The DFN models support our initial field-based hypothesis that fault zone geometry varies with increasing displacement through volcaniclastic units. Fracture concentration appears to be greatest in the upper lava unit, decreases into the volcaniclastic sediments, and decreases further into the lower lava unit. This distribution of fractures appears to be related to the width of the fault zone and the amount of fault damage on the outcrop. For instance, the fault zone is thicker in the upper lava unit and therefore fracture concentration is higher, while in the lower lava unit, the fault zone is narrower and thus fracture concentration is also low. Both field observations and the DFN model indicate that the faults and fractures are steeper in the basalts, and shallower in the volcaniclastic sequences, giving a 'stepped' geometry. To assess the nature of sub-seismic fracturing, fracture attributes (connectivity, spacing, length, and orientation) within the model were analysed quantitatively. Continuing work will integrate the detailed field analysis fully, including 1D and 2D fracture transects, structural logging and mapping as well as microstructural characterisation from collected field samples, to understand the complex nature of fracture networks in inter-layered basalt-volcaniclastic sequences. Fracture attributes, such as the shape, length, aspect ratio, curvature and aperture, will be quantified to provide key parameters for fluid flow simulation. Once these attributes have been assessed, experimental data (porosity and permeability) will be incorporated into the DFN model to constrain the fluid flow potential within these inter-layered volcanic sequences.

Raithatha, Bansri; McCaffrey, Kenneth; Walker, Richard; Brown, Richard; Pickering, Giles

2013-04-01

58

Geometry and earthquake potential of the shoreline fault, central California  

USGS Publications Warehouse

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

Hardebeck, Jeanne L.

2013-01-01

59

Tracking strategies in 3D axial geometries for a MOC solver  

NASA Astrophysics Data System (ADS)

The solution of the neutron transport equation in 3D domains is a high resource demanding task. One of the most successful method of solution of this equation is the Method of Characteristics (MOC). However, the huge number of trajectories constitutes a serious issue in terms of memory needs and in terms of number of floating point operations. In this paper, we propose some techniques to compress tracking data and to speed up the MOC solver. These methods take advantage of regularities of 3D prismatic geometries. The new algorithms have been implemented in the 3D MOC solver TDT and applied to a typical UOx/MOx colorset.

Sciannandrone, Daniele; Santandrea, Simone

2014-06-01

60

Uncertainty assessment of imaging techniques for the 3D reconstruction of stent geometry.  

PubMed

This paper presents a quantitative assessment of uncertainty for the 3D reconstruction of stents. This study investigates a CP stent (Numed, USA) used in congenital heart disease applications with a focus on the variance in measurements of stent geometry. The stent was mounted on a model of patient implantation site geometry, reconstructed from magnetic resonance images, and imaged using micro-computed tomography (CT), conventional CT, biplane fluoroscopy and optical stereo-photogrammetry. Image data were post-processed to retrieve the 3D stent geometry. Stent strut length, separation angle and cell asymmetry were derived and repeatability was assessed for each technique along with variation in relation to ?CT data, assumed to represent the gold standard. The results demonstrate the performance of biplanar reconstruction methods is comparable with volumetric CT scans in evaluating 3D stent geometry. Uncertainty on the evaluation of strut length, separation angle and cell asymmetry using biplanar fluoroscopy is of the order ±0.2mm, 3° and 0.03, respectively. These results support the use of biplanar fluoroscopy for in vivo measurement of 3D stent geometry and provide quantitative assessment of uncertainty in the measurement of geometric parameters. PMID:24894028

Cosentino, Daria; Zwierzak, Iwona; Schievano, Silvia; Díaz-Zuccarini, Vanessa; Fenner, John W; Narracott, Andrew J

2014-08-01

61

Automated geometry measurement of wheel rims based on optical 3D metrology  

NASA Astrophysics Data System (ADS)

One of the economically most important branches is the automotive industry with their component suppliers. The high degree of automation in manufacturing processes, requires automated control and quality assurance equally. In this scope, we present a complex 3D measuring device, consisting of multiple optical 3D sensors, which is designed to capture the geometry of wheel rims. The principal challenge for automated measurements is the variety of rims with respect to design, dimensions and the production flow. Together with connected conveyers, the system automatically sorts good rims without interrupting the manufacturing process. In this work we consider three major steps. At first we discuss the application of the used 3D sensors and the underlying measuring principles for the 3D geometry acquisition. Therefore, we examine the hardware architecture, which is needed to fulfill the requirements concerning to the variety of shapes and to the measuring conditions in industrial environments. In the second part we focus on the automated calibration procedure to integrate and combine the data from the set of sensors. Finally, we introduce the algorithms for the 3D geometry extraction and the mathematical methods which are used for the data preprocessing and interpretation.

Teutsch, Christian; Berndt, Dirk; Schmidt, Nico; Trostmann, Erik

2006-11-01

62

3-D Combinatorial Geometry in the MERCURY Monte Carlo Particle Transport Code  

SciTech Connect

Lawrence Livermore National Laboratory is in the process of developing a new Monte Carlo Particle Transport code named MERCURY. This new code features a 3-D Combinatorial Geometry tracking algorithm. This paper details some of the characteristics of this Monte Carlo tracker

Greenman, G

2004-09-27

63

Effects of gouge fragment shape on fault friction: New 3D modeling results  

NASA Astrophysics Data System (ADS)

The friction of granular fault gouge - the material ripped off the rough walls of a fault during slip - plays an important role in governing the evolving mechanical behavior and hence earthquake potential of active faults. Using numerical modeling, significant progress has been made in recent years towards better understanding the micro-mechanical processes that drive fault gouge evolution. Despite these valuable insights however, many previous numerical models have predicted unrealistically low macroscopic frictional strength. We have developed modified 3D discrete element (DEM) simulations of fault gouge evolution. Our particle-based simulation, modeled on laboratory experiments of gouge shear, includes breakable elastic bonds between individual particles (or particle clusters) allowing fracture of aggregate grains that were initially composed of several thousand bonded particles. The use of particle clusters in our newest simulations ensures that the smallest ‘daughter’ fragments produced during comminution are non-spherical. With accumulated strain, the aggregate grains break up in different ways, gradually evolving in size and shape to produce a textural signature reminiscent of natural faults. Cluster-simulations that produce ‘pseudo-angular’ daughter fragments yield macroscopic frictional strength (0.6) comparable to that measured in laboratory experiments on realistic materials. Whereas, non-cluster simulations, producing both angular and spherical daughter fragments during gouge evolution, have much lower friction levels. We demonstrate that macroscopic friction is not sensitive to microscopic parameters (such as inter-grain friction). This suggests that gouge fragment shape and resulting geometrical interactions strongly control the frictional strength of faults.

Mair, K.; Abe, S.

2009-12-01

64

Discovery of previously unrecognised local faults in London, UK, using detailed 3D geological modelling  

NASA Astrophysics Data System (ADS)

In parts of London, faulting introduces lateral heterogeneity to the local ground conditions, especially where construction works intercept the Palaeogene Lambeth Group. This brings difficulties to the compilation of a ground model that is fully consistent with the ground investigation data, and so to the design and construction of engineering works. However, because bedrock in the London area is rather uniform at outcrop, and is widely covered by Quaternary deposits, few faults are shown on the geological maps of the area. This paper discusses a successful resolution of this problem at a site in east central London, where tunnels for a new underground railway station are planned. A 3D geological model was used to provide an understanding of the local geological structure, in faulted Lambeth Group strata, that had not been possible by other commonly-used methods. This model includes seven previously unrecognised faults, with downthrows ranging from about 1 m to about 12 m. The model was constructed in the GSI3D geological modelling software using about 145 borehole records, including many legacy records, in an area of 850 m by 500 m. The basis of a GSI3D 3D geological model is a network of 2D cross-sections drawn by a geologist, generally connecting borehole positions (where the borehole records define the level of the geological units that are present), and outcrop and subcrop lines for those units (where shown by a geological map). When the lines tracing the base of each geological unit within the intersecting cross-sections are complete and mutually consistent, the software is used to generate TIN surfaces between those lines, so creating a 3D geological model. Even where a geological model is constructed as if no faults were present, changes in apparent dip between two data points within a single cross-section can indicate that a fault is present in that segment of the cross-section. If displacements of similar size with the same polarity are found in a series of adjacent cross-sections, the presence of a fault can be substantiated. If it is assumed that the fault is planar and vertical, then the pairs of constraining data points in each cross-section form a two-dimensional envelope within which the surface trace of the fault must lie. Generally, the broader the area of the model, the longer the envelope defined by the pairs of boreholes is, resulting in better constraint of the fault zone width and azimuth. Repetition or omission of the local stratigraphy in the constraining boreholes can demonstrate reverse or normal dip-slip motion. Even if this is not possible, borehole intercepts at the base of the youngest bedrock unit or at the top of the oldest bedrock unit can constrain the minimum angle of dip of the fault plane. Assessment of the maximum angle of dip requires intrusive investigation. This work is distributed under the Creative Commons Attribution 3.0 Unported License together with an NERC copyright. This license does not conflict with the regulations of the Crown Copyright.

Aldiss, Don; Haslam, Richard

2013-04-01

65

3-D Ground Motion Modeling for M7 Dynamic Rupture Earthquake Scenarios on the Wasatch Fault, Utah  

NASA Astrophysics Data System (ADS)

The Salt Lake City (SLC) segment of the Wasatch fault (WF) forms the eastern edge of the Salt Lake Valley, populated by 1 million people and underlain by alluvial sediments. The WF is capable of producing M7 earthquakes and represents a serious hazard to SLC, Utah. There is a large uncertainty associated with the ground motions expected from such events, due in part to the lack of strong motion records from large normal-faulting earthquakes, and to possible amplification effects from basin focusing and source directivity. We address these uncertainties by performing a series of rupture simulations on the WF using realistic sources, a sophisticated geophysical model of the Salt Lake Basin (SLB) and a complex 3-D model of the SLC segment of the WF. We use the newly developed Wasatch front community velocity model (WFCVM) which consists of detailed site response units and shallow shear wave data atop rule-based representations of basins along the Wasatch front, all embedded in a 3-D crust derived from seismic tomography. The WFCVM is validated by simulating three recorded, local M_w 3.3--3.7 earthquakes. The simulated ground motions reproduce the amplitude and duration of the observations at most sites reasonably well from 0.5--1.0 Hz, suggesting that the WFCVM is sufficiently accurate to be used for ground motion estimation up to 1 Hz. The M7 earthquake scenarios make use of a detailed 3-D model geometry of the SLC segment of the WF that we developed based on geological observations. To obtain a suite of realistic source representations for M7 WF simulations we perform spontaneous-rupture simulations on a planar, 43 km by 23 km fault with the staggered-grid split-node finite difference method. The stress drop and friction parameters were based on probabilistic spectral laws derived from earthquake seismic records. The resulting M_w7 rupture scenarios have maximum surface slip ranging from 2.5 to 3.2 meters. The slip rate histories from the spontaneous rupture scenarios are projected onto the irregular dipping geometry of the SLC fault segment and used to simulate wave propagation in the SLB using a 4th-order, staggered-grid visco-elastic finite difference method. We assess the importance of amplification effects caused by the velocity contrast between the hanging-wall sedimentary basin and the stiffer footwall rocks, quantify the sensitivity of the simulated ground motion to the rupture propagation direction and examine the variability of the simulated peak ground velocities for several rupture scenarios.

Roten, D.; Olsen, K. B.; Pechmann, J. C.; Cruz-Atienza, V.; Magistrale, H.

2008-12-01

66

Geospatial modeling: A breakthrough 3-D technology for understanding complexly faulted geologic structures  

SciTech Connect

Today's geoscientists are required to find hydrocarbons in increasingly complicated geologic structures. These structures are usually faulted and contain complex geometric relationships. Their complexity requires modeling and mapping capabilities beyond traditional surface mapping tools. Geospatial modeling enables geoscientists to create models of complex geologic structures, calculate distributions of properties therein, visualize models in three dimensions, and analyze models through volumetric calculations. Faults and horizons are treated as individual surfaces in three-dimensional space. Fault relationships are controlled by hierarchies, and relationships between stratigraphic layers are specified by simple geologic rules. The following features can thus be accommodated: depositional layers; layers truncated by unconformities; layers cut by channels; channel in-fill; and salt diapirs. Although the resulting model is calculated from a fixed set of geological relationships, input data may change as data are added or existing interpretations altered, allowing for quick update. Property models may be calculated for each layer and/or each fault block. The three-dimensional property modeling utilizes fault and horizon surfaces as boundaries. Properties are correctly calculated near faults and show appropriate displacements across faults. Unique three-dimensionally consistent contour maps and cross sections are extracted from the models. The three-dimensional contouring process determines the spatial extent of layers, defines geometries of fault and unconformity truncation wedge zones, and accurately portrays fault gaps. Increased success is important in today's market. Geospatial modeling technology can address the sizeable problems facing geoscientists working with complexly faulted geologic structures, and can significantly increase overall understanding in a timely manner.

Hoffman, K.S. (Dynamic Graphics, Houston, TX (United States)); Belcher, R.C. (Dynamic Graphics, Inc., Denver, CO (United States))

1996-01-01

67

Articulated registration of 3D human geometry to X-ray image  

Microsoft Academic Search

A fully automatic 3D-2D articulated registration algorithm for aligning a whole-body human geometry to a 2D X-ray image is presented. Domain prior in the form of a hierarchi- cal model encapsulating the kinematic structure of the human body is exploited. A deformation operator is then defined with respect to the hierarchical model. An iterative search using ICP is performed to

Sang N. Le; Jayashree Karlekar; Anthony C. Fang

2008-01-01

68

3D simulation of near-fault strong ground motion: comparison between surface rupture fault and buried fault  

NASA Astrophysics Data System (ADS)

In this paper, near-fault strong ground motions caused by a surface rupture fault (SRF) and a buried fault (BF) are numerically simulated and compared by using a time-space-decoupled, explicit finite element method combined with a multi-transmitting formula (MTF) of an artificial boundary. Prior to the comparison, verification of the explicit element method and the MTF is conducted. The comparison results show that the final dislocation of the SRF is larger than the BF for the same stress drop on the fault plane. The maximum final dislocation occurs on the fault upper line for the SRF; however, for the BF, the maximum final dislocation is located on the fault central part. Meanwhile, the PGA, PGV and PGD of long period ground motions (?1 Hz) generated by the SRF are much higher than those of the BF in the near-fault region. The peak value of the velocity pulse generated by the SRF is also higher than the BF. Furthermore, it is found that in a very narrow region along the fault trace, ground motions caused by the SRF are much higher than by the BF. These results may explain why SRFs almost always cause heavy damage in near-fault regions compared to buried faults.

Liu, Qifang; Yuan, Yifan; Jin, Xing

2007-12-01

69

Preliminary simulation of a M6.5 earthquake on the Seattle Fault using 3D finite-difference modeling  

USGS Publications Warehouse

A three-dimensional finite-difference simulation of a moderate-sized (M 6.5) thrust-faulting earthquake on the Seattle fault demonstrates the effects of the Seattle Basin on strong ground motion in the Puget lowland. The model area includes the cities of Seattle, Bremerton and Bellevue. We use a recently developed detailed 3D-velocity model of the Seattle Basin in these simulations. The model extended to 20-km depth and assumed rupture on a finite fault with random slip distribution. Preliminary results from simulations of frequencies 0.5 Hz and lower suggest amplification can occur at the surface of the Seattle Basin by the trapping of energy in the Quaternary sediments. Surface waves generated within the basin appear to contribute to amplification throughout the modeled region. Several factors apparently contribute to large ground motions in downtown Seattle: (1) radiation pattern and directivity from the rupture; (2) amplification and energy trapping within the Quaternary sediments; and (3) basin geometry and variation in depth of both Quaternary and Tertiary sediments

Stephenson, William J.; Frankel, Arthur D.

2000-01-01

70

Efficient solutions for 3D frictional sliding problems on rough faults: implications for dilatant deformation  

NASA Astrophysics Data System (ADS)

Fluid flow in faults and fractures in many geologic settings and loading conditions depends on the roughness of the frictional sliding surfaces, which can lead to dilatant deformation during sliding and increase fracture permeability. Frictional sliding on quasi-statically deforming faults and fractures can be modeled efficiently using a linear complementarity formulation. We review the formulation for three-dimensional problems including problems of orthotropic friction. This formulation accounts for opening displacements that can occur near regions of non-planarity even under large confining pressures. Such problems are difficult to solve owing to the coupling of relative displacements and tractions; thus, many geomechanical problems tend to neglect these effects. Simple test cases highlight the importance of including friction and allowing for opening when solving quasi-static fault mechanics models, and accurately reproduce analytical solutions to static Coulomb friction sliding problems. We explore parametrically the influence of loading conditions (i.e. stress and pore pressure) and fault roughness to determine under what crustal conditions faults are likely to dilate. We find that opening can take place when faults are rough, in particular when faults exhibit anisotropic roughness, even under realistic in-situ stress states anticipated at depths down to 3km, possibly deeper depending on fault roughness. The efficiency of the solution allows variations in fault behavior, such as slip and opening, to be evaluated through systematic testing of the parameter space including the stress state, fault geometry, or friction. Since constraints on these properties are often limited and are the complex result of many structural and geochemical processes, such a sensitivity analysis provides an assessment of the uncertainty in the modeled parameters. These results underscore the importance of considering the effects of non-planarity in modeling processes associated with crustal faulting, i.e., fluid flow and the hydrothermal mineralization. These effects, in turn, influence fault strength, localization of slip, and the capability of faults to serve as fluid and heat conduits for oil, gas and geothermal energy resources, high-level waste disposal and CO2 sequestration.

Kaven, J. O.; Hickman, S.; Davatzes, N. C.; "fault mechanics", "dilatant deformation", "boundary element method", "linear complementarity"

2011-12-01

71

The 3-D world modeling with updating capability based on combinatorial geometry  

NASA Technical Reports Server (NTRS)

A 3-D world modeling technique using range data is discribed. Range data quantify the distances from the sensor focal plane to the object surface, i.e., the 3-D coordinates of discrete points on the object surface are known. The approach proposed herein for 3-D world modeling is based on the Combinatorial Geometry (CG) method which is widely used in Monte Carlo particle transport calculations. First, each measured point on the object surface is surrounded by a small sphere with a radius determined by the range to that point. Then, the 3-D shapes of the visible surfaces are obtained by taking the (Boolean) union of all the spheres. The result is an unambiguous representation of the object's boundary surfaces. The pre-learned partial knowledge of the environment can be also represented using the CG Method with a relatively small amount of data. Using the CG type of representation, distances in desired directions to boundary surfaces of various objects are efficiently calculated. This feature is particularly useful for continuously verifying the world model against the data provided by a range finder, and for integrating range data from successive locations of the robot during motion. The efficiency of the proposed approach is illustrated by simulations of a spherical robot in a 3-D room in the presence of moving obstacles and inadequate prelearned partial knowledge of the environment.

Goldstein, M.; Pin, F. G.; Desaussure, G.; Weisbin, C. R.

1987-01-01

72

Active fault geometry and kinematics in Parnitha Mountain, Attica, Greece  

Microsoft Academic Search

The Parnitha mountain range lies between two Quaternary rift systems in central Greece: the Gulf of Corinth Rift and the Gulf of Evia rift. We suggest that the range was formed by footwall uplift on active normal faults striking WNW–ESE and NE–SW. We investigated the scarp appearance, geometry and slip rates of three normal faults bounding this mountain range by

A. Ganas; S. B. Pavlides; S. Sboras; S. Valkaniotis; S. Papaioannou; G. A. Alexandris; A. Plessa; G. A. Papadopoulos

2004-01-01

73

Mapping 3-D functional capillary geometry in rat skeletal muscle in vivo  

PubMed Central

We have developed a novel mapping software package to reconstruct microvascular networks in three dimensions (3-D) from in vivo video images for use in blood flow and O2 transport modeling. An intravital optical imaging system was used to collect video sequences of blood flow in microvessels at different depths in the tissue. Functional images of vessels were produced from the video sequences and were processed using automated edge tracking software to yield location and geometry data for construction of the 3-D network. The same video sequences were analyzed for hemodynamic and O2 saturation data from individual capillaries in the network. Simple user-driven commands allowed the connection of vessel segments at bifurcations, and semiautomated registration enabled the tracking of vessels across multiple focal planes and fields of view. The reconstructed networks can be rotated and manipulated in 3-D to verify vessel connections and continuity. Hemodynamic and O2 saturation measurements made in vivo can be indexed to corresponding vessels and visualized using colorized maps of the vascular geometry. Vessels in each reconstruction are saved as text-based files that can be easily imported into flow or O2 transport models with complete geometry, hemodynamic, and O2 transport conditions. The results of digital morphometric analysis of seven microvascular networks showed mean capillary diameters and overall capillary density consistent with previous findings using histology and corrosion cast techniques. The described mapping software is a valuable tool for the quantification of in vivo microvascular geometry, hemodynamics, and oxygenation, thus providing rich data sets for experiment-based computational models.

Milkovich, Stephanie; Goldman, Daniel; Ellis, Christopher G.

2012-01-01

74

Characterization of landslide geometry using 3D seismic refraction traveltime tomography  

NASA Astrophysics Data System (ADS)

The geometry of the bedrock, internal layers and shear surfaces/bands controls the deformation pattern and the mechanisms of landslides. A challenge to progress in the forecast of landslide acceleration in terms of early-warning is therefore to characterize the 3D geometry of the unstable mass at a high level of spatial resolution, both in the horizontal and vertical directions, by integrating information from different surveying techniques. For such characterization, seismic investigations are potentially of a great interest. In the case of complex structures, the measure and the processing of seismic data need to be performed in 3D. The objective of this work is to present the implementation of a 3D seismic refraction traveltime tomography technique based on an existing 2D Simultaneous Iterative Reconstruction Technique (SIRT). First the processing algorithm is detailed and its performance is discussed, and second an application to the La Valette complex landslide is presented. Inversion of first-arrival traveltimes produces a 3D tomogram that underlines the presence of many areas characterized by low P-wave velocity of 500-1800 m.s-1. These low P-wave velocity structures result from the presence of reworked blocks, surficial cracks and in-depth fracture zones. These structures seem to extend to around 25 m in depth over a 80 x 130 m area. Based on borehole geotechnical data and previous geophysical investigations, an interface corresponding to an internal slip surface can be suspected near the isovalue of 1200 m.s-1 at a depth of -10 to -15 m. The stable substratum is characterized by higher values of P-wave velocity of 1800-3000 m.s-1. The features identified in the 3D tomogram allow to better (1) delineate the boundary between the landslide and the surrounding stable slopes, and (2) understand the morphological structures within the landslide at a hectometric scale. The integration of the 3D seismic tomography interpretation to previous geophysical acquisitions using a geostatistical approach allows to construct a 3D geometrical model of the middle and lower part of the La Valette landslide, and to estimate the volume of the unstable mass.

Samyn, K.; Travelletti, J.; Bitri, A.; Grandjean, G.; Malet, J. P.

2012-04-01

75

3d Mechanical Modeling of The Seismic Cycle Along The North Anatolian Fault  

NASA Astrophysics Data System (ADS)

The North Anatolian fault (NAF) is part of a complex tectonic setting that extends over 2000 km, and is one of the most seismically active continental regions of the world with a long and well documented history of earthquakes. It thus constitutes an ideal natural laboratory for the study of earthquake cycles along a major fault system. Using the 3D finite element code ADELI (Hassani et al. 1997) we model the seismic cycle along the NAF and we investigate the influence of the rheology of the lithosphere on postseimic deformation. Fault motion is controlled by a Coulomb type friction, and the rheology of the lithosphere is composed of a frictional upper crust and a viscoelas- tic lower crust and mantle. The lithosphere is supported by a hydrostatic pressure at its base (representing the underlying asthenosphere). In a first step we developed a model of the long term deformation of the surroundings of the fault system by adjusting fric- tional and viscous parameters that control the resulting velocity and stress fields in the deforming Anatolian model. We compare the results thus obtained with geodetic measurements (i.e. McClusky et al., 2000) and tectonic observations to define a real- istic long term model. A second step consist of modeling the seismic cycle in itself. We simulate successive earthquakes on the NAF by varying friction over time. Doing so we introduce a finite dislocation on the surface of the fault at a certain period of the deformation process, representing the occurrence of the earthquake. We chose to illustrate the postseismic response to the solicitation imposed on the fault system by the 1939 event, for different types of rheology obtained in the first step.

Provost, A.-S.; Chéry, J.

76

Fractal geometry of sedimentary rocks: simulation in 3-D using a Relaxed Bidisperse Ballistic Deposition Model  

NASA Astrophysics Data System (ADS)

Several studies, both theoretical and experimental, show that sedimentary rocks have a fractal pore-grain interface. In this paper a computer simulated 3-D sedimentary rock structure generated by the Relaxed Ballistic Bidisperse Deposition Model (RBBDM), is investigated to characterize the micro structure of its pores. The pore volume and the rock-pore interface show the same fractal dimension indicating that the pore volume is a fractal. The two point density correlation is computed for the pore space and the results compare favourably with the range reported from experiments. An array of 2-D X-ray tomography micrograph sections of a real sedimentary rock, an oolitic limestone (pure calcite) from the Mondeville formation of Middle Jurassic age (Paris Basin, France), was used to generate a 3-D bitmap. The 3-D real rock sample generated in this manner, was analysed for similar studies as the simulated structure. The results were compared with those obtained from simulation. The simulation results agree qualitatively with the real rock sample. Diffusion through the connected pore space of the simulated structure was studied using a random walk algorithm and the results compared with the similar simulation study done on the 3-D oolitic limestone specimen. In both cases diffusion was found to be anomalous indicating that the sedimentary rock has a fractal geometry. The favourable comparability of results between the simulated and real rock supports the usefulness of the model of sedimentary rock generation which can be applicable to transport phenomena.

Giri, Abhra; Tarafdar, Sujata; Gouze, Philippe; Dutta, Tapati

2013-03-01

77

Color Constancy Using 3D Scene Geometry Derived From a Single Image.  

PubMed

The aim of color constancy is to remove the effect of the color of the light source. As color constancy is inherently an ill-posed problem, most of the existing color constancy algorithms are based on specific imaging assumptions (e.g., gray-world and white patch assumption). In this paper, 3D geometry models are used to determine which color constancy method to use for the different geometrical regions (depth/layer) found in images. The aim is to classify images into stages (rough 3D geometry models). According to stage models, images are divided into stage regions using hard and soft segmentation. After that, the best color constancy methods are selected for each geometry depth. To this end, we propose a method to combine color constancy algorithms by investigating the relation between depth, local image statistics, and color constancy. Image statistics are then exploited per depth to select the proper color constancy method. Our approach opens the possibility to estimate multiple illuminations by distinguishing nearby light source from distant illuminations. Experiments on state-of-the-art data sets show that the proposed algorithm outperforms state-of-the-art single color constancy algorithms with an improvement of almost 50% of median angular error. When using a perfect classifier (i.e, all of the test images are correctly classified into stages); the performance of the proposed method achieves an improvement of 52% of the median angular error compared with the best-performing single color constancy algorithm. PMID:25051548

Elfiky, Noha; Gevers, Theo; Gijsenij, Arjan; Gonzalez, Jordi

2014-09-01

78

3D Digital Surveying and Modelling of Cave Geometry: Application to Paleolithic Rock Art  

PubMed Central

3D digital surveying and modelling of cave geometry represents a relevant approach for research, management and preservation of our cultural and geological legacy. In this paper, a multi-sensor approach based on a terrestrial laser scanner, a high-resolution digital camera and a total station is presented. Two emblematic caves of Paleolithic human occupation and situated in northern Spain, “Las Caldas” and “Peña de Candamo”, have been chosen to put in practise this approach. As a result, an integral and multi-scalable 3D model is generated which may allow other scientists, pre-historians, geologists…, to work on two different levels, integrating different Paleolithic Art datasets: (1) a basic level based on the accurate and metric support provided by the laser scanner; and (2) a advanced level using the range and image-based modelling.

Gonzalez-Aguilera, Diego; Munoz-Nieto, Angel; Gomez-Lahoz, Javier; Herrero-Pascual, Jesus; Gutierrez-Alonso, Gabriel

2009-01-01

79

3D Digital Surveying and Modelling of Cave Geometry: Application to Paleolithic Rock Art.  

PubMed

3D digital surveying and modelling of cave geometry represents a relevant approach for research, management and preservation of our cultural and geological legacy. In this paper, a multi-sensor approach based on a terrestrial laser scanner, a high-resolution digital camera and a total station is presented. Two emblematic caves of Paleolithic human occupation and situated in northern Spain, "Las Caldas" and "Peña de Candamo", have been chosen to put in practise this approach. As a result, an integral and multi-scalable 3D model is generated which may allow other scientists, pre-historians, geologists…, to work on two different levels, integrating different Paleolithic Art datasets: (1) a basic level based on the accurate and metric support provided by the laser scanner; and (2) a advanced level using the range and image-based modelling. PMID:22399958

González-Aguilera, Diego; Muñoz-Nieto, Angel; Gómez-Lahoz, Javier; Herrero-Pascual, Jesus; Gutierrez-Alonso, Gabriel

2009-01-01

80

Crustal Rheology and Long Term Displacement Along the North Anatolian Fault, Turkey, by 3D Modeling  

NASA Astrophysics Data System (ADS)

The North Anatolian fault (NAF) is part of a complex tectonic setting that extends over 2000 km. In this region of Eastern Mediterranean, the collision of the Arabian, African and Eurasian plates resulted in creation of mountain ranges (i.e., Zagros, Caucasus) and the westward extrusion of the Anatolian block. In this study we investigate the effects of crustal rheology on the long term displacement rate along the NAF. Heat flow and geodesy data were used to constrain our mechanical model, built with the three-dimensional finite element code ADELI (Hassani et al., 1997). Fault motion is controlled by a Coulomb type friction and the rheology of the lithosphere is composed of a frictional upper crust and a viscoelastic lower crust and mantle. The lithosphere is supported by a hydrostatic pressure at its base (representing the asthenosphere). We have developed a model of the long term deformation of the surroundings of the North Anatolian fault by adjusting rheological parameters that control the resulting velocity and stress fields. To do so we used a frictional range of 0.0 to 0.2 for the fault, and a viscosity varying between 1019 and 1021 Pa.s. By comparing our results with geodetic measurements (McClusky et al, 2000) and tectonic observations, we have defined a realistic model in which the displacement rate on the North Anatolian fault reaches 20 mm/yr for a viscosity of 1019 Pa.s and a fault friction of 0.05. One of the most striking results of our rheological tests is that the fault is locked if the friction reaches 0.2, making it a weak fault like the San Andreas fault in California. After adding topography with its corresponding crustal root, gravity flow appears south of the fault in central Anatolia, and the westward velocity of the Anatolian block is reduced in the Eastern regions. Because of a simplification of the geometry of the NAF in our model, we find a poor agreement between our calculated velocity field and what is observed with GPS in the Marmara and the Aegean regions. Indeed, the main trace of the NAF splits at least into two branches in the region of Marmara and dies off in the tensional Aegean region. Taking into account the weaknesses of these deforming regions should allow us to build a more realistic model that would match ground observations more appropriately. On the other hand our results fit well GPS measurements in central Anatolia, setting the basis of modeling crustal rheology in Turkey.

Provost, A.; Chery, J.; Hassani, R.

2002-12-01

81

Systemes d'acquisition d'une geometrie 3D - Essai a la centrale de Chooz B. (3D - Acquisition systems - test in Chooz B nuclear plant).  

National Technical Information Service (NTIS)

EDF needs 3D-acquisition systems to get the precise geometry of critical nuclear spaces in order to prepare computer simulations of operations in these areas. The simulations must lead to an increase of the efficiency of the operation. The acquisition of ...

B. Brillault G. Thibault

1992-01-01

82

Waveform tomography in 2.5-D to appropriately handle 3-D geometry  

NASA Astrophysics Data System (ADS)

In order to improve the tractability of waveform tomography when applied to field data acquired along a crooked-line, we implement 2.5-D forward modeling and inversion. Waveform tomography combines conventional velocity-model building (i.e. tomography) with full-waveform inversion to reconstruct an image of subsurface acoustic velocity. For reasons of computational efficiency, it is desirable to use 2-D full-waveform inversion when processing data acquired with 2-D seismic survey geometry. However, crooked-line acquisition results in a cross-line component of the source-receiver offset that cannot be accounted for by 2-D forward modeling. If the cross-line geometry components are significant, full-waveform inversion may be intractable. To address the latter difficulty, we first apply 3-D traveltime tomography to generate a 2-D cross-sectional initial velocity model by taking a representative average slice through the 3-D model. Then this initial model from traveltime inversion is iteratively updated by 2.5-D full-waveform inversion using a frequency-domain viscoacoustic implementation. The 2.5-D method generates waveform data by combining the solutions of multiple 2-D wave equation components. Each wavefield represents the solution of a modified wave equation in which the cross-line wavenumber takes a value between zero and ~?/c. The results are combined by inverse Fourier transform in the cross-line coordinate. This produces a synthetic wavefield that is a solution to the 3-D viscoacoustic wave equation in a 2-D velocity model. Consequently, the 2.5-D synthetic wavefield better approximates seismic field data (including crooked-line geometry), when compared to a 2-D synthetic result. Cross-line source-receiver offsets can be accounted for by reconstructing the wavefield out-of-plane with respect to the source. The amplitude and phase of the wavefield are consistent with a 3-D solution in a model that is homogeneous in one direction. The 2-D model is ideally aligned along the seismic survey line to minimize cross-line offsets, since this method does not incorporate cross-line model variation. A synthetic result highlights the benefits of this method of full-waveform inversion. A real-data comparison is presented to contrast this result with an approach using a static correction for geometry followed by the more usual 2-D full-waveform inversion. When 3-D geometry is present on the seismic acquisition line, this newly developed 2.5-D method yields improved results over 2-D full-waveform inversion. In addition, the 2.5-D method is substantially less expensive computationally than full 3-D full-waveform inversion applied to 2-D crooked-line acquisition.

Smithyman, B.; Clowes, R. M.

2011-12-01

83

CasimirSim - A Tool to Compute Casimir Polder Forces for Nontrivial 3D Geometries  

SciTech Connect

The so-called Casimir effect is one of the most interesting macro-quantum effects. Being negligible on the macro-scale it becomes a governing factor below structure sizes of 1 {mu}m where it accounts for typically 100 kN m-2. The force does not depend on gravity, or electric charge but solely on the materials properties, and geometrical shape. This makes the effect a strong candidate for micro(nano)-mechanical devices M(N)EMS. Despite a long history of research the theory lacks a uniform description valid for arbitrary geometries which retards technical application. We present an advanced state-of-the-art numerical tool overcoming all the usual geometrical restrictions, capable of calculating arbitrary 3D geometries by utilizing the Casimir Polder approximation for the Casimir force.

Sedmik, Rene; Tajmar, Martin [ARC Seibersdorf research Gmbh, Business field Space Propulsion, A-2444 Seibersdorf (Austria)

2007-01-30

84

The internal geometry of salt structures - A first look using 3D seismic data from the Zechstein of the Netherlands  

NASA Astrophysics Data System (ADS)

We present a first look at the large-scale, complexly folded and faulted internal structure of Zechstein salt bodies in NW Europe using 3D reflection seismic reflection data from two surveys on the Groningen High and the Cleaver Bank High. We focus on a relatively brittle, folded and boudinaged, claystone-carbonate-anhydrite layer (the Z3 stringer) enclosed in ductile salt. A first classification of the structures is presented and compared with observations from salt mines and analogue and numerical models. Z3 stringers not only are reservoirs for hydrocarbons but can also present a serious drilling problem in some areas. Results of this study could provide the basis for better prediction of zones of drilling problems. More generally, the techniques presented here can be used to predict the internal structure of salt bodies, to estimate the geometry of economic deposits of all kinds and locate zones suitable for storage caverns. Structures observed include an extensive network of zones with increased thickness of the stringer. These we infer to have formed by early diagenesis, karstification, gravitational sliding and associated local sedimentation. Later, this template was deformed into large-scale folds and boudins during salt tectonics. Salt flow was rarely plane strain, producing complex fold and boudin geometries. Deformation was further complicated by the stronger zones of increased thickness, which led to strongly non-cylindrical structures. We present some indications that the thicker zones also influence the locations of later suprasalt structures, suggesting a feedback between the early internal evolution of this salt giant and later salt tectonics. This study opens the possibility to study the internal structure of the Zechstein and other salt giants in 3D using this technique, exposing a previously poorly known structure which is comparable in size and complexity to the internal parts of some orogens.

Van Gent, Heijn; Urai, Janos L.; de Keijzer, Martin

2011-03-01

85

3D analysis of geometry and flow changes in a limestone fracture during dissolution  

NASA Astrophysics Data System (ADS)

SummaryThe effects of reactive transport on fracture geometry and fluid flow were investigated through an integrated experimental and modelling approach. A fractured limestone sample (90% calcite) was injected with an acidic CO2-rich solution over a period of 55 h to induce carbonate dissolution. The changes in fracture geometry and related parameters are reported for six data sets obtained from synchrotron X-ray micro-tomography experiments. A series of algorithms was used to extract the aperture and fracture walls from 3D images and allowed quantification of the geometry changes with an optical resolution of 4.91 ?m. In addition, measurement of fluid chemistry, hydraulic tests and computation of Navier-Stokes flow constrained the characterisation of the dissolution process. The effects of reactive transport on fracture geometry and fluid flow were then discussed. The presence of silicates in the rocks led to heterogeneous dissolution at the micro-scale, despite dissolution appearing to be quite homogeneous at sample-scale. No formation of preferential flow pathways was noticed, although heterogeneous dissolution at the micro-scale led to fracture walls and aperture decorrelation, and to modification of the flow velocity profiles in the fracture.

Noiriel, Catherine; Gouze, Philippe; Madé, Benoît

2013-04-01

86

Are climate signals observed in the 3-D ice surface geometry of mountain glaciers?  

NASA Astrophysics Data System (ADS)

Mountain glaciers are among the fastest responding components of the cryosphere to climatic perturbations and are thus an essential parameter in climate system monitoring. The intrinsic link between glacier mass balance and the organisation of ice flow vectors result in a situation where glacier surface profiles tend towards differing geometries in the accumulation and ablation area. These differing geometries can be readily explained, as a function of the mass balance budget, by principles of continuum mechanics and the need for glaciers to conserve mass. However, little work has been done to provide empirical evidence to link these distinct changes in ice surface geometry with observed glacier climate signals such as ELA and mass balance. With the use of remotely sensed optical imagery, global DEM datasets and geospatial methods, we present empirical observations that assess the extent to which ice surface morphology reflects the current state of mountain glaciers in a changing climate. Despite the complex relationship between mass balance, ice flow dynamics and climate, the findings suggest that observations of 3-D ice surface geometry may provide significant insights into how glaciers are responding to climate perturbations.

Hayes, R.; Clark, C.

2013-12-01

87

Development of an algorithm to measure defect geometry using a 3D laser scanner  

NASA Astrophysics Data System (ADS)

Current fatigue life prediction models for coiled tubing (CT) require accurate measurements of the defect geometry. Three-dimensional (3D) laser imaging has shown promise toward becoming a nondestructive, non-contacting method of surface defect characterization. Laser imaging provides a detailed photographic image of a flaw, in addition to a detailed 3D surface map from which its critical dimensions can be measured. This paper describes algorithms to determine defect characteristics, specifically depth, width, length and projected cross-sectional area. Curve-fitting methods were compared and implicit algebraic fits have higher probability of convergence compared to explicit geometric fits. Among the algebraic fits, the Taubin circle fit has the least error. The algorithm was able to extract the dimensions of the flaw geometry from the scanned data of CT to within a tolerance of about 0.127 mm, close to the tolerance specified for the laser scanner itself, compared to measurements made using traveling microscopes. The algorithm computes the projected surface area of the flaw, which could previously only be estimated from the dimension measurements and the assumptions made about cutter shape. Although shadows compromised the accuracy of the shape characterization, especially for deep and narrow flaws, the results indicate that the algorithm with laser scanner can be used for non-destructive evaluation of CT in the oil field industry. Further work is needed to improve accuracy, to eliminate shadow effects and to reduce radial deviation.

Kilambi, S.; Tipton, S. M.

2012-08-01

88

Dynamic Rupture of Shallow 3D Dipping Fault Earthquakes Using a New BIEM Technique for Half-Space Medium  

NASA Astrophysics Data System (ADS)

We developed a new rupture dynamics numerical method to model the spontaneous seismic rupture propagation along a non-planar fault plane in a homogeneous 3D half-space. We examined its accuracy and limitation using different numerical computation techniques. We applied this technique to a real earthquake case. We reconstructed the dynamic rupture of the 2008 Iwate-Miyagi earthquake, Japan (Mw6.9). We use the Boundary Integral Equation Method (BIEM) with triangular elements to compute the rupture dynamics (Fukuyama et al., 2002, AGU). The triangular elements allow us to include any kind of non-planar geometries of the fault, such as kinks, curvatures, segments, topography, etc. Instead of using half-space Green’s functions (Zhang and Chen, 2006, GJI), we employed the full space Green’s functions (Tada, 2006, GJI). We introduced explicitly the free surface elements to achieve the traction free condition. We performed several validation tests to evaluate the accuracy and limitations of our code. The 3D kernels have been successfully validated with a Finite-Difference code (Favreau and Archuleta, 2003, GRL). The final static displacement at the free surface perfectly matches the Okada's solution (Okada, 1992, BSSA). Finally, the ground motions on the free surface reasonably match the solution obtained using a discrete wavenumber method (Coutant, 1989). We applied this method to the 2008 Iwate-Miyagi (Japan) earthquake, which is famous for a 4G PGA record. We used a two steps procedure. First, we computed the spontaneous rupture of this dip-slip thrust fault earthquake, using a kinematic model (Suzuki et al., 2008, AGU) as a constraint on the stress changes on the fault. A constitutive friction law is then obtained for each point of the fault, and is used as the initial parameter to compute the spontaneous dynamic rupture, at the second step. Then we computed the spontaneous rupture using the parameters obtained in the first step. We found that the rupture velocity was not constant in the main asperity, and observed the influence of the free surface interaction on the slip occurring at the shallower part of the fault. The stress drop has been found to rather large, between 30-60MPa in the main asperity region, up to 80MPa in the shallower part, due to high slip (~6m) close to the free surface, associated with a strong tapering. There are no reports from the field survey that the surface ruptured more than 3m. Such a large stress drop at very shallow depth (the top of the fault is set at 715m below the surface in the fault model) is an interesting target to be interpreted. In the modelling, we needed to assume high initial stress conditions, setting loading shear stress to 84MPa and normal stress to 110MPa. In these conditions, we did not obtain any rake rotations, while unclamping occured up to -15MPa in the shallower 2km of the asperity patch. In the asperity, the strength excess was found to range between 5-15MPa, while the fracture energy is ranging 30-60MJ/m2. The latter is one order of magnitude higher than those reported for other earthquakes.

Hok, S.; Fukuyama, E.

2009-12-01

89

Bispectrum feature extraction of gearbox faults based on nonnegative Tucker3 decomposition with 3D calculations  

NASA Astrophysics Data System (ADS)

Nonnegative Tucker3 decomposition(NTD) has attracted lots of attentions for its good performance in 3D data array analysis. However, further research is still necessary to solve the problems of overfitting and slow convergence under the anharmonic vibration circumstance occurred in the field of mechanical fault diagnosis. To decompose a large-scale tensor and extract available bispectrum feature, a method of conjugating Choi-Williams kernel function with Gauss-Newton Cartesian product based on nonnegative Tucker3 decomposition(NTD_EDF) is investigated. The complexity of the proposed method is reduced from o( n N lg n) in 3D spaces to o( R 1 R 2 nlg n) in 1D vectors due to its low rank form of the Tucker-product convolution. Meanwhile, a simultaneously updating algorithm is given to overcome the overfitting, slow convergence and low efficiency existing in the conventional one-by-one updating algorithm. Furthermore, the technique of spectral phase analysis for quadratic coupling estimation is used to explain the feature spectrum extracted from the gearbox fault data by the proposed method in detail. The simulated and experimental results show that the sparser and more inerratic feature distribution of basis images can be obtained with core tensor by the NTD_EDF method compared with the one by the other methods in bispectrum feature extraction, and a legible fault expression can also be performed by power spectral density(PSD) function. Besides, the deviations of successive relative error(DSRE) of NTD_EDF achieves 81.66 dB against 15.17 dB by beta-divergences based on NTD(NTD_Beta) and the time-cost of NTD_EDF is only 129.3 s, which is far less than 1 747.9 s by hierarchical alternative least square based on NTD (NTD_HALS). The NTD_EDF method proposed not only avoids the data overfitting and improves the computation efficiency but also can be used to extract more inerratic and sparser bispectrum features of the gearbox fault.

Wang, Haijun; Xu, Feiyun; Zhao, Jun'ai; Jia, Minping; Hu, Jianzhong; Huang, Peng

2013-11-01

90

3D Image Tour of the Hayward Fault in the East Bay, San Francisco Bay Region, California  

NASA Astrophysics Data System (ADS)

A 3D image tour of the Hayward Fault begins at its northern land-based terminus at Point Pinole from where it continues northward under the waters of San Pablo Bay. From Point Pinole, the Hayward Fault extends southward for about 90 kilometers through the urbanized landscape of the East Bay region, passing through the cities of Richmond, Berkeley, Oakland, San Leandro, Hayward, Fremont, and other communities. At its southern end, the fault forms a series of oblique reverse faults, but at depth it connects with the Calaveras Fault as a through-going structure along the western foothills of the Diablo Range east of the greater San Jose area. This presentation focuses on access to the Hayward Fault in public places where features impacted by active fault creep can be viewed. Features include offset curbs, fractures in sidewalks, parking areas, buildings, and damage to other infrastructure in the active fault zone. Additional images highlight landscape features and historic landmarks along the fault, including those that were impacted by the 1868 Hayward earthquake, and those that were or were engineered both with and without consideration of the location of the fault. Earthquake data and geologic interpretations of the subsurface along the fault zone are also presented. This presentation, and an associated website, is for educational audiences with the intent of promoting public awareness and earthquake preparedness. This work is part of the ongoing outreach and public education efforts by the U.S. Geological Survey in cooperation with the 1868 Hayward Earthquake Alliance in anticipation of the 140th anniversary of the great earthquake. The use of 3D imagery enhances the educational value of the presentation and provides a unique perspective on the subject matter. Red-and-cyan 3D viewing glasses will be available at the presentation.

Stoffer, P.

2007-12-01

91

Rapid, accurate improvement in 3D mask representation via input geometry optimization and crosstalk  

NASA Astrophysics Data System (ADS)

This paper extends the state of the art by demonstrating performance improvements in the Domain Decomposition Method (DDM) from a physical perturbation of the input mask geometry. Results from four testcases demonstrate that small, direct modifications in the input mask stack slope and edge location can result in model calibration and verification accuracy benefit of up to 30%. All final mask optimization results from this approach are shown to be valid within measurement accuracy of the dimensions expected from manufacture. We highlight the benefits of a more accurate description of the 3D EMF near field with crosstalk in model calibration and impact as a function of mask dimensions. The result is a useful technique to align DDM mask model accuracy with physical mask dimensions and scattering via model calibration.

Fryer, David; Lam, Michael; Adam, Kostas; Clifford, Chris; Oliver, Mike; Zuniga, Christian; Sturtevant, John; Wang, ChangAn; Mansfield, Scott

2014-03-01

92

Estimating the detectability of faults in 3D-seismic data - A valuable input to Induced Seismic Hazard Assessment (ISHA)  

NASA Astrophysics Data System (ADS)

In the past several years, some geotechnical operations that inject fluid into the deep subsurface, such as oil and gas development, waste disposal, and geothermal energy development, have been found or suspected to cause small to moderate sized earthquakes. In several cases the largest events occurred on previously unmapped faults, within or in close vicinity to the operated reservoirs. The obvious conclusion drawn from this finding, also expressed in most recently published best practice guidelines and recommendations, is to avoid injecting into faults. Yet, how certain can we be that all faults relevant to induced seismic hazard have been identified, even around well studied sites? Here we present a probabilistic approach to assess the capability of detecting faults by means of 3D seismic imaging. First, we populate a model reservoir with seed faults of random orientation and slip direction. Drawing random samples from a Gutenberg-Richter distribution, each seed fault is assigned a magnitude and corresponding size using standard scaling relations based on a circular rupture model. We then compute the minimum resolution of a 3D seismic survey for given acquisition parameters and frequency bandwidth. Assuming a random distribution of medium properties and distribution of image frequencies, we obtain a probability that a fault of a given size is detected, or respectively overlooked, by the 3D seismic. Weighting the initial Gutenberg-Richter fault size distribution with the probability of imaging a fault, we obtain a modified fault size distribution in the imaged volume from which we can constrain the maximum magnitude to be considered in the seismic hazard assessment of the operation. We can further quantify the value of information associated with the seismic image by comparing the expected insured value loss between the image-weighted and the unweighted hazard estimates.

Goertz, A.; Kraft, T.; Wiemer, S.; Spada, M.

2012-12-01

93

Geometry of Thrust Faults Beneath Amenthes Rupes, Mars  

NASA Technical Reports Server (NTRS)

Amenthes Rupes is a 380 km-long lobate fault scarp located in the eastern hemisphere of Mars near the dichotomy boundary. The scarp is marked by about 1 km of vertical separation across a northeast dipping thrust fault (top to the SW) and offsets heavily-cratered terrain of Late Noachian age, the visible portion of which was in place by 3.92 Ga and the buried portion in place between 4.08 and 4.27 Ga. The timing of scarp formation is difficult to closely constrain. Previous geologic mapping shows that near the northern end of Amenthes Rupes, Hesperian age basalts terminate at the scarp, suggesting that fault slip predated the emplacement of these flows at 3.69 to 3.9 Ga. Maxwell and McGill also suggest the faulting ceased before the final emplacement of the Late Hesperian lavas on Isidis Planitia. The trend of the faults at Amenthes, like many thrust faults at the dichotomy boundary, parallels the boundary itself. Schultz and Watters used a dislocation modeling program to match surface topography and vertical offset of the scarp at Amenthes Rupes, varying the dip and depth of faulting, assuming a slip of 1.5 km on the fault. They modeled faulting below Amenthes Rupes as having a dip of between 25 and 30 degrees and a depth of 25 to 35 km, based on the best match to topography. Assuming a 25 degree dip and surface measurements of vertical offset of between 0.3 and 1.2 km, Watters later estimated the maximum displacement on the Amenthes Rupes fault to be 2.90 km. However, these studies did not determine the geometry of the thrust using quantitative constraints that included shortening estimates. Amenthes Rupes deforms large preexisting impact craters. We use these craters to constrain shortening across the scarp and combine this with vertical separation to infer fault geometry. Fault dip was also estimated using measurements of scarp morphology. Measurements were based on 460 m (1/128 per pixel) digital elevation data from the Mars Orbiter Laser Altimeter (MOLA), an instrument on the Mars Global Surveyor (MGS) satellite.

Vidal, A.; Mueller, K. M.; Golombek, M. P.

2005-01-01

94

Incorporating fault-slip constraints in 3D geomechanical restoration with application to restraining bend systems in the deep-water Niger Delta  

NASA Astrophysics Data System (ADS)

In the past few years, geomechanical restoration has emerged as a new method of structural analysis and has been successfully applied to analyze thrust and normal fault systems. However, the restoration of strike- and oblique fault systems using the restoration workflow does not generally recover sufficient amounts of strike-slip, thus leading to unsatisfactory results. In order to better constrain the restoration of such systems, we propose to combine classical boundary conditions with new fault-slip constraints. We investigate several possible sets of constraints by restoring a synthetic balanced model of a restraining bend system that includes a fold above an oblique-slip fault connecting two right-lateral strike-slip faults. The restored geometries and corresponding strain distribution are compared, showing that the best results are obtained by constraining either the walls of the model or the fault line with known gradients of slip. However, when dealing with natural structures where the slip is not known everywhere along the fault, a more realistic approach consists in constraining only piercing points, which also leads to acceptable results. We then apply this approach to a restraining bend located in the outer fold-and-thrust belt in the deepwater Niger Delta. Although the deformation in the region is largely focused on thrust-fault systems, gradients in the shortening are also accommodated in the northern part of the Delta toe by the development of transport-parallel tear faults. In some locations, steps or relays between tear fault splays result in restraining bend architectures. The high quality of the seismic data in the region allows us to identify and map in detail one of these structures, and to image several channels offsets on the horizons. This provides us fault-slip constraints that are used in our new restoration workflow, yielding an improved assessment of the deformation required to accommodate the tear-faults displacement within the restraining bends. The use of fault-slip constraints combined with classical boundary conditions offers a realistic approach for using geologic observations to constrain 3D restorations of strike- and oblique slip fault systems, enhancing the effectiveness of these methods in addressing the associated deformation.

Durand-Riard, P.; Shaw, J. H.; Plesch, A.

2011-12-01

95

3D modeling to characterize lamina cribrosa surface and pore geometries using in vivo images from normal and glaucomatous eyes  

PubMed Central

En face adaptive optics scanning laser ophthalmoscope (AOSLO) images of the anterior lamina cribrosa surface (ALCS) represent a 2D projected view of a 3D laminar surface. Using spectral domain optical coherence tomography images acquired in living monkey eyes, a thin plate spline was used to model the ALCS in 3D. The 2D AOSLO images were registered and projected onto the 3D surface that was then tessellated into a triangular mesh to characterize differences in pore geometry between 2D and 3D images. Following 3D transformation of the anterior laminar surface in 11 normal eyes, mean pore area increased by 5.1 ± 2.0% with a minimal change in pore elongation (mean change = 0.0 ± 0.2%). These small changes were due to the relatively flat laminar surfaces inherent in normal eyes (mean radius of curvature = 3.0 ± 0.5 mm). The mean increase in pore area was larger following 3D transformation in 4 glaucomatous eyes (16.2 ± 6.0%) due to their more steeply curved laminar surfaces (mean radius of curvature = 1.3 ± 0.1 mm), while the change in pore elongation was comparable to that in normal eyes (?0.2 ± 2.0%). This 3D transformation and tessellation method can be used to better characterize and track 3D changes in laminar pore and surface geometries in glaucoma.

Sredar, Nripun; Ivers, Kevin M.; Queener, Hope M.; Zouridakis, George; Porter, Jason

2013-01-01

96

Two-dimensional scatter integration method for brachytherapy dose calculations in 3D geometry  

NASA Astrophysics Data System (ADS)

In brachytherapy clinical practice, applicator shielding and tissue heterogeneities are usually not explicitly taken into account. None of the existing dose computational methods are able to reconcile accurate dose calculation in complex three-dimensional (3D) geometries with high efficiency and simplicity. We propose a new model that performs two-dimensional integration of the scattered dose component. The model calculates the effective primary dose at the point of interest and estimates the scatter dose as a superposition of the scatter contributions from pyramid-shaped minibeams. The approach generalizes a previous scatter subtraction model designed to calculate the dose for axial points in simple cylindrically symmetric geometry by dividing the scattering volume into spatial regions coaxial with the source-to-measurement point direction. To allow for azimuthal variation of the primary dose, these minibeams were divided into equally spaced azimuthally distributed pyramidal volumes. The model uses precalculated scatter-to-primary ratios (SPRs) for collimated isotropic sources. Effective primary dose, which includes the radiation scattered in the source capsule, is used to achieve independence from the source structure. For realistic models of the HDR and PDR sources, the algorithm agrees with Monte Carlo within 2.5% and for the type 6702 seed within 6%. The 2D scatter integration (2DSI) model has the potential to estimate the dose behind high-density heterogeneities both accurately and efficiently. The algorithm is much faster than Monte Carlo methods and predicts the dose around sources with different -ray energies and differently shaped capsules with high accuracy.

Kirov, Assen S.; Williamson, Jeffrey F.

1997-11-01

97

Numerical Simulation of Fault Zone Guided Waves: Accuracy and 3-D Effects  

Microsoft Academic Search

-- Fault zones are thought to consist of regions with reduced seismic velocity. When sources are located in or close to these low-velocity zones, guided seismic head and trapped waves are generated which may be indicative of the structure of fault zones at depth. Observations above several fault zones suggest that they are common features of near fault radiation, yet

HEINER IGEL; GUNNAR JAHNKE; YEHUDA BEN-ZION

2002-01-01

98

Index spaces for 3D retrieval: toward a better understanding of their geometry and distribution  

NASA Astrophysics Data System (ADS)

Distance is a fundamental concept when considering the information retrieval and cluster analysis of 3D information. That is, a large number of information retrieval descriptor comparison and cluster analysis algorithms are built around the very concept of the distance, such as the Mahalanobis or Manhattan distances, between points. Although not always explicitly stated, a significant proportion of these distances are, by nature, Euclidian. This implies that it is assumed that the data distribution, from a geometrical point of view, may be associated with a Euclidian flat space. In this paper, we draw attention to the fact that this association is, in many situations, not appropriate. Rather, the data should often be characterised by a Riemannian curved space. It is shown how to construct such a curved space and how to analyse its geometry from a topological point of view. The paper also illustrates how, in curved space, the distance between two points may be calculated. In addition, the consequences for information retrieval and cluster analysis algorithms are discussed.

Paquet, E.; Viktor, H. L.

2010-02-01

99

Parallel 3D computation of unsteady wake flows with complex geometries and fluid-structure interactions  

NASA Astrophysics Data System (ADS)

New powerful parallel computational tools are developed for 3D simulation of unsteady wake flows with complex geometries and fluid-structure interactions. The base method for flow simulation is a finite element formulation for the Navier-Stokes equations. The finite element formulation is based on the streamline-upwind/Petrov-Galerkin (SUPG) and pressure-stabilizing/Petrov-Galerkin (PSPG) techniques. These stabilization techniques facilitate simulation of flows with high Reynolds numbers, and allow us to use equal-order interpolation functions for velocity and pressure without generating numerical oscillations. A multi-domain computational method is developed to simulate wake flow both in the near and far downstream. The formulations lead to coupled nonlinear equation systems which are solved, at every time step, with the Newton-Raphson method. The overall formulation and solution techniques are implemented on parallel platforms such as the CRAY T3E and SGI PowerChallenge. Two phases of vortex shedding for flow past a cylinder is simulated to verify the accuracy of this method. The Enhanced-Discretization Interface Capturing Technique (EDICT) is utilized to simulate wake flow accurately. Fluid-structure coupling solution method based on the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation is applied to simulate a parachute behavior in the unsteady wake.

Osawa, Yasuo

100

Finite element simulation of dynamic rupture on complex fault geometries  

NASA Astrophysics Data System (ADS)

The dynamic faulting under slip-dependent friction in a 2D linear elastic domain is considered. Unstructured finite elements, together with a (implicit) Newmark method for the time discretization of the problem, allow for the handling of complex geometries as well as much larger values of the time step than the critical CFL time step. The discrete equations take the form of a variational inequality and are solved using an iterative domain decomposition technique (Schwarz method), by separating the linear problem (wave propagation) on the intact domain and the non linear problem (unilateral contact with slip-dependent friction) on the faults. Several numerical experiments are performed in the in-plane case. The first ones illustrate convergence for a single time step (convergence of the Schwarz algorithm, influence of the mesh size, influence of the time step) and convergence in time (instability capturing, energy dissipation, optimal time step). The influence of both slip weakening and normal stress variations on the evolution of slip are analysed. Special interest is devoted to dynamic interactions, fault branching and supershear transition, depending on the fault geometry and the initial stress map.

Ionescu, I. R.; Wolf, S.; Badea, L.

2006-12-01

101

3D Viscoelastic Damage Rheology Models of Strike-Slip Fault Systems and Their Associated Surface Deformation  

NASA Astrophysics Data System (ADS)

Material and geometric properties of a strike-slip fault zone control the seismicity patterns and spatial distribution of deformation. The goal of this work is to understand the coupled evolution of fault zones and associated deformation phenomena in various settings (lithospheric structure, temperature gradient and rheology). To simulate fault zone evolution, we use a thermodynamically-based continuum damage framework constrained by laboratory data of fracture and friction experiments (e.g., Lyakhovsky et al., 1997; Hamiel et al., 2004). Three dimensional simulations with the damage rheology model are used to investigate fault evolution from a single segment scale to large-scale long-term plate boundary. Our 3D model consists of a layered seismogenic crust governed by visco-elastic damage rheology, underlain by a visco-elastic upper mantle governed by power-law rheology. We compare the surface deformation patterns associated with a single fault embedded in a viscoelastic lithosphere (not governed by the damage rheology) with analytic solutions and with established numerical codes incorporating viscoelastic rheology (e.g., Savage and Prescott, 1978; Johnson and Segall, 2004). These results validate the use of our 3D code with the damage rheology for fault evolution studies constrained by geodetic data. We present initial results showing surface deformation patterns associated with the evolution of simple and complex strike slip fault systems. The initial results indicate that damage zones of strike slip faults form a flower structure with depth. The flower structure consists of broad damage in the top few kilometers of the seismogenic crust, and highly localized damage at depth. The initial results also indicate that the bulk of inelastic strain release during earthquakes is concentrated in the highly damaged cores of the main fault zones, but some portion with low spatial gradient is accommodated over a broad domain.

Finzi, Y.; Hearn, E. H.; Lyakhovsky, V.; Ben-Zion, Y.

2006-12-01

102

3D numerical simulations of negative hydrogen ion extraction using realistic plasma parameters, geometry of the extraction aperture and full 3D magnetic field map.  

PubMed

Decreasing the co-extracted electron current while simultaneously keeping negative ion (NI) current sufficiently high is a crucial issue on the development plasma source system for ITER Neutral Beam Injector. To support finding the best extraction conditions the 3D Particle-in-Cell Monte Carlo Collision electrostatic code ONIX (Orsay Negative Ion eXtraction) has been developed. Close collaboration with experiments and other numerical models allows performing realistic simulations with relevant input parameters: plasma properties, geometry of the extraction aperture, full 3D magnetic field map, etc. For the first time ONIX has been benchmarked with commercial positive ions tracing code KOBRA3D. A very good agreement in terms of the meniscus position and depth has been found. Simulation of NI extraction with different e/NI ratio in bulk plasma shows high relevance of the direct negative ion extraction from the surface produced NI in order to obtain extracted NI current as in the experimental results from BATMAN testbed. PMID:24593578

Mochalskyy, S; Wünderlich, D; Ruf, B; Franzen, P; Fantz, U; Minea, T

2014-02-01

103

3D Geometry-Based Tracking and Segmentation of Carotid Arteries from CE-MR Angiograms Using Locally Adaptive Thresholdin  

Microsoft Academic Search

In this paper, a methodology, based on 3D geometry extracted from Contract-Enhanced MR Angiograms, is presented to identify and segment the internal carotid arteries for stenosis quantification. The internal carotid artery is automatically identified by tracking the carotid bifurcation and selecting the artery branch with no further arterial branches. To avoid the problems encountered using global thresholding, the artery segmentation

D. Stampouli; Martin R. Varley; C. F. Walshaw; A. P. Jones; R. W. Bury; Lik-kwan Shark

2006-01-01

104

Spectral Geometry Image: Image Based 3D Models for Digital Broadcasting Applications  

Microsoft Academic Search

The use of 3D models for progressive transmission and broadcasting applications is an interesting challenge due to the nature and complexity of such content. In this paper, a new image format for the representation of 3D progressive model is proposed. The powerful spectral analysis is combined with the state of art Ge- ometry Image(GI) to encode static 3D models into

Boon-Seng Chew; Lap-Pui Chau; Ying He; Dayong Wang; Steven C. H. Hoi

2011-01-01

105

Subsurface 3D high-resolution fault imaging: An example from the Kamishiro fault in Lake Aoki obtained by acoustic exploration, central Japan  

NASA Astrophysics Data System (ADS)

To visualize 3D inland geologic structure associated with active faulting, one uses high-cost multiple seismic reflection profiles. Here we fortunately face an unusual case: a large lake across one of the most active faults allows us to use acoustic exploration to visualize the subsurface deformation as the 3D high-resolution images. We investigated the Kamishiro fault, which is a northern part of the Itoigawa-Shizuoka tectonic line active fault system (ISTL), to reveal its Holocene activity. Lake Aoki, which is a natural dam reservoir bonded by an old landslide mass located in the city of Omachi, Nagano Prefecture, hides a 30-meter-high N-S striking fault scarp. On the lake, we employed a 10-KHz acoustic sonar equipment which maximum resolution for the images is 5 cm and which maximum depth of acoustic penetration is 20 m. We cruised the 51 transverse lines which interval and length are 25 m and 900 m on average. The entire profile set covers ~ 1.5 km x 1.5 km area and provides us not only the detailed fault traces ever mapped but also multiple paleoseismic event horizons in the deformed lacustrine strata. We found three major fault traces (F1, F2, and F3 from west to east), one of which (F2) corresponds to the previously mapped the N-S striking fault scarp that separates the major basin (west) and shallow sub-basin (east). A newly identified fault (F1) coincides with a steep sub-lake cliff that bounds the western margin of the major basin. These two faults (F1 and F2) are bifurcated from the north coast of the lake to the south and bear the major basin as a pull-apart basin structure. On the sub-basin, strata under a 500-meter-long topographic bulge also show evidence of the recent reverse faulting. Such an imaged complex fault system that strike-slip faults and a reverse fault coexist would cast a new view over the common knowledge of tectonic framework for the future earthquake potential on the ISTL.

Haraguchi, T.; Yoshinaga, Y.; Toda, S.

2006-12-01

106

A 3D resistivity model derived from the transient electromagnetic data observed on the Araba fault, Jordan  

NASA Astrophysics Data System (ADS)

72 inloop transient electromagnetic soundings were carried out on two 2 km long profiles perpendicular and two 1 km and two 500 m long profiles parallel to the strike direction of the Araba fault in Jordan which is the southern part of the Dead Sea transform fault indicating the boundary between the African and Arabian continental plates. The distance between the stations was on average 50 m. The late time apparent resistivities derived from the induced voltages show clear differences between the stations located at the eastern and at the western part of the Araba fault. The fault appears as a boundary between the resistive western (ca. 100 ?m) and the conductive eastern part (ca. 10 ?m) of the survey area. On profiles parallel to the strike late time apparent resistivities were almost constant as well in the time dependence as in lateral extension at different stations, indicating a 2D resistivity structure of the investigated area. After having been processed, the data were interpreted by conventional 1D Occam and Marquardt inversion. The study using 2D synthetic model data showed, however, that 1D inversions of stations close to the fault resulted in fictitious layers in the subsurface thus producing large interpretation errors. Therefore, the data were interpreted by a 2D forward resistivity modeling which was then extended to a 3D resistivity model. This 3D model explains satisfactorily the time dependences of the observed transients at nearly all stations.

Rödder, A.; Tezkan, B.

2013-01-01

107

Development and application of a 3-D geometry/mass model for LDEF satellite ionizing radiation assessments  

NASA Technical Reports Server (NTRS)

A computer model of the three dimensional geometry and material distributions for the LDEF spacecraft, experiment trays, and, for selected trays, the components of experiments within a tray was developed for use in ionizing radiation assessments. The model is being applied to provide 3-D shielding distributions around radiation dosimeters to aid in data interpretation, particularly in assessing the directional properties of the radiation exposure. Also, the model has been interfaced with radiation transport codes for 3-D dosimetry response predictions and for calculations related to determining the accuracy of trapped proton and cosmic ray environment models. The methodology is described used in developing the 3-D LDEF model and the level of detail incorporated. Currently, the trays modeled in detail are F2, F8, and H12 and H3. Applications of the model which are discussed include the 3-D shielding distributions around various dosimeters, the influence of shielding on dosimetry responses, and comparisons of dose predictions based on the present 3-D model vs those from 1-D geometry model approximations used in initial estimates.

Colborn, B. L.; Armstrong, T. W.

1992-01-01

108

THE EFFECT OF PURE MITRAL REGURGITATION ON MITRAL ANNULAR GEOMETRY AND 3-D SADDLE-SHAPE  

PubMed Central

Objectives Chronic ischemic mitral regurgitation (IMR) is associated with mitral annular dilatation in the septal-lateral dimension and flattening of the annular 3-D saddle-shape. To examine whether these perturbations are due to the ischemic insult, mitral regurgitation (MR), or both, we investigated the effects of pure MR (low pressure volume overload) on annular geometry and shape. Methods Eight radiopaque markers were sutured evenly around the mitral annulus in sheep randomized to control (CTRL, n=8) or experimental (HOLE, n=12) groups. In HOLE, a 3.5mm to 4.8mm hole was punched in the posterior leaflet to generate pure MR. 4-D marker coordinates were obtained radiographically 1 and 12 weeks postoperatively. Mitral annular area (MAA), annular septal-lateral (SL) and commissure-commissure (CC) dimensions, and annular height were calculated every 16.7ms. Results MR grade was 0.4±0.4 in CTRL and 3.0±0.8 in HOLE (p<0.001) at 12 weeks. End-diastolic LV volume index was greater in HOLE at both 1 and 12 weeks; end-systolic volume index was larger in HOLE at 12 weeks. MAA increased in HOLE predominantly in the CC dimension, with no difference in annular height between HOLE vs. CTRL at 1 or 12 weeks, respectively. Conclusions In contrast to annular SL dilatation and flattening of annular saddle-shape observed with chronic IMR, pure MR was associated with CC dimension annular dilatation and no change in annular shape. Thus, infarction is a more important determinant of SL dilatation and annular shape than is MR, which reinforces the need for disease-specific designs of annuloplasty rings. ULTRAMINI- ABSTRACT In a chronic pure mitral regurgitation (MR) ovine model, we examined changes in mitral annular dimensions and shape over 12 weeks to understand the contribution of MR to annular remodeling independent of the effects of myocardial infarction. Pure MR resulted in commissure-commissure annular dilatation and no change in annular saddle-shape.

Nguyen, Tom C.; Itoh, Akinobu; Carlhall, Carl J.; Bothe, Wolfgang; Timek, Tomasz A.; Ennis, Daniel B.; Oakes, Robert A.; Liang, David; Daughters, George T.; Ingels, Neil B.; Miller, D. Craig

2008-01-01

109

Modeling 3D Dynamic Rupture on Arbitrarily-Shaped faults by Boundary-Conforming Finite Difference Method  

Microsoft Academic Search

We use a new finite difference method (FDM) and the slip-weakening law to model the rupture dynamics of a non-planar fault embedded in a 3-D elastic media with free surface. The new FDM, based on boundary- conforming grid, sets up the mapping equations between the curvilinear coordinate and the Cartesian coordinate and transforms irregular physical space to regular computational space;

D. Zhu; H. Zhu; Y. Luo; X. Chen

2008-01-01

110

Effect of catheter tip-tissue surface contact on three-dimensional left atrial and pulmonary vein geometries: potential anatomic distortion of 3D ultrasound, fast anatomical mapping, and merged 3D CT-derived images.  

PubMed

Anatomic Distortion of 3D Mapping.?Background: Although catheter tip-tissue contact is known as a reliable basis for mapping and ablation of atrial fibrillation (AF), the effects of different mapping methods on 3-dimensional (3D) map configuration remain unknown. Methods and Results: Twenty AF patients underwent Carto-based 3D ultrasound (US) evaluation. Left atrium (LA)/pulmonary vein (PV) geometry was constructed with the 3D US system. The resulting geometry was compared to geometries created with a fast electroanatomical mapping (FAM) algorithm and 3D US merged with computed tomography (merged 3D US-CT). The 3D US-derived LA volumes were smaller than the FAM- and merged 3D US-CT-derived volumes (75 ± 21 cm(3) vs 120 ± 20 cm(3) and 125 ± 25 cm(3) , P < 0.0001 for both). Differences in anatomic PV orifice fiducials between 3D US- and FAM- and merged 3D US-CT-derived geometries were 6.0 (interquartile range 0-9.3) mm and 4.1 (0-7.0) mm, respectively. Extensive encircling PV isolation guided by 3D US images with real-time 2D intracardiac echocardiography-based visualization of catheter tip-tissue contact generated ablation point (n = 983) drop-out at 1.9 ± 3.8 mm beyond the surface of the 3D US-derived LA/PV geometry. However, these same points were located 1.5 ± 5.4 and 0.4 ± 4.1 mm below the FAM- and merged 3D US-CT-derived surfaces. Conclusions: Different mapping methods yield different 3D geometries. When AF ablation is guided by 3D US-derived images, ablation points fall beyond the 3D US surface but below the FAM- or merged 3D US-CT-derived surface. Our data reveal anatomic distortion of 3D images, providing important information for improving the safety and efficacy of 3D mapping-guided AF ablation. (J Cardiovasc Electrophysiol, Vol. 24, pp. 259-266, March 2013). PMID:23279593

Okumura, Yasuo; Watanabe, Ichiro; Kofune, Masayoshi; Nagashima, Koichi; Sonoda, Kazumasa; Mano, Hiroaki; Ohkubo, Kimie; Nakai, Toshiko; Sasaki, Naoko; Kogawa, Rikitake; Maruyama, Ayako; Hirayama, Atsushi

2013-03-01

111

Reassembling 3D Thin Fragments of Unknown Geometry in Cultural Heritage  

NASA Astrophysics Data System (ADS)

Many fragile antiques had already been broken upon being discovered at archaeology sites. The fragments of these objects cannot be effectively interpreted and studied unless they are successfully reassembled. However, there still exists many problems in the reassembly procedure in existing methods, such as the numerical instabilities of curvature and torsion based methods, the limitation of geometric assumption, and the error accumulation of the pairwise matching approach, etc. Regarding these problems, this paper proposed an approach to match the fragments to each other for their original 3D reconstruction. Instead of the curvatures and torsions, the approach is based on establishing a local Cartesian coordinate at every point of the 3D contour curves. First of all, the 3D meshes of the fragments are acquired by a structure-light based method, with the corresponding 3D contour curves extracted from the outer boundaries. Then, the contour curves are matched and aligned to each other by estimating all the possible 3D rigid transformations of the curve pairs with our defined local Cartesian coordinates, and then the maximum likelihood rigid transformations are selected. Finally, a global refinement is introduced to adjust the alignment errors and improve the final reassembling accuracy. In addition, experiments with two groups of fragments suggest that this approach cannot only match and align fragments effectively, but also improve the accuracy significantly. Comparing with the original 3D model acquired before being broken, the final reassembling accuracy reaches 0.47 mm.

Zheng, S. Y.; Huang, R. Y.; Li, J.; Wang, Z.

2014-05-01

112

Numerical investigation of fault zone roughness: Interplay between fault geometry and friction  

NASA Astrophysics Data System (ADS)

The influence of roughness is central in understanding the behavior of various types of shear zones including faults, landslides and deformation in glacial till. All of these zones contain a non-planar wall, which interacts with either a gouge zone, or another wall. Laboratory friction experiments have traditionally attempted to isolate the role of boundary roughness focusing on shear within the gouge. We use the 3D Discrete Element Method (DEM) and the ESyS-Particle code to investigate both the effect of boundary roughness and friction. The DEM allows us to investigate the micromechanics of the shear zone by directly visualizing force chain magnitude and orientation, and also the distributed or localized nature of shear in the numerical experiment. We use two end-member shear zones: 1) fault gouge is sandwiched between two rough walls and 2) fault gouge is contained inside of two smooth walls. For rough fault models, grooves are 0.8mm in height and have a regular spacing of 1mm, equivalent to standard laboratory friction experiments. In all models the gouge particles range from 100 to 200 micron in diameter in a 3 mm thick layer, the normal stress is held constant at 15 MPa with a constant shear velocity applied to one wall while the other is held stationary. We vary the coefficient of friction between the particles and wall and monitor the shear strength, distribution of forces between particles, force chain orientation, localization of shear, and porosity distribution in the shear zone. We find that when wall friction is equal to gouge friction, large values of interparticle friction promote localization near the shear zone boundary due to the inefficiency of shearing many high friction contacts in the granular zone. A rough fault zone balances this effect by necessitating that shear occurs within the gouge zone and not strictly at the gouge-wall interface; however, variations in the shearing layer are still observed depending on the particle friction. For rough faults the contrast between the friction of the wall and gouge is negligible. Smooth faults exhibit a large dependence on wall friction versus and gouge friction when gouge friction exceeds 0.1. Smooth faults decrease the average force of particle-particle contacts, exponential slope of the probability distribution function, and anisotropy of force chain orientation. From our numeric experiments we conclude that rough naturals faults will have a higher overall strength and transfer more force to frictional grains activating grain scale processes than smooth mature faults

Rathbun, A.; Renard, F.

2012-04-01

113

Dynamic Source Rupture Simulation of Dipping Faults With a 3D Finite-Difference Method  

Microsoft Academic Search

The finite-difference method (FDM) has been widely used for numerical modeling of seismic source problems, including investigation on the dynamic source processes. Owing to both conceptual and computational constraints of FDM, fault models have largely been limited to the cases that the fault planes are parallel to the FDM grid. However, recent observation and kinematic inversion results discover that more

W. Zhang; T. Iwata

2004-01-01

114

Accuracy Evaluation of 3D Geometry from Low-Attitude UAV collections A case at Zijin Mine  

NASA Astrophysics Data System (ADS)

This study investigates the usability of low-attitude unmanned aerial vehicle (UAV) acquiring high resolution images for the geometry reconstruction of opencast mine. Image modelling techniques like Structure from Motion (SfM) and Patch-based Multiview Stereo (PMVS) algorithms are used to generate dense 3D point cloud from UAV collections. Then, precision of 3D point cloud will be first evaluated based on Real-time Kinematic (RTK) ground control points (GCPs) at point level. The experimental result shows that the mean square error of the UAV point cloud is 0.11 m. Digital surface model (DSM) of the study area is generated from UAV point cloud, and compared with that from the Terrestrial Laser Scanner (TLS) data for further comparison at the surface level. Discrepancy map of 3D distances based on DSMs shows that most deviation is less than ±0.4 m and the relative error of the volume is 1.55 %.

Wang, Q.; Wu, L.; Chen, S.; Shu, D.; Xu, Z.; Li, F.; Wang, R.

2014-04-01

115

A Formal Classification of 3D Medial Axis Points and Their Local Geometry  

Microsoft Academic Search

This paper proposes a novel hypergraph skeletal representation for 3D shape based on a formal derivation of the generic structure of its medial axis. By classifying each skeletal point by its order of contact, we show that, genetically, the medial axis consists of five types of points, which are then organized into sheets, curves, and points: 1) sheets (manifolds with

Peter J. Giblin; Benjamin B. Kimia

2004-01-01

116

Restoring complex folded geometries in 3D using paleomagnetic vectors; a new tool to validate underground reconstructions  

NASA Astrophysics Data System (ADS)

Three-dimensional reconstructions of the underground involve the integration of discrete and heterogeneous datasets and have significant socio- economic implications. The problem arises when there are limited data to build 3D models or when deformation processes are complex; these reasons inspired the development of restoration methods to validate subsurface reconstructions. The restoration is based on the application of simple geometric (or mechanic) laws that help reduce the uncertainty and increase geomodel accuracy. Apart from mechanical approaches, geometric methods are based on the initial assumption of global conservation of volume during deformation in addition to the paleo-horizontality of the stratigraphic horizons in the undeformed stage. The problem is that the bedding plane cannot be used as a three-dimensional reference system, because a single vector defines it and additional constraints are required. This is particularly important when dealing with complex structures, such as non-cylindrical structures and the superposition of non-coaxial geometries. In this context, paleomagnetism (known in both the deformed and undeformed stages) can contribute to building a more complete reference system and to reducing the uncertainty in restoration processes. The use of paleomagnetism in restoration tools was suggested in the early 1990's and only a few quantitative map-view applications have been developed since then. In this contribution, we introduce the two first surface restoration methods that use paleomagnetic vectors as a primary reference. The first one is a simple geometric approach based on the piecewise restoration of a triangulated surface into which paleomagnetic variables can be easily incorporated. It is valid for complexly folded structures. The surface is modelled by a mesh and the method starts from a pin-element. Triangles are laid flat and then fitted together to minimize distances between common vertices and paleomagnetic error. However, this first approach is very sensitive to the density and type of triangulation of the mesh, as well as the location of the pin-element. The second one is based on a parametric approach (gOcad code), whereby a curvilinear coordinate system is computed on the folded surface by numerical optimization. We use paleomagnetic data to define constraints for the computation of this frame, which significantly increases the robustness of the restoration method. We assess the accuracy of the restoration algorithms using computer and analogue models. We have developed a new methodology to simulate the paleomagnetic vectors in the models and we are able to obtain reliable 3D images of them under a CT scan. These models allow us to set up a known initial undeformed surface (a horizontal horizon and its magnetic reference). We then perform a forward deformation to obtain a controlled deformed surface. Subsequently, we apply a restoration method to that deformed surface, and compare the result from the restored state with the initial undeformed surface. With an ideal restoration method the two states should match perfectly and, therefore, we can quantify the quality of the restoration by measuring the differences between them. Future work on the method includes the restoration of volumes (now only horizons) and faults (discontinuous deformation). The application to real case studies from the Pyrenean External Sierras, apart from reliable geometric reconstructions of the structures, has to consider the distribution of vectors, which is limited to the surface although it is densely sampled, and the quality, reliability and resolution of real datasets.

José Ramón, Mª; Pueyo, Emilio L.; Briz, José Luis; Caumon, Guillaume; Fernández, Óscar; Ciria, José Carlos; Pocovi, Andrés; Ros, Luis H.

2013-04-01

117

Multi-view coding for image-based rendering using 3-D scene geometry  

Microsoft Academic Search

To store and transmit the large amount of image data necessary for Image-based Rendering (IBR), efficient coding schemes are required. This paper presents two different approaches which exploit three-dimensional scene geometry for multi-view compression. In texture-based coding, images are converted to view-dependent texture maps for compression. In model-aided predictive coding, scene geometry is used for disparity compensation and occlusion detection

Marcus A. Magnor; Prashant Ramanathan; Bernd Girod

2003-01-01

118

Structural geometry of faulting in the Nile delta: Implications for hydrocarbon traps  

SciTech Connect

Pliocene-Pleistocene sediments of parts of the Nile delta are strongly faulted by north-dipping listric extensional faults. Both fault surfaces and rotated fault blocks are imaged on seismic data, and interpretations of fault geometry have been tested by fault restoration techniques, construction of balanced section, and analysis of fault displacement gradients along faults. Hanging wall profiles provide the basis for the reconstruction of fault surfaces and depth to detachment calculations. These methods define more clearly the geometry of potential hydrocarbon traps and better constrain the stratigraphic interpretation of the area. The analysis demonstrates both the importance of transfer faults separating different fault compartments and detachment faults separating different levels, enhancing prospectivity by isolating additional closed structures. In many respects the Nile delta structures are like those found along the US Gulf Coast. The recent recognition of oil and gas potential in the Nile delta should act as a catalyst for understanding more carefully the fault and trap geometry. Examples from the excellent seismic data base will be used to illustrate the different aspects of fault geometry.

Beach, A.; Trayner, P.

1988-08-01

119

Effects of Training Method and Gender on Learning 2D\\/3D Geometry  

Microsoft Academic Search

This article reports the findings of an experimental study involving 36 primary school students (16 girls, 20 boys, Mean age = 9.5 years, age range: 8-10 years) in geometrical understanding of 2D and 3D objects. Students were assigned into two experimental groups and one control group based on a stratified random sampling procedure. The first experimental group trained in an

Samsudin Khairulanuar; Abd Rashid Nazre; Omar Khan Sairabanu; Fabil Norasikin

2010-01-01

120

Flow properties along field lines in a 3-D tilted-dipole geometry  

Microsoft Academic Search

A 3-D MHD simulation of a global, tilted-dipole solar wind flow pattern is analyzed to determine flow properties along individual magnetic field lines. In the model, flow conditions near the Sun are chosen to provide a reasonable match to the interplanetary configuration prevailing during the recent south polar passage by Ulysses, i.e., a streamer belt inclined approximately 30 deg to

V. J. Pizzo

1995-01-01

121

Fast joint estimation of silhouettes and dense 3D geometry from multiple images.  

PubMed

We propose a probabilistic formulation of joint silhouette extraction and 3D reconstruction given a series of calibrated 2D images. Instead of segmenting each image separately in order to construct a 3D surface consistent with the estimated silhouettes, we compute the most probable 3D shape that gives rise to the observed color information. The probabilistic framework, based on Bayesian inference, enables robust 3D reconstruction by optimally taking into account the contribution of all views. We solve the arising maximum a posteriori shape inference in a globally optimal manner by convex relaxation techniques in a spatially continuous representation. For an interactively provided user input in the form of scribbles specifying foreground and background regions, we build corresponding color distributions as multivariate Gaussians and find a volume occupancy that best fits to this data in a variational sense. Compared to classical methods for silhouette-based multiview reconstruction, the proposed approach does not depend on initialization and enjoys significant resilience to violations of the model assumptions due to background clutter, specular reflections, and camera sensor perturbations. In experiments on several real-world data sets, we show that exploiting a silhouette coherency criterion in a multiview setting allows for dramatic improvements of silhouette quality over independent 2D segmentations without any significant increase of computational efforts. This results in more accurate visual hull estimation, needed by a multitude of image-based modeling approaches. We made use of recent advances in parallel computing with a GPU implementation of the proposed method generating reconstructions on volume grids of more than 20 million voxels in up to 4.41 seconds. PMID:21808082

Kolev, Kalin; Brox, Thomas; Cremers, Daniel

2012-03-01

122

Large scale 3D geometry of deformation structures in the Aar massif and overlying Helvetic nappes (Central Alps, Switzerland) - A combined remote sensing and field work approach  

NASA Astrophysics Data System (ADS)

Allowing deep insight into the formation history of a rock complex, shear zones, faults and joint systems represent important sources of geological information. The granitic rocks of the Haslital valley (Switzerland) show very good outcrop conditions to study these mechanical anisotropies. Furthermore, they permit a quantitative characterisation of the above-mentioned deformation structures on the large-scale, in terms of their 3D orientation, 3D spatial distribution, kinematics and evolution in 3D. A key problem while developing valid geological 3D models is the three-dimensional spatial distribution of geological structures, particularly with increasing distance from the surface. That is especially true in regions, where only little or even no "hard" underground data (e.g. bore holes, tunnel mappings and seismics) is available. In the study area, many subsurface data are available (e.g. cross sections, tunnel and pipeline mappings, bore holes etc.). Therefore, two methods dealing with the problems mentioned are developed: (1) A data acquisition, processing and visualisation method, (2) A methodology to improve the reliability of 3D models regarding the spatial trend of geological structures with increasing depth: 1) Using aerial photographs and a high-resolution digital elevation model, a GIS-based remote-sensing structural map of large-scale structural elements (shear zones, faults) of the study area was elaborated. Based on that lineament map, (i) a shear zone map was derived and (ii) a geostatistical analysis was applied to identify sub regions applicable for serving as field areas to test the methodology presented above. During fieldwork, the shear zone map was evaluated by verifying the occurrence and spatial distribution of the structures designated by remote sensing. Additionally, the geometry of the structures (e.g. 3D orientation, width, kinematics) was characterised and parameterised accordingly. These tasks were partially done using a GPS based Slate PC and the FieldMoveTM software, in order to ease the subsequent data processing. 2) Findings from the field work were visualised in 3D using the MoveTM software suite. Applying its specific tools and incorporating own field data, the structure's near-surface 3D settings was modelled. In a second step, the combined use of surface and subsurface data helped to predict their trend with increasing distance from the surface, bypassing a height difference of partially more than 2000m. Field work shows that the remote-sensing structural map fits very well with the field observations. Nevertheless, the shear zone map underwent an iterative refinement process, based on own observations in the field as well as on already existing maps. It now clearly describes the lithological subdivision of the study area. The incorporation of the data into the 3D modelling software points towards the fact, that own large-scale data fits very well with small-scale structures provided by recent studies in the same area. Yet, their exact interplay in terms of orientation, kinematics and evolution is not clear. Additional analysis is needed in order to gain more detailed insight into the deformation history of the rocks in the study area.

Baumberger, R.; Wehrens, Ph.; Herwegh, M.

2012-04-01

123

Mechanical constraints imposed by 3D cellular geometry and arrangement modulate growth patterns in the Arabidopsis embryo  

PubMed Central

Morphogenesis occurs in 3D space over time and is guided by coordinated gene expression programs. Here we use postembryonic development in Arabidopsis plants to investigate the genetic control of growth. We demonstrate that gene expression driving the production of the growth-stimulating hormone gibberellic acid and downstream growth factors is first induced within the radicle tip of the embryo. The center of cell expansion is, however, spatially displaced from the center of gene expression. Because the rapidly growing cells have very different geometry from that of those at the tip, we hypothesized that mechanical factors may contribute to this growth displacement. To this end we developed 3D finite-element method models of growing custom-designed digital embryos at cellular resolution. We used this framework to conceptualize how cell size, shape, and topology influence tissue growth and to explore the interplay of geometrical and genetic inputs into growth distribution. Our simulations showed that mechanical constraints are sufficient to explain the disconnect between the experimentally observed spatiotemporal patterns of gene expression and early postembryonic growth. The center of cell expansion is the position where genetic and mechanical facilitators of growth converge. We have thus uncovered a mechanism whereby 3D cellular geometry helps direct where genetically specified growth takes place.

Bassel, George W.; Stamm, Petra; Mosca, Gabriella; Barbier de Reuille, Pierre; Gibbs, Daniel J.; Winter, Robin; Janka, Ales; Holdsworth, Michael J.; Smith, Richard S.

2014-01-01

124

Mechanical constraints imposed by 3D cellular geometry and arrangement modulate growth patterns in the Arabidopsis embryo.  

PubMed

Morphogenesis occurs in 3D space over time and is guided by coordinated gene expression programs. Here we use postembryonic development in Arabidopsis plants to investigate the genetic control of growth. We demonstrate that gene expression driving the production of the growth-stimulating hormone gibberellic acid and downstream growth factors is first induced within the radicle tip of the embryo. The center of cell expansion is, however, spatially displaced from the center of gene expression. Because the rapidly growing cells have very different geometry from that of those at the tip, we hypothesized that mechanical factors may contribute to this growth displacement. To this end we developed 3D finite-element method models of growing custom-designed digital embryos at cellular resolution. We used this framework to conceptualize how cell size, shape, and topology influence tissue growth and to explore the interplay of geometrical and genetic inputs into growth distribution. Our simulations showed that mechanical constraints are sufficient to explain the disconnect between the experimentally observed spatiotemporal patterns of gene expression and early postembryonic growth. The center of cell expansion is the position where genetic and mechanical facilitators of growth converge. We have thus uncovered a mechanism whereby 3D cellular geometry helps direct where genetically specified growth takes place. PMID:24912195

Bassel, George W; Stamm, Petra; Mosca, Gabriella; Barbier de Reuille, Pierre; Gibbs, Daniel J; Winter, Robin; Janka, Ales; Holdsworth, Michael J; Smith, Richard S

2014-06-10

125

Characterization of a landslide geometry using 3D seismic refraction traveltime tomography: The La Valette landslide case history  

NASA Astrophysics Data System (ADS)

The geometry of the bedrock, internal layers and shear surfaces/bands controls the deformation pattern and the mechanisms of landslides. A challenge to progress in the forecast of landslide acceleration in terms of early-warning is therefore to characterize the 3D geometry of the unstable mass at a high level of spatial resolution, both in the horizontal and vertical directions, by integrating information from different surveying techniques. For such characterization, seismic investigations are potentially of a great interest. In the case of complex structures, the measure and the processing of seismic data need to be performed in 3D. The objective of this work is to present the development of a 3D extension of a seismic refraction traveltime tomography technique based on a Simultaneous Iterative Reconstruction Technique (SIRT). First the processing algorithm is detailed and its performance is discussed, and second an application to the La Valette complex landslide is presented. Inversion of first-arrival traveltimes produces a 3D tomogram that underlines the presence of many areas characterized by low P-wave velocity of 500-1800 m.s- 1. These low P-wave velocity structures result from the presence of reworked blocks, surficial cracks and in-depth fracture zones. These structures seem to extend to around 25 m in depth over a 80 × 130 m area. Based on borehole geotechnical data and previous geophysical investigations, an interface corresponding to an internal slip surface can be suspected near the isovalue of 1200 m.s- 1 at a depth of - 10 to - 15 m. The stable substratum is characterized by higher values of P-wave velocity of 1800-3000 m.s- 1. The features identified in the 3D tomogram allow to better (1) delineate the boundary between the landslide and the surrounding stable slopes, and (2) understand the morphological structures within the landslide at a hectometric scale. The integration of the 3D seismic tomography interpretation to previous geophysical acquisitions using a geostatistical approach allows to construct a 3D geometrical model of the middle and lower part of the La Valette landslide, and to estimate the volume of the unstable mass.

Samyn, K.; Travelletti, J.; Bitri, A.; Grandjean, G.; Malet, J.-P.

2012-11-01

126

Geometry and fracture distribution in fault-propagation folds in nature and experiments  

SciTech Connect

Fault-propagation folds in compressional terranes are attractive reservoir targets, particularly where deformation processes such as fracturing and faulting enchance reservoir and transport properties. Field examples and laboratory modeling suggest that fold geometry, fracture distribution, and propagation of the master fault vary with lithologic layering. Fault-propagation folds in the Absaroka thrust sheet, Salt River Range, Wyoming, are characterized by a complexly folded and faulted sequence overlying imbricate thrust ramps. The lower Paleozoic section consists of a mechanically anisotropic rock sequence that has variable bedding thickness and relative ductility. Above thrust ramps, thick-bedded brittle units shorten by isolated faulting and fracturing. The faulted and fractured zones are separated by disharmonic folds and zones of interlayer slip in the thinly bedded units. This geometry suggests that fault-propagation folds in mechanically layered rock grow by the linking of structurally higher isolated faulted segments rather than by the continuous propagation of the master thrust upsection.

Chester, J.S.

1988-01-01

127

3D Strain Geometry and Crystallographic Fabric in Experimental HT Deformation of Solnhofen Limestone  

Microsoft Academic Search

Under conditions where calcite deforms plastically, high temperature deformation tests on Solnhofen limestone have been run using different strain configurations: axi-symmetric shortening and extension, and direct shear. The aim of the work is to relate strain geometry and the development of crystallographic fabrics in different strain paths. We produced constrictional, flattening, and nearly plane strain deformations. In addition to this,

S. Llana-Funez; E. H. Rutter

2003-01-01

128

The Emergence of 3D Geometry From Children's (Teacher-Guided) Classification Tasks  

Microsoft Academic Search

Geometry, classification, and the classification of geometrical objects are integral aspects of recent curriculum documents in mathematics education. Such curriculum documents, however, leave open how the work of classifying objects according to geometrical properties can be accomplished given that the knowledge of these properties is the planned outcome of the curriculum or lesson. The fundamental question of the present study

Wolff-Michael Roth; Jennifer S. Thom

2009-01-01

129

Math in Action. 3-D Geometry Comes in All Shapes and Sizes.  

ERIC Educational Resources Information Center

Two mathematics activities introduce elementary students to geometry, using depth, width, and height. A primary level activity involves students with sorting and classifying geometric solids and with comparing numerical quantities. The activity requires building blocks or geometric solids. An intermediate level activity teaches students about…

Bresser, Rusty; Sheffield, Stephanie

1996-01-01

130

The Emergence of 3D Geometry from Children's (Teacher-Guided) Classification Tasks  

ERIC Educational Resources Information Center

Geometry, classification, and the classification of geometrical objects are integral aspects of recent curriculum documents in mathematics education. Such curriculum documents, however, leave open how the "work" of classifying objects according to geometrical properties can be accomplished given that the knowledge of these properties is the…

Roth, Wolff-Michael; Thom, Jennifer S.

2009-01-01

131

Responsive culture platform to examine the influence of microenvironmental geometry on cell function in 3D  

PubMed Central

We describe the development of a well-based cell culture platform that enables experimenters to control the geometry and connectivity of cellular microenvironments spatiotemporally. The base material is a hydrogel comprised of photolabile and enzyme-labile crosslinks and pendant cell adhesion sequences, enabling spatially-specific, in situ patterning with light and cell-dictated microenvironment remodeling through enzyme secretion. Arrays of culture wells of varying shape and size were patterned into the hydrogel surface using photolithography, where well depth was correlated with irradiation dose. The geometry of these devices can be subsequently modified through sequential patterning, while simultaneously monitoring changes in cell geometry and connectivity. Towards establishing the utility of these devices for dynamic evaluation of the influence of physical cues on tissue morphogenesis, the effect of well shape on lung epithelial cell differentiation (i.e., primary mouse alveolar type II cells, ATII cells) was assessed. Shapes inspired by alveoli were degraded into hydrogel surfaces. ATII cells were seeded within the well-based arrays and encapsulated by the addition of a top hydrogel layer. Cell differentiation in response to these geometries was characterized over 7 days of culture with immunocytochemistry (surfactant protein C, ATII; T1? protein, alveolar type I (ATI) differentiated epithelial cells) and confocal image analysis. Individual cell clusters were further connected by eroding channels between wells during culture via controlled two-photon irradiation. Collectively, these studies demonstrate the development and utility of responsive hydrogel culture devices to study how a range of microenvironment geometries of evolving shape and connectivity might influence or direct cell function.

Kloxin, April M.; Lewis, Katherine J. R.; DeForest, Cole A.; Seedorf, Gregory; Tibbitt, Mark W.; Balasubramaniam, Vivek

2012-01-01

132

Applying and validating the RANS-3D flow-solver for evaluating a subsonic serpentine diffuser geometry  

NASA Technical Reports Server (NTRS)

Subsonic inlet ducts for advanced, high-performance aircraft are evolving towards complex three-dimensional shapes for reasons of overall integration and weight. These factors lead to diffuser geometries that may sacrifice inlet performance, unless careful attention to design details and boundary layer management techniques are employed. The ability of viscous computational fluid dynamic (CFD) analysis of such geometries to aid the aircraft configurator in this complex design problem is herein examined. The RANS-3D Reynolds-Averaged Navier-Stokes solver is applied to model the complex flowfield occurring in a representative diffuser geometry and the solutions are compared to experimental results from a static test of the inlet duct. The computational results are shown to compare very favorably with experimental results over a range of mass flow rates, including those involving large amounts of separation in the diffuser. In addition, a novel grid topology is presented, and two turbulence models are evaluated in this study as part of the RANS-3D code.

Fletcher, Michael J.; Won, Mark J.; Cosentino, Gary B.; Te, Alexander

1993-01-01

133

Integrated approach to 3-D seismic acquisition geometry analysis: emphasizing the influence of the inhomogeneous subsurface  

Microsoft Academic Search

The seismic reflection method for imaging of the earth's interior is an essential part of the exploration and exploitation of hydrocarbon resources. A seismic survey should be designed such that the acquired data leads to a sufficiently accurate subsurface image.\\u000aThe survey geometry analysis method presented in this thesis is based on the previously developed focal beam analysis concept. It

E. J. van Veldhuizen

2006-01-01

134

Stratigraphic architecture and fault offsets of alluvial terraces at Te Marua, Wellington fault, New Zealand, revealed by pseudo-3D GPR investigation  

NASA Astrophysics Data System (ADS)

earthquake slips on faults are commonly determined by measuring morphological offsets at current ground surface. Because those offsets might not always be well preserved, we examine whether the first 10 m below ground surface contains relevant information to complement them. We focus on the Te Marua site, New Zealand, where 11 alluvial terraces have been dextrally offset by the Wellington fault. We investigated the site using pseudo-3D Ground Penetrating Radar and also produced a high-resolution digital elevation model (DEM) of the zone to constrain the surface slip record. The GPR data reveal additional information: (1) they image the 3D stratigraphic architecture of the seven youngest terraces and show that they are strath terraces carved into graywacke bedrock. Each strath surface is overlain by 3-5 m of horizontally bedded gravel sheets, including two pronounced and traceable reflectors; (2) thanks to the multilayer architecture, terrace risers and channels are imaged at three depths and their lateral offsets can be measured three to four times, constraining respective offsets and their uncertainties more reliably; and (3) the offsets are better preserved in the subsurface than at the ground surface, likely due to subsequent erosion-deposition on the latter. From surface and subsurface data, we infer that Te Marua has recorded six cumulative offsets of 2.9, 7.6, 18, 23.2, 26, and 31 m (± 1-2 m). Large earthquakes on southern Wellington fault might produce 3-5 m of slip, slightly less than previously proposed. Pseudo-3D GPR thus provides a novel paleoseismological tool to complement and refine surface investigations.

Beauprêtre, S.; Manighetti, I.; Garambois, S.; Malavieille, J.; Dominguez, S.

2013-08-01

135

The Geometry of the Subducting Slabs Beneath the PRVI Microplate Based on 3D Tomography  

NASA Astrophysics Data System (ADS)

The Puerto Rico and the Virgin Islands (PRVI) microplate is located between two subduction zones, with the Puerto Rico trench to the north and the Muertos trough to the south. The Puerto Rico trench is caused by southward-directed subduction of the North American Plate, and the Muertos trough is the northern boundary of the Caribbean Plate. There is no active volcanism on Puerto Rico; however, earthquake depths and seismic tomography imply that the slab of Caribbean plate continues northward beneath Puerto Rico. Puerto Rico overlies these two slabs with extension to both the west (Mona Passage) and southeast (Anacapa Passage). The cause of the extension is unknown, but GPS measurements show that Puerto Rico is experiencing anti-clockwise rotation, and the extension associated with the Anacapa Passage may be produced by this rotation. To the west, it is debated whether the Mona Passage is a boundary between two micro-plates or simple a local rift basin. To address the sources of the extension and the cause of the rotation, we are investigating if the deep structures can be the dynamic source for the observed kinematic movements. We collected data on earthquakes occurring between 2009-2011 in the PRVI region and relocated them using the SEISAN code provided by the Institute of Solid Earth Physics, University of Bergen. The FMTOMO code from Australian National University was used for 3D tomography from P and S wave arrival times. By comparing the relocated epicenters and the 3D tomography results, the subducting slabs were identified. When integrated with the results of previous studies, the geometric model of the slabs is a critical key to understanding the evolution of the PRVI microplate in the past and the future.

Xu, X.; Keller, G. R.; Holland, A. A.; Keranen, K. M.; Li, H.

2011-12-01

136

3D simulations of the early stages of AGN jets: geometry, thermodynamics and backflow  

NASA Astrophysics Data System (ADS)

We investigate the interplay between jets from active galactic nuclei (AGNs) and the surrounding interstellar medium (ISM) through full 3D, high-resolution, adaptive mesh refinement simulations performed with the FLASH code. We follow the jet-ISM system for several Myr in its transition from an early, compact source to an extended one including a large cocoon. During the jet evolution, we identify three major evolutionary stages and we find that, contrary to the prediction of popular theoretical models, none of the simulations shows a self-similar behaviour. We also follow the evolution of the energy budget, and find that the fraction of input power deposited into the ISM (the AGN coupling constant) is of the order of a few per cent during the first few Myr. This is in broad agreement with galaxy formation models employing AGN feedback. However, we find that in these early stages, this energy is deposited only in a small fraction (<1 per cent) of the total ISM volume. Finally, we demonstrate the relevance of backflows arising within the extended cocoon generated by a relativistic AGN jet within the ISM of its host galaxy, previously proposed as a mechanism for self-regulating the gas accretion on to the central object. These backflows tend later to be destabilized by the 3D dynamics, rather than by hydrodynamic (Kelvin-Helmholtz) instabilities. Yet, in the first few hundred thousand years, backflows may create a central accretion region of significant extent, and convey there as much as a few millions of solar masses.

Cielo, S.; Antonuccio-Delogu, V.; Macciò, A. V.; Romeo, A. D.; Silk, J.

2014-04-01

137

3D architecture and structural characterization of the Lima Valley low-angle fault system (Northern Apennines, Italy).  

NASA Astrophysics Data System (ADS)

The nappe pile of the northern Apennines is characterized, from bottom to top, by metamorphic units (Apuane and Massa), overlain by the anchimetamorphic cover unit (Tuscan Nappe), in turn overlain by remnants of former intraoceanic accretionary wedge (Subligurian and Ligurian units) and by the Epiligurian wedge-top sediments. The upper part of the structural edifice, in several areas, is dismembered and thinned by low-angle extensional fault systems, such as those described in southern Tuscany (Carmignani et al., 1994) and in southernmost Liguria (e.g. Tellaro detachment, Storti, 1995). Here we present another example of such low-angle fault systems, exposed in the Lima valley (northern Tuscany). It consists of a well developed bedding-parallel fault system which appears to be, in turn, affected by superimposed folds and late-stage normal faults (Botti et al., 2010). The original geometry of the low-angle fault system has been reconstructed and superimposed deformations have been restored. The fault system is composed by two first order segments, both of them showing bedding-parallel attitude and top-to-NE kinematics. The uppermost segment causes the tectonic repetition of the pelagic sediments of Scaglia fm. (Upper Cretaceous - Oligocene) and the sandstone of Macigno fm. (Oligocene - Miocene); the lowermost one causes the direct contact of the Macigno fm. on the pelagic carbonate of the Maiolica fm. (Upper Jurassic - Lower Cretaceous), via the elision of the Scaglia fm.. In the central part of the study area, other formations are elided by the lowermost fault segment, giving the direct contact of the Macigno fm. with the Calcare selcifero di Limano fm. (Lower Jurassic). The damage zone of the two main tectonic contacts has been studied in detail to investigate the role of the different lithologies involved. In the Macigno sandstone, a foliated cataclasite developed in the proximity of the fault core, intercalated with smaller lithons of less deformed rock associated with crushed breccias. At increasing distances from the fault core, the thickness of the deformed domains decrease up to millimetric scale while the thickness of the undeformed rock domain increase up to decimetric scale. In the Scaglia fm., a very intense fault parallel foliation developed in the shale layers while the more competent limestone layers are affected by low-angle subsidiary faults. In the Maiolica limestone, the presence of abundant calcite filled veins is the evidence of intense fluid circulation. Fault sealing and fluid confinement processes are testified by the strong increasing of the vein volume in the proximity of the fault and the almost complete absence of veins in the hanginwall. Fluids overpressure in the Maiolica fm. had a strong impact on active deformation mechanisms and shear localization. In the portions of rock characterized by lower fluid volume, the veins are not deformed. With increasing fluid volume, vein get more deformed and tension gashes develop. In the proximity of the fault core, where the fluids constitute more than 90% of the whole rock volume, vein array is involved in an S-C type shear fabric.

Clemenzi, L.; Molli, G.; Botti, F.; Ungari, A.; Storti, F.

2012-04-01

138

Geometry and kinematics of glaciotectonic deformation superimposed on the Cenozoic fault-tectonic framework in the central Polish Lowlands  

NASA Astrophysics Data System (ADS)

The distribution of glaciotectonic structures can be controlled by the occurrence of tectonic or neotectonic faulting of the pre-Quaternary basement. The faulted and thus undulated pre-Quaternary basement influenced the thinning or pinching out of weak deformable surficial sediments and could play a role of buried obstacles to forcing by ice-sheets. In both cases, such faulting could result in a predisposition to the development of glaciotectonic deformations. The present study has demonstrated how the geometry and kinematics of the glaciotectonic structures was controlled by the pre-Quaternary framework related to the Kleczew graben tectonics (the central Polish Lowlands). The assumption has been made in this study that the tectonic fractures and faults could influence the reduction of strength and mechanical anisotropy within the pre-Quaternary sediments, which were also remobilised by glaciotectonic forces. The renewed stress build-up by the glaciotectonic forces assumed herein could reactivate the pre-existing fractures and faults at a lower stress level rather than produce new structures that require a higher stress level. The results presented in this study are focused on detailed structural and kinematic analysis of the glaciotectonic faults and fractures. For each glaciotectonic fault studied, the slip vector was directly calculated based on the orientation of the fault striations and indirectly calculated from analysis of the small fractures that developed along the fault. Additionally, the data from this analysis were integrated with the surface-based 3D structural model obtained from the borehole data. This approach revealed the relationships between the geometry, orientation and kinematics of the glaciotectonic structures and the tectonic framework of the pre-Quaternary basement. The different modes of glaciotectonic faulting were determined, depending on the geometry and orientation of the pre-existing reactivated faults and fractures with respect to the direction of the glaciotectonic contraction. In addition to reverse dip-slip displacements, the strike-slip and oblique-slip displacements were recognised. This study was performed in the Kleczew graben (the middle part of the Polish Lowlands) in which the Quaternary and the Miocene sediments are affected by glaciotectonic deformations. Moreover, the Miocene sediments were also tectonically deformed in response to the development of the graben.

W?odarski, Wojciech

2014-06-01

139

3D Faulting Numerical Model Related To 2009 L'Aquila Earthquake Based On DInSAR Observations  

NASA Astrophysics Data System (ADS)

We investigate the surface displacements in the area affected by the April 6, 2009 L'Aquila earthquake (Central Italy) through an advanced 3D numerical modeling approach, by exploiting DInSAR deformation velocity maps based on ENVISAT (Ascending and Descending orbits) and COSMO-SkyMed data (Ascending orbit). We benefited from the available geological and geophysical information to investigate the impact of known buried structures on the modulation of the observed ground deformation field; in this context we implemented the a priori information in a Finite Element (FE) Environment considering a structural mechanical physical approach. The performed analysis demonstrate that the displacement pattern associated with the Mw 6.3 main-shock event is consistent with the activation of several fault segments of the Paganica fault. In particular, we analyzed the seismic events in a structural mechanical context under the plane stress mode approximation to solve for the retrieved displacements. We defined the sub-domain setting of the 3D FEM model using the information derived from the CROOP M-15 seismic line. We assumed stationarity and linear elasticity of the involved materials by considering a solution of classical equilibrium mechanical equations. We evolved our model through two stages: the model compacted under the weight of the rock successions (gravity loading) until it reached a stable equilibrium. At the second stage (co-seismic), where the stresses were released through a slip along the faults, by using an optimization procedure we retrieved: (i) the active seismogenic structures responsible for the observed ground deformation, (ii) the effects of the different mechanical constraints on the ground deformation pattern and (iii) the spatial distribution of the retrieved stress field. We evaluated the boundary setting best fit configuration responsible for the observed ground deformation. To this aim, we first generated several forward structural mechanical models, obtained through the activation of different structural segments; then, we compared the synthetic (related to the performed forward model) and the measured ground deformation fields, in order to select the minimum RMS solution. We search for the best model results using an optimization algorithm based on the genetic algorithm, providing an accurate spatial characterization of ground deformation. Our results improve kinematic solutions for the Paganica fault and allow identification of additional fault segments that have contributed to the observed complex ground deformation pattern. The FEM-based methodology is applicable to other seismic areas where the complexity of buried structures plays a fundamental role on the associated surface deformation pattern.

Castaldo, Raffaele; Tizzani, Pietro; Solaro, Giuseppe; Pepe, Susi; Lanari, Riccardo

2014-05-01

140

Validation of Direct Numerical Simulations in 3D pore geometries and Large-Eddy Simulations  

NASA Astrophysics Data System (ADS)

Numerical solutions of the Navier-Stokes Equations became more popular in recent decades with increasingly accessible and powerful computational resources. Simulations in reconstructed or artificial pore geometries are often performed to gain insight into microscopic fluid flow structures or are used for upscaling quantities of interest, like hydraulic conductivity. A physically adequate representation of pore scale flow fields requires analysis of large domains in combination with turbulence models. We solve incompressible Navier-Stokes Equations in a cubic lattice and cubic close packing of spheres placed in a square duct with Direct Numerical Simulations (DNS) and analyze the validity of the results. The influence of the number of spheres and mesh discretization is investigated for fluid flow up to Reynolds numbers of 5000 based on the spheres' diameter. The numerical simulations are performed with the OpenFOAM open-source CFD software. We statistically investigate spatial and temporal properties of the resulting fluid flow field and its kinetic energy spectra, and compare them to Large-Eddy Simulations (LES) performed for the same geometries. Differences between the DNS and LES are discussed together with upscaled hydraulic properties with respect to the number of spheres and the Reynolds number.

Naumov, Dmitri

2013-04-01

141

Geometry and kinematics of adhesive wear in brittle strike-slip fault zones  

Microsoft Academic Search

Detailed outcrop surface mapping in Late Paleozoic cataclastic strike-slip faults of coastal Maine shows that asymmetric sidewall ripouts, 0.1 200 m in length, are a significant component of many mapped faults and an important wall rock deformation mechanism during faulting. The geometry of these structures ranges from simple lenses to elongate slabs cut out of the sidewalls of strike-slip faults

Mark T. Swanson

2005-01-01

142

Geometry and kinematics of adhesive wear in brittle strike-slip fault zones  

Microsoft Academic Search

Detailed outcrop surface mapping in Late Paleozoic cataclastic strike-slip faults of coastal Maine shows that asymmetric sidewall ripouts, 0.1–200m in length, are a significant component of many mapped faults and an important wall rock deformation mechanism during faulting. The geometry of these structures ranges from simple lenses to elongate slabs cut out of the sidewalls of strike-slip faults by a

Mark T. Swanson

2005-01-01

143

Flow properties along field lines in a 3-D tilted-dipole geometry  

NASA Technical Reports Server (NTRS)

A 3-D MHD simulation of a global, tilted-dipole solar wind flow pattern is analyzed to determine flow properties along individual magnetic field lines. In the model, flow conditions near the Sun are chosen to provide a reasonable match to the interplanetary configuration prevailing during the recent south polar passage by Ulysses, i.e., a streamer belt inclined approximately 30 deg to the solar equator and speeds ranging from 325-800 km/s. Field lines all across the stream pattern are traced from 1 to 10 AU by following the motion of marker particles embedded in the flow. It is found that those field lines threading the core of the interaction region are subject to significant latitudinal and relative longitudinal displacement over this range of heliocentric distance. Thus, observations taken at a fixed latitude in the inner solar system sample, over the course of a solar rotation, field lines which connect to a range of latitudes in the outer heliosphere. Maps of the field line displacements are presented to help visualize these connections. In addition, it is found that depending upon the location relative to the CIR structure, the radial evolution of fluid elements frozen to different field lines can deviate considerably from that of the canonical solar wind. That is, for selected subsets of field lines, large speed changes (not just at shocks) can be experienced; the density variation can be far from 1/r(exp 2), and the magnetic field intensity need not decay monotonically with distance.

Pizzo, V. J.

1995-01-01

144

Relation Between the 3D-Geometry of the Coronal Wave and Associated CME During the 26 April 2008 Event  

NASA Technical Reports Server (NTRS)

We study the kinematical characteristics and 3D geometry of a large-scale coronal wave that occurred in association with the 26 April 2008 flare-CME event. The wave was observed with the EUVI instruments aboard both STEREO spacecraft (STEREO-A and STEREO-B) with a mean speed of approx 240 km/s. The wave is more pronounced in the eastern propagation direction, and is thus, better observable in STEREO-B images. From STEREO-B observations we derive two separate initiation centers for the wave, and their locations fit with the coronal dimming regions. Assuming a simple geometry of the wave we reconstruct its 3D nature from combined STEREO-A and STEREO-B observations. We find that the wave structure is asymmetric with an inclination toward East. The associated CME has a deprojected speed of approx 750 +/- 50 km/s, and it shows a non-radial outward motion toward the East with respect to the underlying source region location. Applying the forward fitting model developed by Thernisien, Howard, and Vourlidas we derive the CME flux rope position on the solar surface to be close to the dimming regions. We conclude that the expanding flanks of the CME most likely drive and shape the coronal wave.

Temmer, M.; Veronig, A. M.; Gopalswamy, N.; Yashiro, S.

2011-01-01

145

3D Strain Geometry and Crystallographic Fabric in Experimental HT Deformation of Solnhofen Limestone  

NASA Astrophysics Data System (ADS)

Under conditions where calcite deforms plastically, high temperature deformation tests on Solnhofen limestone have been run using different strain configurations: axi-symmetric shortening and extension, and direct shear. The aim of the work is to relate strain geometry and the development of crystallographic fabrics in different strain paths. We produced constrictional, flattening, and nearly plane strain deformations. In addition to this, we were also able to obtain strain geometries where the vorticity axis in a non-coaxial deformation was either perpendicular to the extension direction (as in simple and sub-simple shear) or parallel to it. In order to keep constant as many parameters as possible, all experiments used the same starting material and the same experimental conditions of temperature 600 \\deg C, confining pressure 200 MPa and comparable strain rates 10-4s-1. At these conditions, and taking into account the special features of Solnhofen limestone (i.e. fine grain size and the presence of impurities preventing grain growth), the predominant deformation mechanism was intracrystalline plasticity. We used pole figures of different calcite lattice elements, measured by electron back-scattered diffraction techniques (EBSD), to characterize the asymmetry of the crystallographic patterns and particularly c-axis pole figures to identify the presence of different fabric components. Further analysis of inverse pole figures in particular experimental directions allowed us to characterize the extension and compression directions of the strain ellipsoid as they geometrically determine the operation of slip systems. Two main aspects can be highlighted from our experimental results. First, it proved particularly useful to combine inverse pole figures with pole figures to characterize not only the shape of the strain ellipsoid in predominantly plastic deformation but also the sense of shear. Second, there is an extraordinary sensitivity of crystal-plastic deformation of calcite to changes in strain geometry, involving changes in shape of the strain ellipsoid but also variations in non-coaxiality. We would expect the same principle to apply to other mineral phases, as long as crystal plasticity is the predominant deformation mechanism.

Llana-Funez, S.; Rutter, E. H.

2003-12-01

146

High order spatial expansion for the method of characteristics applied to 3-D geometries  

SciTech Connect

The method of characteristics is an efficient and flexible technique to solve the neutron transport equation and has been extensively used in two-dimensional calculations because it permits to deal with complex geometries. However, because of a very fast increase in storage requirements and number of floating operations, its direct application to three-dimensional routine transport calculations it is not still possible. In this work we introduce and analyze several modifications aimed to reduce memory requirements and to diminish the computing burden. We explore high-order spatial approximation, the use of intermediary trajectory-dependent flux expansions and the possibility of dynamic trajectory reconstruction from local tracking for typed subdomains. (authors)

Naymeh, L.; Masiello, E.; Sanchez, R. [CEA/DEN/DM2S, SERMA/LSTD, Centre de Saclay, PC 57, 91191 Gif-sur-Yvette cedex (France)] [CEA/DEN/DM2S, SERMA/LSTD, Centre de Saclay, PC 57, 91191 Gif-sur-Yvette cedex (France)

2013-07-01

147

Characterization of 3D filament dynamics in a MAST SOL flux tube geometry  

NASA Astrophysics Data System (ADS)

Non-linear simulations of filament propagation in a realistic MAST SOL flux tube geometry using the BOUT++ fluid modelling framework show an isolation of the dynamics of the filament in the divertor region from the midplane region due to three features of the magnetic geometry; the variation of magnetic curvature along the field line, the expansion of the flux tube and strong magnetic shear. Of the three effects, the latter two lead to a midplane ballooning feature of the filament, whilst the former leads to a ballooning around the X-points. In simulations containing all three effects the filament is observed to balloon at the midplane, suggesting that the role of curvature variation is sub-dominant to the flux expansion and magnetic shear. The magnitudes of these effects are all strongest near the X-point which leads to the formation of parallel density gradients. The filaments simulated, which represent filaments in MAST, are identified as resistive ballooning, meaning that their motion is inertially limited, not sheath limited. Parallel density gradients can drive the filament towards a Boltzmann response when the collisionalityof the plasma is low. The results here show that the formation of parallel density gradients is a natural and inevitable consequence of a realistic magnetic geometry and therefore the transition to the Boltzmann response is a consequence of the use of realistic magnetic geometry and does not require initializing specifically varying background profiles as in slab simulations. The filaments studied here are stable to the linear resistive drift-wave instability but are subject to the non-linear effects associated with the Boltzmann response, particularly Boltzmann spinning. The Boltzmann response causes the filament to spin on an axis. In later stages of its evolution a non-linear turbulent state develops where the vorticity evolves into a turbulent eddy field on the same length scale as the parallel current. The transition from interchange motion to the Boltzmann response occurs with increasing temperature through a decrease in collisionality. This is confirmed by measuring the correlation between density and potential perturbations within the filament, which is low in the antisymmetric state associated with the interchange mechanism, but high in the Boltzmann regime. In the Boltzmann regime net radial transport is drastically reduced whilst a small net toroidal transport is observed. This suggests that only a subset of filaments, those driven by the interchange mechanism at the separatrix, can propagate into the far SOL. Filaments in the Boltzmann regime will be confined to the near separatrix region and quickly disperse. It is plausible that filaments in both regimes can contribute to the SOL transport observed in experiment; the former by propagating the filament into the far SOL and the latter by dispersion of the density within the filament.

Walkden, N. R.; Dudson, B. D.; Fishpool, G.

2013-10-01

148

TART97 a coupled neutron-photon 3-D, combinatorial geometry Monte Carlo transport code  

SciTech Connect

TART97 is a coupled neutron-photon, 3 Dimensional, combinatorial geometry, time dependent Monte Carlo transport code. This code can on any modern computer. It is a complete system to assist you with input preparation, running Monte Carlo calculations, and analysis of output results. TART97 is also incredibly FAST; if you have used similar codes, you will be amazed at how fast this code is compared to other similar codes. Use of the entire system can save you a great deal of time and energy. TART97 is distributed on CD. This CD contains on- line documentation for all codes included in the system, the codes configured to run on a variety of computers, and many example problems that you can use to familiarize yourself with the system. TART97 completely supersedes all older versions of TART, and it is strongly recommended that users only use the most recent version of TART97 and its data riles.

Cullen, D.E.

1997-11-22

149

3D Geometry and Quantitative Variation of the Cervico-Thoracic Region in Crocodylia.  

PubMed

This study aims to interpret the axial patterning of the crocodylian neck, and to find a potential taxonomic signal that corresponds to vertebral position. Morphological variation in the cervico-thoracic vertebrae is compared in fifteen different crocodylian species using 3D geometric morphometric methods. Multivariate analysis indicated that the pattern of intracolumnar variation was a gradual change in shape of the vertebral series (at the parapophyses, diapophyses, prezygapohyses, and postzygapohyses), in the cervical (C3 to C9) and dorsal (D1-D2) regions which was quite conservative among the crocodylians studied. In spite of this, we also found that intracolumnar shape variation allowed differentiation between two sub regions of the crocodylian neck. Growth is subtly correlated with vertebral shape variation, predicting changes in both the vertebral centrum and the neural spine. Interestingly, the allometric scaling for the pooled sample is equivalently shared by each vertebra studied. However, there were significant taxonomic differences, both in the average shape of the entire neck configuration (regional variation) and by shape variation at each vertebral position (positional variation) among the necks. The average neck vertebra of crocodylids is characterized by a relatively cranio-caudally short neural arch, whereby the spine is relatively longer and pointed orthogonal to the frontal plane. Conversely, the average vertebra in alligatorids has cranio-caudally longer neural spine and arch, with a relatively (dorso-ventrally) shorter spine. At each vertebral position there are significant differences between alligatorids and crocodylids. We discuss that the delayed timing of neurocentral fusion in Alligatoridae possibly explains the observed taxonomic differences. Anat Rec, 297:1278-1291, 2014. © 2014 Wiley Periodicals, Inc. PMID:24753482

Chamero, Beatriz; Buscalioni, Angela D; Marugán-Lobón, Jesús; Sarris, Ioannis

2014-07-01

150

Preliminary Pseudo 3-D Imagery of the State Line Fault, Stewart Valley, Nevada Using Seismic Reflection Data  

Microsoft Academic Search

The Pahrump Fault system is located in the central Basin and Range region and consists of three main fault zones: the Nopah range front fault zone, the State Line fault zone and the Spring Mountains range fault zone. The State Line fault zone is made up north-west trending dextral strike-slip faults that run parallel to the Nevada- California border. Previous

S. C. Saldaña; C. M. Snelson; W. J. Taylor; M. Beachly; C. M. Cox; R. Davis; M. Stropky; R. Phillips; C. Robins; C. Cothrun

2007-01-01

151

The Role of Faulting on the Growth of a Carbonate Platform: Evidence from 3D Seismic Analysis and Section Restoration  

NASA Astrophysics Data System (ADS)

Tectonics in addition to other environmental factors impacts the growth of carbonate platforms and plays an important role in shaping the internal architecture of the platforms. Detailed of faults and fractures development and healing in carbonate environment have not been explored sufficiently. Using 3D seismic and well data, we attempt to reconstruct the structural evolution of a Miocene carbonate platform in Central Luconia Province, offshore Malaysia. Luconia Province is located in the NW coast of Borneo and has become one of the largest carbonate factories in SE Asia. Seismic interpretations including seismic attribute analysis are applied to the carbonate platform to discern its sedimentology and structural details. Detailed seismic interpretations highlight the relationships of carbonate deposition with syn-depositional faulting. Branching conjugate faults are common in this carbonate platform and have become a template for reef growth, attesting lateral facies changes within the carbonate environments. Structural restoration was then appropriately performed on the interpreted seismic sections based on sequential restoration techniques, and provided images different from those of horizon flattening methods. This permits us to compensate faults' displacement, remove recent sediment layers and finally restore the older rock units prior to the fault motions. It allows prediction of platform evolution as a response to faulting before and after carbonate deposition and also enhances the pitfalls of interpretation. Once updated, the reconstructions allow unravelling of the un-seen geological features underneath the carbonate platform, such as paleo-structures and paleo-topography which in turn reflects the paleo-environment before deformations took place. Interestingly, sections balancing and restoration revealed the late-phase (Late Oligocene-Early Miocene) rifting of South China Sea, otherwise difficult to visualize on seismic sections. Later it is shown that this carbonate platform was possibly originated from two or more connected reef build-ups. The platform evolution in terms of tectonic influences on carbonate growth and development may serve as a case example for re-evaluation of pre-Late Miocene structures as a new potential target for hydrocarbon exploration in Central Luconia Province. Eventually, techniques used in this study might be of interest to oil and gas explorers in carbonate system.

Nur Fathiyah Jamaludin, Siti; Pubellier, Manuel; Prasad Ghosh, Deva; Menier, David; Pierson, Bernard

2014-05-01

152

Simulations of nonlinear dynamics of electron Bernstein waves in a 3D geometry  

NASA Astrophysics Data System (ADS)

In a slab geometry, particle-in-cell simulations have confirmed efficient conversions of extraordinary(X) or Ordinary(O) modes to an electron Bernstein wave (EBW). It is has been shown that nonlinear wave-particle interactions such as parametric decays and nonlinear Landau damping play an important role in wave propagations and absorptions. Recently, it is found^1 that as an electron Bernstein wave propagates in an inhomogeneous plasma, its second harmonic wave can be excited at the resonant place where the matching condition for the wave numbers is satisfied. A significant portion of the wave energy will be transferred from the fundamental to its second harmonic. In order to demonstrate possible generations of the second harmonic EBW, and its effect on power deposition of the incident wave, the simulation of particle-wave interactions in a experimental configuration like a torus is highly desired, and yet very challenging. In this work, computational simulations of nonlinear wave dynamics of EBWs in a cylinder (and torus) are carried out using VORPAL PIC code.^2 For an incident wave power which is experimentally available, the generation of the second EBWs is observed. The power absorption at the half cyclotron-harmonics-frequency is also demonstrated. The roles of nonlinear Landau dampings and parametric decays of EBWs are also discussed. [0pt] ^1Xiang and Cary, Phys. Rev. Lett., 100, 085002 (2008). ^2Chet and Cary, J. Comp. Phys., 196, 448 (2004).

Cary, John R.; Xiang, Nong

2008-11-01

153

Algorithm of geometry correction for airborne 3D scanning laser radar  

NASA Astrophysics Data System (ADS)

Airborne three-dimensional scanning laser radar is used for wholesale scanning exploration to the target realm, then three-dimensional model can be established and target features can be identified with the characteristics of echo signals. So it is used widely and have bright prospect in the modern military, scientific research, agriculture and industry. At present, most researchers are focus on higher precision, more reliability scanning system. As the scanning platform is fixed on the aircraft, the plane cannot keep horizontal for a long time, also impossibly for a long time fly in the route without deviation. Data acquisition and the subsequence calibration rely on different equipments. These equipments bring errors both in time and space. Accurate geometry correction can amend the errors created by the process of assembly. But for the errors caused by the plane during the flight, whole imaging process should be analyzed. Take the side-roll as an example; scanning direction is inclined, so that the scanning point deviates from the original place. New direction and coordinate is the aim to us. In this paper, errors caused by the side-roll, pitch, yaw and assembly are analyzed and the algorithm routine is designed.

Liu, Yuan; Chen, Siying; Zhang, Yinchao; Ni, Guoqiang

2009-11-01

154

Validation and Analysis of Forward Osmosis CFD Model in Complex 3D Geometries  

PubMed Central

In forward osmosis (FO), an osmotic pressure gradient generated across a semi-permeable membrane is used to generate water transport from a dilute feed solution into a concentrated draw solution. This principle has shown great promise in the areas of water purification, wastewater treatment, seawater desalination and power generation. To ease optimization and increase understanding of membrane systems, it is desirable to have a comprehensive model that allows for easy investigation of all the major parameters in the separation process. Here we present experimental validation of a computational fluid dynamics (CFD) model developed to simulate FO experiments with asymmetric membranes. Simulations are compared with experimental results obtained from using two distinctly different complex three-dimensional membrane chambers. It is found that the CFD model accurately describes the solute separation process and water permeation through membranes under various flow conditions. It is furthermore demonstrated how the CFD model can be used to optimize membrane geometry in such as way as to promote the mass transfer.

Gruber, Mathias F.; Johnson, Carl J.; Tang, Chuyang; Jensen, Mogens H.; Yde, Lars; Helix-Nielsen, Claus

2012-01-01

155

Source geometry estimation using the mass excess criterion to constrain 3-D radial inversion of gravity data  

NASA Astrophysics Data System (ADS)

We present a gravity-inversion method for estimating the geometry of an isolated 3-D source, assuming prior knowledge about its top and density contrast. The subsurface region containing the geological sources is discretized into an ensemble of 3-D vertical prisms juxtaposed in the vertical direction of a right-handed coordinate system. The prisms' thicknesses and density contrasts are known, but their horizontal cross-sections are described by unknown polygons. The horizontal coordinates of the polygon vertices approximately represent the edges of horizontal depth slices of the 3-D geological source. The polygon vertices of each prism are described by polar coordinates with an unknown origin within the prism. Our method estimates the horizontal Cartesian coordinates of the unknown origin and the radii associated with the vertices of each polygon for a fixed number of equally spaced central angles from 0o to 360o. By estimating these parameters from gravity data, we retrieve a set of vertically stacked prisms with polygonal horizontal sections that represents a set of juxtaposed horizontal depth slices of the estimated source. This set, therefore, approximates the 3-D source's geometry. To obtain stable estimates we impose constraints on the source shape. The judicious use of first-order Tikhonov regularization on either all or a few parameters allows estimating both vertical and inclined sources whose shapes can be isometric or anisometric. The estimated solution, despite being stable and fitting the data, will depend on the maximum depth assumed for the set of juxtaposed 3-D prisms. To reduce the class of possible solutions compatible with the gravity anomaly and the constraints, we use a criterion based on the relationship between the data-misfit measure and the estimated total-anomalous mass computed along successive inversions, using different tentative maximum depths for the set of assumed juxtaposed 3-D prisms. In applying this criterion, we plotted the curve of the estimated total-anomalous mass mt versus data-misfit measure s for the range of different tentative maximum depths. The tentative value for the maximum depth producing the smallest value of data-misfit measure in the mt×s curve is the best estimate of the true (or minimum) depth to the bottom of the source, depending on whether the true source produces a gravity anomaly that is able (or not) to resolve the depth to the source bottom. This criterion was theoretically deduced from Gauss' theorem. Tests with synthetic data shows that the correct depth-to-bottom estimate of the source is obtained if the minimum of s on the mt×s curve is well defined; otherwise this criterion provides just a lower bound estimate of the source's depth to the bottom. These synthetic results show that the method efficiently recovers source geometries dipping at different angles. Test on real data from the Matsitama intrusive complex (Botswana) retrieved a dipping intrusion with variable dips and strikes and with bottom depth of 8.0 ± 0.5 km.

Oliveira, Vanderlei C., Jr.; Barbosa, Valéria C. F.; Silva, João. B. C.

2011-11-01

156

SNR efficient 3D reconstruction algorithm for multi-source inverse geometry CT system  

NASA Astrophysics Data System (ADS)

The multi-source Inverse-Geometry CT(MS-IGCT) system uses a 2D array of sources opposite a smaller 2D detector array. One sample system design uses 3 rows of 21 sources each. Because the MS-IGCT system provides sufficient sampling in the axial direction, cone beam artifacts can be reduced. Projection data from the 21 sources at the same zlocation can be rebinned into one cone beam projection, therefore, we can have 3 different cone beam projection data sets after rebinning, and reconstruction can be performed by using the FDK algorithm. However, if FDK is used, each of the three data sets by itself produces different cone beam artifacts. For example, the upper sources can provide artifact free images in the upper reconstruction volume, but cone beam artifacts can be observed in the central and lower reconstruction volume. The central and lower sources also provide artifact free image at different z-locations. We can achieve an artifact free volume by using artifact free images at different z-locations. However, if we could use all the data, the SNR can be improved. In this study, we develop a method to combine reconstructed volumes in Fourier space, and the main goal is to keep the exactness and improve the SNR in the combined image. The method was tested with a simulation of a Defrise phantom and the proposed method did not show cone beam artifacts. A noise simulation was also performed by using ideal bowtie filter so that all projection data had the same noise level. A noise simulation showed that the noise variance was ~1/3 of that in a single FDK reconstruction.

Baek, Jongduk; Pelc, Norbert J.

2009-02-01

157

Atmospheric correction of thermal-infrared imagery of the 3-D urban environment acquired in oblique viewing geometry  

NASA Astrophysics Data System (ADS)

This research quantifies and discusses atmospheric effects, which alter the radiance observed by a ground-based thermal-infrared (TIR) camera. The TIR camera is mounted on a boom at a height of 125 m above ground on top of a high-rise building in the city of Berlin, Germany (52.4556° N, 13.3200° E) and observes the Earth's surface. The study shows that atmospheric correction of TIR imagery of the three-dimensional (3-D) urban environment acquired in oblique viewing geometry has to account for spatial variability of line-of-sight (LOS) geometry. We present an atmospheric correction procedure that uses these spatially distributed LOS geometry parameters, the radiative transfer model MODTRANTM5.2 and atmospheric profile data derived from meteorological measurements in the field of view (FOV) of the TIR camera. The magnitude of atmospheric effects varies during the analysed 24-hourly period (6 August 2009) and is particularly noticeable for surfaces showing a strong surface-to-air temperature difference. The differences between uncorrected and corrected TIR imagery reach up to 6.7 K at 12:00. The use of non-spatially distributed LOS parameters leads to errors of up to 3.7 K at 12:00 and up to 0.5 K at 24:00.

Meier, F.; Scherer, D.; Richters, J.; Christen, A.

2011-05-01

158

Atmospheric correction of thermal-infrared imagery of the 3-D urban environment acquired in oblique viewing geometry  

NASA Astrophysics Data System (ADS)

This research quantifies and discusses atmospheric effects that alter the radiance observed by a ground-based thermal-infrared (TIR) camera mounted on top of a high-rise building in the city of Berlin, Germany. The study shows that atmospheric correction of ground-based TIR imagery of the three-dimensional (3-D) urban environment acquired in oblique viewing geometry has to account for spatial variability of line-of-sight (LOS) geometry. We present an atmospheric correction procedure that uses these spatially distributed LOS geometry parameters, the radiative transfer model MODTRAN 5.2 and atmospheric profile data derived from meteorological measurements in the field of view (FOV) of the TIR camera. The magnitude of atmospheric effects varies during the analysed 24-hourly period (8 August 2009) and is particularly notable for surfaces showing a strong surface-to-air temperature difference. The differences between uncorrected and corrected TIR imagery reach up to 7.7 K at 12:00. Atmospheric effects are biased up to 4.3 K at 12:00 and up to 0.6 K at 24:00, if non-spatially distributed LOS parameters are used.

Meier, F.; Scherer, D.; Richters, J.; Christen, A.

2010-12-01

159

Geometry and kinematics of adhesive wear in brittle strike-slip fault zones  

NASA Astrophysics Data System (ADS)

Detailed outcrop surface mapping in Late Paleozoic cataclastic strike-slip faults of coastal Maine shows that asymmetric sidewall ripouts, 0.1-200 m in length, are a significant component of many mapped faults and an important wall rock deformation mechanism during faulting. The geometry of these structures ranges from simple lenses to elongate slabs cut out of the sidewalls of strike-slip faults by a lateral jump of the active zone of slip during adhesion along a section of the main fault. The new irregular trace of the active fault after this jump creates an indenting asperity that is forced to plow through the adjoining wall rock during continued adhesion or be cut off by renewed motion along the main section of the fault. Ripout translation during adhesion sets up the structural asymmetry with trailing extensional and leading contractional ends to the ripout block. The inactive section of the main fault trace at the trailing end can develop a 'sag' or 'half-graben' type geometry due to block movement along the scallop-shaped connecting ramp to the flanking ripout fault. Leading contractional ramps can develop 'thrust' type imbrication and forces the 'humpback' geometry to the ripout slab due to distortion of the inactive main fault surface by ripout translation. Similar asymmetric ripout geometries are recognized in many other major crustal scale strike-slip fault zones worldwide. Ripout structures in the 5-500 km length range can be found on the Atacama fault system of northern Chile, the Qujiang and Xiaojiang fault zones in western China, the Yalakom-Hozameen fault zone in British Columbia and the San Andreas fault system in southern California. For active crustal-scale faults the surface expression of ripout translation includes a coupled system of extensional trailing ramps as normal oblique-slip faults with pull-apart basin sedimentation and contractional leading ramps as oblique thrust or high angle reverse faults with associated uplift and erosion. The sidewall ripout model, as a mechanism for adhesive wear during fault zone deformation, can be useful in studies of fault zone geometry, kinematics and evolution from outcrop- to crustal-scales.

Swanson, Mark T.

2005-05-01

160

In vitro analog of human bone marrow from 3D scaffolds with biomimetic inverted colloidal crystal geometry  

PubMed Central

In vitro replicas of bone marrow can potentially provide a continuous source of blood cells for transplantation and serve as a laboratory model to examine human immune system dysfunctions and drug toxicology. Here we report the development of an in vitro artificial bone marrow based on a 3D scaffold with inverted colloidal crystal (ICC) geometry mimicking the structural topology of actual bone marrow matrix. To facilitate adhesion of cells, scaffolds were coated with a layer of transparent nanocomposite. After seeding with hematopoietic stem cells (HSCs), ICC scaffolds were capable of supporting expansion of CD34+ HSCs with B-lymphocyte differentiation. Three-dimensional organization was shown to be critical for production of B cells and antigen specific-antibodies. Functionality of bone marrow constructs was confirmed by implantation of matrices containing human CD34+ cells onto the backs of severe combined immunodeficiency (SCID) mice with subsequent generation of human immune cells.

Nichols, Joan E.; Cortiella, Joaquin; Lee, Jungwoo; Niles, Jean A.; Cuddihy, Meghan; Wang, Shaopeng; Cantu, Andrea; Mlcak, Ron; Valdivia, Esther; Yancy, Ryan; Bielitzki, Joseph; McClure, Matthew L.; Kotov, Nicholas A.

2009-01-01

161

DIF3D nodal neutronics option for two- and three-dimensional diffusion theory calculations in hexagonal geometry. [LMFBR  

SciTech Connect

A nodal method is developed for the solution of the neutron-diffusion equation in two- and three-dimensional hexagonal geometries. The nodal scheme has been incorporated as an option in the finite-difference diffusion-theory code DIF3D, and is intended for use in the analysis of current LMFBR designs. The nodal equations are derived using higher-order polynomial approximations to the spatial dependence of the flux within the hexagonal-z node. The final equations, which are cast in the form of inhomogeneous response-matrix equations for each energy group, involved spatial moments of the node-interior flux distribution plus surface-averaged partial currents across the faces of the node. These equations are solved using a conventional fission-source iteration accelerated by coarse-mesh rebalance and asymptotic source extrapolation. This report describes the mathematical development and numerical solution of the nodal equations, as well as the use of the nodal option and details concerning its programming structure. This latter information is intended to supplement the information provided in the separate documentation of the DIF3D code.

Lawrence, R.D.

1983-03-01

162

The formation of the Tyrrhenian Basin by 3-D interaction among faulting and magmatism  

NASA Astrophysics Data System (ADS)

The Tyrrhenian basin has been formed by extension of overriding continental lithosphere driven by roll back of the Ionian slab across the mantle. The basin is not actively extending but the tectonic structure provides information of the processes that controlled rifting and formation of conjugate margins. The basin opened from west to east, with rifting stopping after progressively larger stretching factors from north to south. The northern region stopped opening at extension factors about 1.8. Towards the south extension continued until full crustal separation that produced first intense magmatism that subsequently was followed by mantle exhumation. The final structure displays two conjugate margins with structures that evolved from symmetric to asymmetric as extension rates increase and a complex tectonic structure in between. The basin provides a natural laboratory to investigate a full rift system with variable amounts of extension. We present observations from a two-ship wide-angle (WAS) and multichannel reflection seismic (MCS) experiment that took place in spring 2010. The experiment took place on two legs: The first leg with Spanish R/V Sarmiento de Gamboa and Italian R/V Urania collected five WAS profiles striking E-W across the entire basin recorded on ocean bottom seismic stations and land stations with a 4800 c.i. G-II gun array as source. The second leg with R/V Sarmiento de Gamboa collected 16 MCS profiles (about 1500 km) using a 3.75 km-long streamer and a 3100 c.i. G-II gun array as source. MCS profiles were shot coincident with WAS profiles. WAS - MCS transects were located in regions with different amount of extension the study the full structure including the two conjugate margins. Additional MCS lines were shot concentrated in the region where mantle exhumation has taken place. The seismic information is placed in a 3D context with the integration of the multibeam bathymetry that covers the entire basin. We present the interpretation of the tectonic structure from MCS images and bathymetry and the calibrated stratigraphy of the basin that gives information of timing, duration, and amount of the tectonic extension for the different transects. We compare those results with the final P-wave velocity models from the five WAS profiles that supply information on the nature of the crust. Each transect provides information of the relationships among extension rates, crustal thickness, nature of the crust, and style of deformation. This information allows to interpret mechanisms of deformation, to infer the importance of magmatism in the rifting process, and to interpret the changes leading of mantle exhumation. Furthermore, the data provide insight in the process of formation of the structure conjugated margins.

Ranero, C. R.; Sallares, V.; Grevemeyer, I.; Zitellini, N.; Vendrell, M. G.; Prada, M.; Moeller, S.; de Franco, R.

2012-12-01

163

3D seismic detection of shallow faults and fluid migration pathways offshore Southern Costa Rica: Application of neural-network meta-attributes  

NASA Astrophysics Data System (ADS)

We employ a seismic meta-attribute workflow to detect and analyze probable faults and fluid-pathways in 3D within the sedimentary section offshore Southern Costa Rica. During the CRISP seismic survey in 2011 we collected an 11 x 55 km grid of 3D seismic reflection data and high-resolvability EM122 multibeam data, with coverage extending from the incoming plate to the outer-shelf. We mapped numerous seafloor seep indicators, with distributions ranging from the lower-slope to ~15 km landward of the shelf break [Kluesner et al., 2013, G3, doi:10.1002/ggge.20058; Silver et al., this meeting]. We used the OpendTect software package to calculate meta-attribute volumes from the 3D seismic data in order to detect and visualize seismic discontinuities in 3D. This methodology consists of dip-steered filtering to pre-condition the data, followed by combining a set of advanced dip-steered seismic attributes into a single object probability attribute using a user-trained neural-network pattern-recognition algorithm. The parameters of the advanced seismic attributes are set for optimal detection of the desired geologic discontinuity (e.g. faults or fluid-pathways). The product is a measure of probability for the desired target that ranges between 0 and 1, with 1 representing the highest probability. Within the sedimentary section of the CRISP survey the results indicate focused fluid-migration pathways along dense networks of intersecting normal faults with approximately N-S and E-W trends. This pattern extends from the middle slope to the outer-shelf region. Dense clusters of fluid-migration pathways are located above basement highs and deeply rooted reverse faults [see Bangs et al., this meeting], including a dense zone of fluid-pathways imaged below IODP Site U1413. In addition, fault intersections frequently show an increased signal of fluid-migration and these zones may act as major conduits for fluid-flow through the sedimentary cover. Imaged fluid pathways root into high-backscatter pockmarks and mounds on the seafloor, which are located atop folds and clustered along intersecting fault planes. Combining the fault and fluid-pathway attribute volumes reveals qualitative first order information on fault seal integrity within the CRISP survey region, highlighting which faults and/or fault sections appear to be sealing or leaking within the sedimentary section. These results provide 3D insight into the fluid-flow behavior offshore southern Costa Rica and suggest that fluids escaping through the deeper crustal rocks are predominantly channeled along faults in the sedimentary cover, especially at fault intersections.

Kluesner, J. W.; Silver, E. A.; Nale, S. M.; Bangs, N. L.; McIntosh, K. D.

2013-12-01

164

Subsurface fault geometry inferred from topographic relief and footwall geologic information: An example from the Ikoma fault zone, southwest Japan  

NASA Astrophysics Data System (ADS)

To improve seismic hazard assessment caused by inland earthquakes, it is necessary to clarify subsurface fault geometry and fault slip sense. Although seismic reflection profiles are commonly used to image subsurface fault geometry and associated deformation, there are numerous technical and conditional limitations that often prevent us seeing deeper extension of the fault. To perform the best estimate of the subsurface fault at seismogenic depth, we use all the geomorphic and geologic information to better constrain numerical fault models. Here we choose the Ikoma fault zone, east of the Osaka plain, southwest Japan, as a case study to infer subsurface fault geometry with a great deal of shallow geologic information. The Ikoma fault zone composes a part of NS-trending topographic relief of basins and ranges in Osaka-Kyoto region where significant EW contraction has been continuously occurring in the late Quaternary (Huzita, 1962). To model the east Osaka basin and the Ikoma Mountains, both of which corresponds to footwall and hanging wall of the Ikoma fault, we employ dislocation model in an elastic half space of Okada (1992). We first calculate surface displacement with a simple rectangular fault, and then compare with the present topographic profile across the fault. We find our best estimate of the fault width, dip, and top depth to maximize the cross correlation and/or to minimize the root mean square of the residual between the model and the topographic profile by grid search technique. Since we apply the dislocation model to the topographic profile across an active fault, we introduce information of the confirmed fault position at the Earth's surface into our model when calculated displacement pattern and topographic cross section are compared. Our result shows that a 14-km-wide shallow dipping thrust fault better explains the topographic relief across the Ikoma fault. However, such fault models cannot reproduce the basin-forming deformation on the footwall. Numerous geologic data of pre-Tertiary bedrock, Pleistocene to Holocene marine and non-marine sediments beneath the Osaka plane (e.g., Horikawa et al., 2003) provide several well-constrained chronological key units which allow us to incorporate the information into our models. In the case of bedrock deformation, our best estimate is a combination of fault width 19km, dip 50°, and top depth 2 km. To explain the thick Quaternary sedimentary units up to ~1,500 m on the footwall, fault dip must be deeper than 50°. None of the traditional geologic fold models (e.g., fault-propagation fold), most of which take detachment into account, can explain such significant basin subsidence. However, one could criticize limitations of the elastic half space model for the long-term geologic processes of tens of thousand years to a few million years. We thus intend to perform further experiments considering viscoelastic relaxation of lower crust, topographic change in upheaval side due to rapid surface erosion, newly-formed dislocation (fault) beyond elaselastic limit.

Tani, E.; Toda, S.

2013-12-01

165

Strike-slip fault evolution on Europa: evidence from tailcrack geometries  

Microsoft Academic Search

Secondary cracks are commonly produced at stress concentration points at the tips of slipping interfaces such as faults. These so-called tailcracks form an antisymmetric pattern at opposite tips of the fault with a fracture geometry that is a mechanical indicator of the sense of slip, whether left-lateral or right-lateral. I present descriptions of tailcracks along numerous strike-slip faults on Europa.

Simon A. Kattenhorn

2004-01-01

166

Scale-relationships and geometry of normal faults reactivated during gravitational gliding of Albian rafts (Espírito Santo Basin, SE Brazil)  

NASA Astrophysics Data System (ADS)

Three-dimensional (3D) seismic-reflection data from SE Brazil are used to investigate the geometry and significance of normal faults reactivated during gravitational gliding of Albian rafts. Late Cretaceous gravitational instability in the study area led to the fragmentation of Albian strata in individual rafts separated by listric (roller) faults and associated sub-basins (Stage 1). Renewed gravitational gliding caused Albian rafts to be translated downslope until salt welds were formed and Albian strata became grounded over pre-salt sequences (Stage 2). Diachronous grounding promoted the reactivation of faults and folds, which at places developed into pop-up structures and broad anticlines sub-parallel to the strike of individual rafts (Stage 3). In this paper we present a new methodology to identify and date reactivated (i.e. shortened) fault families. Statistical analyses of six main fault families confirm that fault reactivation was diachronous in the study area, and its cessation depended on: i) the complete grounding of Albian rafts or, ii) gravitational stabilisation of the rafts imposed by sediment loading and cessation of tectonic tilting of the slope. The results of this study show that tectonically generated pulses of compression and uplift, commonly related to the Andean Orogeny, are not the only mechanisms deforming post-salt overburden units in proximal extensional-dominated regions of the southeast Brazilian margin. This is a crucial piece of information for geodynamic reconstructions and hydrocarbon exploration, as the close control of Albian rafts on fault reactivation induced a continuum of overburden deformation in the Espírito Santo Basin, rather than discrete episodes of inversion.

Alves, Tiago M.

2012-05-01

167

Software development for a 3D gravity inversion and application to study of the Border Ranges Fault System, south-central Alaska  

NASA Astrophysics Data System (ADS)

The Border Ranges Fault System (BRFS) bounds the Cook Inlet and Susitna Basins, and is an important petroleum province within south-central Alaska. A primary goal of our research is to test several plausible models of structure along the BRFS using a novel three-dimensional inversion technique utilizing gravity data, constrained with other geophysical, borehole and surface geological information. This research involves the development of 3D inversion modeling software using C++ Builder from Embarcadero's XE2 Suite. The novel inversion approach directly models known geology with a priori uncertainties assigned to the geologic model to allow researchers to compare alternative interpretations. This technique was developed to evaluate three-dimensional structure in regions of complex and poorly known geology. Our software computes the density solution of a geologic structure by utilizing its location within the gravity field as well as the gridded surface files of known topography and subsurface units. The total gravitational effect of each body is calculated with a series of semi-infinite vertical line elements which improves the computational efficiency of computing forward models of structures with extremely complex geometry. The inversion algorithm considers a priori geophysical constraints and uncertainties due to gravity measurements, surface file inconsistencies, and forward calculations in the model solution. In addition, a Kalman-based filtering estimator is used to minimize our observation and processing noise. The estimator allows the a posteriori covariance matrix to avoid its dependence on the non-singularity of the Jacobian (model) matrix.

Cardenas, Rolando

168

Fault and joint geometry at Raft River geothermal area, Idaho  

SciTech Connect

Raft River geothermal reservoir is formed by fractures in sedimentary strata of the Miocene and Pliocene Salt Lake Formation. The fracturing is most intense at the base of the Salt Lake Formation, along a decollement that dips eastward at less than 5/sup 0/ on top of metamorphosed Precambrian and Lower Paleozoic rocks. Core taken from less than 200 m above the decollement contains two sets of normal faults. The major set of faults dips between 50/sup 0/ and 70/sup 0/. These faults occur as conjugate pairs that are bisected by vertical extension fractures. The second set of faults dips 10/sup 0/ to 20/sup 0/ and may parallel part of the basal decollement or reflect the presence of listric normal faults in the upper plate. Surface joints form two suborthogonal sets that dip vertically. East-northeast-striking joints are most frequent on the limbs of the Jim Sage anticline, a large fold that is associated with the geothermal field. The north-trending joint set is prominent in the fold's hinge. Surface joint intensity decreases in proximity to known faults, indicating that surface joint intensity mapping may be useful for locating the surface traces of faults in the reservoir.

Guth, L.R.; Bruhn, R.L.; Beck, S.L.

1981-07-01

169

3D geometrical inspection of complex geometry parts using a novel laser triangulation sensor and a robot.  

PubMed

This article discusses different non contact 3D measuring strategies and presents a model for measuring complex geometry parts, manipulated through a robot arm, using a novel vision system consisting of a laser triangulation sensor and a motorized linear stage. First, the geometric model incorporating an automatic simple module for long term stability improvement will be outlined in the article. The new method used in the automatic module allows the sensor set up, including the motorized linear stage, for the scanning avoiding external measurement devices. In the measurement model the robot is just a positioning of parts with high repeatability. Its position and orientation data are not used for the measurement and therefore it is not directly "coupled" as an active component in the model. The function of the robot is to present the various surfaces of the workpiece along the measurement range of the vision system, which is responsible for the measurement. Thus, the whole system is not affected by the robot own errors following a trajectory, except those due to the lack of static repeatability. For the indirect link between the vision system and the robot, the original model developed needs only one first piece measuring as a "zero" or master piece, known by its accurate measurement using, for example, a Coordinate Measurement Machine. The strategy proposed presents a different approach to traditional laser triangulation systems on board the robot in order to improve the measurement accuracy, and several important cues for self-recalibration are explored using only a master piece. Experimental results are also presented to demonstrate the technique and the final 3D measurement accuracy. PMID:22346569

Brosed, Francisco Javier; Aguilar, Juan José; Guillomía, David; Santolaria, Jorge

2011-01-01

170

Geometry of Thrust Faults Beneath Amenthes Rupes, Mars  

Microsoft Academic Search

Amenthes Rupes is a large lobate scarp which deforms a crater at the dichotomy boundary. Shortening estimates from this crater are made and combined with axial surface mapping and mechanical modeling to constrain fault depth.

A. Vidal; K. M. Mueller; M. P. Golombek

2005-01-01

171

Shiremoor Geothermal Heat Project: reducing uncertainty around fault geometry and permeability using MoveTM for structural model building and stress analysis  

NASA Astrophysics Data System (ADS)

Structural model building software, Midland Valley's MoveTM, was used to reduce uncertainty around fault geometry and analyse the likelihood of encountering fault-driven enhanced permeability for a proposed geothermal heat production borehole in Shirmoor, UK. Stress analysis was used to predict dilatant or compressional damage zones, and to assess likely permeability, under the present day stress regime. Before assessing whether a particular fault will have increased or decreased permeability, it was first necessary to build a structurally valid, constrained fault framework. Two seismic lines from the project area show evidence of faulting and deformation of horizons. After a simple depth conversion was applied, assuming average velocities for known lithologies, interpretation of the two lines, with additional information from the geological reports, maps and borehole data nearby allowed the construction of a first pass 3D valid structural model of the site using MoveTM software. All geological models constructed by Midland Valley use structural geology principles (such as bed length or area balance) and known geometric relationships between faults and folds to build structurally valid models. This valid geological model was analysed to give insights as to the type of material that might be entrained in the fault cores, the amount of displacement on individual faults and hence potential damage zone sizes and critically the geometry and relationship to key horizons of the fault framework. Stress analysis of the linkage of faults was used to highlight potential areas of either compressional or dilatant damage zones and hence the predicted impact on fault permeability.

Ellis, Jenny; Mannino, Irene; Johnson, Gareth; Felix, Michael E. J.; Younger, Paul L.; Vaughan, Alan P. M.

2014-05-01

172

Preliminary 3D Depth Migration of a Network of 2D Seismic Lines for Fault Imaging at a Pyramid Lake, Nevada Geothermal Prospect  

NASA Astrophysics Data System (ADS)

Many of the current geothermal power plants in western Nevada are found in extensional regimes that are associated with dilational faults and fault intersections. Most of these systems are blind and require advanced seismic imaging techniques to map target faults and reduce drilling risk. Surface features including fumaroles, hot springs, or hydrothermal deposits, like travertine and tufa, are indicators of a potential geothermal resource at depth, which still require advanced seismic imaging techniques for efficient development. One of the most notable locations of tufa deposits in western Nevada is in and around Pyramid Lake. With the abundant hydrothermal venting in the area, the tufa deposits indicate a prime locations for geothermal exploration. In 2010 and previous years, we collected about 38 km of vibroseis reflection data in a network of sixteen 2D lines of various orientations off the northwest side of Pyramid Lake. Most of these lines are within an area of only 10 square km. The 2010 survey used three heavy vibrators, and recorded 6-sec records of 8-sec, 10-100 Hz linear sweeps. Source and receiver spacing varied from 17-67 m, with up to 240 channels live for maximum offsets varying from 1000-5000 m, depending on line length. Preliminary 2D processing with first-arrival velocity optimization shows strong fault-plane reflections and several sets of stratigraphic terminations against faults. We interpret three sets of faults, which appear to intersect at about 1.25 km depth. Despite the three fault sets each appearing on several lines, only the lines trending perpendicular to fault strike show direct imaging of fault-plane reflections. We hypothesize that a 3D depth migration will reveal additional direct images of the faults. We are testing this hypothesis with a 3D Kirchhoff prestack migration of the data from this dense network of 2D lines. The 3D depth migration will take full account of lateral velocity changes. This migration should directly image additional steeply dipping fault planes at this prospect. The Pyramid Lake Paiute Tribe will use this information to build 3D geologic and hydrologic models for geothermal power development.

Frary, R.; Louie, J. N.; Pullammanappallil, S.; Eisses, A.

2011-12-01

173

3D current path in stacked devices: Metrics and challenges  

Microsoft Academic Search

Although magnetic current imaging (MCI) is useful in fault isolation of devices with 2D current distributions, MCI alone cannot give the exact information of current paths in complex 3D stacked devices. Previous work has demonstrated the ability of a simulation approach to find a short circuit in 3D geometry. This approach has been challenged in the case of dense and

H. B. Kor; F. Infante; P. Perdu; C. L. Gan; D. Lewis

2011-01-01

174

Relationship between earthquake source faults and 3D density structures derived by gravity anomaly inversion in Japan  

Microsoft Academic Search

In Japan, prediction of strong ground motion has important role for prevention of earthquake hazards. Information of subsurface and crust structure including source fault are require for the strong ground motion estimation. Various geological and geophysical information are required to define earthquake fault and underground models. Active fault trace is the major information to construct earthquake source faults. On the

N. Inoue; N. Kitada; K. Takemura

2008-01-01

175

Vectorization of a 2D-1D Iterative Algorithm for the 3D Neutron Transport Problem in Prismatic Geometries  

NASA Astrophysics Data System (ADS)

The past few years have been marked by a noticeable increase in the interest in 3D whole-core heterogeneous deterministic neutron transport solvers for reference calculations. Due to the extremely large problem sizes tackled by such solvers, they need to use adapted numerical methods and need to be efficiently implemented to take advantage of the full computing power of modern systems. As for numerical methods, one possible approach consists in iterating over resolutions of 2D and 1D MOC problems by taking advantage of prismatic geometries. The MICADO solver, developed at EDF R&D, is a parallel implementation of such a method in distributed and shared memory systems. However it is currently unable to use SIMD vectorization to leverage the full computing power of modern CPUs. In this paper, we describe our first effort to support vectorization in MICADO, typically targeting Intel© SSE CPUs. Both the 2D and 1D algorithms are vectorized, allowing for high expected speedups for the whole spatial solver. We present benchmark computations, which show nearly optimal speedups for our vectorized implementation on the TAKEDA case.

Moustafa, Salli; Févotte, François; Lathuilière, Bruno; Plagne, Laurent

2014-06-01

176

Seismic tomography of the Canterbury Plains and the geometry and evolution of seismicity of the Greendale fault system, New Zealand  

NASA Astrophysics Data System (ADS)

The previously unknown Greendale fault produced the September 4, 2010 M 7.1 Darfield earthquake and later triggered the destructive February 22, 2011 M 6.3 Christchurch earthquake, as well as later M>5 aftershocks east of Christchurch. Surface rupture from the Darfield earthquake indicates up to 5 m of strike-slip motion along the main portion of the Greendale fault, while various geodetic and seismic models also indicate reverse faulting on surrounding smaller faults. We combine seismic data from a variety of sources (permanent network seismometers and strong motion instruments, temporary intermediate to broadband seismometers) to understand the geometry of these various sections of faults and the evolution of seismicity along them for the first four months of aftershocks from the Darfield earthquake. We identify 4 to 5 fault segments that were likely active in the Darfield earthquake and an additional 5 to 6 segments that were active during the study period, prior to the Christchurch earthquake. While relocating hypocenters, we also jointly invert for 3D Vp, Vs, and Vp/Vs in the Canterbury region using an extended version of the double-difference tomography code tomoDD (Zhang et al., 2009). In the area of the Greendale and associated faults, Vp, Vs, and Vp/Vs are generally reduced from the top 8 km of the average velocity model for the Canterbury region of New Zealand. from the surface to ~8 km depth, below which the resolution begins to decline. Beneath Christchurch and areas immediately to the south and west, Vp and Vs are elevated and Vp/Vs is reduced from the surface to ~8 km depth, corresponding to the location of a negative Bouguer gravity anomaly and an increase in depth to basement (Hicks, 1989). In the northwest portion of the model, Vp and Vs increase when approaching the foothills of the Southern Alps. There are no clearly defined features in the velocity model that cross or are offset by the Greendale fault and no apparent contrast in velocities across the fault, preventing us from conjecturing about the age or total offset along the fault over its lifespan based on the velocity models alone.

Syracuse, E. M.; Thurber, C. H.; Savage, M. K.

2012-12-01

177

On the Effects of Non-Planar Fault Geometry on Strong Ground Motion  

NASA Astrophysics Data System (ADS)

We quantify the effects of complex fault geometry on low-frequency (<1 Hz) strong ground motion using numerical modeling of dynamic rupture. Our tests include the computation of synthetic seismograms for several simple rupture scenarios with planar and curved fault approximations of the 1994 Northridge and the 1992 Landers earthquakes. We use the boundary integral equation method (BIEM) to compute the dynamic rupture process, which includes the normal stress effects along the curved fault geometries. The wave propagation and computation of synthetic seismograms are modeled using a fourth-order finite-difference method (FDM). The near-field ground motion is significantly affected by the acceleration, deceleration and arrest of rupture due to fault bending, as well as the the variation in directivity of the rupture. We compare 1-Hz near-fault peak velocities for 40o-dipping, thrust faults buried 5 km with dimensions 24 km by 16 km. Compared to that for a planar fault, such as most approximations of the Northridge earthquake, a 6-km-long hanging-wall or footwall splay with a maximum offset of 1 km can change peak velocities by up to a factor of 2-3 above the fault. This change is caused in part by a variation in directivity, in part by differences in the rupture dynamics for the scenarios. In particular, the curved faults cause a gradual arrest of rupture, while the planar fault rupture stops abruptly with a resulting increase in moment. Our tests suggest that the differences in waveform are larger on the hanging wall compared to those on the footwall. The results imply that kinematic ground motion estimates and slip inversion may be significantly biased by the omission of dynamic rupture effects and of relatively gentle variation in fault geometry, even for long-period waves.

Olsen, K. B.; Aochi, H.

2002-12-01

178

Detailed characterization of 2D and 3D scatter-to-primary ratios of various breast geometries using a dedicated CT mammotomography system  

NASA Astrophysics Data System (ADS)

With a dedicated breast CT system using a quasi-monochromatic x-ray source and flat-panel digital detector, the 2D and 3D scatter to primary ratios (SPR) of various geometric phantoms having different densities were characterized in detail. Projections were acquired using geometric and anthropomorphic breast phantoms. Each phantom was filled with 700ml of 5 different water-methanol concentrations to simulate effective boundary densities of breast compositions from 100% glandular (1.0g/cm3) to 100% fat (0.79g/cm3). Projections were acquired with and without a beam stop array. For each projection, 2D scatter was determined by cubic spline interpolating the values behind the shadow of each beam stop through the object. Scatter-corrected projections were obtained by subtracting the scatter, and the 2D SPRs were obtained as a ratio of the scatter to scatter-corrected projections. Additionally the (un)corrected data were individually iteratively reconstructed. The (un)corrected 3D volumes were subsequently subtracted, and the 3D SPRs obtained from the ratio of the scatter volume-to-scatter-corrected (or primary) volume. Results show that the 2D SPR values peak in the center of the volumes, and were overall highest for the simulated 100% glandular composition. Consequently, scatter corrected reconstructions have visibly reduced cupping regardless of the phantom geometry, as well as more accurate linear attenuation coefficients. The corresponding 3D SPRs have increased central density, which reduces radially. Not surprisingly, for both 2D and 3D SPRs there was a dependency on both phantom geometry and object density on the measured SPR values, with geometry dominating for 3D SPRs. Overall, these results indicate the need for scatter correction given different geometries and breast densities that will be encountered with 3D cone beam breast CT.

Shah, Jainil; Pachon, Jan H.; Madhav, Priti; Tornai, Martin P.

2011-03-01

179

The effects of 3D channel geometry on CTC passing pressure - towards deformability-based cancer cell separation.  

PubMed

Various lab on a chip devices have been developed recently to detect and separate circulating tumour cells (CTCs) for early stage cancer detection. Because CTCs are extremely rare in the blood, next generation CTC microfilters aim at significant improvement in both efficiency and throughput. CTC microfilters based on cell deformability seem to be a promising direction. In the present research, we study a CTC passing event through a micro-filtering channel with various 3D geometries. The pressure signatures for different types of cells passing through different channels are characterized numerically. Specifically, five kinds of cross-sections, circular, square, triangular and two kinds of rectangular channels with aspect ratios of 2 and 5, are studied in this work. The total pressures for cells passing through the channels are calculated and reveal different behaviour from what is predicted by the static surface tension model. Among all five cross-sections studied, the circular cross-section features the highest critical pressure and thus is most suitable for high efficiency CTC separation. The square filtering channel provides the second largest critical pressure, and the triangular cross-section provides the least critical pressure among these three cross-sections. All these three cross-sections are better than the rectangular channels with aspect ratios of 2 and 5. For the rectangular channel, a high aspect ratio channel may lead to cell splitting at high speed, which will result in a periodic pressure signature. Our findings will provide valuable information for the design of next generation CTC microfilters. PMID:24895079

Zhang, Zhifeng; Xu, Jie; Hong, Bin; Chen, Xiaolin

2014-06-17

180

Incorporation of Sweep in a Transonic Fan Design Using a 3D Blade-Row Geometry Package Intended for Aero-Structural-Manufacturing Optimization.  

National Technical Information Service (NTIS)

A new 3D blade row geometry package was developed and implemented. In the new representation the blade is described by six Bezier surfaces two of which represent the pressure and suction surfaces with sixteen points each. The leading and trailing edges ar...

H. F. Abdelhamid

1997-01-01

181

A Mohr circle method for 3D strain measurement using the geometry of no finite longitudinal strain and the R XZ strain ratio  

Microsoft Academic Search

This paper proposes a new method for 3D finite strain analysis. This method utilizes a Mohr circle construction combined with stereographic projection of the geometry of no finite longitudinal strain and with the strain ratio on the XZ-plane of the finite strain ellipsoid. The method is described using numerical examples and then it is tested by applying it to the

Khalil Sarkarinejad; Babak Samani; Ali Faghih

2011-01-01

182

Use of 3D Geometry Modeling of Osteochondrosis-like Iatrogenic Lesions as a Template for Press-and-Fit Scaffold Seeded with Mesenchymal Stem Cells  

Microsoft Academic Search

Summary Computed tomography (CT) is an effective diagnostic modality for three-dimensional imaging of bone structures, including the geometry of their defects. The aim of the study was to create and optimize 3D geometrical and real plastic models of the distal femoral component of the knee with joint surface defects. Input data included CT images of stifle joints in twenty miniature

P. KRUPA; P. KRŠEK; M. JAVORNÍK; O. DOSTÁL; R. SRNEC; D. USVALD

2007-01-01

183

Guidelines for 2D\\/3D FE transient modeling of inductive saturable-core Fault Current Limiters  

Microsoft Academic Search

Fault Current Limiters (FCLs) are expected to play an important role in protection of future power systems. FCLs can be classified in three groups: passive, solid-state and hybrid FCLs. Passive FCLs have merit to inherently react on a fault, requiring no fault detection and triggering circuit. Inductive FCLs based on core saturation belong to this group. Analytical models, used for

D. Cvoric; S. W. H. de Haan; J. A. Ferreira

2009-01-01

184

Earthquake-Driven Fluid Redistribution Around Mechanically Interacting, Segmented Normal Faults: Predictions of 3-D Numerical Models  

Microsoft Academic Search

Observed hydrologic responses to major normal fault earthquakes demonstrate that such seismic events significantly perturb the regional groundwater flow field. We attempt to characterize this process in three dimensions using numerical models of the hydrologic response to slip along segmented normal fault systems. We propose that sudden perturbations in mean normal stresses adjacent to mechanically interacting fault segments induce pressure

F. D. Pearce; S. A. Kattenhorn

2001-01-01

185

Near-Surface Seismic Images and Geometry of the San Andreas Fault, Santa Cruz Mountains, California  

Microsoft Academic Search

In July 2005, the US Geological Survey and the University of Nevada-Las Vegas acquired a 305-m-long, high-resolution, combined seismic reflection and refraction profile across the San Andreas fault within the Los Trancos Open Space Preserve in Palo Alto, California. The objective of the seismic investigation was to determine the geometry and seismic velocities of the San Andreas fault along a

S. C. Saldana; R. D. Catchings; M. J. Rymer; M. R. Goldman; C. M. Snelson

2005-01-01

186

On the Effects of Non-planar Geometry for Blind Thrust Faults on Strong Ground Motion  

NASA Astrophysics Data System (ADS)

We quantify the effects of complex fault geometry on low-frequency (<1 Hz) strong ground motion using numerical modeling of dynamic rupture. Our tests include the computation of synthetic seismograms for several simple rupture scenarios with planar and curved fault approximations of the 1994 Northridge earthquake. We use the boundary integral equation method (BIEM) to compute the dynamic rupture process, which includes the normal stress effects along the curved fault geometries. The wave propagation and computation of synthetic seismograms are modeled using a fourth-order finite-difference method (FDM). The near-field ground motion is significantly affected by the acceleration, deceleration and arrest of rupture due to the curvature of the faults, as well as the variation in directivity of the rupture. For example, a 6-km-long hanging-wall or footwall splay with a maximum offset of 1 km can change 1-Hz peak velocities by up to a factor of 2-3 near the fault. Our tests suggest that the differences in waveform are larger on the hanging wall compared to those on the footwall, although the differences in amplitude are larger in the forward rupture direction (footwall). The results imply that kinematic ground motion estimates may be biased by the omission of dynamic rupture effects and even relatively gentle variation in fault geometry, and even for long-period waves.

Aochi, Hideo; Olsen, Kim B.

2004-12-01

187

Analysis of normal fault populations in the Kumano Forearc Basin, Nankai Trough, Japan: 1. Multiple orientations and generations of faults from 3-D coherency mapping  

NASA Astrophysics Data System (ADS)

Analyses of normal faults in the Kumano forearc basin of the Nankai Trough reveal multiple normal fault populations in a region generally thought to be under compression. Most faults have offsets of less than 20 m and dips of 60-70° and show no growth structures, indicating that the faults were active for short periods of time. The oldest generation of faults is older than ~0.9 Ma and strikes ~50-60°. The next oldest faults strike ~160-170°, are older than 0.44 Ma, and are related to local uplift along the western edge of the region. The youngest faults cut the seafloor; shallow faults near the SE margin of the basin curve from ~100° in the middle of the survey area to ~145° at the SE corner of the area. The pattern of the two youngest fault populations is consistent with the regional stress pattern (maximum horizontal stress subparallel to the trench). Orientations of older fault populations are caused by uplift of the underlying accretionary prism, implying that the forearc basin region is not as stable as previously thought. Reconstruction of displacements on the youngest faults shows that the overall horizontal extension is less than 2%, concentrated near the seaward edge of the basin. The active normal faults distributed throughout the basin support the idea that the horizontal stress parallel to the plate convergence direction does not reach the critical stress to activate or form thrust faults and produce horizontal shortening within the shallow portion of the inner wedge.

Moore, G. F.; Boston, B. B.; Sacks, A. F.; Saffer, D. M.

2013-06-01

188

Joints at high angles to normal fault strike: an explanation using 3-D numerical models of fault-perturbed stress fields  

Microsoft Academic Search

Structural methods based on homogeneous stress states predict that joints growing in an extending crust form with strike orientations identical to normal faults. However, we document a field example where the strikes of genetically related normal faults and joints are almost mutually perpendicular. Field relationships allowed us to constrain the fracture sequence and tectonic environment for fault and joint growth.

Simon A. Kattenhorn; Atilla Aydin; David D. Pollard

2000-01-01

189

Comparative geometry of the San Andreas Fault, California, and laboratory fault zones  

USGS Publications Warehouse

Textural examination of fault gouge deformed in triaxial friction experiments has revealed differences in the orientations of secondary shear sets between the stably sliding and stick-slip samples. In order to determine whether such differences can be identified in natural faults, maps of recently active breaks along the San Andreas fault were examined to compare the types and orientations of secondary structures mapped in the creeping and locked sections. The fault zone was divided into 52 geometrically defined segments of uniform strike, which were then grouped into 7 sections: 4 straight and two curved sections, and Cholame Valley. Many of the gross geometric characteristics of the individual segments, such as length, width, and stepover size, reflect their position in either a straight or a curved section. In contrast, with respect to the orientations of the recent breaks within the segments, the single creeping section differs from all of the locked sections, both straight and curved. -from Authors

Moore, D. E.; Byerlee, J. D.

1991-01-01

190

An example of complex fault geometries in a young, rapidly deforming transform fault system: The Maacama Fault in northern California  

NASA Astrophysics Data System (ADS)

The Maacama Fault Zone (MFZ) in northern California is a young transform system that developed behind the northward migrating Mendocino Triple Junction, and comprises a complex set of active, linked fault strands that form a series of pull-apart basins within the rapidly slipping (~13.9 mm/yr) right-lateral fault system. Surface fault traces within the MFZ are defined by geomorphic features, shallow resistivity profiles, and previously published surface creep and paleoseismic trenching studies. The surface traces of these faults outline classic pull-apart rhomohedrons, with all of the bounding faults inferred to be kinematically linked and currenty active. This activity is supported not only by paleoseismic and surface creep studies, which have tended to focus on the single main strand of the Maacama Fault, but also by the location of tabular seismogenic zones that project from the subsurface into several of the mapped surface fault traces. For each of the 3 mapped pull-apart basins, at least two of the interpreted bounding faults can be shown to be currently active, requiring near-synchronous activity on all of the kinematically linked faults. Historically, active displacement across the MFZ has been assigned to only one relatively well-studied main strand of the fault zone, which slips at ~6.5 mm/yr, resulting in an apparent slip deficit of ~7.4 mm/yr. However, the newly studied adjacent faults in this complex system could accommodate as much or more slip than the historically defined main fault trace, thus resulting in a possibly broader zone of seismic hazard, but less risk of major earthquakes on the main trace. Timing of pull-apart basin initiations is not well constrained, with data permitting either the interpretation that basins formed due to oblique subduction and are currently being reactivated by similar stresses, or that they are newly formed and rapidly evolving. Limited data even allows that the largest pull-apart system may be a reactivated pre-existing structure, while the remaining two pull-aparts are newly formed. At several locations, the MFZ clearly reactivates pre-existing Franciscan subduction-related structures. Evidence of this includes the correlation of surface projections of seismogenic zones with outcrops of subduction related fault zones, and also best-fit planes through seismicity that have the same attitude as the pre-existing reverse faults that are seen in the Franciscan accretionary prism. Outcrops along these pre-existing fault zones have been analyzed by thin-section and XRD analysis, and include abundant mixed-layer clays, serpentine and chrysotile, and silica-carbonate. While each of these sheared deposits are evidence of a fault zone, the abundant clay in particular may be responsible for facilitating fault creep, such as the ~6.5 mm/yr seen on the main strand of the MFZ, and as has been suggested in the same formation at the SAFOD site in central California. The complexity of the MFZ is interpreted to result at least partially from the fact that it deforms heterogeneous Fransican mélange lithologies, which offer a closely spaced set of weak pre-existing fault planes that accommodate rapid displacement along the young San Andreas transform boundary.

Schroeder, R. D.; Brady, R. J.

2009-12-01

191

3D Interface-Enriched Generalized Finite Element Method for Weakly Discontinuous Problems with Complex Internal Geometries.  

National Technical Information Service (NTIS)

An interface-enriched generalized finite element method (GFEM) is introduced for 3D problems with discontinuous gradient fields. The proposed method differs from conventional GFEM by assigning the generalized degrees of freedom to the interface nodes, i.e...

P. H. Geubelle S. Soghrati

2012-01-01

192

Near-Surface Seismic Images and Geometry of the San Andreas Fault, Santa Cruz Mountains, California  

NASA Astrophysics Data System (ADS)

In July 2005, the US Geological Survey and the University of Nevada-Las Vegas acquired a 305-m-long, high-resolution, combined seismic reflection and refraction profile across the San Andreas fault within the Los Trancos Open Space Preserve in Palo Alto, California. The objective of the seismic investigation was to determine the geometry and seismic velocities of the San Andreas fault along a part of the surface rupture area of the 1906 M 7.9 San Francisco earthquake. Seismic sources (sledge hammer blows) and geophones (40-Hz single-element verticals) were co-located (1-m lateral offsets) and were spaced at 5-m increments along the profile. The data were recorded with two 60-channel seismographs without acquisition filters. From the resulting seismic data, we developed tomographic P-wave velocity models of the upper 80 m and stacked and migrated reflection images of the upper few hundred meters along the profile. Seismic P-wave velocities range from about 800 m/s to 4500 m/s in the upper 80 m. For rocks with velocities greater than 2500 m/s, the San Andreas fault is expressed as a well-defined low-velocity zone that is about 60 to 80 m wide. In stacked reflection images, the near-surface (upper 100 m) San Andreas fault zone includes multiple vertically offset reflectors with varying dips. On the basis of offset reflectors and lateral variations in the velocity structure, we suggest that the active fault zone is wider than previously indicated by some geologic maps. Surface ruptures from earthquakes prior to the 1906 rupture have likely involved some or all of the imaged near-surface splays. Other more populated areas along the San Andreas fault probably have similar near-surface geometries, and land-use planning in those areas should assume similar complex geometries for the San Andreas fault.

Saldana, S. C.; Catchings, R. D.; Rymer, M. J.; Goldman, M. R.; Snelson, C. M.

2005-12-01

193

Improving the resolution of the 2010 Haiti earthquake fault geometry using temporary seismometer deployments  

NASA Astrophysics Data System (ADS)

Haiti has been the locus of a number of large and damaging historical earthquakes. The recent January 12, 2010, Mw 7.0 earthquake affected cities that were largely unprepared, which resulted in tremendous losses. It was initially assumed that the earthquake ruptured the Enriquillo Plantain Garden Fault (EPGF), a major active structure in southern Haiti, known from geodetic measurements and its geomorphic expression to be capable of producing M7 or larger earthquakes. However, GPS and InSAR data showed that the event ruptured a previously unmapped fault, the Léogâne fault, a north dipping oblique blind thrust located immediately north of the Enriquillo Fault. Following the earthquake several groups installed temporary seismic stations to record aftershocks, including ocean bottom seismometers on either side of the EPGF. We use data from the complete set of stations deployed after the event, on land and offshore, to relocate all aftershocks from 10 February to 24 June 2010, to determine a one-dimensional regional crustal velocity model, and calculate focal mechanisms. The aftershock locations from the combined data set clearly delineate the Léogâne fault, with a geometry close to that inferred from geodetic data. Its strike and dip closely agrees with that of the global centroid moment tensor solution of the mainshock, but it is more steeply dipping than the plane inferred from previously determined finite fault inversions. The aftershocks also delineate a structure with shallower southward dip offshore and to the west of the rupture zone, which could indicate triggered seismicity on the offshore Trois Baies reverse fault. We use first-motion focal mechanisms to clarify the relationship of the fault geometry to the triggered aftershocks.

Douilly, R.; Haase, J. S.; Ellsworth, W. L.; Bouin, M.; Calais, E.; Symithe, S. J.; Armbruster, J. G.; Mercier De Lepinay, B. F.; Deschamps, A.; Meremonte, M. E.; Hough, S. E.; Saint Louis, M.

2012-12-01

194

Crustal structure and fault geometry of the 2010 Haiti earthquake from temporary seismometer deployments  

USGS Publications Warehouse

Haiti has been the locus of a number of large and damaging historical earthquakes. The recent 12 January 2010 Mw 7.0 earthquake affected cities that were largely unprepared, which resulted in tremendous losses. It was initially assumed that the earthquake ruptured the Enriquillo Plantain Garden fault (EPGF), a major active structure in southern Haiti, known from geodetic measurements and its geomorphic expression to be capable of producing M 7 or larger earthquakes. Global Positioning Systems (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data, however, showed that the event ruptured a previously unmapped fault, the Léogâne fault, a north?dipping oblique transpressional fault located immediately north of the EPGF. Following the earthquake, several groups installed temporary seismic stations to record aftershocks, including ocean?bottom seismometers on either side of the EPGF. We use data from the complete set of stations deployed after the event, on land and offshore, to relocate all aftershocks from 10 February to 24 June 2010, determine a 1D regional crustal velocity model, and calculate focal mechanisms. The aftershock locations from the combined dataset clearly delineate the Léogâne fault, with a geometry close to that inferred from geodetic data. Its strike and dip closely agree with the global centroid moment tensor solution of the mainshock but with a steeper dip than inferred from previous finite fault inversions. The aftershocks also delineate a structure with shallower southward dip offshore and to the west of the rupture zone, which could indicate triggered seismicity on the offshore Trois Baies reverse fault. We use first?motion focal mechanisms to clarify the relationship of the fault geometry to the triggered aftershocks.

Douilly, Roby; Haase, Jennifer S.; Ellsworth, William L.; Bouin, Marie?Paule; Calais, Eric; Symithe, Steeve J.; Armbruster, John G., Mercier de Lépinay, Bernard; Deschamps, Anne; Mildor, Saint?Louis; Meremonte, Mark E.; Hough, Susan E.

2013-01-01

195

3-D Geometry of the Philippine Sea Plate Slab just beneath the Tokyo Metropolitan Area and its Vicinity, Japan  

Microsoft Academic Search

We present a new view of three-dimensional geometry of slab(s) subducted just beneath the Tokyo metropolitan area, central Japan. Previously, several different models of the surface geometry of the subducted Philippine sea plate slab (PH slab) have been published using seismological data. First, we discriminate previously unknown seismic slab (called slab SG, or seismic slab SG) above the downgoing Pacific

T. Eguchi; S. Hori

2007-01-01

196

How Students Solve Problems in Spatial Geometry while Using a Software Application for Visualizing 3D Geometric Objects  

ERIC Educational Resources Information Center

In schools, learning spatial geometry is usually dependent upon a student's ability to visualize three dimensional geometric configurations from two dimensional drawings. Such a process, however, often creates visual obstacles which are unique to spatial geometry. Useful software programs which realistically depict three dimensional geometric…

Widder, Mirela; Gorsky, Paul

2013-01-01

197

Control of preexisting faults and near-surface diapirs on geometry and kinematics of fold-and-thrust belts (Internal Prebetic, Eastern Betic Cordillera)  

NASA Astrophysics Data System (ADS)

We have determined, for the first time, the 3D geometry of a sector of the eastern Internal Prebetic comprised between Parcent and Altea diapirs, combining structural, borehole and multichannel seismic reflection data. The tectonic structure of the Jurassic-Cretaceous carbonate series is characterized by regional ENE-WSW fold-and-thrusts that interact with oblique N-S and WNW-ESE folds, detached over Triassic evaporites and clays. The structural style comprises box-shape anticlines, and N-vergent anticlines with vertical to overturned limbs frequently bordered by reverse and strike-slip faults. The anticlines surround a triangular broad synclinal structure, the Tárbena basin, filled by a late Oligocene to Tortonian sedimentary sequence that recorded folding and thrusting history. The location and geometrical characteristics of fold-and-thrusts may be controlled by the positive inversion of pre-existing Mesozoic normal faults, and by the position and shape of near-surface diapirs composed of Triassic rocks. Therefore, we propose an initial near-surface diapir emplacement of Triassic evaporitic rocks driven by late Jurassic to early Cretaceous rifting of the southern Iberian paleomargin. Thrusting and folding started during the latest Oligocene (?28-23 Ma) roughly orthogonal to the NW-directed shortening. Deformation migrated to the south during Aquitanian (?23-20 Ma), when tectonic inversion implied the left-lateral transpressive reactivation of N-S striking former normal faults and right-lateral/reverse reactivation of inherited WNW-ESE faults. We show two mechanisms driving the extrusion of the diapirs during contraction: lateral migration of a pre-existing near-surface diapir associated with dextral transpression; and squeezing of a previous near-surface diapir at the front of an anticline. Our study underlines the value of 3D geological modeling to characterize geometry and kinematics of complex fold-and-thrust belts influenced by preexisting faults and near-surface diapirs.

Pedrera, Antonio; Marín-Lechado, Carlos; Galindo-Zaldívar, Jesús; García-Lobón, José Luis

2014-07-01

198

Fault geometry of the 2004 off the Kii peninsula earthquake inferred from offshore pressure waveforms  

NASA Astrophysics Data System (ADS)

We could successfully obtain water pressure fluctuations after a series of two off the Kii peninsula earthquakes that took place on September 5 in 2004, using two pressure gauges deployed at deep ocean-bottom off Muroto. The earthquakes caused two tsunamis in the southern coast of the southwestern Japan with maximum wave heights of 0.9 m, and we could identify the tsunami signals from the acquired dataset ca. 20 min before the arrivals of the tsunamis to the coastline nearest to the sensors. Two earthquakes are assumed as one for a foreshock and the other for a main-shock. Although seismological studies, without aftershock distributions, showed a lack of constraints to distinguish if the main-shock was caused by either southwest dipping fault or by the other, i.e., northeast dipping fault, we found that the difference in the pressure fluctuations for the tsunamis could attribute to the determination of the fault plane in the fault models. In this paper, we evaluate the fault geometry of the main shock by using tsunami waveforms obtained by those unique instruments in following procedure: (1) We first simulate pressure waveforms caused by earthquakes of the two fault geometries, one for southwest dipping place and the other for the northeast, at the location of the pressure gauges, and (2) we then compare the simulated results with observed waveforms. Our results demonstrate that the main-shock should be caused by a fault whose strike lies in northwest-to-southeast with a dip towards southwest direction.

Matsumoto, H.; Mikada, H.

2005-03-01

199

Resolving the nature and geometry of major fault systems from geophysical and structural analysis: The Palmerville Fault in NE Queensland, Australia  

Microsoft Academic Search

The Palmerville Fault in northeastern Queensland, Australia, forms a major terrane-bounding structure that probably had a major influence on the evolution of the adjacent Palaeozoic Hodgkinson Province, the northernmost part of the Tasman Fold Belt System in eastern Australia. The nature and subsurface expression of the Palmerville Fault remain poorly constrained and models for contrasting geometries exist. In addition to

I. M. A. Vos; F. P. Bierlein; M. A. Barlow; P. G. Betts

2006-01-01

200

User's manual. SPIN, a program for 3-D axisymmetric geometry generation. [In FORTRAN for CDC 7600 and CRAY-1  

SciTech Connect

SPIN is designed to take two-dimensional quadrilateral input, rotate the data about an axis, and produce three-dimensional bricks. The two-dimensional database is discussed in this manual (it is the same as the output of the ZONE program (UCID-17139)). The output of SPIN is in the format for the DYNA3D/NIKE3D programs (UCID-17268). Both the input and output files are card images, not binary, so the files may be easily edited with a text editor for any other program. Additionally, the slide-planes between various layers may also be generated. The program is available on both CDC7600 and CRAY-1 computers.

Brown, B.E.

1980-08-01

201

Studies of fiber volume fraction and geometry of variable cross-section tubular 3D five-direction braided fabric  

Microsoft Academic Search

The requirements for the size and performance of fabric 3D five-directional braided variable cross-sectional tube can be met by using the appropriate reducing-yarn technique. Compared with the fabric processed with invariable cross-sectional yarns, the theoretical model of geometric structure and properties of variable cross-sectional yarn fabric is more complex. Based on the constituting method of yarn and the variation law

Wensuo Ma; Jianxun Zhu; Yun Jiang

2012-01-01

202

High-resolution 3D seismic waveform imaging of the fault zone structure in southwest China using double-difference seismic tomography and generalized Radon transform  

NASA Astrophysics Data System (ADS)

The Sichuan-Yunnan region in southwestern China lies in the transition zone between the uplifted Tibetan plateau to the west and the Yangtze continental platform to the east. This region has a very complicated geological structure and is one of the most active areas of continental earthquakes in the world. We collected 3-component waveforms recorded by 26 Yunnan provincial stations for ~5000 events in the period of 1999 to 2004 and calculated waveform cross-correlation delay times using the BCSEIS algorithm of Du et al. (2004). The double-difference seismic tomography method is used to determine event locations and the velocity structure. Clear velocity contrasts are associated with some faults, such as the Lancangjiang Fault, the Red River Fault and the Xiaojiang Fault. Seismic tomography can, however, only resolve the smooth variations in elastic properties in Earth's interior. To better characterize the structure discontinuities, the scattered seismic waveforms need to be used. The generalized Radon transform (GRT), an inverse scattering method, was recently successfully applied to the local earthquake data around the SAFOD site, California and revealed several vertical reflectors, similar to the imaging results from an active source survey (Zhang et al., 2009). We will apply the GRT to the seismic waveform data in the Yunnan region to better understand the fault geometry in depth. This research is partly supported by SinoProbe-2 Project of Ministry of Land and Resources of China.

Zhang, Haijiang; Wang, Ping; Wang, Weijun

2010-05-01

203

The 3D fault and vein architecture of strike-slip releasing- and restraining bends: Evidence from volcanic-centre-relatedmineral deposits  

USGS Publications Warehouse

High-temperature, volcanic-centre-related hydrothermal systems involve large fluid-flow volumes and are observed to have high discharge rates in the order of 100-400 kg/s. The flows and discharge occur predominantly on networks of critically stressed fractures. The coupling of hydrothermal fluid flow with deformation produces the volumes of veins found in epithermal mineral deposits. Owing to this coupling, veins provide information on the fault-fracture architecture in existence at the time of mineralization. They therefore provide information on the nature of deformation within fault zones, and the relations between different fault sets. The Virginia City and Goldfield mining districts, Nevada, were localized in zones of strike-slip transtension in an Early to Mid-Miocene volcanic belt along the western margin of North America. The Camp Douglas mining area occurs within the same belt, but is localized in a zone of strike-slip transpression. The vein systems in these districts record the spatial evolution of strike-slip extensional and contractional stepovers, as well as geometry of faulting in and adjacent to points along strike-slip faults where displacement has been interrupted and transferred into releasing and restraining stepovers. ?? The Geological Society of London 2007.

Berger, B. R.

2007-01-01

204

SDM - A geodetic inversion code incorporating with layered crust structure and curved fault geometry  

NASA Astrophysics Data System (ADS)

Currently, inversion of geodetic data for earthquake fault ruptures is most based on a uniform half-space earth model because of its closed-form Green's functions. However, the layered structure of the crust can significantly affect the inversion results. The other effect, which is often neglected, is related to the curved fault geometry. Especially, fault planes of most mega thrust earthquakes vary their dip angle with depth from a few to several tens of degrees. Also the strike directions of many large earthquakes are variable. For simplicity, such curved fault geometry is usually approximated to several connected rectangular segments, leading to an artificial loss of the slip resolution and data fit. In this presentation, we introduce a free FORTRAN code incorporating with the layered crust structure and curved fault geometry in a user-friendly way. The name SDM stands for Steepest Descent Method, an iterative algorithm used for the constrained least-squares optimization. The new code can be used for joint inversion of different datasets, which may include systematic offsets, as most geodetic data are obtained from relative measurements. These offsets are treated as unknowns to be determined simultaneously with the slip unknowns. In addition, a-priori and physical constraints are considered. The a-priori constraint includes the upper limit of the slip amplitude and the variation range of the slip direction (rake angle) defined by the user. The physical constraint is needed to obtain a smooth slip model, which is realized through a smoothing term to be minimized with the misfit to data. In difference to most previous inversion codes, the smoothing can be optionally applied to slip or stress-drop. The code works with an input file, a well-documented example of which is provided with the source code. Application examples are demonstrated.

Wang, Rongjiang; Diao, Faqi; Hoechner, Andreas

2013-04-01

205

Reorienting in Virtual 3D Environments: Do Adult Humans Use Principal Axes, Medial Axes or Local Geometry?  

PubMed Central

Studies have shown that animals, including humans, use the geometric properties of environments to orient. It has been proposed that orientation is accomplished primarily by encoding the principal axes (i.e., global geometry) of an environment. However, recent research has shown that animals use local information such as wall length and corner angles as well as local shape parameters (i.e., medial axes) to orient. The goal of the current study was to determine whether adult humans reorient according to global geometry based on principal axes or whether reliance is on local geometry such as wall length and sense information or medial axes. Using a virtual environment task, participants were trained to select a response box located at one of two geometrically identical corners within a featureless rectangular-shaped environment. Participants were subsequently tested in a transformed L-shaped environment that allowed for a dissociation of strategies based on principal axes, medial axes and local geometry. Results showed that participants relied primarily on a medial axes strategy to reorient in the L-shaped test environment. Importantly, the search behaviour of participants could not be explained by a principal axes-based strategy.

Ambosta, Althea H.; Reichert, James F.; Kelly, Debbie M.

2013-01-01

206

Estimating crown base height for Scots pine by means of the 3D geometry of airborne laser scanning data  

Microsoft Academic Search

Crown base height (CBH) is an important factor in relation to several characteristics of the tree stock. This paper introduces approaches for estimating tree-level CBH from airborne laser scanning (ALS) data that employ features of computational geometry. For that purpose, the concepts of Delaunay triangulations and alpha shapes were applied and compared with approaches based on analysing return frequencies and

Jari Vauhkonen

2008-01-01

207

Microdosimetry of alpha particles for simple and 3D voxelised geometries using MCNPX and Geant4 Monte Carlo codes.  

PubMed

Microdosimetry using Monte Carlo simulation is a suitable technique to describe the stochastic nature of energy deposition by alpha particle at cellular level. Because of its short range, the energy imparted by this particle to the targets is highly non-uniform. Thus, to achieve accurate dosimetric results, the modelling of the geometry should be as realistic as possible. The objectives of the present study were to validate the use of the MCNPX and Geant4 Monte Carlo codes for microdosimetric studies using simple and three-dimensional voxelised geometry and to study their limit of validity in this last case. To that aim, the specific energy (z) deposited in the cell nucleus, the single-hit density of specific energy f(1)(z) and the mean-specific energy were calculated. Results show a good agreement when compared with the literature using simple geometry. The maximum percentage difference found is <6 %. For voxelised phantom, the study of the voxel size highlighted that the shape of the curve f(1)(z) obtained with MCNPX for <1 µm voxel size presents a significant difference with the shape of non-voxelised geometry. When using Geant4, little differences are observed whatever the voxel size is. Below 1 µm, the use of Geant4 is required. However, the calculation time is 10 times higher with Geant4 than MCNPX code in the same conditions. PMID:21993801

Elbast, M; Saudo, A; Franck, D; Petitot, F; Desbrée, A

2012-07-01

208

Neotectonic evolution and fault geometry change along a major extensional fault system in the Mission and Flathead Valleys, NW-Montana  

NASA Astrophysics Data System (ADS)

Analysis of 3.5 kHz high-resolution seismic data from Flathead Lake, combined with results from onshore geologic mapping and literature review from previous studies in the area, reveals a significant change in fault geometry and seismic activity along strike of the Mission Fault system in the Mission and Flathead Valleys of northwestern Montana. The Mission Fault system is composed of faults with normal sense of motion and faults with minor oblique-slip and strike-slip motion. It evolves from a single fault strand in the Mission Valley south of Flathead Lake into a multiple strand fault system in the Flathead Lake basin and north of the lake. Fault activity decreases to the north as suggested by northward decreasing fault scarp heights in the lake basin. North of the lake the Mission Fault system is truncated by oblique strike-slip faults and the extensional strain is accommodated by the Swan Fault, another major normal fault north and east of the study area. We observed five phases of increased tectonic activity in the lake basin during the last 15,000 years. The oldest phase (phase B), active between 15,000 and 13,000 cal yr BP, resulted in fault scarps with up to 14 m of relief along the Mission Fault and the Kalispell-Finley Point Fault. We calculated average displacement rates as high as 1 mm/yr for this oldest phase. Phases C-F represent smaller tectonic events in the lake basin during the last 10,000 cal yr BP. Offset of seismic reflectors during these younger events is generally at dm-scale, indicating relatively low average displacement rates.

Hofmann, Michael H.; Hendrix, Marc S.; Sperazza, Michael; Moore, Johnnie N.

2006-07-01

209

Extension axes in the Kumano forearc basin from inversion of fault populations mapped in a 3D seismic volume, Nankai Trough, SE Japan  

NASA Astrophysics Data System (ADS)

Analysis of a 3D seismic volume across the Nankai Trough off Kii Peninsula defines a population of normal faults that indicate subhorizontal extension within the recent (0-3.8 Ma) forearc basin strata. IODP drilling (as part of the Nankai Trough Seismogenic Zone Experiment, or NanTroSEIZE) within the seismic survey area documented an abrupt change in the orientation of the maximum horizontal stress across a major out-of-sequence-thrust fault (OOST). This fault, termed the “megasplay,” extends >120 km along strike and forms the seaward boundary of the Kumano forearc basin. Borehole breakouts indicate that the orientation of maximum horizontal stress changes from 150/330 degrees in the prism to 134/314 degrees in the forearc basin across the megasplay, just 10 km landward. A borehole 15 km further landward in the forearc basin indicates that the orientation of the maximum horizontal stress is 150/330 degrees. These orientations are hypothesized to reflect the mechanical behavior of the plate boundary fault systems at depth. The 3D seismic dataset is the link between the point data at boreholes and the surrounding three-dimensional rock volume. In the Kumano Basin, normal faults are generally restricted to the gently dipping cover sequence that unconformably overlies the older (late Miocene) accretionary prism. From a population of more than 400 normal faults we used 240 that cut the seafloor to infer strains associated with ongoing deformation. Four sub-populations strike between 45/225 and 100/280 degrees. Two sub-populations strike between 140/320 and 170/350 degrees. All populations include conjugate sets with a preferred NNW (ENE in the case of NW striking) dip direction, and fault dips are between 45 and 75 degrees, most >55. We used the method of Marrett and Allmendinger (1990) to invert the populations for the orientations of principle strains and the Molnar (1983) method to calculate the kinematic moment tensors, assuming that 1) motion along faults is purely dip-slip, and 2) all faults are weighted equally. A displacement-weighted calculation of moment tensors is in progress. Our preliminary inversion indicates a maximum extension direction oriented ~161/341 degrees, nearly parallel to the direction of plate convergence, and also approximately parallel to the shortening direction inferred for the outer accretionary wedge near the trench. Separating the total population into geographic sub-groups reveals a systematic change in the orientation of maximum extension, from NNW/SSE (parallel to plate convergence) at the forearc high to ENE/WSW in the landward portion of the basin. The strains determined from our inversion are consistent with stresses inferred from borehole breakouts at the two IODP boreholes in the basin. Several mechanisms have been proposed to drive the extension observed in forearc wedges, including localized underplating and coseismic deformation. In the Nankai subduction zone, this extension may be attributed to prevailing stress conditions within the accretionary wedge, a response to gravitational stresses within the shallow sediments, or tilting of the basin related to slip on the megasplay fault.

Sacks, A.; Saffer, D. M.; Fisher, D. M.

2010-12-01

210

Relationships between sliding behavior and internal geometry of laboratory fault zones and some creeping and locked strike-slip faults of California  

NASA Astrophysics Data System (ADS)

Moore, D.E. and Byerlee, J., 1992. Relationships between sliding behavior and internal geometry of laboratory fault zones and some creeping and locked strike-slip faults of California. In: T. Mikumo, K. Aki, M. Ohnaka, L.J. Ruff and P.K.P. Spudich (Editors), Earthquake Source Physics and Earthquake Precursors. Tectonophysics, 211: 305-316. In order to relate fault geometries to sliding behavior, maps of recently active breaks within the Hayward fault of central California, which is characterized by fault creep, have been examined and compared to maps of the San Andreas fault. The patterns of recent breaks of the Hayward fault are consistent with those found within the creeping section of the San Andreas, and they appear to have plausible physical explanations in the findings of laboratory experiments. The distinguishing geometric features of the examined locked and creeping faults are: (1) P-type second-order traces predominate over R(Riedel)-type traces in creeping sections; and (2) R-type second-order traces make smaller angles to the local fault strike in creeping sections than they do in locked sections. Two different maps of the Hayward fault gave similar results, supporting the inference that the patterns identified are basic characteristics of the fault rather than artifacts of a particular mapping procedure. P shears predominate over R shears under laboratory conditions that allow dilation within the fault zone. In our own experiments, P-shear development was favored by the generation of excess pore-fluid pressures. We propose that creep in California faults also is the result of fluid overpressures that are maintained in a low-permeability gouge zone and that significantly lower effective stresses, thus helping to stabilize slip and producing high values of the ratio P/R. Small R-trace angles may also be an indicator of low effective stresses, but the evidence for this is not conclusive because other factors can also affect the size of the angles.

Moore, D. E.; Byerlee, J.

1992-09-01

211

Modelling of bubbly and annular two-phase flow in subchannel geometries with BACCHUS-3D/TP  

SciTech Connect

The theoretical and computational bases of the BACCHUS-3D/TP computer program are reviewed. The computer program is used for thermal-hydraulic analyses of nuclear fuel bundles under normal and accident conditions. The present program combines two models and solution procedures previously used separately, namely, the Improved Slip Model (ISM) and the Separated-Phases Model (SPM). The former model uses mixture equations with accounting for slip between the phases, whereas the latter uses separate continuity and momentum equations. At the present stage of development, both assume thermodynamic equilibrium. Techniques used to affect smooth transition between the two models are described. including treatment of frictional pressure drop and solution of the Poisson and momentum equations. A detailed derivation of the computation of mass transfer between the phases is given because it is a central and novel feature of the model.

Bottoni, M.; Lyczkowski, R.W.

1992-01-01

212

Deep mantle dynamics in 3D spherical geometry incorporating a realistic phase diagram calculated by free energy minimization  

NASA Astrophysics Data System (ADS)

Deep mantle dynamics and the resulting thermo-chemical-phase structures are here studied using thermo- chemical mantle convection simulations in a 3D spherical shell that incorporate composition-dependent phase diagrams calculated by free energy minimization. This improves on our previous studies, which used simple depth-dependent thermodynamic properties and calculated seismic anomalies based on linearized derivatives around a pyrolitic mean composition. Realistic mineral assemblages of mantle rocks have several high pressure and temperature phases, which vary substantially as composition changes from MORB-like to harzburgitic. Linearized treatments probably do not adequately capture the variation of physical properties with composition and temperature. In order to get closer to a realistic mineralogy, we here calculate composition- dependent mineral assemblages and their physical properties using the code PERPLEX, which minimizes free energy for a given combination of oxides as a function of temperature and pressure, and use the resulting properties in a 3-D spherical numerical model of thermo-chemical mantle convection, with three-dimensionally- varying physical properties [Nakagawa et al., 2007 in Goldschmidt conference]. Preliminary results are that while thermo-chemical structures are not greatly different from in the previous treatment, the spectral profiles of seismic anomalies seem to match seismic tomographic models more closely. Here we extend these results to focus on seismic signatures of the deep mantle including the post-perovskite phase transition. There is still uncertainty in the thermodynamic properties of the post-perovskite phase; hence the phase relationship of post-perovskite and its composition-dependence is treated as 'adjustable' within mineral physics uncertainties. The thermal- chemical-phase structures in our latest numerical simulation models are compared to the latest seismologically- observed structures.

Nakagawa, T.; Tackley, P. J.; Deschamps, F.; Connolly, J. A.

2007-12-01

213

Imaging the Fault Geometry From the MultiChannel Seismic Reflection Data in the Marmara Sea, Tekirdag Basin, Turkey  

Microsoft Academic Search

Determination of the fault geometry in the Marmara Sea has been a major problem for the researchers after the occurence of 17 August 1999 ?zmit (M=7.4) and 12 Novenber 1999 D\\\\x81zce (M=7.2) earthquakes. We used Pre-Stack Kirchhoff Depth Migration Technique to ivestigate the fault geometry in the Tekirda? Basin in western Marmara Sea by using the multi-channel seismic reflection data

Z. Kanbur; O. Alptekin

2002-01-01

214

Estimating Geometry of the Main Detachment and Slip Rates on Active Faults in Taiwan Using Interseismic GPS Data  

Microsoft Academic Search

We use elastic half-space and viscoelastic-coupling models to estimate the fault geometry and slip rates in central Taiwan using GPS data collected from 1990-1999 (Yu et al., BSSA 2001, Tectonophysics 2001). The geometry of active faults in Taiwan is a debated topic. Many researchers have prescribed to the accretionary wedge theory in which most of the deformation in Taiwan occurs

K. M. Johnson; P. Segall

2002-01-01

215

Internal Architecture, External Geometry, and Cyclicity of Mass Transport Complexes in the Gulf of Mexico From 3-D Seismic Data  

NASA Astrophysics Data System (ADS)

High resolution data from a three-dimensional seismic survey in the Gulf of Mexico was evaluated to determine the three-dimensional external geometry and internal architecture of two mass transport (landslide) complexes, and to investigate the link between sea level changes and mass transport complex development. Most common external geometries are channel-form with concave up basal surfaces and nearly flat upper contacts. The mass-transport complexes exhibit significant pinching and swelling both along dip and along strike sections, the overall thickness of the complex generally controlled by the depth of the lower (incisional) surface of the mass-transport complex. The portions of the mass transport complexes most proximal to the shelf and furthest shoreward tend to be composed of fairly coherent (still stratified) reflectors, whereas the reflectors (sediments) become progressively more disaggregated down-slope. The most distal position of the mass transport complexes is composed typically of completely reflector-free or chaotic seismic stratigraphy, interpreted to indicate complete disaggregation of previously stratified sediments. At least one mass transport complex is observed to share (laterally) a basal contact with an unslumped cut and fill succession of reflectors that exhibit a consistent down-slope dip into the cut, which is a seismic geometry that typically would be interpreted as a basin floor fan, in this case filling a mini-basin. We find this and other evidence suggestive that these mass transport complexes are typically composed of sediments originally deposited during highstands of sea level and then resedimented as large slide sheets during subsequent lowstands.

Dykstra, M.; Kneller, B.

2002-12-01

216

Fault geometry and segmentation of the MTL active fault system in the Iyo_|nada Sea, western Shikoku, in Japan  

Microsoft Academic Search

The Median Tectonic Line (MTL) active fault system is one of the most active fault system in Japan, which is an east-west trending, 190 km-long fault system and consists of several rupture segments in Shikoku. A long active fault system such as the MTL active fault system may not rupture along its entire length in a single earthquake but instead

M. Ikeda; F. Nanayama; K. Miura; K. Outsuka; S. Kobayashi; Y. Ohno; S. Kanayama; T. Hasegawa; Y. Sugiyama; E. Tsukuda

2002-01-01

217

The effects of mass redistribution due to erosion and sedimentation on the distribution of fault activity within extensional fault arrays: An investigation by using fully coupled 3D finite-element models with a landscape evolution tool.  

NASA Astrophysics Data System (ADS)

Mass redistribution on the Earth's surface creates loads that may influence the rate of crustal deformation. Using three-dimensional finite-element models solved with the commercial finite-element software ABAQUS and implementing the landscape evolution with the CASQUS tool (Kurfeß and Heidbach 2009) we investigate how surface processes may affect the spatiotemporal distribution of fault slip within horst and graben structures in extensional tectonic settings. The finite-element models comprised of normal faults arranged in en echelon arrays that form graben or horst structures within a 200 km x 200-km-wide and 15-km-thick upper crust. Previous studies have shown that surface processes may affect fault slip rates on normal faults during extension phases and prolong fault activity after the onset of tectonic quiescence (Maniatis et al., 2009, Turpeinen et al., in press). In the present study we show that not only the parameters controlling the surface processes (e.g. diffusion constant) have an effect on the slip rate of individual faults but also the spatial distribution of erosion and deposition affects fault slip rates to different degrees depending on the fault's position within an array. By adding a subsequent phase of tectonic quiescence to the models, we investigate how ongoing erosion and sedimentation might prolong fault slip accumulation for up to millions of years after the cessation of extension across the fault arrays. Our models show that the amount and duration of additional fault slip are controlled by parameters such as the diffusion constant, fault length and fault dip. The results of the present study therefore imply that the feedbacks of erosion and deposition on tectonics should be additionally considered when evaluating the spatial distribution of fault activity within graben and horst systems. Furthermore, the potential of erosion and sedimentation to prolong fault activity in extensional settings should be taken into account when constraining the timing of the cessation of regional extension phases. References Kurfeß, D., Heidbach, O., 2009. CASQUS: a new simulation tool for coupled 3d finite element modeling of tectonic and surface processes based on ABAQUS™ and CASCADE. Comput. Geosci. 35, 1959-1967. http://dx.doi.org/10.1016/j.cageo.2008.10.019. Maniatis, G., Kurfeß, D., Hampel, A., Heidbach, O., 2009. Slip acceleration on normal faults due to erosion and sedimentation—results from a new three-dimensional numerical model coupling tectonics and landscape evolution. Earth Planet. Sci. Lett. 284, 570-582. http://dx.doi.org/10.1016/j.epsl.2009.05.024. Turpeinen, H., Maniatis, G., Hampel, A., Slip on normal faults induced by surface processes after the cessation of regional extension—Insights from three-dimensional numerical modelling, Geomorphology (in press), http://dx.doi.org/10.1016/j.geomorph.2013.12.008

Maniatis, Georgios; Turpeinen, Heidi; Hampel, Andrea

2014-05-01

218

Optimizing an SEM-based 3D surface imaging technique for recording bond coat surface geometry in thermal barrier coatings  

NASA Astrophysics Data System (ADS)

Creation of three-dimensional representations of surfaces from images taken at two or more view angles is a well-established technique applied to optical images and is frequently used in combination with scanning electron microscopy (SEM). The present work describes specific steps taken to optimize and enhance the repeatability of three-dimensional surfaces reconstructed from SEM images. The presented steps result in an approximately tenfold improvement in the repeatability of the surface reconstruction compared to more standard techniques. The enhanced techniques presented can be used with any SEM friendly samples. In this work the modified technique was developed in order to accurately quantify surface geometry changes in metallic bond coats used with thermal barrier coatings (TBCs) to provide improved turbine hot part durability. Bond coat surfaces are quite rough, and accurate determination of surface geometry change (rumpling) requires excellent repeatability. Rumpling is an important contributor to TBC failure, and accurate quantification of rumpling is important to better understanding of the failure behavior of TBCs.

Shahbazmohamadi, Sina; Jordan, Eric H.

2012-12-01

219

Constraining Basin Geometry and Fault Kinematics on the Santo Tomas Segment of the Agua Blanca Fault Through a Combined Geophysical and Structural Study  

NASA Astrophysics Data System (ADS)

The Santo Tomas basin, located in northern Baja California, formed at a right step in the dextral Agua Blanca fault (ABF). The ABF extends for more than 120km east from Punta Banda, with an east-west strike, and represents the southernmost fault in the San Andreas system of faulting. The basin is located roughly 40km south of Ensenada where the Agua Blanca fault intersects the Maximos fault. A detailed geophysical analysis defines the basin geometry, and helps to constrain the distribution and offset of mapped and concealed faults. Geophysical and structural data sets are combined to constrain the kinematic evolution of the Santo Tomas basin, including determining the relative amount of dip-slip and strike-slip motion on basin-bounding faults. Gravity data was collected over seven transects across and along the axis of the basin at 500 meter intervals, with 200 meter intervals at locations of known or inferred faults. Magnetic data were taken over the same lines, and are used in conjunction with gravity data to constrain the locations, geometries and displacements of intrabasinal faults. The combined gravity and magnetic data are modeled using Geosoft Oasis montaj software to create 2 3/4D models along profiles across the study area. Modeling of the geophysical data combined with structural mapping indicates that the Santo Tomas basin is bound by two major strike-slip faults, the ABF on the northeastern side and the Maximos fault on south, Based on offset markers, most of the strike-slip motion appears to be concentrated on the ABF on the north side of the basin. The ABF fault is characterized by multiple subparallel fault strands that appear to coalesce into single strands to the northwest and southeast of the basin. The Maximos is characterized by a single strand throughout the basin and it exhibits a minor dip-slip component. Basin sediments thicken slightly against the Maximos fault to as much as 1km. A third fault, cutting across the basin southeast of the town of Santo Tomas also exhibits a component of dip-slip motion. The total strike-slip offset on the two basin-bounding faults is inferred to be between 5 and 7 km (northern ABF) and <3 km (Maximos fault), for a combined ~9 km. This total is intermediate between the total slip on the ABF from studies to the southeast (22 km, Allen et al., 1960) and to the northwest (7 km, Callihan et al., 2008) suggesting that the fault is losing slip toward the northwest.

Springer, A.; Wetmore, P.; Fletcher, J.; Connor, C. B.; Callihan, S.; Beeson, J.; Wilson, J.

2008-12-01

220

Differential Geometry of Fault Surfaces and Glacial Beds: Associated Deformation Patterns  

NASA Astrophysics Data System (ADS)

We measure glacial sliding surfaces and the striations on them and argue that these surfaces at the base of hard-bedded mountain glaciers can be compared to geologic fault surfaces albeit the obvious rheological differences. The reorientation of glacial striations around topographic anomalies provides quantifiable information about the otherwise inaccessible conditions. We use a ground-based LiDAR to measure the first high-precision orientations of these streaks at a field locality near Tenaya Lake, CA. We find that they are resolvably deflected around topographic highs. For example, bumps of about 0.3 m deflect the striations by up to 10°. Deviations from planar geometries can be quantified using the principles of differential geometry. These methods calculate the principal normal curvatures at each point on the surface and admit classification of one of eight basic shapes. Two of these shapes (synform and antiform) exhibit a zero principal normal curvature in one direction, one (plane) has no nonzero curvature, and another (perfect saddle) requires equal but opposite principal curvatures. None of these shapes are found in raw field data, so a curvature threshold and/or spectral filtering are applied to remove curvatures not distinguishable from zero. Common sliding surface shapes that can be described by this classification are domes, basins, antiformal, synformal, and perfect saddles. These non- developable shapes induce strains in the adjacent rock and ice masses as relative particle motions on either side of the fault or sliding surface are expected to be non-zero. These strains are not induced by surfaces with at most one non-zero principal normal curvature if the sliding direction is perpendicular to the direction of non-zero principal normal curvature. The additional strains may lead to nonparallel striations and off-fault deformation. Our goal is to relate the magnitudes of the two principle curvatures to changes in sliding direction. We show how the geometric shapes of the glacial sliding surfaces compare and contrast with fault surface shapes and how these shapes relate to glacial striations and slickenlines preserved on faults. Our field examples reveal the significance of geometric complexities to the mechanics of faulting and glacial sliding, and elucidate the interplay of surface geometry and slip behavior.

Kaven, J.; Brodsky, E.; van der Elst, N.; Sagy, A.; Pollard, D. D.

2007-12-01

221

Aspects of a Discontinuous Galerkin Approach for 3D Dynamic Rupture Modeling in the Case of a Complex Fault System  

NASA Astrophysics Data System (ADS)

We will present recent developments concerning the extensions of the arbitrary high-order derivative Discontinuous Galerkin (ADER-DG) method to solve three dimensional dynamic rupture problems on unstructured tetrahedral meshes. First of all, we verify our implementation by comparing results of the SCEC test case with other numerical methods such as Finite Difference and Spectral Boundary Integral. An important result of the benchmark is that the ADER-DG method avoids spurious high-frequency contributions in the slip rate spectra and therefore does not require artificial Kelvin-Voigt damping or a posteriori filtering of synthetic seismograms. Then, we present a detailed convergence study to ensure the systematic correctness. To demonstrate the capabilities of the high-order accurate ADER-DG scheme on unstructured meshes we use the 1992 Landers earthquake as an example. It represents a complex fault system including branching and six curved fault segments. Furthermore, topography is respected in the discretized model to capture the surface waves correctly. Strong mesh coarsening or refinement at areas of interest is applied to keep the computational costs feasible. Finally current problems and further developments will be discussed.

Pelties, C.; de la Puente, J.; Ampuero, J. P.; Brietzke, G. B.; Kaeser, M.

2011-12-01

222

1-D closure models for slender 3-D viscoelastic free jets: von Karman flow geometry and elliptical cross section  

SciTech Connect

In this paper we derive one space dimensional, reduced systems of equations (1-D closure models) for viscoelastic free jets. We begin with the three-dimensional system of conservation laws and a Maxwell-Jeffreys constitutive law for an incompressible viscoelastic fluid. First, we exhibit exact truncations to a finite, closed system of 1-D equations based on classical velocity assumptions of von Karman. Next, we demonstrate that the 3-D free surface boundary conditions overconstrain these truncated systems, so that only a very limited class of solutions exist. We then proceed to derive approximate 1-D closure theories through a slender jet asymptotic scaling, combined with appropriate definitions of velocity, pressure and stress unknowns. Our nonaxisymmetric 1-D slender jet models incorporate the physical effects of inertia, viscoelasticity (viscosity, relaxation and retardation), gravity, surface tension, and properties of the ambient fluid, and include shear stresses and time dependence. Previous special 1-D slender jet models correspond to the lowest order equations in the present asymptotic theory by an a posteriori suppression to leading order of some of these effects, and a reduction to axisymmetry. Solutions of the lowest order system of equations in this asymptotic analysis are presented: For the special cases of elliptical inviscid and Newtonian free jets, subject to the effects of surface tension and gravity, our model predicts oscillation of the major axis of the free surface elliptical cross section between perpendicular directions with distance down the jet, and drawdown of the cross section, in agreement with observed behavior. 15 refs.

Bechtel, S.E.; Forest, M.G.; Holm, D.D.; Lin, K.J.

1988-01-01

223

The 2009 L'Aquila seismic sequence (Central Italy): fault system geometry and kinematics  

NASA Astrophysics Data System (ADS)

On April 6 (01:32 UTC) 2009 a destructive MW 6.3 earthquake struck the Abruzzi region in Central Italy, causing nearly 300 deaths, 40.000 homeless, and strong damage to the cultural heritage of the L'Aquila city and its province. Two strong earthquakes hit the area in historical times (e.g. the 1461 and 1703 events), but the main fault that drives the extension in this portion of the Apennines was unknown. The ground surveys carried out after the earthquake find ambiguous evidence of surface faulting. We use aftershocks distribution to investigate the geometry of the activated fault system and to report on spatio-temporal seismicity pattern and kinematics of the whole seismic sequence. Seismic data were recorded at both permanent stations of the Centralized Italian National Seismic Network managed by the INGV and 45 temporary stations installed in the epicentral area. To manage such a large amount of earthquakes, we implemented a semi-automatic procedure able to identify local earthquakes and to provide consistently weighted P- and S-wave arrival times. We show that this procedure yields consistent earthquake detection and high-quality arrival times data for hundreds of events per day. The accurate location for thousands of aftershocks defines a complex, 40 km long, NW-trending normal fault system, with seismicity nucleating within the upper 12 km of the crust. We show the geometry of two major SW-dipping normal faults that form a right lateral en-echelon system. The main fault activated by the 6th of April earthquake is 20 km-long, NW-trending and about 50° SW-dipping and is located below the city of L'Aquila. To the north, we find a second fault, activated on the 9th of April by a MW 5.4 earthquake, that is about 12-km-long and shows a dip angle of about 40° with hypocenters mainly located in the 6 to 10 km depth range.

Valoroso, L.; Amato, A.; Cattaneo, M.; Cecere, G.; Chiarabba, C.; Chiaraluce, L.; de Gori, P.; Delladio, A.; de Luca, G.; di Bona, M.; di Stefano, R.; Govoni, A.; Lucente, F. P.; Margheriti, L.; Mazza, S.; Monachesi, G.; Moretti, M.; Olivieri, M.; Piana Agostinetti, N.; Selvaggi, G.; Improta, L.; Piccinini, D.; Mariscal, A.; Pequegnat, C.; Schlagenhauf, A.; Salaun, G.; Traversa, P.; Voisin, C.; Zuccarello, L.; Azzaro, R.

2009-12-01

224

3D Model Retrieval  

Microsoft Academic Search

The topic of this paper is content-based retrieval of 3D models that are represented as triangle meshes. An object from some 3D geometry database can traditionally be accessed using attached structural information such as textual annotation. However, there are frequent requirements for a content-based retrieval of various multimedia contents. A content-based 3D model retrieval system has been implemented and this

D. Saupe

225

Cyberchase 3D Builder  

NSDL National Science Digital Library

This Cyberchase iOS geometry app ($) enables students to use 2D nets to create 3D shapes. The app includes eight levels which increase in difficulty; increasing the complexity of the nets and combining different 3D shapes together.

Kids, Pbs

2014-01-21

226

3-D Geometry of the Philippine Sea Plate Slab just beneath the Tokyo Metropolitan Area and its Vicinity, Japan  

NASA Astrophysics Data System (ADS)

We present a new view of three-dimensional geometry of slab(s) subducted just beneath the Tokyo metropolitan area, central Japan. Previously, several different models of the surface geometry of the subducted Philippine sea plate slab (PH slab) have been published using seismological data. First, we discriminate previously unknown seismic slab (called slab SG, or seismic slab SG) above the downgoing Pacific plate slab (PC slab), second propose possible models of the slab SG internal structure, and third discuss and demonstrate the tectonic background of slab SG. It is clear that the recent surface models of PH slab corresponds to the shallowest part of slab SG. Most of previous studies paid little attention to the tectonic characteristics of the vertical extent and/or the bottom geometry of slab SG with variable thickness. The bottom extent of slab SG beneath the Metropolitan area reaches 36.5N at least. The horizontal extent of seismic slab SG covers most of the Kanto Plain Lowland. The bottom depth of slab SG is approximately 120km near 36.5N and 139.0E, being the same as of the surface depth of PC slab there. Below the Sagami trough axis near 34.5N and 140.0E, slab SG locates at a depth of 80 to 90km. We confirmed that southernmost part of slab SG extends to areas around 34.3N and 140.3E at least, where seismic observation network density is not sufficient to locate correctly seismic events. The deepest portion of slab SG generally strikes the NNW-SSE direction, being approximately parallel to the volcanic front. The thickness of slab SG decreases gradually at areas west of the NNW-SSE striking deepest corner. We propose four basic internal models of slab SG as follows. (1) Slab SG consists of both PH slab at shallower depth and a deeper underlain slab (slab SL). (2) Bookshelf-like configuration of northwardly inclined multi-slabs on PC slab due to the intermittent southward shift of accumulation sites of short slab tips with episodic subduction at just south of the previously active paleo-Sagami trough(s). The evolutional bookshelf model is partly similar to accretion process near the deep trench system, but dynamic situation is not the same. (3) A structure combining models (1) and (2). (4) Slab SG is merely the eastern part, having been cooled by the downgoing PC slab, of 65 to 70km thick lithosphere of IOB (Izu Outer Block). IOB is the northeastern margin of the Philippine sea plate, ranging from the volcanic front along the Izu-Bonin Island arc to the Izu-Bonin trench.

Eguchi, T.; Hori, S.

2007-12-01

227

The origin of high frequency radiation in earthquakes and the geometry of faulting  

NASA Astrophysics Data System (ADS)

In a seminal paper of 1967 Kei Aki discovered the scaling law of earthquake spectra and showed that, among other things, the high frequency decay was of type omega-squared. This implies that high frequency displacement amplitudes are proportional to a characteristic length of the fault, and radiated energy scales with the cube of the fault dimension, just like seismic moment. Later in the seventies, it was found out that a simple explanation for this frequency dependence of spectra was that high frequencies were generated by stopping phases, waves emitted by changes in speed of the rupture front as it propagates along the fault, but this did not explain the scaling of high frequency waves with fault length. Earthquake energy balance is such that, ignoring attenuation, radiated energy is the change in strain energy minus energy released for overcoming friction. Until recently the latter was considered to be a material property that did not scale with fault size. Yet, in another classical paper Aki and Das estimated in the late 70s that energy release rate also scaled with earthquake size, because earthquakes were often stopped by barriers or changed rupture speed at them. This observation was independently confirmed in the late 90s by Ide and Takeo and Olsen et al who found that energy release rates for Kobe and Landers were in the order of a MJ/m2, implying that Gc necessarily scales with earthquake size, because if this was a material property, small earthquakes would never occur. Using both simple analytical and numerical models developed by Addia-Bedia and Aochi and Madariaga, we examine the consequence of these observations for the scaling of high frequency waves with fault size. We demonstrate using some classical results by Kostrov, Husseiny and Freund that high frequency energy flow measures energy release rate and is generated when ruptures change velocity (both direction and speed) at fault kinks or jogs. Our results explain why super shear ruptures are only observed when faults are relatively flat and smooth, and why complex geometry inhibits fast ruptures.

Madariaga, R.

2004-12-01

228

Effect of the sample geometry on the intermediate state in mesoscopic 3D Type-I superconductors  

NASA Astrophysics Data System (ADS)

The intermediate state (IS) of type-I superconductors (SC) has recently became a topic of increasing interest [1,2]. Direct imaging of type-I SC reveals two distinct topologies of the intermediate state: flux tubes are formed upon magnetic field penetration and laminar patterns appear upon flux exit [2]. However, spheres and cones show no hysteresis with flux tubes dominating the IS [1]. In this work we investigate the effect of the sample topology on the formation of the flux patterns in mesoscopic type-I SC using the phenomenological Ginzburg-Landau theory. We carry out simulations on three-dimensional samples of different geometries. We show that in the samples with sharp boundaries (cubes and disks) laminar structures are mostly located along the boundary, whereas radial distribution of the flux patterns is obtained for cones and spheres. The effect of the edge defects on the observed structures will also be studied. [1] R.Prozorov, Phys. Rev. Lett. 98, 257001 (2007). [2] M. Menghini et al., Phys. Rev. B 75, 014529 (2007).

Berdiyorov, Golibjon; Hernandez, Alexander; Peeters, Francois

2008-03-01

229

Modelling and 3D optimisation of CdTe pixels detector array geometry - Extension to small pixels  

NASA Astrophysics Data System (ADS)

CdTe and CdZnTe pixel detectors offer great interest for many applications, especially for medical and industrial imaging. Up to now, the material, generally, used and investigated for pixel arrays was CZT (Hamel et al., IEEE Trans. Nucl. Sci. 43 (3) (1996) 1422; Barrett et al., Phys. Rev. Lett. 75 (1) (1995) 156; Bennett et al., Nucl. Instr. and Meth. A 392 (1997) 260; Eskin et al., J. Appl. Phys. 85 (2) (1999) 647; Brunett et al., J. Appl. Phys. 86 (7) (1999) 3926; Luke, Nucl. Instr. and Meth. A 380 (1996) 232), but cadmium telluride can also be an appropriate choice, as shown here. However, we clearly demonstrate here that the optimal pixel configuration is highly dependent on the electrical transport properties of the material. Depending on the field of primary interest, either energy resolution or counting rate efficiency in the photopeak, the geometry for each case has to be optimised. For that purpose, we have developed a calculation of the signal induced onto the pixel. Two distinct parts are used: after showing our approach for the weighting potential calculation, we present our results performed by a "pseudo-Monte Carlo" simulation. Results are supported by a few experimental comparisons. We argue about the optimum sizes with clarifying the problems caused by too small and too large pixel sizes. The study field is chosen to be vast, i.e. pixel size to detector thickness ratios ( W/ L) of 1/8-1, and detector thickness of 1.0-8.0 mm. In addition, several electrical transport properties are used. Since efficiency is often of primary interest, thick detectors could be very attractive, which are shown to be really feasible even on CdTe.

Zumbiehl, A.; Hage-Ali, M.; Fougeres, P.; Koebel, J. M.; Regal, R.; Rit, C.; Ayoub, M.; Siffert, P.

2001-08-01

230

3-D Model of Earthquake Sources in the Los Angeles Basin, CA  

NASA Astrophysics Data System (ADS)

We present a digital 3d model of the major, seismogenic fault system in the Los Angeles basin. The model is a prototype for a community-based fault characterization effort initiated by the Southern California Earthquake Center, Phase 2 (SCEC2). Faults were selected by consensus within the SCEC2 community based on geologic relevance, perceived hazard, and quality of descriptive data. Our first iteration model was populated with most of the important faults and with the deformed basement surface, which represents the main velocity interface in the basin. Constraints on fault geometries and positions include surface traces, surficial neotectonic data, seismic reflection profiles, wells, cross-sections, hypocentral locations, and focal mechanisms. Accurate geospatial registration proved essential. We use advanced geometric modeling software to integrate these various geophysical and geologic data in a 3d space, and to interpolate and extrapolate the fault surfaces. The model describes the geometry of imbricated blind-thrust faults that underlie the northern Los Angeles basin (Puente Hills, Las Cienegas, San Vicente, Elysian Park), as well as the basin bounding structures including the Santa Monica, Sierra Madre, and Cucamonga systems. In the case of the Santa Monica thrust, the 3d construction suggests the presence of a previously undocumented blind extension of this system to the northeast, below the Hollywood fault, and perhaps coinciding in parts with the North Salt Lake fault. The model also describes the 3D geometry of the major strike-slip systems in the basin, including the Newport-Inglewood and Whittier faults. The model provides a medium to investigate the spatial and temporal interactions of these fault systems based on their precise 3D geometries.

Plesch, A.; Shaw, J. H.

2001-12-01

231

The influence of normal fault geometry on porous sandstone deformation: Insights from mechanical models into conditions leading to Coulomb failure and shear-enhanced compaction  

NASA Astrophysics Data System (ADS)

Slip on non-planar faults produces stress perturbations in the surrounding host rock that can yield secondary faults at a scale too small to be resolved on seismic surveys. Porosity changes during failure may affect the ability of the rock to transmit fluids through dilatant cracking or, in porous rocks, shear-enhanced compaction (i.e., cataclastic flow). Modeling the mechanical behavior of the host rock in response to slip on non-planar faults can yield insights into the role of fault geometry on regions of enhanced or inhibited fluid flow. To evaluate the effect of normal fault geometry on deformation in porous sandstones, we model the system as a linear elastic, homogeneous, whole or half space using the boundary-element modeling program Poly3D. We consider conditions leading to secondary deformation using the maximum Coulomb shear stress (MCSS) as an index of brittle deformation and proximity to an elliptical yield envelope (Y), determined experimentally for porous sandstone (Baud et al., JGR, 2006), for cataclastic flow. We model rectangular faults consisting of two segments: an upper leg with a constant dip of 60° and a lower leg with dips ranging 15-85°. We explore far-field stress models of constant and gradient uniaxial strain. We investigate the potential damage in the host rock in two ways: [1] the size of the damage zone, and [2] regions of enhanced deformation indicated by elevated MCSS or Y. Preliminary results indicate that, along a vertical transect passing through the fault kink, [1] the size of the damage zone increases in the footwall with increasing lower leg dip and remains constant in the hanging wall. [2] In the footwall, the amount of deformation does not change as a function of lower leg dip in constant stress models; in gradient stress models, both MCSS and Y increase with dip. In the hanging wall, Y decreases with increasing lower leg dip for both constant and gradient stress models. In contrast, MCSS increases: as lower leg dip increases for constant stress models, and as the difference between lower leg dip and 60° increases for gradient stress models. These preliminary results indicate that the dip of the lower fault segment significantly affects the amount and style of deformation in the host rock.

Allison, K.; Reinen, L. A.

2011-12-01

232

Geometry and faults tectonic activity of the Okavango Rift Zone, Botswana: Evidence from magnetotelluric and electrical resistivity tomography imaging  

NASA Astrophysics Data System (ADS)

We used Magnetotelluric (MT) and Electrical Resistivity Tomography (ERT) to investigate the geometry and nature of faults activity of the Okavango Rift Zone (ORZ) in Botswana, an incipient rift at the southern tip of the Southwestern Branch of the East African Rift System. The ORZ forms a subtle topographic depression filled with Quaternary lacustrine and fluvio-deltaic sediments and is bounded by NE-trending normal faults that are more prominent in the southeastern portion of the rift basin. An MT model from a regional (˜140 km) NW-SE trending MT transect shows that much of the rift basin is underlain by a broad asymmetrical low resistivity anomaly that slopes gently (˜1°) from NW to SE reaching a depth of ˜300 m. This anomaly suggests that faults in the southeastern part of the rift form a NW-dipping border fault zone and that the lacustrine and fluvio-deltaic sediments contain brackish to saline water filling the broad half-graben structure. Furthermore, MT and ERT models from detailed (4-13 km long) MT transects and resistivity profiles show that one border fault (Thamalakane) and two within-basin faults (Lecha and Tsau) in the southeastern part of the ORZ are characterized by a localized high conductivity anomaly while another border fault (Kunyere) lacks such an anomaly. These localized anomalies are attributed to channelized fresh surface water and saline groundwater percolating through these faults forming "fault zone conductors" and suggest actively displacing faults. The lack of a "fault zone conductor" in the Kunyere fault is interpreted as indicating diminishing displacement on this fault, and that strain was transferred to the Thamalakane fault further to the east. The fluids provide lubricant for the ORZ faults, hence preventing infrequent large magnitude earthquakes, but favoring frequent micro-seismicity.

Bufford, Kelsey Mosley; Atekwana, Estella A.; Abdelsalam, Mohamed G.; Shemang, Elijah; Atekwana, Eliot A.; Mickus, Kevin; Moidaki, Moikwathai; Modisi, Motsoptse P.; Molwalefhe, Loago

2012-04-01

233

3D seismic imaging of an active, normal fault zone in southern Apennines (Italy): Clues on fluid-driven microearthquake fracturing  

NASA Astrophysics Data System (ADS)

We have reconstructed a 3D detailed image of the crustal volume embedding the active normal fault system in southern Apennines (Italy). It is obtained by the inversion of P and S first arrival times from microearthquakes recorded in the area. The issues of data quality and the implementation of robust tomographic inversion strategy have been addressed to improve the resolution of the seismic image. The arrival times measurements are enhanced by applying techniques based on polarization filtering and refined re-picking. Data inversion has been performed by using a delay-time 3D tomographic method for the joint determination of source locations and velocity model. The dataset consists of 1311 events with magnitude ranging between [0.1, 3.2], recorded from August 2005 to April 2011 by 42 stations operated by the consortium AMRA scarl and INGV. We used a multi-scale inversion approach, in order to first estimate the large wavelength components of the velocity model and then to progressively introduce smaller scale components. P- and S-wave velocity models show a strong lateral variation along a direction orthogonal to the Apeninic chain, between 0-15 km depth. This variation defines two geological formations which are characterized by relatively low and high P-wave velocities. The sharpest lateral transition occurs in the NE direction: it is well correlated with the location of the NW-SE oriented, primary normal fault associated with the 1980, Ms 6.9 earthquake, which cuts at SW the outcrops of the carbonatic Campanian platform, and separates at NE the older Mesozoic limestone formations from the younger Pliocene-Quaternary basin deposits. The main lithological formations, as identified in the referenced active seismic CROP04 profile, can be recognized in the inferred velocity model. In particular, the structural feature associated with the uplift of the Apulian Platform is well detected by the high P-velocity anomaly ranging between 6.0-6.8 km/s. The thickening of the Lagonegro units located in the axial sector is well reproduced by the low P-wave anomalies ranging between 4.0-4.5 km/s. Their eastward extension is just above the Apulian Platform in the depth range between 4.0 and 8.0 km . The seismicity spatial distribution delineates at SE the border of the Irpinia master fault, while at NE it shows a more diffused pattern due to the presence of a system of highly organized, sub-parallel normal faults as it has been inferred from the fault mechanisms and the coherent orientation of the tensional axes. The Vp/Vs ratio shows a large variability ranging from 1.7-1.8 at shallow depths and increasing up to 2-2.2 between 5 km and 12 km depths, where most of present microseismicity occurs. Such high values are a strong proxy for a fluid-saturated state of rock formations and of their inner pore pressure conditions. The evidence for a predominant microearthquake activity confined within the volume of highest Vp/Vs ratio indicates that pore pressure changes induced by fluid flow/diffusion in a highly fractured medium, may be the primary mechanism controlling and driving the background seismic activity along the Irpinia fault zone.

Amoroso, O.; Zollo, A.; Virieux, J.

2012-12-01

234

Displacement and interaction of normal fault segments branched at depth: Implications for fault growth and potential earthquake rupture size  

Microsoft Academic Search

We present field data from segmented normal faults having particular displacement and overlapping geometries that may be related to down-dip branching of the fault segments. Based on a 3-D numerical modeling study of computed displacement and stress fields around different geometries of down-dip branched normal fault segments, we show that the bends of fault surfaces that coalesce at depth exert

R. Soliva; A. Benedicto; R. A. Schultz; L. Maerten; L. Micarelli

2008-01-01

235

A Mohr circle method for 3D strain measurement using the geometry of no finite longitudinal strain and the R XZ strain ratio  

NASA Astrophysics Data System (ADS)

This paper proposes a new method for 3D finite strain analysis. This method utilizes a Mohr circle construction combined with stereographic projection of the geometry of no finite longitudinal strain and with the strain ratio on the XZ-plane of the finite strain ellipsoid. The method is described using numerical examples and then it is tested by applying it to the deformed Deh Vazir conglomerate in the southwestern part of the Sanandaj-Sirjan HP-LT metamorphic belt, within the Zagros orogenic belt in Iran. The results of this method compare well with previous finite strain measurements using strain ratios on three principal planes of finite strain. Calculation of finite strain from strain ratios on the XY and YZ principal planes is advantageous when preparation of 3 perpendicular sections is difficult or impossible.

Sarkarinejad, Khalil; Samani, Babak; Faghih, Ali

2011-04-01

236

Real-time inversions for finite fault slip models and rupture geometry based on high-rate GPS data  

NASA Astrophysics Data System (ADS)

We present an inversion strategy capable of using real-time high-rate GPS data to simultaneously solve for a distributed slip model and fault geometry in real time as a rupture unfolds. We employ Bayesian inference to find the optimal fault geometry and the distribution of possible slip models for that geometry using a simple analytical solution. By adopting an analytical Bayesian approach, we can solve this complex inversion problem (including calculating the uncertainties on our results) in real time. Furthermore, since the joint inversion for distributed slip and fault geometry can be computed in real time, the time required to obtain a source model of the earthquake does not depend on the computational cost. Instead, the time required is controlled by the duration of the rupture and the time required for information to propagate from the source to the receivers. We apply our modeling approach, called Bayesian Evidence-based Fault Orientation and Real-time Earthquake Slip, to the 2011 Tohoku-oki earthquake, 2003 Tokachi-oki earthquake, and a simulated Hayward fault earthquake. In all three cases, the inversion recovers the magnitude, spatial distribution of slip, and fault geometry in real time. Since our inversion relies on static offsets estimated from real-time high-rate GPS data, we also present performance tests of various approaches to estimating quasi-static offsets in real time. We find that the raw high-rate time series are the best data to use for determining the moment magnitude of the event, but slightly smoothing the raw time series helps stabilize the inversion for fault geometry.

Minson, S. E.; Murray, Jessica R.; Langbein, John O.; Gomberg, Joan S.

2014-04-01

237

Imaging the basin and fault geometry from the multichannel seismic reflection data in the Tekirda? Basin, Marmara Sea, Turkey  

NASA Astrophysics Data System (ADS)

Determination of the fault geometry in the Marmara Sea has been a major problem for the researchers after the occurrence of the 1999 August 17 Golcuk (M = 7.4) earthquake. To shed a light to the problem we applied the pre-stack Kirchhoff depth migration technique to the multichannel seismic reflection data of three profiles to investigate the basin and fault geometry in the Tekirda? Basin in the western Marmara Sea. The boundary of the basin and its sediments were revealed in N-S and NE-SW directions in depth sections. We identify major fault types involving these structures at different locations in Tekirdag Basin showing that the basin is developed under their movement. The North Anatolian Fault is imaged and interpreted as transtensional character at the centre of the Tekirda? Basin that is symmetrically divided with a large distributed zone. The fault plane is imaged through the depth of 2 km dipping to the north with 90° in the upper 350 m and 82° in the lower part. The basin thickness reaches about 2.5 km at that point. Syn-transform sediments of the basin are disturbed by some normal faults dipping to the north. These faults are represented by notable displacements of the reflections which prompted us to consider them as a potential tsunami source if they move during a large earthquake along the major fault. Another major fault is identified at the westernmost of the basin. Because it shows the same character as Ganos fault, it might be submarine part of it. It has reverse component with the dip angle of 65° to the north and trending along the western flank of the basin. A reverse fault is identified appearing in low angle (~20°) surrounding the edge of the submarine slide at southwest of the basin. From its geometry it is interpreted as a local fault formed between two main faults. From the sketch of the basin and the fault geometry obtained from the images we suggest that the basin should be formed by a pull-apart system.

Kanbur, Zakir; Alptekin, Ömer; Utkucu, Murat; Kanbur, Süveyla

2007-05-01

238

Structure Segmentation and Transfer Faults in the Marcellus Shale, Clearfield County, Pennsylvania: Implications for Gas Recovery Efficiency and Risk Assessment Using 3D Seismic Attribute Analysis  

NASA Astrophysics Data System (ADS)

The Marcellus Shale has become an important unconventional gas reservoir in the oil and gas industry. Fractures within this organic-rich black shale serve as an important component of porosity and permeability useful in enhancing production. Horizontal drilling is the primary approach for extracting hydrocarbons in the Marcellus Shale. Typically, wells are drilled perpendicular to natural fractures in an attempt to intersect fractures for effective hydraulic stimulation. If the fractures are contained within the shale, then hydraulic fracturing can enhance permeability by further breaking the already weakened rock. However, natural fractures can affect hydraulic stimulations by absorbing and/or redirecting the energy away from the wellbore, causing a decreased efficiency in gas recovery, as has been the case for the Clearfield County, Pennsylvania study area. Estimating appropriate distances away from faults and fractures, which may limit hydrocarbon recovery, is essential to reducing the risk of injection fluid migration along these faults. In an attempt to mitigate the negative influences of natural fractures on hydrocarbon extraction within the Marcellus Shale, fractures were analyzed through the aid of both traditional and advanced seismic attributes including variance, curvature, ant tracking, and waveform model regression. Through the integration of well log interpretations and seismic data, a detailed assessment of structural discontinuities that may decrease the recovery efficiency of hydrocarbons was conducted. High-quality 3D seismic data in Central Pennsylvania show regional folds and thrusts above the major detachment interval of the Salina Salt. In addition to the regional detachment folds and thrusts, cross-regional, northwest-trending lineaments were mapped. These lineaments may pose a threat to hydrocarbon productivity and recovery efficiency due to faults and fractures acting as paths of least resistance for induced hydraulic stimulation fluids. These lineaments may represent major transfer faults that serve as pathways for hydraulic fluid migration. Detection and evaluation of fracture orientation and intensity and emphasis on the relationship between fracture intensity and production potential is of high interest in the study area as it entails significant time and cost implications for both conventional and unconventional hydrocarbon exploration and production.

Roberts, Emily D.

239

Relationships between sliding behavior and internal geometry of laboratory fault zones and some creeping and locked strike-slip faults of California  

USGS Publications Warehouse

Moore, D.E. and Byerlee, J., 1992. Relationships between sliding behavior and internal geometry of laboratory fault zones and some creeping and locked strike-slip faults of California. In: T. Mikumo, K. Aki, M. Ohnaka, L.J. Ruff and P.K.P. Spudich (Editors), Earthquake Source Physics and Earthquake Precursors. Tectonophysics, 211: 305-316. In order to relate fault geometries to sliding behavior, maps of recently active breaks within the Hayward fault of central California, which is characterized by fault creep, have been examined and compared to maps of the San Andreas fault. The patterns of recent breaks of the Hayward fault are consistent with those found within the creeping section of the San Andreas, and they appear to have plausible physical explanations in the findings of laboratory experiments. The distinguishing geometric features of the examined locked and creeping faults are: (1) P-type second-order traces predominate over R(Riedel)-type traces in creeping sections; and (2) R-type second-order traces make smaller angles to the local fault strike in creeping sections than they do in locked sections. Two different maps of the Hayward fault gave similar results, supporting the inference that the patterns identified are basic characteristics of the fault rather than artifacts of a particular mapping procedure. P shears predominate over R shears under laboratory conditions that allow dilation within the fault zone. In our own experiments, P-shear development was favored by the generation of excess pore-fluid pressures. We propose that creep in California faults also is the result of fluid overpressures that are maintained in a low-permeability gouge zone and that significantly lower effective stresses, thus helping to stabilize slip and producing high values of the ratio P/R. Small R-trace angles may also be an indicator of low effective stresses, but the evidence for this is not conclusive because other factors can also affect the size of the angles. ?? 1992.

Moore, D. E.; Byerlee, J.

1992-01-01

240

Delineation of faulting and basin geometry along a seismic reflection transect in urbanized San Bernardino Valley, California  

USGS Publications Warehouse

Fourteen kilometers of continuous, shallow seismic reflection data acquired through the urbanized San Bernardino Valley, California, have revealed numerous faults between the San Jacinto and San Andreas faults as well as a complex pattern of downdropped and uplifted blocks. These data also indicate that the Loma Linda fault continues northeastward at least 4.5 km beyond its last mapped location on the southern edge of the valley and to within at least 2 km of downtown San Bernardino. Previously undetected faults within the valley northeast of the San Jacinto fault are also imaged, including the inferred western extension of the Banning fault and several unnamed faults. The Rialto-Colton fault is interpreted southwest of the San Jacinto fault. The seismic data image the top of the crystalline basement complex across 70% of the profile length and show that the basement has an overall dip of roughly 10?? southwest between Perris Hill and the San Jacinto fault. Gravity and aeromagnetic data corroborate the interpreted location of the San Jacinto fault and better constrain the basin depth along the seismic profile to be as deep as 1.7 km. These data also corroborate other fault locations and the general dip of the basement surface. At least 1.2 km of apparent vertical displacement on the basement is observed across the San Jacinto fault at the profile location. The basin geometry delineated by these data was used to generate modeled ground motions that show peak horizontal amplifications of 2-3.5 above bedrock response in the 0.05- to 1.0-Hz frequency band, which is consistent with recorded earthquake data in the valley.

Stephenson, W. J.; Odum, J. K.; Williams, R. A.; Anderson, M. L.

2002-01-01

241

Understanding the thermal history, exhumation patterns, and role of fault systems on Goodenough Island, Papua New Guinea: Insights from 3D thermo-kinematic modelling  

NASA Astrophysics Data System (ADS)

The world's youngest eclogites, exhumed from depths of ca. 90 km since 8 Ma, are located in the D'Entrecasteaux Islands in the active Woodlark rift of southeastern Papua New Guinea. These (U)HP rocks formed during/following subduction of Australian margin-derived volcaniclastic sediments, and were exhumed during rifting within the larger, obliquely convergent Australian-Pacific plate boundary zone. Several (U)HP exhumation mechanisms have been proposed including diapiric rise of buoyant crust from mantle to crustal depths, and rifting of heterogeneous crust ahead of the east-to-west propagating Woodlark seafloor spreading center. In order to constrain the relative importance of different exhumation mechanisms through time (i.e., timing and rates of diapirism vs crustal faulting), we apply 3D thermo-kinematic modeling (Pecube) to constrain cooling and exhumation histories derived from thermochronologic data from Goodenough Island, the western-most of the D'Entrecasteaux Islands. More than 500,000 Pecube inverse models were run to evaluate scenarios involving vertical exhumation velocities (i.e., simulating simple buoyancy due to diapirism), low-angle normal faulting and combinations of both processes. These preliminary models assume steady-state topography. Preliminary models (starting at 8 Ma) include: (i) continuous exhumation, (ii) two exhumation phases with different exhumation rates (increasing and/or decreasing), and (iii) three exhumation phases with variable exhumation rates. For buoyancy-only models, the first two scenarios (i and ii) result in poor fits between model-derived and observed (experimental) data. Notably, scenarios (i) and (ii) produce indistinguishable ages for all thermochronologic systems, uniformly long apatite fission-track (AFT) lengths, excessive temperatures at the Moho and geological starting parameters (depth, T) that are not consistent with other data. Scenario (iii) with three exhumation phases has the least misfit between model-derived vs observed thermochronologic data and long AFT lengths. The best-fit scenario suggests exhumation starting at 8-6 Ma at very high rates (8-10 km/Myr), followed by deceleration between 2-0.7 Ma, then very rapid (1-15 km/Myr) exhumation starting ca. 0.7 Ma. However, buoyancy models alone do not reproduce the rock exhumation patterns recorded on Goodenough Island. Models that involve low-angle normal faulting, in combination with buoyancy models more accurately reproduce the variability of the thermochronologic database. In all these models, at least three exhumation phases are necessary to reproduce the variability in thermal histories preserved in exhumed rocks on Goodenough Island.

Bermudez, M. A.; Baldwin, S.; Fitzgerald, P. G.; Braun, J.

2012-12-01

242

Timing and geometry of left-slip faulting and compressional folding in Hondo Field, Western Santa Barbara Channel  

SciTech Connect

Hondo field is located within the Santa Ynez offshore lease unit, approximately 5 mi south of Gaviota, California. Production is from Monterey fractured shales and deeper sandstone horizons. Two types of structures are well imaged on 3-D reflection data from the east end of the field, which has undergone 3-D prestack time migration. The most conspicuous structure is an east-west compressional fold with a gently to moderately dipping southern limb and a shorter and more steeply dipping north limb. The shape of the fold suggests that uplift was related to southward transport up a north dipping thrust ramp at (subseismic) depth. The northern limb of this structure is widest at the level of the top Sisquoc Formation and narrowest in sediments 2-3 cycles beneath the sea floor. This triangular panel of north dip indicates growth of the structure commenced during deposition of the lower Pico Formation in the Pliocene, and continued through the Pleistocene. The second-order structures that control trap distribution within the field include high-angle faults that trend roughly eastwest. The northernmost of these faults, the north bounding fault (NBF) is known from well data to have 1500 feet of throw and to dip steeply to the south. It would restore to a vertical or steep north dip upon removal of the effects of Pliocene-Pleictocene folding. The southernmost of these faults (SF) appears to change displacement from down-to-the-south in the east to down-to-the-north in the west and also dips steeply. A high-angle fault in the center of the field (CF) also has a variable sense of offset across it. Several prominent northeast-southwest faults lie between the CF and SF and clearly exhibit normal separation on vertical time sections and left separation on time slices. Variable thicknesses of Sisquoc Formation and roughly uniform thicknesses on Monterey Formation indicate that these faults were active in latest Miocene to early Pliocene.

McGroder, M. (Exxon Production Research Co., Houston, TX (United States)); Millson, C.; Gardner, D. (Exxon Co., Thousand Oaks, CA (United States))

1994-04-01

243

A large 3D target with small inner details: A difficult cocktail for imaging purposes without a priori knowledge on the scatterers geometry  

NASA Astrophysics Data System (ADS)

To accurately image a complex shape but large 3D target whose scattered field has been measured in an anechoic environment at high frequencies (18 and 20 GHz), we have developed a complete imaging process, combining experimental and numerical works. The adopted strategy exploits the maximum of available information related to the measurements, both in terms of quantity and accuracy without any a priori knowledge on the scatterer geometry. We first determine the position and then the dimension of the spatial domain which contains the target. This localization is realized directly from the analysis of the spectrum of the measured fields taking into account the random noise disturbing the measurement points. Then, we construct a quantitative permittivity map of this investigation domain thanks to an iterative inversion procedure based on a Bayesian formulation where the spatial diversity of the real random noise is adequately exploited. By following this strategy, we have been able to quantitatively retrieve the target both in terms of dimension, shape and electromagnetic properties, even with a very limited number of measurement points and for a single polarization case. With such a process, even spheres with a diameter equal to ?/3 are correctly reconstructed at 20 GHz.

Eyraud, Christelle; Geffrin, Jean-Michel; Litman, AméLie; Spinelli, Jean-Pierre

2012-02-01

244

MICADO: Parallel implementation of a 2D-1D iterative algorithm for the 3D neutron transport problem in prismatic geometries  

SciTech Connect

The large increase in computing power over the past few years now makes it possible to consider developing 3D full-core heterogeneous deterministic neutron transport solvers for reference calculations. Among all approaches presented in the literature, the method first introduced in [1] seems very promising. It consists in iterating over resolutions of 2D and ID MOC problems by taking advantage of prismatic geometries without introducing approximations of a low order operator such as diffusion. However, before developing a solver with all industrial options at EDF, several points needed to be clarified. In this work, we first prove the convergence of this iterative process, under some assumptions. We then present our high-performance, parallel implementation of this algorithm in the MICADO solver. Benchmarking the solver against the Takeda case shows that the 2D-1D coupling algorithm does not seem to affect the spatial convergence order of the MOC solver. As for performance issues, our study shows that even though the data distribution is suited to the 2D solver part, the efficiency of the ID part is sufficient to ensure a good parallel efficiency of the global algorithm. After this study, the main remaining difficulty implementation-wise is about the memory requirement of a vector used for initialization. An efficient acceleration operator will also need to be developed. (authors)

Fevotte, F.; Lathuiliere, B. [EDF R and D (France)] [EDF R and D (France)

2013-07-01

245

Revisiting the use of offset surface features to recover fault slip histories: insights from pseudo-3D GPR imaging of offset alluvial terraces at Te Marua, Wellington fault, New Zealand  

NASA Astrophysics Data System (ADS)

We use dense, pseudo-3D, high-resolution Ground Penetrating Radar (GPR) acquisitions to investigate the Te Marua site in the northern Island of New Zealand, where a well-preserved flight of ? 10 Holocene alluvial strath terraces of different ages are laterally offset by the dextral Wellington fault. These lateral offsets have been extensively studied in prior works. We acquired forty ? 600 m long, 5 m spaced GPR profiles (100 and 250 MHz), parallel to the fault and evenly distributed on either side. We also acquired a high-resolution GPS-derived DEM of the entire site. The analysis of the GPR profiles reveals three paleo-surfaces buried in the first ? 7 m below the ground. The deepest interface (? 5 m) is the strath incision surface in the greywacke bedrock, while the two above surfaces (? 1 and 2 m) separate distinct alluvium layers. All alluvial landforms that shape the ground surface (? 30 recognized features) similarly imprint the three buried surfaces. Therefore, any marker has its lateral offset measurable n times, with n the number of interfaces where it is expressed. Using this property, we measured a total of 146 fault offsets, while, so far, only a tenth of such measurements had been reported from surface observation. We find that the offsets measured at the ground surface are systematically markedly lower than those measured further at depth on the same markers, while the morphological expression of the markers is clearer in the sub-surface. We infer that the fault slip record is best preserved in the sub-surface. Additionally, the buried record is longer than the surface record. The statistical analysis of the dense offset collection leads to only retain 5 robustly constrained cumulative slip values, of 3.3 ± 1, 7.8 ± 1, 18 ± 1, 26.8 ± 2, and 51 ± 3-4 m. We find that the most recent large earthquake on the Wellington fault at Te Marua has produced a coseismic slip of 3.7 ± 1.7 m. A total of at least 15 large earthquakes broke the fault at the site over the last 9-10 ka. These earthquakes seem to have been fairly characteristic, and we estimate their magnitude in the range Mw 6.9-7.6. Combined with available age constraints, our results suggest that such large earthquakes might repeat every 500-600 yrs on average. As the most recent large earthquake is taken to have occurred at 110-750 cal yr B.P., our results suggest that it cannot be excluded that the next large earthquake on the southern Wellington fault might occur over the next century. Our work confirms that GPR-based paleoseismology is a powerful approach to derive fault and earthquake slip information complementary, and possibly more precise, than the surface record.

Beaupretre, S.; Manighetti, I.; Garambois, S.; Malavieille, J.; Chatton, M.; Dominguez, S.

2012-12-01

246

Geometry, kinematics and deformation rates along the active normal fault system in the southern Apennines: Implications for fault growth  

NASA Astrophysics Data System (ADS)

Throw rates, throws and kinematic data have been collected from a localised system of active normal faults in the southern Apennines, Italy, to assess how its growth history differs from that for a distributed fault system in the central Apennines. Both show evidence for fault interaction in that (1) faults located centrally along strike have higher throws and throw rates than distal faults, and (2) cumulative throw and throw-rate profiles summed across strike show central maxima with values decreasing to zero at fault system tips. However, although throw rates increased through time in the central Apennines, we are unable to resolve such changes if they exist for the southern Apennines. Specifically, throw rates derived from offsets of 18 ka geomorphic surfaces are consistent with total throws in the southern Apennines when extrapolated back through time, but overestimate total throws in the central Apennines by a factor of 2.4, suggesting an increase in throw-rate through time for the latter. We discuss why some fault systems appear to have throw rates that are constant through time whilst others accelerate during growth/interaction.

Papanikolaou, Ioannis D.; Roberts, Gerald P.

2007-01-01

247

3D Modeling By Consolidation Of Independent Geometries Extracted From Point Clouds - The Case Of The Modeling Of The Turckheim's Chapel (Alsace, France)  

NASA Astrophysics Data System (ADS)

Turckheim is a small town located in Alsace, north-east of France. In the heart of the Alsatian vineyard, this city has many historical monuments including its old church. To understand the effectiveness of the project described in this paper, it is important to have a look at the history of this church. Indeed there are many historical events that explain its renovation and even its partial reconstruction. The first mention of a christian sanctuary in Turckheim dates back to 898. It will be replaced in the 12th century by a roman church (chapel), which subsists today as the bell tower. Touched by a lightning in 1661, the tower then was enhanced. In 1736, it was repaired following damage sustained in a tornado. In 1791, the town installs an organ to the church. Last milestone, the church is destroyed by fire in 1978. The organ, like the heart of the church will then have to be again restored (1983) with a simplified architecture. From this heavy and rich past, it unfortunately and as it is often the case, remains only very few documents and information available apart from facts stated in some sporadic writings. And with regard to the geometry, the positioning, the physical characteristics of the initial building, there are very little indication. Some assumptions of positions and right-of-way were well issued by different historians or archaeologists. The acquisition and 3D modeling project must therefore provide the current state of the edifice to serve as the basis of new investigations and for the generation of new hypotheses on the locations and historical shapes of this church and its original chapel (Fig. 1)

Koehl, M.; Fabre, Ph.; Schlussel, B.

2014-06-01

248

Skewed orientation groups in scatter plots of earthquake fault plane solutions: Implications for extensional geometry at oceanic spreading centers  

NASA Astrophysics Data System (ADS)

analysis of earthquake focal solutions derived from centroid moment tensors shows well-defined orientation groups in scatterplots of fault plane normals and associated slip line vectors. Consideration of the geometry implied by these orientation groups can allow resolution of the ambiguity inherent in the choice as to which of the two conjugate fault plane solutions should apply, and in many cases, the same classification can be applied to the entire orientation group. Examining scatter plots of data from normal fault earthquakes on spreading ridges typically shows orthogonal relations but there are also many cases where there is a skew with respect to the great circles defined by faults on adjacent transform faults. This can be explained by finite rock strength in the adjacent transforms, requiring resolved shear stress to allow movement, thus requiring rotation of the trajectories of the deviatoric stress axes: anticlockwise for right-lateral transforms and clockwise for left-lateral transforms. This asymmetry also requires formation of tilt block geometries reminiscent of Basin and Range style continental extension.

Lister, G. S.; Tkal?i?, H.; McClusky, S.; Forster, M. A.

2014-03-01

249

Focal mechanisms of earthquake multiplets in the western part of the Corinth Rift (Greece): influence of the velocity model and constraints on the geometry of the active faults  

NASA Astrophysics Data System (ADS)

The composite fault plane solutions for 24 large multiplets recorded in the western part of the Corinth Rift between 2000 and 2007 are computed by jointly inverting P polarities and Sv/P, Sh/P, Sv/Sh amplitude ratios of the direct waves. The fault plane solutions are determined using 1-D and 3-D velocity models. Solutions computed with the 3-D velocity model are preferred to the ones computed with the 1-D model because overall, 3-D solutions have a better score function. They correspond essentially to E-NE/W-SW and W-NW/E-SE striking normal faults, which is consistent with the N-S extensional/vertical shortening tectonic regime of the area. For 15 multiplets, one of the nodal planes is similar to the plane delineated by the earthquakes. It is then possible to determine which nodal plane is the fault plane. The analysis of the fault plane solutions highlights a clear decrease of their dip with depth and towards the north. Several multiplets with steeply dipping fault planes (50°-60°) located at depths of 7-8 km are clearly located at the base of onshore and offshore faults that crop out close to the south border of the Corinth Gulf, indicating that these faults are steep down to 7-8 km depth. To the north, multiplets underline a low angle north-dipping structure (20°-30°) on which steep north-dipping faults could take root.

Godano, Maxime; Deschamps, Anne; Lambotte, Sophie; Lyon-Caen, Hélène; Bernard, Pascal; Pacchiani, Francesco

2014-06-01

250

Modelling of 3D fractured geological systems - technique and application  

NASA Astrophysics Data System (ADS)

All rocks in the earth's crust are fractured to some extent. Faults and fractures are important in different scientific and industry fields comprising engineering, geotechnical and hydrogeological applications. Many petroleum, gas and geothermal and water supply reservoirs form in faulted and fractured geological systems. Additionally, faults and fractures may control the transport of chemical contaminants into and through the subsurface. Depending on their origin and orientation with respect to the recent and palaeo stress field as well as on the overall kinematics of chemical processes occurring within them, faults and fractures can act either as hydraulic conductors providing preferential pathways for fluid to flow or as barriers preventing flow across them. The main challenge in modelling processes occurring in fractured rocks is related to the way of describing the heterogeneities of such geological systems. Flow paths are controlled by the geometry of faults and their open void space. To correctly simulate these processes an adequate 3D mesh is a basic requirement. Unfortunately, the representation of realistic 3D geological environments is limited by the complexity of embedded fracture networks often resulting in oversimplified models of the natural system. A technical description of an improved method to integrate generic dipping structures (representing faults and fractures) into a 3D porous medium is out forward. The automated mesh generation algorithm is composed of various existing routines from computational geometry (e.g. 2D-3D projection, interpolation, intersection, convex hull calculation) and meshing (e.g. triangulation in 2D and tetrahedralization in 3D). All routines have been combined in an automated software framework and the robustness of the approach has been tested and verified. These techniques and methods can be applied for fractured porous media including fault systems and therefore found wide applications in different geo-energy related topics including CO2 storage in deep saline aquifers, shale gas extraction and geothermal heat recovery. The main advantage is that dipping structures can be integrated into a 3D body representing the porous media and the interaction between the discrete flow paths through and across faults and fractures and within the rock matrix can be correctly simulated. In addition the complete workflow is captured by open-source software.

Cacace, M.; Scheck-Wenderoth, M.; Cherubini, Y.; Kaiser, B. O.; Bloecher, G.

2011-12-01

251

Initiation of deformation of the Eastern California Shear Zone: Constraints from Garlock fault geometry and GPS observations  

USGS Publications Warehouse

We suggest a 2-stage deformation model for the Eastern California Shear Zone (ECSZ) to explain the geometry of the Garlock fault trace. We assume the Garlock fault was originally straight and then was gradually curved by right-lateral shear deformation across the ECSZ. In our 2-stage deformation model, the first stage involves uniform shear deformation across the eastern part of the shear zone, and the second stage involves uniform shear deformation across the entire shear zone. In addition to the current shape of the Garlock fault, our model incorporates constraints on contemporary deformation rates provided by GPS observations. We find that the best fitting age for initiation of shear in eastern part of the ECSZ is about 5.0 ?? 0.4 Ma, and that deformation of the western part started about 1.6 Myr later.

Gan, W.; Zhang, P.; Shen, Z. -K.; Prescott, W. H.; Svarc, J. L.

2003-01-01

252

Source-Averaged Basin Effects from 3D Ground Motion Simulations  

Microsoft Academic Search

We simulate long-period (0-0.5 Hz) ground motion time histories for a suite of sixty scenario earthquakes (Mw 6.3 to Mw 7.1) within the Los Angeles basin region. Fault geometries are based upon the Southern California (SCEC) Community Fault Model, and 3D seismic velocity structure is based upon the SCEC Community Velocity Model. The ground motion simulations are done using 5

S. M. Day; J. Bielak; D. Dreger; R. Graves; S. Larsen; K. B. Olsen; A. Pitarka; L. Ramirez

2004-01-01

253

A Close View Into the 3D Geometry of Grain-to-Grain Contacts and Surface Roughness in Sandstones Using Laser Scanning Confocal Microscopy  

NASA Astrophysics Data System (ADS)

Due to its sharp resolution (< 1 micron) and its ability in building 3D reconstructions from images scanned at various depths, laser scanning confocal microscopy (LSCM) is a powerful tool to render the three-dimensional geometry of microstructural features like pores, cracks and grains. This technique was used in particular to study the grain-to-grain contacts and grain surface topology at small scale in several sandstones. For that purpose, the rock samples to be studied were impregnated with a fluorescent dyed (Rhodamine B) resin in order to discriminate the void space from the grains. The next stage is then to make thin-sections with a thickness larger than usual (> 100 microns) that can be studied under LSCM. Three different sandstones have been studied: the Rothbach sandstone (Vosges mountains, Eastern France), the Bentheim sandstone (Germany) and the Darley Dale sandstone (UK). On each sample several three dimensional blocks have been investigated with size 228 by 152 microns and depths ranging from 35 to 100 microns. From each block, series of tens of parallel "virtual sections" have been recorded, separated by 1 or 2 microns in depth. We show on several examples the complex structure of grain-to-grain contacts which may be associated to the heterogeneity in cement distribution. In particular for the Rothbach sandstone, we found that the topology of the grain surfaces is dominated by the coating of clay particles which leads to a high surface roughness. Complementary SEM studies revealed that the clays are also present as cementing material between the grains. A thorough petrophysical study has shown that the anisotropy of P wave velocity in the Rothbach sandstone can be explained by an anisotropic distribution of cement: whereas this could not be confirmed from our LSCM and SEM analysis, we observed that the spatial distribution of contact lengths is anisotropic which explains qualitatively the spatial variability of P wave velocity. Finally we show examples of Hertzian cracks that initiated from the contact between grains in Darley Dale sandstone samples that experienced mechanical loading under triaxial conditions.

Menendez, B.; David, C.; Louis, L.; Martinez Nistal, A.

2003-12-01

254

The strength of faults in a convergent margin, determined by neotectonic computer simulations  

Microsoft Academic Search

In order to better understand the fault strength in convergent tectonic settings, we investigated the behavior of faults in the Taiwan region using a modified version of the neotectonic finite element code SHELLS. We generated a finite element grid that contains topography, surface heat flow, and a realistic 3D geometry of active faults. The lithosphere is assumed to be in

Christoph Moder; Sara Carena

2010-01-01

255

Geometry of the North Anatolian fault beneath the Gulf of Izmit and extent of the 1999 seafloor rupture  

NASA Astrophysics Data System (ADS)

High-resolution multibeam bathymetry data acquired during two recent surveys clearly highlight the trace of the North Anatolian Fault beneath Izmit Gulf. The fault follows the approximate axis of the Darica (Western) Basin and the Karamürsel (Central) Basin, and has an overall orientation consistent with Present relative plate motion documented by GPS measurements. In detail, the fault displays the en echelon geometry typical of right-lateral transform faults, with right-stepping en echelon folds and left-stepping Riedel shear fractures along its strike. Seafloor relief across the fault ranges from less than 1 m to over 100 m, indicating that strike-slip motion is often associated with a component of vertical slip. Holocene submerged shorelines are visible north of the fault which do not appear affected by vertical tectonics. In contrast, the corresponding shorelines cannot be unambiguously located south of the fault,. This may partly reflect the higher sediment supply south of the fault. It also suggests most of the vertical component of slip in central and western Izmit basins is accommodated by subsidence of the southern block. The August 17, 1999 earthquake produced more than 4 m of lateral slip in Golcuk on the eastern end of Karamursel basin, but did not affect Hersek Peninsula on the western end. On the other hand, several InSAR, GPS, and seismicity analysis concur to indicate 1--2 m of slip within the subsurface west of Hersek Peninsula. Multibeam backscatter data do not reveal any disturbance in Darica and Karamursel Basins, except close to Golcuk near 29^o43'E, where sub-parallel EW lineaments and very reflective seafloor affect the entire width of the Bay. We tentatively interpret this anomalous seafloor as underwater mole tracks and dewatering features associated with the 1999 seafloor rupture. In combination with the lack of evidence for ground rupture on Hersek, acoustic backscatter data suggest that the surface rupture terminated near 29^o43'E. Bathymetry data reveal an intricate pattern of escarpments at that location, including a 20m-high, 2km-long NS escarpment intersecting a WNW 4m-high escarpment. These features may indicate a 2--3 km releasing step-over of the fault W of Golcuk, and could explain why the surface rupture ended at that location. However, we cannot rule out that light sediments may be thrown in suspension by ground shaking during earthquakes and redeposit over the fault trace, masking any evidence for surface rupture west of 29^o43'E. Video observations and sampling along the fault trace beneath Izmit Bay might provide some useful answers.

Cormier, M.-H.; Seeber, L.; Polonia, A.; Cagatay, M. N.; Emre, O.; McHugh, C. M. G.; Bortoluzzi, G.; Gorur, N.

2003-04-01

256

Four-dimensional evolution of a salt-related fault network: Eugene Island Block 330 field, offshore Louisiana  

Microsoft Academic Search

The Eugene Island Block 330 field consists of two anticlinal rollovers in the hanging wall of a listric normal fault system that detaches along a deep salt weld. We use interpretation of well and 3D seismic data, 3D structural restoration, and fault analysis techniques to investigate the evolution of the three-dimensional geometry through time and its impact on hydrocarbon migration

M. G. Rowan; B. S. Hart; S. Nelson; P. B. Flemings

1996-01-01

257

3-D Terrain Corrections to Heat Flow Data, Topographically-Driven Groundwater Flow, and the Strength of the San Andreas Fault at Parkfield, CA  

Microsoft Academic Search

The lack of a detectable heat flow anomaly along the San Andreas Fault (SAF) constitutes one important piece of evidence used to argue that the fault supports low shear stresses (<20 MPa averaged over the upper 10 km). However, key uncertainties in existing heat flow data, such as the effects of heat advection by topographically-driven groundwater flow, topographic refraction (terrain

P. M. Fulton; D. M. Saffer; B. A. Bekins; R. N. Harris

2003-01-01

258

Shallow Geometry and Velocities Along the Rialto-Colton Fault, San Bernardino Basin, California  

NASA Astrophysics Data System (ADS)

The Rialto-Colton fault, part of and located southwest of the San Jacinto fault zone, extends along the southwestern margin of the San Bernardino basin. There, the Rialto-Colton fault is buried beneath Quaternary alluvium. Ground-water studies suggest that the Rialto-Colton fault extends northwestward, structurally bounding the San Bernardino basin and acting as a ground-water barrier. Potential-field studies also show evidence for variations in basement depth along the presumed trace of the fault. To better locate the Rialto-Colton fault and to better assess its potential earthquake hazard, the U.S. Geological Survey acquired five combined, high-resolution seismic reflection and refraction profiles along the expected trace of the fault. Our seismic reflection images show that the Rialto-Colton fault consists of an approximately 1-km-wide zone of small-offset (approximately 20 to 30 m) faults in the upper 1 km depth. No single large-offset fault was imaged along any of the seismic profiles. Reflections extend to depths of at least 800 m along most of the seismic profiles, suggesting that basement is at least 800 m deep. We also used tomographic methods to invert first-arrival refractions for the velocity structure along each of the seismic profiles. P-wave velocities range from about 300 m/s at the surface to about 2500 m/s at depths of about 100 m. Our seismic velocity images show that the ground-water table largely correlates with the 1500 m/s contours, and the velocity images show that the ground-water table is disrupted across the reflection-imaged fault zone at shallow depths. Some of the faults extend to within a few meters of the surface, suggesting that there has been recent activity on the Rialto-Colton fault. Because the densely populated and growing cites of San Bernardino, Rialto, Colton, and Fontana are located along the projected trend of the Rialto-Colton fault, rupture along the fault may present a significant earthquake hazard to the region.

Gandhok, G.; Catching, R. D.; Rymer, M. J.; Goldman, M. R.

2003-12-01

259

Subsurface geometry of the San Andreas-Calaveras fault junction: influence of the Coast Range Ophiolite  

NASA Astrophysics Data System (ADS)

Potential-field modeling, surface geologic mapping, and relocated seismicity are used to investigate the three-dimensional structure of the San Andreas-Calaveras fault junction to gain insight into regional tectonics, fault kinematics, and seismic hazard. South of the San Francisco Bay area, the San Andreas and Hayward-Calaveras fault zones join to become a single San Andreas Fault. The fault junction, as defined in this study, represents a three-dimensional volume of crust extending from San Juan Bautista in the north to Bitterwater Valley in the south, bounded by the San Andreas Fault on the southwest and the Calaveras fault zone on the northeast. South of Hollister, the Calaveras fault zone includes the Paicines, San Benito, and Pine Rock faults. Within the junction, the San Andreas and Calaveras faults are both creeping at the surface, and strike parallel to each other for about 50 km, separated by only 2 to 6 km, but never actually merge at the surface. Geophysical evidence suggests that the San Andreas and Calaveras faults dip away from each other within the northern portion of the fault junction, bounding a triangular wedge of crust. This wedge changes shape to the south as the dips of both the San Andreas and Calaveras faults vary along strike. The main trace of the San Andreas Fault is clearly visible in cross-sections of relocated seismicity as a vertical to steeply southwest-dipping structure between 5 and 10 km depth throughout the junction. The Calaveras fault dips steeply to the northeast in the northern part of the junction. Near the intersection with the Vallecitos syncline, the dip of the Calaveras fault, as identified in relocated seismicity, shallows to 60 degrees. Northeast of the Calaveras fault, we identify a laterally extensive magnetic body 1 to 8 km below the surface that we interpret as a folded 1 to 3 km-thick tabular body of Coast Range Ophiolite at the base of the Vallecitos syncline. Potential-field modeling and relocated seismicity indicate that the southwestern edge of this magnetic body is defined by a northeast-dipping structure that we interpret as part of the Calaveras fault. The base of this magnetic slab, which is folded up along the Calaveras fault, may represent a roof thrust formed by an eastward-migrating wedge of Franciscan Complex. Fragments of Coast Range Ophiolite caught up within the San Andreas-Calaveras junction may facilitate creep and slip transfer between structures that have no apparent connection at the surface. Combined geological and geophysical results suggest that during development of the junction, the Calaveras fault preferentially followed a zone of weakness represented by the roof thrust and associated Coast Range Ophiolite. The Hayward fault occupies a similar position with respect to the Coast Range Ophiolite near San Leandro to the north.

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

2013-12-01

260

dc3dm: Software to efficiently form and apply a 3D DDM operator for a nonuniformly discretized rectangular planar fault  

NASA Astrophysics Data System (ADS)

My poster will describe dc3dm, a free open source software (FOSS) package that efficiently forms and applies the linear operator relating slip and traction components on a nonuniformly discretized rectangular planar fault in a homogeneous elastic (HE) half space. This linear operator implements what is called the displacement discontinuity method (DDM). The key properties of dc3dm are: 1. The mesh can be nonuniform. 2. Work and memory scale roughly linearly in the number of elements (rather than quadratically). 3. The order of accuracy of my method on a nonuniform mesh is the same as that of the standard method on a uniform mesh. Property 2 is achieved using my FOSS package hmmvp [AGU 2012]. A nonuniform mesh (property 1) is natural for some problems. For example, in a rate-state friction simulation, nucleation length, and so required element size, scales reciprocally with effective normal stress. Property 3 assures that if a nonuniform mesh is more efficient than a uniform mesh (in the sense of accuracy per element) at one level of mesh refinement, it will remain so at all further mesh refinements. I use the routine DC3D of Y. Okada, which calculates the stress tensor at a receiver resulting from a rectangular uniform dislocation source in an HE half space. On a uniform mesh, straightforward application of this Green's function (GF) yields a DDM I refer to as DDMu. On a nonuniform mesh, this same procedure leads to artifacts that degrade the order of accuracy of the DDM. I have developed a method I call IGA that implements the DDM using this GF for a nonuniformly discretized mesh having certain properties. Importantly, IGA's order of accuracy on a nonuniform mesh is the same as DDMu's on a uniform one. Boundary conditions can be periodic in the surface-parallel direction (in both directions if the GF is for a whole space), velocity on any side, and free surface. The mesh must have the following main property: each uniquely sized element must tile each element larger than itself. A mesh generated by a family of quadtrees has this property. Using multiple quadtrees that collectively cover the domain enables the elements to have a small aspect ratio. Mathematically, IGA works as follows. Let Mn be the nonuniform mesh. Define Mu to be the uniform mesh that is composed of the smallest element in Mn. Every element e in Mu has associated subelements in Mn that tile e. First, a linear operator Inu mapping data on Mn to Mu implements smooth (C^1) interpolation; I use cubic (Clough-Tocher) interpolation over a triangulation induced by Mn. Second, a linear operator Gu implements DDMu on Mu. Third, a linear operator Aun maps data on Mu to Mn. These three linear operators implement exact IGA (EIGA): Gn = Aun Gu Inu. Computationally, there are several more details. EIGA has the undesirable property that calculating one entry of Gn for receiver ri requires calculating multiple entries of Gu, no matter how far away from ri the smallest element is. Approximate IGA (AIGA) solves this problem by restricting EIGA to a neighborhood around each receiver. Associated with each neighborhood is a minimum element size s^i that indexes a family of operators Gu^i. The order of accuracy of AIGA is the same as that of EIGA and DDMu if each neighborhood is kept constant in spatial extent as the mesh is refined.

Bradley, A. M.

2013-12-01

261

The 3-D Tectonic Crustal Stress Field and Style of Faulting Along the Pacific North America Plate Boundary in Southern California  

NASA Astrophysics Data System (ADS)

We invert for the state of stress in the southern California crust using recent high quality earthquake focal mechanisms catalog (1981-2010). To interpret the stress field we determine the maximum horizontal compressive stress (SHmax) orientations and the style of faulting across southern California at four different scales of resolution, with grid spacing of 5 and 10 km, and with 15 or 30 events per grid. The stress field is best resolved where seismicity rates are high but sufficient data are available to constrain the stress field across most of the region. The trend of SHmax exhibits significant regional and local spatial heterogeneities. The regional trend of SHmax varies from north along the San Andreas system to NNE to the east in the Eastern California Shear Zone as well as to the west, within the Continental Borderland and the western Transverse Ranges. The transition zones from one state of stress to the other are very sharp and occur over a distance of a few kilometers, following a trend from Yucca Valley to Imperial Valley to the east, and the western edge of the Peninsular Ranges to the west. The local scale heterogeneities in the SHmax trend include NNW trends along the San Andreas Fault near Cajon Pass, Tejon Pass, and the Cucapa Range, as well as NNE trends near the northern San Jacinto Fault and the Wheeler Ridge region. The style of faulting exhibits similar complexity, ranging from predominantly normal faulting in the high Sierra Nevada, to strike-slip faulting along the San Andreas system, to three consecutive bands of thrust faulting in the Wheeler Ridge area and the western Transfer Ranges. The local variations in the style of faulting include normal faulting at the north end of the San Jacinto Fault and scattered regions of thrust faulting. We compare the pattern of SHmax trend in the crust with the GPS measured maximum shortening strain rate tensor and upper mantle anisotropy. The regional variations in the SHmax trends are very similar to the pattern of the maximum shortening axes of surface strain rate tensor field although the strain filed tends to be smoother and appears to capture some of the upper mantle deformation field. The mean trend of SHmax depart about approximately 14° to the east from the trend of the maximum shortening directions of anisotropy in the upper mantle.tacked SHmax profile across the Cajon Pass from the Continental Borderland to the Basin and Range. GPS velocity profile is in cyan.

Yang, W.; Hauksson, E.

2012-12-01

262

Near-surface location, geometry, and velocities of the Santa Monica Fault Zone, Los Angeles, California  

USGS Publications Warehouse

High-resolution seismic-reflection and seismic-refraction imaging, combined with existing borehole, earthquake, and paleoseismic trenching data, suggest that the Santa Monica fault zone in Los Angeles consists of multiple strands from several kilometers depth to the near surface. We interpret our seismic data as showing two shallow-depth low-angle fault strands and multiple near-vertical (???85??) faults in the upper 100 m. One of the low-angle faults dips northward at about 28?? and approaches the surface at the base of a topographic scarp on the grounds of the Wadsworth VA Hospital (WVAH). The other principal low-angle fault dips northward at about 20?? and projects toward the surface about 200 m south of the topographic scarp, near the northernmost areas of the Los Angeles Basin that experienced strong shaking during the 1994 Northridge earthquake. The 20?? north-dipping low-angle fault is also apparent on a previously published seismic-reflection image by Pratt et al. (1998) and appears to extend northward to at least Wilshire Boulevard, where the fault may be about 450 m below the surface. Slip rates determined at the WVAH site could be significantly underestimated if it is assumed that slip occurs only on a single strand of the Santa Monica fault or if it is assumed that the near-surface faults dip at angles greater than 20-28??. At the WVAH, tomographic velocity modeling shows a significant decrease in velocity across near-surface strands of the Santa Monica fault. P-wave velocities range from about 500 m/sec at the surface to about 4500 m/sec within the upper 50 m on the north side of the fault zone at WVAH, but maximum measured velocities on the south side of the low-angle fault zone at WVAH are about 3500 m/sec. These refraction velocities compare favorably with velocities measured in nearby boreholes by Gibbs et al. (2000). This study illustrates the utility of com- bined seismic-reflection and seismic-refraction methods, which allow more accurate reflection imaging and compositional estimations across areas with highly variable velocities, a property that is characteristic of most fault zones.

Catchings, R. D.; Gandhok, G.; Goldman, M. R.; Okaya, D.; Rymer, M. J.; Bawden, G. W.

2008-01-01

263

Subsurface fault geometries and crustal extension in the eastern Basin and Range Province, western U.S.  

NASA Astrophysics Data System (ADS)

We provide the first synthesis of seismic reflection data and active present-day crustal deformation for the greater Wasatch fault zone. We analyzed a number of previously unpublished seismic reflection lines, horizontal and vertical crustal velocities from continuous GPS, and surface geology to investigate the relationships between interseismic strain accumulation, subsurface fault geometry, and geologic slip rates on seismogenic faults across the eastern third of the northern Basin and Range Province. The seismic reflection data show recent activity along high-angle normal faults that become listric with depth and appear to sole into preexisting décollements, possibly reactivating them. We interpret these listric normal faults as reactivated Sevier-age structures that are connected at depth with a regionally extensive detachment horizon. These observations of subsurface structure are consistent with the mapped geology in areas that have experienced significant extension. We modeled the crustal deformation data using a buried dislocation source in a homogeneous elastic half space. The estimated model results include a low-angle dislocation (~ 8-20°) at a locking depth of ~ 7-10 km and slipping at 3.2 ± 0.2 mm/yr. Despite the model's relative simplicity, we find that the predicted location of the dislocation is consistent with the interpreted seismic reflection data, and suggests an active regionally extensive sub-horizontal surface in the eastern Basin and Range. This result may imply that this surface represents aseismic creep across a reactivated low-angle fault plane or the onset of ductile flow in the lower crust at or beneath the brittle-ductile transition zone under the present-day Basin and Range extensional regime. This result may also have implications for crustal rheology, and suggests that geodesy might, under some circumstances, serve as an appropriate tool for inferring deeper crustal structure.

Velasco, M. Soledad; Bennett, Richard A.; Johnson, Roy A.; Hreinsdóttir, Sigrún

264

Geometry  

NSDL National Science Digital Library

This collection, created by Salman Khan of the Khan Academy, features videos on geometry. A basic understanding of Algebra I necessary to understand the fundamental elements featured in this collection. Altogether, the site contains 23 videos the cover an array of topics under the field of geometry. After these lessons, you'll certainly be ready for Trigonometry.

Khan, Salman

2011-01-03

265

3D non-Planar Finite Difference Dynamic Rupture: Application to the Landers Earthquake  

NASA Astrophysics Data System (ADS)

Many aspects of seismic complexity have been explained in the last thirty years thanks to the development of numerical approaches allowing seismologists to simulate the dynamic rupture of earthquakes. Heterogeneities in both the initial stress field and the surrounding medium are extremely important elements. The constitutive law describing the physics of the breakdown process which relates the fault friction to fault kinematics is also determinant. However, given the increasing amount of high quality seismological data, more sophisticated approaches are needed to explain observations so that others important physical factors, such as the real fault geometry, could be integrated into simulations. Bearing in mind these new high quality observations along with the current computational power, a great interest has arisen in the last five years to develop 3D numerical codes to simulate earthquakes with real fault geometries. Recently, Cruz-Atienza and Virieux (2004) have introduced a 2D finite difference (FD) approach for modeling the dynamic rupture of non-planar faults. In this work we analyze the 3D extension of such an approach. On that account, the new 3D code may consider arbitrary heterogeneous media, composite friction laws and non-planar fault geometries. The numerical criteria for rupture boundary conditions to model rupture processes accurately were determined experimentally finding consistency with those determined for the 2D case: the source is discretized by a set of numerical cells. Given a spatial grid step for wave propagation, the number of grid nodes contained in each cell should be adapted accordingly. The smaller the spatial step the greater the number of nodes. We have performed dynamic rupture simulations for different curved 3D faults and compared results with those given by a BIE method (Aochi et al., 2000). Consistency between solutions yielded by different numerical approaches is essential since it is the only way to have confidence in these kinds of complex simulations for which no theoretical solutions are available. This benchmarking exercise has also allowed us to better understand and quantify the effect of fault curvature on near-source seismograms and fault solutions. Finally, we applied our numerical approach to model the 1992 Landers earthquake (Mw=7.3). Several simulations were carried out including a heterogeneous initial stress field, layered elastic medium and the non-planar fault trace geometry. Complexity in near-field seismograms enhances the importance of both a heterogeneous surrounding medium and non-planar fault geometry due to their intimate interaction during rupture process. Aochi, H., E. Fukuyama and M. Matsu'ura, 2000, Pure. Appl. Geophys., 157, 2003-2027. Cruz-Atienza, V.M. and J. Virieux, 2004, Geophys. J. Int., 158, 939-954.

Cruz-Atienza, V. M.; Virieux, J.; Aochi, H.; Peyrat, S.

2004-12-01

266

High-spin versus spin-crossover versus low-spin: geometry intervention in cooperativity in a 3D polymorphic iron(II)-tetrazole MOFs system.  

PubMed

Reported here are three 3D metal-organic framework (MOF) polymorphs with the chemical formula [Fe(2)(H(0.67)bdt)(3)]·xH(2)O (H(2)bdt = 5,5'-(1,4-phenylene)bis(1H-tetrazole)), all of which are constructed from similar Fe(II)-tetrazole rod secondary building units (SBUs) via covalent links, but exhibit diverse spin states regulated by inter-chain cooperativity. PMID:22428157

Yan, Zheng; Li, Mian; Gao, Hui-Ling; Huang, Xiao-Chun; Li, Dan

2012-04-25

267

Active forearc shortening in Tohoku, Japan: Constraints on fault geometry from erosion rates and fluvial longitudinal profiles  

NASA Astrophysics Data System (ADS)

Convexities in the longitudinal profiles of actively incising rivers are typically considered to represent the morphologic signal of a transient response to external perturbations in tectonic or climatic forcing. Distinguishing such knickzones from those that may be anchored to the channel network by spatial variations in rock uplift, however, can be challenging. Here, we combine stream profile analysis, 10Be watershed-averaged erosion rates, and numerical modeling of stream profile evolution to evaluate whether knickzones in the Abukuma massif of northeast Japan represent a temporal or spatial change in rock uplift rate in relation to forearc shortening. Knickzones in channels that drain the eastern flank of the Abukuma massif are characterized by breaks in slope-area scaling and separate low-gradient, alluvial upper-channel segments from high-gradient, deeply-incised lower channel segments. Average erosion rates inferred from 10Be concentrations in modern sediment below knickzones exceed erosion rates above knickzones by 20-50%. Although profile convexities could be interpreted as a transient response to an increase in rock uplift rate associated with slip on the range-bounding fault, geologic constraints on the initiation of fault slip and the magnitude of displacement cannot be reconciled with a recent, spatially uniform increase in slip rate. Rather, we find that knickzone position, stream profile gradients, and basin averaged erosion rates are best explained by a relatively abrupt spatial increase in uplift rate localized above a flat-ramp transition in the fault system. These analyses highlight the importance of considering spatially non-uniform uplift in the interpretation of stream profile evolution and demonstrate that the adjustment of river profiles to fault displacement can provide constraints on fault geometry in actively eroding landscapes.

Regalla, Christine; Kirby, Eric; Fisher, Donald; Bierman, Paul

2013-08-01

268

Subsurface Geometry of the Sani-Chelungpu Faults and Fold Scarp Formation in the 1999 Chi-Chi Taiwan Earthquake  

NASA Astrophysics Data System (ADS)

A set of detailed cross sections reveal three-dimensional ramp-flat geometry of the Sani and Chelungpu faults in central Taiwan, where the Chi-Chi earthquake occurred. Along the Choshui River, the Chelungpu fault dips toward the east at 30o-40 o and detached at a depth of 10 km. Along with decreasing ramp-dip to 20o-25 o, the decollement changes from 10 km northward to 6 km deep in the Chungliao section, an average 32o dip toward south in 6 km distance. The decollement lies at a roughly constant depth of 6-7 km from Chungliao northward to the Wufeng­VKuoshing section, where it steps from 6 km to 3 km deep in the Fengyuan-Tamaopu section (average 8 o dip toward south). About 10 km north of Fengyuan, drilling wells show that the Chelungpu fault lies less than 1 km along the Taan River (average 10 o dip). South of Wufeng, the Chelungpu-Sani fault emplaced the Pliocene Chinshu Shale ontop the Pleistocene Toukoushan Formation; whereas in the north, the Sani thrust imbrcates from the Chelungpu fault and cuts down-section northward. North from the Taan River, the late Quaternary Tungshih anticline in the hanging-wall of the Sani thrust localizes the surface ruptures and grows during the Chi-Chi earthquake. Fold scarps of the Chi-Chi earthquake appear in the Ailiao village (east of Tsaotun), Hsintse folded terrace, and western limb of the Tungshih antcilne. They are developed associated with coseismic fault-bend folding. Applying a schematic relationship between fault slip, folding vector and height, width and dip of fold scarp as well as terrace dating and geodetic data to the Shuichin (ele. 600m) and Dana (ele. 500m) terraces in the Hsintse area, a geologic slip rate of 5 mm/yr, or a minimum of 38 Chi-Chi equivalent earthquakes is needed to form the 100m-high fold scarp. Results of comparing coseismic and finite excess area in the Tungshih anticline show that Quaternary structures in the north of the Taan River are relatively younger than terraces in the Hsintse area.

Hung, J.; Suppe, J.

2002-12-01

269

Relationships between the geometry of seismogenic faults and observed seismicty: a contribute from reflection seismic  

NASA Astrophysics Data System (ADS)

We analyze the seismogenic structures of the the Colfiorito area (central Italy), strucked by the 1997-98 relevant seismic sequence. This area has been used as a test site to investigate the possible interactions between earthquake seismology, reflection seismology and structural geology. Here we show the results obtained from the interpretation of the re-processed seismic reflection profile, acquired in the 80' for hydrocarbon exploration by ENI-Agip, crossing the epicentral area and the relationships between relating hypocentral locations and geological features derived from surface and from seismic data. The dense distribution of seismic stations connected to a temporary network installed after the occurrence of the first two large shocks (Mw=5.7 and Mw=6.0) provided high quality data showing earthquakes located at depth varying from 3 to 9 km and characterised by normal faulting mechanisms, with a NE-SW tension axis oriented about N55^o. The non conventional reprocessing sequence adopted was aimed to the early removal of the coherent and random noise and to the optimal definition of fault systems. The obtained profile shows an outstanding increase in the resolution of the geological structures with a better evidence of the faults and allows a much better correlation of surface geology features with the reflectors and the banning of parts of the profiles which run along the strike of the geological structures. The profile also shows a good image of the deep structure which has been interpreted as the depth image of the major fault of the Colfiorito fault system. A first attempt of projection of the earthquakes of the 1997-98 sequence shows a basic consistence with the inferred extensional structures at depth. The study also evidences that at least the upper part of the basement is involved in the thrust sheets, with a stepping and deepening of the basement from west to east from 5.5, to 9 km depth. The average dip at depth of the active faults is about 40^o fitting with the slip plane inferred from the focal mechanism of the main shocks and with the aftershocks distribution alignment in cross section of the aftershock sequence. At a depth of about 8 km, the trace of the active normal fault corresponds to the position of a Basement step, hence suggesting that the position of the Basement steps, generated by Miocene-Pliocene thrust tectonics, may have controlled the location of the subsequent normal faults.

Ciaccio, M. G.; Mirabella, F.; Stucchi, E.

2003-04-01

270

Congestion aware, fault tolerant, and thermally efficient inter-layer communication scheme for hybrid NoC-bus 3D architectures  

Microsoft Academic Search

hree-dimensional IC technology offers greater device integration and shorter interlayer interconnects. In order to take advantage of these attributes, 3D stacked mesh architecture was proposed which is a hybrid b etween pac ket-switched netw ork and a bus. Stacked mesh is a feasible arch itecture wh ich p rovides both perfo rmance and area benefits, while suf fering from inef

Amir-Mohammad Rahmani; Pasi Liljeberg; Khalid Latif; Juha Plosila; Kameswar Rao Vaddina; Hannu Tenhunen

2011-01-01

271

Geometry and deformation features of the most recent co-seismic surface ruptures along the Xiaojiang Fault and its tectonic implications for the Tibetan Plateau  

NASA Astrophysics Data System (ADS)

The Anninghe, Zemuhe, Xiaojiang and Daliangshan faults bound the southeastern margin of the Tibetan Plateau, which has almost been entirely ruptured by strong earthquakes during the past 500 years. The geometry and deformation features of the most recent co-seismic surface ruptures show not only the surface morphology of the source seismogenic fault, but also the structural characteristics of the upper crust, as well as the pre-existing tectonic environment. Hence, the most recent co-seismic surface ruptures along the Xiaojiang Fault zone reveal the surface deformation of the southeastern Tibetan Plateau. Our investigation reveal that the 1833 Songming rupture zone is about 150 km, with maximum co-seismic offset of 8.4 m, and the re-evaluated moment magnitude is about M 7.5-7.6 which is lower than previously estimated M 8.0. The 1500 Yiliang rupture zone is about 80 km, with maximum co-seismic offset of 8.0 m, and the re-evaluated moment magnitude of M 7.2-7.5, which is higher than previously demonstrated M 7.0. The spatial distribution of the surface rupture zones along Xiaojiang Fault shows an arcuate geometry. Our findings also reveal that strong earthquakes rupture not only the two major strands but also the en echelon faults between them. The arcuate geometry of the fault zone and the development of these en echelon faults are consistent with the clockwise rotation of the southeastern Tibetan Plateau.

Ren, Zhikun

2013-11-01

272

CONTROL OF RUPTURE BY FAULT GEOMETRY DURING THE 1966 PARKFIELD EARTHQUAKE  

Microsoft Academic Search

A reanalysis of the available data for the 1966 Parkfleld, California, earthquake (Mr -- 5½) suggests that although the ground breakage and aftershocks extended about 40 km along the San Andreas Fault, the initial dynamic rupture was only 20 to 25 km in length. The foreshocks and the point of initiation of the main event locate at a small bend

ALLAN G. LINDH; DAVID M. BOORE

273

Lack of continuity of the San Andreas Fault in southern California: Three-dimensional fault models and earthquake scenarios  

Microsoft Academic Search

The 1200-km-long San Andreas Fault loses its apparent continuity in southern California near San Gorgonio Pass [Allen, 1957], which raises significant questions given the dominant role of this fault in active California tectonics. What is the fundamental three-dimensional (3-D) geometry and kinematic behavior of the San Andreas fault system in this complex region? Is a throughgoing, if complex, San Andreas

Sara Carena; John Suppe; Honn Kao

2004-01-01

274

3D Shape from Unorganized 3D Point Clouds  

Microsoft Academic Search

\\u000a We present a framework to automatically infer topology and geometry from an unorganized 3D point cloud obtained from a 3D\\u000a scene. If the cloud is not oriented, we use existing methods to orient it prior to recovering the topology. We develop a quality\\u000a measure for scoring a chosen topology\\/orientation. The topology is used to segment the cloud into manifold components

George Kamberov; Gerda Kamberova; Amit Jain

2005-01-01

275

The geometry of the active strike-slip El Tigre Fault, Precordillera of San Juan, Central-Western Argentina: integrating resistivity surveys with structural and geomorphological data  

NASA Astrophysics Data System (ADS)

The geometry and related geomorphological features of the right-lateral strike-slip El Tigre Fault, one of the main morphostructural discontinuities in the Central-Western Precordillera of Argentina, were investigated. Achievements of this survey include: recognition of structural and geometrical discontinuities along the fault trace, identification and classification of landforms associated with local transpressional and transtensional sectors, observation of significant changes in the fault strike and detection of right and left bends of different wavelength. In the Central Segment of the El Tigre Fault, 2D electrical resistivity tomography surveys were carried out across the fault zone. The resistivity imaging permitted to infer the orientation of the main fault surface, the presence of blind fault branches along the fault zone, tectonic tilting of the Quaternary sedimentary cover, subsurface structure of pressure ridges and depth to the water table. Based on this information, it is possible to characterize the El Tigre Fault also as an important hydro-geological barrier. Our survey shows that the main fault surface changes along different segments from a high-angle to a subvertical setting whilst the vertical-slip component is either reverse or normal, depending on the local transpressive or transtensive regime induced by major bends along the trace. These local variations are expressed as sections of a few kilometres in length with relatively homogeneous behaviour and frequently separated by oblique or transversal structures.

Fazzito, Sabrina Y.; Cortés, José M.; Rapalini, Augusto E.; Terrizzano, Carla M.

2013-07-01

276

From ramp to platform: building a 3D model of depositional geometries and facies architectures in transitional carbonates in the Miocene, northern Sardinia  

Microsoft Academic Search

The depositional geometry and facies distribution of an Early Miocene (Burdigalian) carbonate system in the Perfugas Basin\\u000a (NW Sardinia) comprise a well-exposed example of a transition from a ramp to a steep-flanked platform. The carbonate succession\\u000a (Sedini Limestone Unit) is composed of two depositional sequences separated by a major erosional unconformity. The lower (sequence\\u000a 1) records a ramp dominated by

Sara Tomás; M. Zitzmann; M. Homann; M. Rumpf; F. Amour; M. Benisek; G. Marcano; M. Mutti; C. Betzler

2010-01-01

277

3-D Numerical Simulation and Analysis of Complex Fiber Geometry RaFC Materials with High Volume Fraction and High Aspect Ratio based on ABAQUS PYTHON  

NASA Astrophysics Data System (ADS)

Organic and inorganic fiber reinforced composites with innumerable fiber orientation distributions and fiber geometries are abundantly available in several natural and synthetic structures. Inorganic glass fiber composites have been introduced to numerous applications due to their economical fabrication and tailored structural properties. Numerical characterization of such composite material systems is necessitated due to their intrinsic statistical nature, which renders extensive experimentation prohibitively time consuming and costly. To predict various mechanical behavior and characterizations of Uni-Directional Fiber Composites (UDFC) and Random Fiber Composites (RaFC), we numerically developed Representative Volume Elements (RVE) with high accuracy and efficiency and with complex fiber geometric representations encountered in uni-directional and random fiber networks. In this thesis, the numerical simulations of unidirectional RaFC fiber strand RVE models (VF>70%) are first presented by programming in ABAQUS PYTHON. Secondly, when the cross sectional aspect ratios (AR) of the second phase fiber inclusions are not necessarily one, various types of RVE models with different cross sectional shape fibers are simulated and discussed. A modified random sequential absorption algorithm is applied to enhance the volume fraction number (VF) of the RVE, which the mechanical properties represents the composite material. Thirdly, based on a Spatial Segment Shortest Distance (SSSD) algorithm, a 3-Dimentional RaFC material RVE model is simulated in ABAQUS PYTHON with randomly oriented and distributed straight fibers of high fiber aspect ratio (AR=100:1) and volume fraction (VF=31.8%). Fourthly, the piecewise multi-segments fiber geometry is obtained in MATLAB environment by a modified SSSD algorithm. Finally, numerical methods including the polynomial curve fitting and piecewise quadratic and cubic B-spline interpolation are applied to optimize the RaFC fiber geometries. Based on the multi-segments fiber geometries and aforementioned techniques, smooth curved fiber geometries depicted by cubic B-spline polynomial interpolation are obtained and different types of RaFC RVEs with high fiber filament aspect ratio (AR>3000:1) and high RVE volume fraction (VF>40.29%) are simulated by ABAQUS scripting language PYTHON programming.

Jin, BoCheng

278

Differential Geometry of Fault Surfaces and Glacial Beds: Associated Deformation Patterns  

Microsoft Academic Search

We measure glacial sliding surfaces and the striations on them and argue that these surfaces at the base of hard-bedded mountain glaciers can be compared to geologic fault surfaces albeit the obvious rheological differences. The reorientation of glacial striations around topographic anomalies provides quantifiable information about the otherwise inaccessible conditions. We use a ground-based LiDAR to measure the first high-precision

J. Kaven; E. Brodsky; N. van der Elst; A. Sagy; D. D. Pollard

2007-01-01

279

Age-related changes in bone density, geometry and biomechanical properties of the proximal femur: CT-based 3D hip structure analysis in normal postmenopausal women.  

PubMed

The geometry as well as bone mineral density (BMD) of the proximal femur contributes to fracture risk. How and the extent to which they change due to natural aging is not fully understood. We assessed BMD and geometry in the femoral neck and shaft separately, in 59 normal Japanese postmenopausal women aged 54-84 years, using clinical computed tomography (CT) and commercially available software, at baseline and 2-year follow-up. This system detected significant reductions over the 2-year interval in total BMD (%change/year = -0.900 ± 0.257, p < 0.0005), cortical cross-sectional area (CSA) (-0.800 ± 0.423%/year, p < 0.05) and cortical thickness (-1.120 ± 0.453%/year, p < 0.01) in the femoral neck. In the femoral shaft, cortical BMD decreased significantly (-0.642 ± 0.188%/year, p < 0.005). Regarding biomechanical parameters in the femoral neck, the cross-sectional moment of inertia (CSMI) and section modulus (SM) decreased (-1.38 ± 3.65%/year, p < 0.01 and -1.37 ± 2.96%/year, p < 0.005) and the buckling ratio (BR) increased significantly (1.48 ± 4.81%/year, p < 0.05), whereas no changes were found in the femoral shaft. The distinct patterns of age-related changes in the geometry and biomechanical properties in the femoral neck and shaft suggest that improved geometric measures are possible with the current non-invasive method using clinical CT. PMID:21087686

Ito, Masako; Nakata, Tomoko; Nishida, Akifumi; Uetani, Masataka

2011-03-01

280

An application of enhanced 3D-CAD methods with integrated geometry creation algorithms for PVC-seams in automotive body in white design  

NASA Astrophysics Data System (ADS)

State of the art automotive development processes are based on virtual product models, which include a digital representation of complete vehicle geometry and structures. Increasing computation performance and continuously growing demands on virtual development processes lead to the application of precise product representation within common CAD software packages. A specific challenge represents the creation of PVC-seams, which are used for corrosion protection of sheet metal components in automotive body in white design. Besides the high requirements of accurate geometric modeling in digital representation, modern development processes call for an increasing level of design automation. To fit both, the present approach introduces a method for an automatic generation of PVC-seams using the functionalities of commercial CAD software. [Figure not available: see fulltext.

Frener, Gernot; Thum, Katharina; Hirz, Mario; Harrich, Alexander

2012-06-01

281

3-D sediment-basement tomography of the Northern Marmara trough by a dense OBS network at the nodes of a grid of controlled source profiles along the North Anatolian fault  

NASA Astrophysics Data System (ADS)

A 3-D tomographic inversion of first arrival times of shot profiles recorded by a dense 2-D OBS network provides an unprecedented constraint on the P-wave velocities heterogeneity of the upper-crustal part of the North Marmara Trough (NMT), over a region of 180 km long by 50 km wide. One of the specific aims of this controlled source tomography is to provide a 3-D initial model for the local earthquake tomography (LET). Hence, in an original way, the controlled source inversion has been performed by using a code dedicated to LET. After several tests to check the results trade-off with the inversion parameters, we build up a 3-D a priori velocity model, in which the sea-bottom topography, the acoustic and the crystalline basements and the Moho interfaces have been considered. The reliability of the obtained features has been checked by checkerboard tests and also by their comparison with the deep-penetration multichannel seismic profiles, and with the wide-angle reflection and refraction modelled profiles. This study provides the first 3-D view of the basement topography along the active North Anatolian fault beneath the Marmara Sea, even beneath the deepest part of three sedimentary basins of NMT. Clear basement depressions reaching down 6 km depth below the sea level (bsl) have been found beneath these basins. The North Imrali Basin located on the southern continental shelf is observed with a similar sedimentary thickness as its northern neighbours. Between Central and Çinarcik basins, the Central High rises up to 3 km depth below (bsl). Its crest position is offset by 10 km northwestward relatively to the bathymetric crest. On the contrary, Tekirda? and Central basins appear linked, forming a 60-km-long basement depression. Beneath the bathymetric relief of Western High low velocities are observed down to 6 km depth (bsl) and no basement high have been found. The obtained 3-D Vp heterogeneity model allows the consideration of the 3-D supracrustal heterogeneity into the future earthquake relocations in this region. The topographic map of the pre-kinematic basement offers the possibility to take into account the locking depth variations in future geohazard estimations by geomechanical modelling in this region.

Bayrakci, G.; Laigle, M.; Bécel, A.; Hirn, A.; Taymaz, T.; Yolsal-Çevikbilen, S.; Seismarmara Team

2013-09-01

282

Oceanic transform earthquakes with unusual mechanisms or locations - Relation to fault geometry and state of stress in the adjacent lithosphere  

NASA Technical Reports Server (NTRS)

Results are presented of a search for transform earthquakes departing from the pattern whereby they occur on the principal transform displacement zone (PTDZ) and have strike-slip mechanisms consistent with transform-parallel motion. The search was conducted on the basis of source mechanisms and locations taken from the Harvard centroid moment tensor catalog and the bulletin of the International Seismological Center. The source mechanisms and centroid depths of 10 such earthquakes on the St. Paul's, Marathon, Owen, Heezen, Tharp, Menard, and Rivera transforms are determined from inversions of long-period body waveforms. Much of the anomalous earthquake activity on oceanic transforms is associated with complexities in the geometry of the PTDZ or the presence of large structural features that may influence slip on the fault.

Wolfe, Cecily J.; Bergman, Eric A.; Solomon, Sean C.

1993-01-01

283

Direct Measurements of Dust Attenuation in z ~ 1.5 Star-forming Galaxies from 3D-HST: Implications for Dust Geometry and Star Formation Rates  

NASA Astrophysics Data System (ADS)

The nature of dust in distant galaxies is not well understood, and until recently few direct dust measurements have been possible. We investigate dust in distant star-forming galaxies using near-infrared grism spectra of the 3D-HST survey combined with archival multi-wavelength photometry. These data allow us to make a direct comparison between dust around star-forming regions (A V, H II ) and the integrated dust content (A V, star). We select a sample of 163 galaxies between 1.36 <= z <= 1.5 with H? signal-to-noise ratio >=5 and measure Balmer decrements from stacked spectra to calculate A V, H II . First, we stack spectra in bins of A V, star, and find that A V, H II = 1.86 A V, star, with a significance of ? = 1.7. Our result is consistent with the two-component dust model, in which galaxies contain both diffuse and stellar birth cloud dust. Next, we stack spectra in bins of specific star formation rate (log SSFR), star formation rate (log SFR), and stellar mass (log M *). We find that on average A V, H II increases with SFR and mass, but decreases with increasing SSFR. Interestingly, the data hint that the amount of extra attenuation decreases with increasing SSFR. This trend is expected from the two-component model, as the extra attenuation will increase once older stars outside the star-forming regions become more dominant in the galaxy spectrum. Finally, using Balmer decrements we derive dust-corrected H? SFRs, and find that stellar population modeling produces incorrect SFRs if rapidly declining star formation histories are included in the explored parameter space.

Price, Sedona H.; Kriek, Mariska; Brammer, Gabriel B.; Conroy, Charlie; Förster Schreiber, Natascha M.; Franx, Marijn; Fumagalli, Mattia; Lundgren, Britt; Momcheva, Ivelina; Nelson, Erica J.; Skelton, Rosalind E.; van Dokkum, Pieter G.; Whitaker, Katherine E.; Wuyts, Stijn

2014-06-01

284

Neotectonic reactivation of shear zones and implications for faulting style and geometry in the continental margin of NE Brazil  

NASA Astrophysics Data System (ADS)

The eastern continental margin of South America comprises a series of rift basins developed during the breakup of Pangea in the Jurassic-Cretaceous. We integrated high resolution aeromagnetic, structural and stratigraphic data in order to evaluate the role of reactivation of ductile, Neoproterozoic shear zones in the deposition and deformation of post-rift sedimentary deposits in one of these basins, the Paraíba Basin in northeastern Brazil. This basin corresponds to the last part of the South American continent to be separated from Africa during the Pangea breakup. Sediment deposition in this basin occurred in the Albian-Maastrichtian, Eocene-Miocene, and in the late Quaternary. However, our investigation concentrates on the Miocene-Quaternary, which we consider the neotectonic period because it encompasses the last stress field. This consisted of an E-W-oriented compression and a N-S-oriented extension. The basement of the basin forms a slightly seaward-tilted ramp capped by a late Cretaceous to Quaternary sedimentary cover ~ 100-400 m thick. Aeromagnetic lineaments mark the major steeply-dipping, ductile E-W- to NE-striking shear zones in this basement. The ductile shear zones mainly reactivated as strike-slip, normal and oblique-slip faults, resulting in a series of Miocene-Quaternary depocenters controlled by NE-, E-W-, and a few NW-striking faults. Faulting produced subsidence and uplift that are largely responsible for the present-day morphology of the valleys and tablelands in this margin. We conclude that Precambrian shear zone reactivation controlled geometry and orientation, as well as deformation of sedimentary deposits, until the Neogene-Quaternary.

Bezerra, F. H. R.; Rossetti, D. F.; Oliveira, R. G.; Medeiros, W. E.; Neves, B. B. Brito; Balsamo, F.; Nogueira, F. C. C.; Dantas, E. L.; Andrades Filho, C.; Góes, A. M.

2014-02-01

285

Strong Ground Motion Simulation of the 1999 Chi-Chi, Taiwan, Earthquake from a Realistic 3D Source and Crustal Structure  

NASA Astrophysics Data System (ADS)

The strong ground motion records during the 1999 Chi-Chi, Taiwan, earthquake (Mw=7.6) show various characteristics at different sites in Taiwan. The goal of our study is to make a realistic 3D forward simulation of the strong-motion field based upon the kinetic source model obtained from an inversion study with identical 3D path effects. Considering complex fault geometry and Green's functions in full 3D scale, we invert the spatial/temporal slip distribution of the 1999 Chi-Chi earthquake using the best available and most densely populated strong motion waveform data. We perform the inversion by developed a parallel non-negative least squares (Parallel NNLS) program under a parallel environment utilizing multiple-time window to manage the large data volume and source parameters. Inversion results indicate that most slip occurred at the shallower portion of the fault above the decollement. Two major asperities are found, one in the middle of the fault, and another one at the northern portion of the fault near the bend in the fault trace. This 3D source model is then applied to the 3D wavefield forward simulation. Comparisons between the simulation results and observed waveforms from dense island-wide strong motion stations demonstrate that the fault geometry, lateral velocity variation and complex source rupture process greatly influence the distribution of strong ground shaking. The simulation has reproduced the heavy damage area that is mainly concentrated in the hanging wall, especially close to the surface break of the Chelungpu fault. The source directivity effect is also reproduced and shows serious shaking along the northward rupture direction. This comprehensive study emphasizes the importance of realistic fault geometry, 3D Green's functions, and parallel inversion technique in correctly accounting for both the detailed source rupture process and its relationship with the strong ground motion of this intense earthquake.

Lee, S.; Ma, K.; Chen, H.

2006-12-01

286

Elastic anisotropy and pore space geometry of schlieren granite: direct 3-D measurements at high confining pressure combined with microfabric analysis  

NASA Astrophysics Data System (ADS)

Pore space geometry of granitic rocks and its evolution with depth are key factors in large-scale seismics or in projects of enhanced geothermal systems or of deep hazardous waste repositories. In this study, we studied macroscopically anisotropic schlieren-bearing granite by experimental P-wave velocity (VP) measurements on spherical sample in 132 directions at seven different confining pressures in the range 0.1-400 MPa. In order to discriminate the phenomena affecting the rock elastic properties we analysed the orientation of microcracks and of grain boundaries and we measured the anisotropy of magnetic susceptibility of the rock. Three sets of microcracks were defined, with two of them linked to the massif exfoliation process and one to cooling contraction of the massif. During pressurization the measured mean VP and VP anisotropy degree at ambient pressure and at highest confinement (400 MPa) yielded 3.3 km s-1 and 24 per cent, and 6.2 km s-1 and 3 per cent, respectively. The associated VP anisotropy pattern was transversely isotropic and governed by the schlieren, with a minimum VP direction perpendicular to them and a girdle of high VP directions parallel to them. The highest change in VP was observed between 0.1 and 10 MPa, suggesting a significant closure of porosity below depths of 500 m. Change of the VP anisotropy pattern to orthorhombic together with increase of mean VP and VP anisotropy degree during depressurization was attributed to inelastic response of one of the sets of microcracks to the loading-unloading cycle.

Stan?k, Martin; Géraud, Yves; Lexa, Ondrej; Špa?ek, Petr; Ulrich, Stanislav; Diraison, Marc

2013-07-01

287

Quantitative Process of CAOB Orogeny: Insights into the Geometry and Kinematic Evolution of the Central Segment of Wu'erhe-Xiazijie Fault at the Northwestern Margin of Junggar Basin, China  

NASA Astrophysics Data System (ADS)

How do the Central Asia Orogenic Belts (CAOB) accrete or propagate since the Carboniferous Period is a key issue to understand its orogenic style and evolution processes. To make use of the new acquired seismic data, 2-D and 3-D, drilled cores and logging data, and surface geology at the Wu'erhe-Xiazijie thrust zone (WXTZ) at the northwestern margin of Junggar Basin, the paper studies the geometry and kinematics of the central segment of WXTZ. At the end of Carboniferous, it formed a fault-bend fold in the Carboniferous with the thrust fault (F1) soled into the intra-Carboniferous detachment zone and stepped-up to the surface and subjected to erosion, and thus with the very lowest Permian Jiamuhe Formation (P1j) unconformablly overlain it. The slip and horizontal shortening of F1 are 2.69km and 2.66km respectively. The second phase of thrusting was in the depositional stage of Early Permian Fengcheng Formation (P1f). By utilizing the old lower flat (F1) and a new upper detachment (F2) in the top Carboniferous it formed a tectonic wedge with a back-thrust fault developed in the overlying strata. The slip and horizontal shortening of the wedge are 9.93km and 9.43km respectively. Then it subsided and filled with thick-sediments till the earliest Triassic Period. The third phase of thrusting formed a meso-scale fault-bend fold in the Permian with the F2 as the lower detachment and the upper flat (F3) located at the base of Fengcheng Formation (P1f). The slip and horizontal shortening of the fault (F2 or F3) are the same as 4.48km. The fourth phase of thrusting took place at the latest Triassic, the fault (F4) cutoff F2 downwards and propagated upward into the upper Permian and formed a fault-propagation fold in the Triassic strata, with the fault-slip and horizontal shortening of 4.67km and 4.07km respectively. The fault-propagation fold is so-called Fengcheng anticline and a giant oil field nowadays. Besides thrusting of F4, the thrust faults, Wulanlinge( F5) and Da'erbut (F6) thrust also into the basin in a backward sequence at this time of period. Since Jurassic, it evolved into a quiescent period with the Jurassic, Cretaceous, and Paleogene strata upwardly onlapping the thrust zone. However, the Da'erbut Fault (F6) reactivated during the Late Neogene to the Quaternary. It showed a composite character of sinistral strike-slipping and reverse-faulting, which modified the structure of WXTZ. WXTZ shows episodic thrusting during Carboniferous to Triassic and exhibits a breaking-backward style with the fault-slip and horizontal shortening more than 21.74km and 20.64km respectively.

He, Dengfa; Wu, Xiaozhi; ma, Delong

2014-05-01

288

The May 10, 1997 Ardekul (Zirkuh) earthquake in Iran: Crustal deformation constrained by Interferometric Synthetic Aperture Radar and inversions for fault slip, geometry, and elastic parameters.  

NASA Astrophysics Data System (ADS)

The tectonic style of northeastern Iran is dominated by N-S right lateral and E-W left lateral faults which partially accommodate the convergence between Arabia and Eurasia. The Mw 7.2 Ardekul (Zirkuh) earthquake of May 10, 1997, occurred in eastern Iran near the Afghanistan border. We produce a map of the co-seismic deformation using Interferometric Synthetic Aperture Radar (InSAR) data from one ascending and two descending orbital tracks. The different line of sight components provided by the different tracks enable us to constrain two components of deformation over many portions of the coseismic displacement field. We invert this data for a model of the fault geometry and for the slip distribution on the fault plane. The top of the fault is constrained by the location of surface rupture. We use a constrained least squares inversion scheme combined with a grid search to describe the complete parameter space associated with this earthquake, including variations in fault geometry, multiple fault segments, and depth dependent elastic parameters. Our inversion results agree with the surface offsets of up to 2 m measured in the field by Berberian et al. (1999).

Lohman, R. B.; Simons, M.

2001-12-01

289

3-D seismic improves structural mapping of a gas storage reservoir (Paris basin)  

Microsoft Academic Search

In the Paris basin, anticlinal structures with closure of no more than 80 m and surface area of a few km[sup 2] are used for underground gas storage. At Soings-en-Sologne, a three-dimensional (3-D) survey (13 km[sup 2]) was carried out over such a structure to establish its exact geometry and to detail its fault network. Various reflectors were picked automatically

F. Huguet; C. Pinson

1993-01-01

290

Future earthquake source faults on deep sea-floor around the Boso triple plate junction revealed by tectonic geomorphology using 3D images produced from 150 meter grid DEM  

NASA Astrophysics Data System (ADS)

Boso triple junction, which is the only example of a triple trench junction on earth, is located off the southeast of Boso peninsula, where the Izu-Bonin trench meets with the Japan trench and the Sagami trench. Boso submarine canyon, which is extended to Katsuuma basin about 7000m deep, forms an incised meander along the north side of Sagami trough. Taito spur separate Katsuuma basin from Bando abyssal basin about 9000m deep, where Japan trench meet with Isu-Bonin trench. In this paper, we present detailed stereo-paired topographic images produced from 0.002 degree (about 150m) DBEM (Digital Bathymetry Model), which processed from the depth sounding data obtained by Japan Coast Guard and JAMSTEC around Boso triple junction. It enables us to observe submarine geomorphology easily and precisely. We identified submarine active faults and other tectonic features related to subduction by using the similar standard for air-photo interpretation of inland active faults. We made more precise submarine active tectonic geomorphological map around Boso triple junction than that by previous workers. Numerous distinct faults on the so-called outer rise associated with subduction of Pacific plate are regarded as normal faulting as widely accepted. While the normal faults on the outer rise are parallel to the trench in the southern part of the Japan trench and the northern part of the Izu-Bonin trench, these normal faults around the east of the triple junction with NNW-SSE extend slightly oblique to the trench. The western margin of Bando abyssal basin is bounded by the thrust faults, which form east-facing 200-500m-high convex scarps associated with raised basin floor to the west of the scarp. These faults also deform Mogi submarine fan surface and uplift to the west along the extension of the scarp. The antecedent valley is extended for about 10km across Taito spur that is an active anticlinal ridge about 1000m high. Katsuura basin is surrounded by terraced former basin floor that is tilted to the west, indicating up-growing of Taito spur. Northeastern part of Izu bar on Philippine Sea plate is characterized by rather smooth extensive convex slope between 1500m-7500m for over 200km long along the trench. On the lower part of the slope below 6000m, several gullies such as Mikura canyon and Kita-Hachijo canyon dissecting the slope forms rapids, probably due to continuous up-warping by subsurface thrusting dipping to the west under the slope. It is noteworthy that we can identify prominent active tectonic features on even very deep sea-floor along the plate boundaries, by using 3D images produced from 150 meter grid DEM.

Goto, H.; Nakata, T.; Watanabe, M.; Suzuki, Y.; Izumi, N.; Nishizawa, A.; Horiuchi, D.; Kido, Y. N.

2013-12-01

291

Unassisted 3D camera calibration  

NASA Astrophysics Data System (ADS)

With the rapid growth of 3D technology, 3D image capture has become a critical part of the 3D feature set on mobile phones. 3D image quality is affected by the scene geometry as well as on-the-device processing. An automatic 3D system usually assumes known camera poses accomplished by factory calibration using a special chart. In real life settings, pose parameters estimated by factory calibration can be negatively impacted by movements of the lens barrel due to shaking, focusing, or camera drop. If any of these factors displaces the optical axes of either or both cameras, vertical disparity might exceed the maximum tolerable margin and the 3D user may experience eye strain or headaches. To make 3D capture more practical, one needs to consider unassisted (on arbitrary scenes) calibration. In this paper, we propose an algorithm that relies on detection and matching of keypoints between left and right images. Frames containing erroneous matches, along with frames with insufficiently rich keypoint constellations, are detected and discarded. Roll, pitch yaw , and scale differences between left and right frames are then estimated. The algorithm performance is evaluated in terms of the remaining vertical disparity as compared to the maximum tolerable vertical disparity.

Atanassov, Kalin; Ramachandra, Vikas; Nash, James; Goma, Sergio R.

2012-02-01

292

3D input for 3D worlds  

Microsoft Academic Search

Virtual Worlds present a 3D space to the user. However, input devices are typically 2D. This unnatural mapping reduces the engagement of the experience. We are exploring using Wii controllers to provide 3D gesture-based input to the 3D virtual world, Second Life. By evaluating its usability, we found that gesture-based interfaces are appealing and natural for hand gestures such as

Sreeram Sreedharan; Edmund S. Zurita; Beryl Plimmer

2007-01-01

293

Toward DRM for 3D geometry data  

NASA Astrophysics Data System (ADS)

Computationally efficient encryption techniques for polygonal mesh data are proposed which exploit the prioritization of data in progressive meshes. Significant reduction of computational demand can be achieved as compared to full encryption, but it turns out that different techniques are required to support both privacy-focussed applications and try-and-buy scenarios.

Gschwandtner, Michael; Uhl, Andreas

2008-03-01

294

3D analysis of deformation bands in unconsolidated Pleistocene sediments  

NASA Astrophysics Data System (ADS)

Deformation bands are planar structural elements that occur in porous sandstones, even in the unconsolidated state (e.g. Aydin, 1978, Fossen et al., 2007). Whereas faults are discrete surfaces, deformation bands are much thicker, tabular zones of continuous displacement (Draganits et al. 2005). They have attracted much attention in the past because of their low permeabilities and their potential impact on fluid flow in sedimentary basins (e.g. Fossen & Bale, 2007). We present an outcrop-based study on the 3D geometry and strain of deformation band faults, which developed in Pleistocene unconsolidated sands in northern Germany. We digitally photographed a 150 × 150 cm square, near-vertical outcrop wall in a quarry, against an orthogonal scale. Then 15 cm of sand was scraped away and the procedure repeated. A total of ten sections were procured. The photographs were interpreted for upper and lower boundaries of the deformation band faults and distinctive stratigraphic horizons. The sections were then imported into Move2009.1 (Midland Valley Exploration Ltd, 2009) with the correct orientation and scale. Using the Move2009.1 software, we analysed the thickness of the deformation band faults, along-strike displacement of beds along the faults, and the total extension caused by faulting. The three-dimensional model is cut by a set of nine major deformation band faults, all with a normal sense of displacement; one set of six faults strike SE-NW, dipping NE by ca. 50o, the other set of three faults strike NNE-SSW, dipping WSW by ca. 45o. The former cross-cut the latter, thus their age relationship is shown. In the dip direction the faults are straight, but slightly arcuate in their strike direction. We identified seven distinct stratigraphic horizons, from which we were able to analyse along-strike displacement and total extension due to faulting. The three dimensional model shows that thickness of the deformation band faults varies elliptically and ranges from zero to 4.5 cm. Analysis of along-strike fault displacement proves that fault thickness is inversely proportional to fault displacement. We calculated horizontal extension along three sections, perpendicular to the strike of the faults. Because fault displacement varies so much along-strike, extension ranges from 30 to 60%. Clearly the deformation is unevenly distributed on this scale. Nevertheless, these are very high amounts of deformation and this has wide implications when upscaled to the whole outcrop or locality. Aydin, A., 1978, Small faults formed a deformation bands in sandstone: Pure and Applied Geophysics 116, 913-930. Draganits, E., Grasemann, B. & Hager, C., 2005, Conjugate deformation band faults in the Lower Devonian Muth Formation (Tethyan Zone, NW India): evidence for pre-Himalayan deformation structures. Geological Magazine 142, 765-781. Fossen, H. & Bale, A., 2007, Deformation bands and their influence on fluid flow: Association of American Petroleum Geologists Bulletin 91, 1685-1700. Fossen, H., Schultz, R.A., Shipton, Z.K. & Mair, K., 2007, Deformation bands in sandstone: a review: Journal of the Geological Society, 164, 755-769. Midland Valley Exploration Ltd, 2009, Move2009.1 suite: Glasgow.

Tanner, David C.; Brandes, Christian

2010-05-01

295

Geometry of the North Anatolian fault beneath the Gulf of Izmit and extent of the 1999 seafloor rupture  

Microsoft Academic Search

High-resolution multibeam bathymetry data acquired during two recent surveys clearly highlight the trace of the North Anatolian Fault beneath Izmit Gulf. The fault follows the approximate axis of the Darica (Western) Basin and the Karamürsel (Central) Basin, and has an overall orientation consistent with Present relative plate motion documented by GPS measurements. In detail, the fault displays the en echelon

M.-H. Cormier; L. Seeber; A. Polonia; M. N. Cagatay; O. Emre; C. M. G. McHugh; G. Bortoluzzi; N. Gorur

2003-01-01

296

Europeana and 3D  

NASA Astrophysics Data System (ADS)

The current 3D hype creates a lot of interest in 3D. People go to 3D movies, but are we ready to use 3D in our homes, in our offices, in our communication? Are we ready to deliver real 3D to a general public and use interactive 3D in a meaningful way to enjoy, learn, communicate? The CARARE project is realising this for the moment in the domain of monuments and archaeology, so that real 3D of archaeological sites and European monuments will be available to the general public by 2012. There are several aspects to this endeavour. First of all is the technical aspect of flawlessly delivering 3D content over all platforms and operating systems, without installing software. We have currently a working solution in PDF, but HTML5 will probably be the future. Secondly, there is still little knowledge on how to create 3D learning objects, 3D tourist information or 3D scholarly communication. We are still in a prototype phase when it comes to integrate 3D objects in physical or virtual museums. Nevertheless, Europeana has a tremendous potential as a multi-facetted virtual museum. Finally, 3D has a large potential to act as a hub of information, linking to related 2D imagery, texts, video, sound. We describe how to create such rich, explorable 3D objects that can be used intuitively by the generic Europeana user and what metadata is needed to support the semantic linking.

Pletinckx, D.

2011-09-01

297

Stratigraphic and structural interpretation with 3-D seismic coherence  

Microsoft Academic Search

3-D seismic discontinuity is useful for identifying faults, stratigraphic features and the relationship between them. This paper covers the application of coherence technology to three basins; the Gulf of Mexico, the North Sea, and the Ardmore Basin of Oklahoma. In the Gulf of Mexico, 3-D coherence data may be used to simultaneously view faults and stratigraphic features and therefore see

M. Bahorich; J. Lopez; N. Haskell; S. Nissen; A. Poole

1996-01-01

298

3D ladar ATR based on recognition by parts  

Microsoft Academic Search

LADAR imaging is unique in its potential to accurately measure the 3D surface geometry of targets. We exploit this 3D geometry to perform automatic target recognition on targets in the domain of military and civilian ground vehicles. Here we present a robust model based 3D LADAR ATR system which efficiently searches through target hypothesis space by reasoning hierarchically from vehicle

Erik Sobel; Joel Douglas; Gil Ettinger

2003-01-01

299

Algorithm for 3D Point Cloud Denoising  

Microsoft Academic Search

The raw data of point cloud produced by 3D scanning tools contains additive noise from various sources. This paper proposes a method for 3D unorganized point cloud denoising by making full use of the depth information of unorganized points and space analytic geometry theory, applying over-domain average method for 2D image of image denoising theory to 3D point data. The

Wenming Huang; Yuanwang Li; Peizhi Wen; Xiaojun Wu

2009-01-01

300

Stereo vision based 3D input device  

Microsoft Academic Search

This paper concerns extracting 3D motion information from a 3D input device in real time focused to enabling effective human-computer. interaction. In particular, we develop a novel algorithm for extracting 6 degrees-of-freedom motion information from a 3D input device by employing an epipolar geometry of stereo camera, color, motion, and structure information, free from requiring the aid of camera calibration

SangMin Yoon; Ig-Jae Kim; Sang Chul Ahn; H. Ko; HyoungGon Kim

2002-01-01

301

Coulomb stress accumulation along the San Andreas Fault system  

Microsoft Academic Search

Stress accumulation rates along the primary segments of the San Andreas Fault system are computed using a three-dimensional (3-D) elastic half-space model with realistic fault geometry. The model is developed in the Fourier domain by solving for the response of an elastic half-space due to a point vector body force and analytically integrating the force from a locking depth to

Bridget Smith; David Sandwell

2003-01-01

302

3D shape coding with superquadrics  

Microsoft Academic Search

We present a geometric coding method for 3D real and virtual objects transmission and visualization. We describe object surfaces with a set of superellipsoids which are structured with a constructive solid geometry (CSG) tree. An unstructured cloud of 3D points lying on the original object surface is considered as initial data. The tree is obtained using a split and merge

L. Chevalier; F. Jaillet; A. Baskurt

2001-01-01

303

Geometry, slip distribution, and kinematics of surface rupture on the Sakarya fault segment during the 17 August 1999 I??zmit, Turkey, earthquake  

USGS Publications Warehouse

The Mw 7.4 17 August 1999 I??zmit earthquake ruptured five major fault segments of the dextral North Anatolian Fault Zone. The 26-km-long, N86??W - trending Sakarya fault segment (SFS) extends from the Sapanca releasing step-over in the west to near the town of Akyaz?? in the east. The SFS emerges from Lake Sapanca as two distinct fault traces that rejoin to traverse the Adapazar?? Plain to Akyaz??. Offsets were measured across 88 cultural and natural features that cross the fault, such as roads, cornfield rows, rows of trees, walls, rails, field margins, ditches, vehicle ruts, a dike, and ground cracks. The maximum displacement observed for the I??zmit earthquake (???5.1 m) was encountered on this segment. Dextral displacement for the SFS rises from less than 1 m at Lake Sapanca to greater than 5 m near Arifiye, only 3 km away. Average slip decreases uniformly to the east from Arifiye until the fault steps left from Sagir to Kazanc?? to the N75??W, 6-km-long Akyaz?? strand, where slip drops to less than 1 m. The Akyaz?? strand passes eastward into the Akyaz?? Bend, which consists of a high-angle bend (18??-29??) between the Sakarya and Karadere fault segments, a 6-km gap in surface rupture, and high aftershock energy release. Complex structural geometries exist between the I??zmit, Du??zce, and 1967 Mudurnu fault segments that have arrested surface ruptures on timescales ranging from 30 sec to 88 days to 32 yr. The largest of these step-overs may have acted as a rupture segmentation boundary in previous earthquake cycles.

Langridge, R. M.; Stenner, H. D.; Fumal, T. E.; Christofferson, S. A.; Rockwell, T. K.; Hartleb, R. D.; Bachhuber, J.; Barka, A. A.

2002-01-01

304

Roten Daniel Olsen Keb. Beckmann J-C. Cruz-Atencio VCM. magistrate Harold 2011 3D simulations Mw7 earthquakes Wasatch fault Utah Part along-period (01 Hz) ground motion: Bulletin Seismological Society America v. 101 p. 2 0452 063.  

EPA Pesticide Factsheets

Did you mean Roten Daniel Olsen Keb. Beckmann J-C. Cruz-Atencio VCM. magistrate Harold 2011 3D simulations Mw7 earthquakes Wasatch fault Utah Part along-period (01 Hz) ground motion: Bulletin Seismological Society America v. 101 p. 2 0452 063. ?

305

Crustal Deformation Analysis Using a 3D FE High-fidelity Model with a Fast Computation Method and Its Application to Inversion Analysis of Fault Slip in the 2011 Tohoku Earthquake  

NASA Astrophysics Data System (ADS)

Crustal deformation analysis is important in order to understand the interplate coupling and coseismic fault slips. To perform it more accurately, we need a high-fidelity crustal structure model. However, in spite of accumulated crustal data, models with simplified flat shapes or relatively low resolution have been used, because the computation cost using high-fidelity models with a large degree-of-freedom (DOF) could be significantly high. Especially, estimation of the interplate coupling and coseismic fault slip requires the calculation of Green's function (the response displacement due to unit fault slip). To execute this computation in a realistic time, we need to reduce the computation cost. The objectives of our research is following: (1)To develop a method to generate 3D Finite Element (FE) models which represent heterogeneous crustal layers with the complex shape of crustal structure; (2)To develop a fast FE analysis method to perform crustal deformation analysis many times using single computation node, supposing the use of a small-scale computation environment. We developed an automatic FE model generation method using background grids with high quality meshes in a large area by extending the method of (Ichimura et al, 2009). We used Finite Element Method (FEM) because it has an advantage in representing the shape. Hybrid meshes consisting of tetrahedral and voxel elements are generated; the former is used when the interface surfaces and the grids intersect so that the shape of the crust is represented well, while the latter is used in the homogeneous areas. Also, we developed a method for crustal deformation analysis due to fault slip, which solves the FEM equation Ku=f assuming that the crust is an elastic body. To compute it fast, firstly we solved the problem by CG method with a simple preconditioning, parallelizing it by OpenMP. However, this computation took a long time, so we improved the method by introducing Multigrid Method (Saam, 2003) to the preconditioner, which uses a solution obtained by a lower resolution model generated in the same area to improve the convergence of the iterative solver. Also, the preconditioner is solved in single precision. As a result, the computation time is significantly reduced. Verification for our method is done by comparing the results with the analytical solution in a half-space (Okada, 1985.) As an application example, we performed an inversion analysis of fault slip in the 2011 Tohoku earthquake using Northeast Japan models generated by both our method and a conventional method (corresponding to Okada's analytical solution.) Our model has more than 150 million DOF and 4 layers with complex shape and different material properties. As a result, a significant difference in the results by the two models was seen, indicating the importance of introducing the layer shape of crust and heterogeneity of material in the models. The total computation time for Green's function is reduced by almost 1/7 because of the improvement of the computation method. We expect that this method will be a core technique of crustal deformation analysis. Our next plan is to take the ambiguity of the shape and the material property of the crust into consideration. Also, we would like to introduce viscoelasticity to the models.

Agata, R.; Ichimura, T.; Hori, T.; Hirahara, K.; Hori, M.

2012-12-01

306

Teaching about Plate Tectonics and Faulting Using Foam Models  

NSDL National Science Digital Library

This demonstration of plate tectonic principles, plate boundary interactions, and the geometry and relative motions of faulting of geologic layers uses 3-D foam models. The models aid in visualization and understanding of plate motions and faulting because they are three-dimensional, concrete rather than abstract descriptions or diagrams, can be manipulated by the instructor and the students, and can show the motions of the plates and faults through time in addition to the three-dimensional configuration of the plates or layers. The models illustrate relatively simple motions and geologic structures, including faulting and plate boundaries, compressional motion and resulting reverse (also called thrust) faults, horizontal slip or strike-slip fault motion, slip or strike-slip fault motion, transform or strike-slip plate boundaries, and elastic rebound.

Braile, Larry

307

Java 3D  

NSDL National Science Digital Library

Java3D is a low level 3D scene-graph based graphics programming API for the java language. It does not form part of the core APIs required by the Java specification. The class libraries exist under the javax.media.j3d top level package as well as utility classes provided in javax.vecmath.

308

3D photoacoustic imaging  

Microsoft Academic Search

Our group has concentrated on development of a 3D photoacoustic imaging system for biomedical imaging research. The technology employs a sparse parallel detection scheme and specialized reconstruction software to obtain 3D optical images using a single laser pulse. With the technology we have been able to capture 3D movies of translating point targets and rotating line targets. The current limitation

Jeffrey J. L. Carson; Michael Roumeliotis; Govind Chaudhary; Robert Z. Stodilka; Mark A. Anastasio

2010-01-01

309

3-D seismology in the Arabian Gulf  

SciTech Connect

Since 1977 when Aramco and GSI (Geophysical Services International) pioneered the first 3-D seismic survey in the Arabian Gulf, under the guidance of Aramco`s Chief Geophysicist John Hoke, 3-D seismology has been effectively used to map many complex subsurface geological phenomena. By the mid-1990s extensive 3-D surveys were acquired in Abu Dhabi, Oman, Qatar and Saudi Arabia. Also in the mid-1990`s Bahrain, Kuwait and Dubai were preparing to record surveys over their fields. On the structural side 3-D has refined seismic maps, focused faults and fractures systems, as well as outlined the distribution of facies, porosity and fluid saturation. In field development, 3D has not only reduced drilling costs significantly, but has also improved the understanding of fluid behavior in the reservoir. In Oman, Petroleum Development Oman (PDO) has now acquired the first Gulf 4-D seismic survey (time-lapse 3D survey) over the Yibal Field. The 4-D survey will allow PDO to directly monitor water encroachment in the highly-faulted Cretaceous Shu`aiba reservoir. In exploration, 3-D seismology has resolved complex prospects with structural and stratigraphic complications and reduced the risk in the selection of drilling locations. The many case studies from Saudi Arabia, Oman, Qatar and the United Arab Emirates, which are reviewed in this paper, attest to the effectiveness of 3D seismology in exploration and producing, in clastics and carbonates reservoirs, and in the Mesozoic and Paleozoic.

Al-Husseini, M. [Gulf PetroLink, Manama (Bahrain); Chimblo, R. [Saudi Aramco, Dhahran (Saudi Arabia)

1995-08-01

310

Megathrust splay fault geometry and uplift history along the western margin of the subducted Yakutat Terrane, Prince William Sound, Alaska  

NASA Astrophysics Data System (ADS)

High resolution sparker and crustal-scale airgun seismic reflection data, coupled with repeat bathymetric surveys, document the fault distribution and Holocene uplift history across the western edge of the subducted Yakutat terrane, western Prince William Sound, Alaska. Vintage and modern bathymetric surveys suggest that uplift related to the 1964 earthquake was focused along a series of approximately margin-parallel faults that extend from the Alaska mainland south across Prince William Sound into the Gulf of Alaska. Bathymetric surveys indicate that the greatest uplift from the 1964 earthquake was offshore and along strike of the Patton Bay fault that ruptured on Montague Island. Additionally, we document significant uplifts from the 1964 earthquake along parallel faults both landward and seaward of the Patton Bay fault. Sparker seismic reflection data document the post-glacial deposition/tectonic history and suggest out of sequence faulting, active splay faults beneath the Alaska mainland, and active faults that span Prince William Sound and adjacent Gulf of Alaska. Crustal seismic data show these megathrust splay faults separately root into a mid-crustal decollement that defines the top of the seismogenic zone. Faults that splay upward from the decollement correlate with mid-crustal seismic velocity and/or topography changes, with the largest Holocene displacements occurring at the southern margin of the subducted Yakutat terrane. Our new observations place constraints on local tsunami and earthquake sources and suggest changing mid-crustal lithologies play a strong role in splay fault formation. Although the greatest surface ruptures from Holocene earthquakes have been focused around Montague Island, splay faults that offset the sea floor beneath Prince William Sound, the Gulf of Alaska, and the Alaska mainland may be activated during the next large earthquake.

Liberty, L. M.; Finn, S.; Peterson, A. D.; Haeussler, P. J.; Pratt, T. L.

2012-12-01

311

Shallow Subsurface Geometry of Active Thrust Faults Along the Itoigawa-Shizuoka Tectonic Line, Central Japan, Determined From Closely Spaced Gravity Survey and Fault Dislocation Model.  

NASA Astrophysics Data System (ADS)

The Itoigawa-Shizuoka Tectonic Line (ISTL) is one of the most active intraplate faults in central Japan with a slip rate as high as 6-9 mm/yr in the Late Quaternary. Although slip rate is rather uniform along the entire length of the ISTL, characteristics of Quaternary faulting change remarkably along strike. The northern portion of the ISTL is thrust with the east side upthrown (i.e., Okubo et al., 2000), whereas the southern portion is left-slip or thrust with the west side upthrown (Matsuta et al., 2000). First, we conducted closely-spaced gravity measurements along three lines across the southern portion of the ISTL: these are, from south to north, Ichinose upland, Fujimi, and Chino lines. We analyzed the gravity data using the two-dimensional Talwani's method, and determined the density structures along these three lines. In the Ichinose upland section, back tilting of 100 ka alluvial fans in the foothills suggests thrust component, whereas no evidence exists for strike slip. The density boundary between Middle Miocene rocks and Quaternary basin fill sediments lies in front of the foothills, not at the topographic range front. The boundary fault dips about 18 degrees west. Elongated pressure ridges develop along the range front in the Fujimi section. The pressure ridges are bounded on the west by left-slip faults; shallow excavations have revealed these faults nearly vertical. However, the density boundary between pre-Miocene rocks and Quaternary sediments dips about 15 degrees west, and is situated a few kilometers east of the pressure ridges, where middle Pleistocene alluvial fans have been back tilted. Thus the vertical faults bounding the pressure ridges are secondary faults formed as a result of oblique slip on the west-dipping, low-angle thrust. In the Chino section, 50 ka terrace risers have been displaced left-laterally by more than 400 meters, and hence strike slip seems dominant here. However, the density structure is essentially the same as the above two sections, although more detailed terrain corrections are needed for such a section with rugged topography. Next, we conducted try-and-error parameter calculations of the fault dislocation model in order to clarify whether the low-angle thrust fault could create observed land-surface tectonic features, such as backward tilting fan and asymmetric bulge in the Ichinose upland and the Fujimi regions. The result shows that the model of low-angle thrust fault at 200m beneath surface with short high-angle back thrust indicate good agreement with observed geomorphic features under the condition of fixed total slip amount derived from average slip rate and tephra chronology, compared to another candidate model of high angle strike-slip master fault with flower-structure type short faults. Our results indicate that the ISTL south of Suwa basin is basically a west-dipping fault, formed as one of west-dipping imbricated thrust faults due to collision of the Izu-Bonin arc against Honshu in Miocene-Pliocene time. Our results provide an example of how pre-existing structures rejuvenate under new stress fields.

Kuriyama, M.; Kumamoto, T.; Ishihara, K.; Futagami, Y.; Ikeda, Y.

2004-12-01

312

Supracrustal faults of the St. Lawrence rift system, Québec: kinematics and geometry as revealed by field mapping and marine seismic reflection data  

NASA Astrophysics Data System (ADS)

The St. Lawrence rift system from the Laurentian craton core to the offshore St. Lawrence River system is a seismically active zone in which fault reactivation is believed to occur along late Proterozoic to early Paleozoic normal faults related to the opening of the Iapetus ocean. The rift-related faults fringe the contact between the Grenvillian basement to the NW and Cambrian-Ordovician rocks of the St. Lawrence Lowlands to the SE and occur also within the Grenvillian basement. The St. Lawrence rift system trends NE-SW and represents a SE-dipping half-graben that links the NW-SE-trending Ottawa-Bonnechère and Saguenay River grabens, both interpreted as Iapetan failed arms. Coastal sections of the St. Lawrence River that expose fault rocks related to the St. Lawrence rift system have been studied between Québec city and the Saguenay River. Brittle faults marking the St. Lawrence rift system consist of NE- and NW-trending structures that show mutual crosscutting relationships. Fault rocks consist of fault breccias, cataclasites and pseudotachylytes. Field relationships suggest that the various types of fault rocks are associated with the same tectonic event. High-resolution marine seismic reflection data acquired in the St. Lawrence River estuary, between Rimouski, the Saguenay River and Forestville, identify submarine topographic relief attributed to the St. Lawrence rift system. Northeast-trending seismic reflection profiles show a basement geometry that agrees with onshore structural features. Northwest-trending seismic profiles suggest that normal faults fringing the St. Lawrence River are associated with a major topographic depression in the estuary, the Laurentian Channel trough, with up to 700 m of basement relief. A two-way travel-time to bedrock map, based on seismic data from the St. Lawrence estuary, and comparison with the onshore rift segment suggest that the Laurentian Channel trough varies from a half-graben to a graben structure from SW to NE. It is speculated that natural gas occurrences within both the onshore and offshore sequences of unconsolidated Quaternary deposits are possibly related to degassing processes of basement rocks, and that hydrocarbons were drained upward by the rift faults.

Tremblay, Alain; Long, Bernard; Massé, Manon

2003-07-01

313

Normal Fault Basin Geometries From Gravity Analyses in the La Paz - Los Cabos Region, Baja California Sur, Mexico  

NASA Astrophysics Data System (ADS)

The southern cape region of the Baja California peninsula is ruptured by an array of roughly north-striking, left-stepping active normal faults, which accommodate regional transtension. Dominant faults within this system include the Carrizal, San Juan de los Planes (SJP) (and offshore Espiritu Santo fault), La Gata, and San Jose del Cabo (SJC) faults. We conducted gravity surveys across the basins bounded by these faults to gain insight into fault slip rates and basin evolution to better understand the role of upper-crustal processes during development of an obliquely rifted plate margin. The geodetic location of each gravity observation station was measured to cm-scale accuracy with real-time kinematic GPS and the relative gravity was measured with a LaCoste and Romberg Model G gravity meter to an accuracy of 0.01 mgal. Gravity data were modeled as a 2D two-layer model with a bedrock density of 2.67 g/cm3 and a basin fill density of 2.1 or 2.2 g/cm3. The hanging wall of the east-dipping Carrizal fault hosts the La Paz basin. In the subsurface, this basin is a half-graben that is manifest as two smaller basins (few hundred meters deep) separated by a bedrock high, which likely reflects the two main east-dipping splays (Carrizal and Centenario faults). The SJP basin is a graben bound by the SJP fault on the west and the La Gata fault on the east and has a modeled maximum depth of approximately 1.5 km. This basin is marked by a series of relict normal faults dipping toward the basin center. The maximum depth to bedrock is just northwest of center, asymmetric toward the SJP fault, indicating that slip may be greater along the SJP than along the La Gata fault. It might also mark the possible location of basin inception, indicating that as the basin evolved, faulting moved outward to the presently active SJP and La Gata Faults. The SJC basin has a maximum depth of approximately 2.5 km. The favored gravity model depicts the SJC basin as resulting from slip along a series of normal faults predominantly dipping toward the basin center (east). Bedrock topography within the basin could be attributed to paleotopography; however, with up to 1 km of relief, the interpreted faults seem more likely. The SJC basin has the greatest depth to bedrock, signifying that it accommodates a greater slip rate than the other faults within this system or that it accommodates equal slip but was the first to initiate. The adjacent topography is also the highest, indicating that the modern deformation has been stationary spatially for some time in contrast to the SJP fault, which has low footwall topography. It is likely that the SJP basin is a graben that serves to transfer strain between the larger Carrizal and Espiritu Santo faults and the SJC fault. An offshore CHIRP survey completed in late August, 2008 will provide further insight into the extent and interactions of faults within this system.

Busch, M. M.; Coyan, J. A.; Arrowsmith, J. R.; Umhoefer, P. J.; Martinez-Gutierrez, G.

2008-12-01

314

TAURUS. 3-d Finite Element Code Postprocessor  

SciTech Connect

TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D (ESTSC 139), DYNA3D (ESTSC 138), TACO3D (ESTSC 287), TOPAZ3D (ESTSC 231), and GEMINI (ESTSC 455) and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

Whirley, R.G. [Lawrence Livermore National Lab., CA (United States)

1991-05-01

315

TAURUS. 3-D Finite Element Code Postprocessor  

SciTech Connect

TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

Whirley, R.G. [Lawrence Livermore National Lab., CA (United States)

1984-05-01

316

TAURUS. 3-D Finite Element Code Postprocessor  

SciTech Connect

TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

Whirley, R.G. [Lawrence Livermore National Lab., CA (United States)

1992-03-03

317

TAURUS. 3-D Finite Element Code Postprocessor  

SciTech Connect

TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories, and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

Kennedy, T. [IBM Corporation, Waltham, MA (United States)

1992-03-03

318

TAURUS. 3-d Finite Element Code Postprocessor  

SciTech Connect

TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D (ESTSC 139), DYNA3D (ESTSC 138), TACO3D (ESTSC 287), TOPAZ3D (ESTSC 231), and GEMINI (ESTSC 455) and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

Whirley, R.G. [Lawrence Livermore National Lab., CA (United States)

1992-03-03

319

TAURUS. 3-D Finite Element Code Postprocessor  

SciTech Connect

TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

Whirley, R.G. [Lawrence Livermore National Lab., CA (United States)

1993-11-30

320

A 3-D Geodynamic Model of Strain Partitioning in Southern California  

NASA Astrophysics Data System (ADS)

In southern California, strain resulting from the relative motion between the Pacific and the North American plates is partitioned in a complex system of transcurrent, transcompressional, and transtensional faults. High-precision GPS measurements in this region have enabled kinematic modeling of the present-day strain partitioning between major faults in southern California. However, geodynamic models are needed to understand the cause of strain partitioning and to determine strain in regions where faults are blind or diffuse. We have developed a regional-scale geodynamic model of strain partitioning in southern California. This 3-D viscoelasto-plastic finite element model incorporates first-order fault geometry of the major active faults in the region. The model domain includes an elastoplastic upper crust on top of a viscoelastic lower lithospheric layer. Deformation is driven by the relative motion between the Pacific and the North American plates, imposed as a displacement boundary condition. Plastic deformation both within the fault zones and in the unfaulted surrounding crust is calculated. Our results show that the Big Bend of the San Andreas Fault, and other geometric complexity of faults in southern California, plays a major role in strain partitioning. The observed variations of strain portioning in southern California can be explained by the geometric configuration of fault systems relative to the relative plate motion, without appealing to basal traction of a flowing lower lithosphere. The model predicts concentrated plastic strain under the reverse fault systems in the Transverse Ranges and the young and diffuse faults in the Eastern California Shear Zone across the Mojave Desert, where a number damaging earthquakes occurred in the past decades.

Ye, J.; Liu, M.; Lin, F.

2012-12-01

321

3-D seismic improves structural mapping of a gas storage reservoir (Paris basin)  

SciTech Connect

In the Paris basin, anticlinal structures with closure of no more than 80 m and surface area of a few km[sup 2] are used for underground gas storage. At Soings-en-Sologne, a three-dimensional (3-D) survey (13 km[sup 2]) was carried out over such a structure to establish its exact geometry and to detail its fault network. Various reflectors were picked automatically on the migrated data: the top of the Kimmeridgian, the top of the Bathoinian and the base of the Hettangian close to the top of the reservoir. The isochron maps were converted into depth using data from 12 wells. Horizon attributes (amplitude, dip, and azimuth) were used to reconstruct the fault's pattern with much greater accuracy than that supplied by interpretation from previous two-dimensional seismic. The Triassic and the Jurassic are affected by two systems of conjugate faults (N10-N110, inherited from the Hercynian basement and N30-N120). Alternating clay and limestone are the cause of numerous structural disharmonies, particularly on both sides of the Bathonian. Ridges associated with N30-N120 faults suggest compressive movements contemporaneous with the tertiary events. The northern structure in Soings-en-Sologne thus appear to be the result of polyphased tectonics. Its closure (25 m), which is associated either with dips or faults, is described in detail by 3-D seismic, permitting more accurate forecast of the volume available for gas storage.

Huguet, F. (Gaz de France/DETN, la Plaine St. Denis (France)); Pinson, C. (CGG/Geotop, Massy (France))

1993-09-01

322

Constraining the slip distribution and fault geometry of the Mw 7.9, 3 November 2002, Denali fault earthquake with Interferometric Synthetic Aperture Radar and Global Positioning System data  

USGS Publications Warehouse

The Mw 7.9, Denali fault earthquake (DFE) is the largest continental strike-slip earthquake to occur since the development of Interferometric Synthetic Aperture Radar (InSAR). We use five interferograms, constructed using radar images from the Canadian Radarsat-1 satellite, to map the surface deformation at the western end of the fault rupture. Additional geodetic data are provided by displacements observed at 40 campaign and continuous Global Positioning System (GPS) sites. We use the data to determine the geometry of the Susitna Glacier fault, thrusting on which initiated the DFE, and to determine a slip model for the entire event that is consistent with both the InSAR and GPS data. We find there was an average of 7.3 ?? 0.4 m slip on the Susitna Glacier fault, between 1 and 9.5 km depth on a 29 km long fault that dips north at 41 ?? 0.7?? and has a surface projection close to the mapped rupture. On the Denali fault, a simple model with large slip patches finds a maximum of 8.7 ?? 0.7 m of slip between the surface and 14.3 ?? 0.2 km depth. A more complex distributed slip model finds a peak of 12.5 ?? 0.8 m in the upper 4 km, significantly higher than the observed surface slip. We estimate a geodetic moment of 670 ?? 10 ?? 10 18 N m (Mw 7.9), consistent with seismic estimates. Lack of preseismic data resulted in an absence of InSAR coverage for the eastern half of the DFE rupture. A dedicated geodetic InSAR mission could obviate coverage problems in the future.

Wright, T. J.; Lu, Z.; Wicks, C.

2004-01-01

323

3D with Kinect  

Microsoft Academic Search

We analyze Kinect as a 3D measuring device, experimentally investigate depth measurement resolution and error properties and make a quantitative comparison of Kinect accuracy with stereo reconstruction from SLR cameras and a 3D-TOF camera. We propose Kinect geometrical model and its calibration procedure providing an accurate calibration of Kinect 3D measurement and Kinect cameras. We demonstrate the functionality of Kinect

Jan Smisek; Michal Jancosek; Tomas Pajdla

2011-01-01

324

3D whiteboard: collaborative sketching with 3D-tracked smart phones  

NASA Astrophysics Data System (ADS)

We present the results of our investigation of the feasibility of a new approach for collaborative drawing in 3D, based on Android smart phones. Our approach utilizes a number of fiduciary markers, placed in the working area where they can be seen by the smart phones' cameras, in order to estimate the pose of each phone in the room. Our prototype allows two users to draw 3D objects with their smart phones by moving their phones around in 3D space. For example, 3D lines are drawn by recording the path of the phone as it is moved around in 3D space, drawing line segments on the screen along the way. Each user can see the virtual drawing space on their smart phones' displays, as if the display was a window into this space. Besides lines, our prototype application also supports 3D geometry creation, geometry transformation operations, and it shows the location of the other user's phone.

Lue, James; Schulze, Jürgen P.

2014-02-01

325

3D Imaging.  

ERIC Educational Resources Information Center

Discusses 3 D imaging as it relates to digital representations in virtual library collections. Highlights include X-ray computed tomography (X-ray CT); the National Science Foundation (NSF) Digital Library Initiatives; output peripherals; image retrieval systems, including metadata; and applications of 3 D imaging for libraries and museums. (LRW)

Hastings, S. K.

2002-01-01

326

Holographic 3-D printer  

Microsoft Academic Search

This paper proposes a holographic printer, which produces 3-D hard copies of computer processed objects. For the purpose of automatic making of 3-D hard copies of distortion free, a new method to synthesize holographic stereogram is proposed. It is is flat format and lippmann type holographic stereogram which can be printed by one optical step. The proposed hologram has not

Masahiro Yamaguchi; Nagaaki Ohyama; Toshio Honda

1990-01-01

327

3D Shapes Video  

NSDL National Science Digital Library

This upbeat music video reviews 3D shapes including the sphere, cylinder, cube, and cone. As each 3D shape is presented, examples of things we see every day that have the same shape are also shown for reinforcement. (Length: 3:18)

Kindergarten, Harry

2011-06-17

328

3D Shape Synthesis.  

National Technical Information Service (NTIS)

We present a novel approach to 3D shape synthesis of closed surfaces. A curved or polyhedral 3D object of genus zero is represented by a curvature distribution on a spherical mesh that has nearly uniform distribution with known connectivity among mesh nod...

H. Y. Shum M. Hebert K. Ikeuchi

1995-01-01

329

3D Shape Similarity.  

National Technical Information Service (NTIS)

We study the 3D shape similarity between closed surfaces. We represent a curved or polyhedral 3D object of genus zero using a mesh representation that has nearly uniform distribution with known connectivity among mesh nodes. We define a shape similarity m...

H. Y. Shum M. Hebert K. Ikeuchi

1995-01-01

330

3D virtual colonoscopy  

Microsoft Academic Search

The authors present here a method called 3D virtual colonoscopy, which is an alternative method to existing procedures of imaging the mucosal surface of the colon. Using 3D reconstruction of helical CT data and volume visualization techniques, the authors generate images of the inner surface of the colon as if the viewer's eyes were inside the colon. They also create

Lichan Hong; Arie Kaufman; Yi-Chih Wei; Ajay Viswambharan; M. Wax; Zhengrong Liangs

1995-01-01

331

Dynamic earthquake rupture modelled with an unstructured 3-D spectral element method applied to the 2011 M9 Tohoku earthquake  

NASA Astrophysics Data System (ADS)

An important goal of computational seismology is to simulate dynamic earthquake rupture and strong ground motion in realistic models that include crustal heterogeneities and complex fault geometries. To accomplish this, we incorporate dynamic rupture modelling capabilities in a spectral element solver on unstructured meshes, the 3-D open source code SPECFEM3D, and employ state-of-the-art software for the generation of unstructured meshes of hexahedral elements. These tools provide high flexibility in representing fault systems with complex geometries, including faults with branches and non-planar faults. The domain size is extended with progressive mesh coarsening to maintain an accurate resolution of the static field. Our implementation of dynamic rupture does not affect the parallel scalability of the code. We verify our implementation by comparing our results to those of two finite element codes on benchmark problems including branched faults. Finally, we present a preliminary dynamic rupture model of the 2011 Mw 9.0 Tohoku earthquake including a non-planar plate interface with heterogeneous frictional properties and initial stresses. Our simulation reproduces qualitatively the depth-dependent frequency content of the source and the large slip close to the trench observed for this earthquake.

Galvez, P.; Ampuero, J.-P.; Dalguer, L. A.; Somala, S. N.; Nissen-Meyer, T.

2014-08-01

332

3D silicon detectors  

NASA Astrophysics Data System (ADS)

Significant process in 3D detectors has taken place since Sherwood parker proposed the 3D silicon detector in 1997. The 3D detector was conceived as a method to overcome the radiation induced reduction in carrier lifetime in heavily irradiated silicon detectors via the use of advanced MEMS device fabrication techniques. This paper reviews the state of the art in 3D detectors. Work performed within the major fabrication institutes will be discussed, including modifications to the original design to reduce complexity and increase device yield. Characterization of 3D detectors up to the maximum radiation fluence expected at the high luminosity LHC operation will be presented. Results from both strip and pixel devices will be shown using characterization methods that include 90-Sr betas, focused laser and high-energy pions.

Bates, R. L.

2012-08-01

333

Triangular framework mesh generation of 3D geological structure  

NASA Astrophysics Data System (ADS)

The dynamic simulation of oil migration and accumulation is an important issue on the research of petroleum exploration, and it is a numerical simulation process with special requirement on the framework mesh of 3D geological models, which means that the mesh should have same geometry and topology relation near the intersected part of geological surfaces. In this paper, basing on the conforming Delaunay triangulation algorithm to construct mesh of individual geological stratum or fault, a novel link-Delaunay-triangulation method is presented to achieve the geometric and topological consistency in the intersected line between two surfaces, also with the analysis of termination of our algorithm. Finally, some examples of the geological framework mesh are provided and the experimental result proved that the algorithm's effectiveness in engineering practice.

Meng, Xianhai; Zhou, Kun; Li, Jigang; Yang, Qin

2013-03-01

334

Investigation Of North Anatolian Fault In The Sea Of Marmara: Fault Geometry, The Cumulative Extension, Age Modeling In Çinarcik Basin Using Multi Channel Seismic Reflection Data  

NASA Astrophysics Data System (ADS)

Marmara Sea is a limelight area for investigations due to its tectonic structure and remarkable seismic activity of North Anatolian Fault Zone (NAFZ). As NAFZ separates into 3 branches in the Marmara Sea, it has a complicated tectonic structure which gives rise to debates among researchers. Ç?narc?k Basin, which is close to Istanbul and very important for its tectonic activity is studied in this thesis. Two different multichannel seismic reflection data were used in this thesis. First data were acquired in 2008 in the frame of TAMAM (Turkish American Multichannel Project) and second data were in 2010 in the frame of TAMAM-2 (PirMarmara) onboard R/V K.Piri Reis. Also high resolution multibeam data were used which is provided by French Marine Institute IFREMER. In the scope of TAMAM project total 3000 km high resolution multi channel data were collected. 3000 km of multichannel seismic reflection profiles were collected in 2008 and 2010 using 72, 111, and 240 channels of streamer with a 6.25 m group interval. The generator-injector airgun was fired every 12.5 or 18.75 m and the resulting MCS data has 10-230 Hz frequency band. In this study, a detailed fault map of the basin is created and the fault on the southern slope of the basin which is interpreted by many researchers in many publications was investigated. And there is no evidence that such a fault exists on the southern part of the basin. With the multichannel seismic reflection data seismic stratigrafic interpretations of the basin deposits were done. The yearly cumulative north-south extension of the basin was calculated by making some calculations on the most active part of the faulting in the basin. In addition, the tilt angles of parallel tilted sediments were calculated and correlated with global sea level changes to calculate ages of the deposits in the basin. Keywords: NAFZ, multi channel seismic reflection, Ç?narc?k Basin

Atg?n, Orhan; Çifçi, Günay; Soelien, Christopher; Seeber, Leonardo; Steckler, Michael; Shillington, Donna; Kurt, Hülya; Dondurur, Derman; Okay, Seda; Gürçay, Sava?; Sar?ta?, Hakan; Mert Küçük, H.; Bar?n, Burcu

2013-04-01

335

Cn3D  

NSDL National Science Digital Library

Introduction to Cn3D for retrieving and viewing individual biomolecular structures and structure alignments. Additional topics include sequence imports and conservation, annotating a structure, saving structures and images, and advanced topics.

National Center for Biotechnology Information (NCBI)

336

3D Plasmon Ruler  

SciTech Connect

In this animation of a 3D plasmon ruler, the plasmonic assembly acts as a transducer to deliver optical information about the structural dynamics of an attached protein. (courtesy of Paul Alivisatos group)

None

2011-01-01

337

The 3-D Universe  

NSDL National Science Digital Library

This Moveable Museum article, available as a printable PDF file, looks at how astronomers use data to create 3-D models of the universe. Explore these concepts further using the recommended resources mentioned in this reading selection.

338

3D Transmographer  

NSDL National Science Digital Library

Build your own polygon and transform it in the Cartesian coordinate system. Experiment with reflections across any line, revolving around any line (which yields a 3-D image), rotations about any point, and translations in any direction.

339

Stereo techniques for 3D mapping of object surface temperatures  

Microsoft Academic Search

In this paper, we present two stereo methods to obtain 3D mappings of object surface temperatures. The first method uses a pair of trichromatic cameras to recover the 3D geometry and then maps the temperature data from a thermal camera onto the recovered surface. The second method recovers the 3D surface temperature map using a pair of thermal cameras by

Surya Prakash; Pei Yean Lean; Antonio Robles-Kelly

2007-01-01

340

TRACE 3-D documentation  

SciTech Connect

TRACE 3-D is an interactive beam-dynamics program that calculates the envelopes of a bunched beam, including linear space-charge forces, through a user-defined transport system. TRACE 3-D provides an immediate graphics display of the envelopes and the phase-space ellipses and allows nine types of beam-matching options. This report describes the beam-dynamics calculations and gives detailed instruction for using the code. Several examples are described in detail.

Crandall, K.R.

1987-08-01

341

DYNA3D  

Microsoft Academic Search

DYNA3D is an explicit, three-dimensional, finite element program for analyzing the large deformation dynamic response of inelastic solids and structures. DYNA3D contains 30 material models and 10 equations of state (EOS) to cover a wide range of material behavior. The material models implemented are: elastic, orthotropic elastic, kinematic\\/isotropic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, Blatz-Ko rubber, high explosive

1989-01-01

342

3-D Simulations  

NSDL National Science Digital Library

Three-dimensional (3-D) rendering and animation technology is not only used for entertai