Main Plate Research Articles

Active faults in Eurasia: general remarks

The database and map of active faults of Eurasia, 1:5,000,000, have been compiled according to the ILP Project II-2 “World Map of Major Active Faults.” The map shows the complicated distribution of active faulting. The major faults group in broad mobile belts between relatively weakly faulted parts of the main plates. The faults form the plates, microplates and crustal blocks boundaries there and are accompanied by deformation of the boundary areas. Using active fault data for the seismic hazard assessment (estimation of maximum possible magnitudes of earthquakes in fault zones), it is necessary to take into account the total neotectonic activity of the territory and average rate and sense of motion on the fault. Because trenching gives a possibility to determine only vertical earthquake offset on a fault, it is necessary to make corrections for strike–slip faults to estimate the earthquake magnitude by using this parameter.

면내 조합하중과 횡압을 받는 선박 이중판의 강도 평가

A study for the structural strength evaluation of doubler plates subjected to the in-plane combined load and lateral pressure load has been performed through a systematic evaluation process. In order to properly estimate the static strength of doubler plate, elasto-plastic large deflection analysis is introduced including the contact effect between main plate and doubler. The characteristics of stiffness and strength variation are discussed based on the analysis results. Also, in order to compare the doubler structure with the original strength of main plate without doubler, a simple formula for the evaluation of the equivalent flat plate thickness is derived based on the additional series analysis of fiat plate structure. Using this derived equation, the thickness change of a equivalent flat plate is analyzed according to the variation of various design parameters of doubler plate and some design guides are suggested In order to maintain the original strength of main plate without doubler reinforcement. Finally, correlation between derived equivalent plate thickness formula and the developed buckling strength formulas for intact plates by author et al. is discovered and these relations are formulated for the future development of simple strength evaluation formula of doubler plate structure.

Extension along the Australian‐Pacific transpressional transform plate boundary near Macquarie Island

The Australian‐Pacific transform plate boundary fault zone along the Macquarie and McDougall segments of the Macquarie Ridge Complex (MRC), south of New Zealand, is characterized by dominantly normal faults and pull‐apart basins, in apparent conflict with the regional transpressional tectonic setting. We propose that present‐day curvature of the transform is inherited from a preexisting divergent plate boundary and that the overall extensional kinematics shown by faults along the main plate boundary trace and exposed on Macquarie Island result from local stresses related to right‐lateral, right stepping, en echelon plate boundary faults and not to the current transpressional setting. Transpression along the Australian‐Pacific transform plate boundary has resulted in uplift along the ∼1500 km long Macquarie Ridge Complex. Macquarie Island, the only subaerial exposure of the complex, sits atop a ∼5 km high, ∼50 km wide submarine ridge of oceanic crust and lies ∼4.5 km east of the major active plate boundary fault zone. Thus Macquarie Island and the surrounding seafloor provide a unique opportunity to study an active oceanic transform fault using complementary marine geophysical and land‐based geological data. Mapping of recent faults affecting the topography of Macquarie Island shows that the island is extensively cut by high‐angle normal faults forming pull‐apart basins. Furthermore, evidence for reverse motion is rare. Using marine geophysical data, including swath bathymetry, reflectivity, and seismic reflection data, collected along the Australian‐Pacific plate boundary north and south of the island, we have defined a 5–15 km wide plate boundary zone. A series of right stepping en echelon faults, within this zone, lies along the main plate boundary trace. At the right stepping fault terminations, elongate depressions (≤10 km wide and 1.2 km deep) parallel the plate boundary, which we interpret as extensional relay zones or pull‐apart basins. We propose that transpression is partitioned into en echelon strike‐slip faults at the plate boundary and a convergent component that flexes the crust, causing the anomalous bathymetric ridge and trough morphology of the McDougall and Macquarie segments of the MRC.

Free vibration and stability analysis of stiffened sandwich plates

Description is given of the development of a B-spline finite strip method for predicting the natural frequencies of vibration and the buckling stresses of rectangular sandwich panels. Each panel comprises a flat sandwich main plate which is reinforced by a number of longitudinal compact plate stiffeners attached to the faceplates. The core of the main plate is represented as a three-dimensional solid whilst the faceplates and the stiffening plates may in general be composite laminates which are represented, in turn, as either shear-deformable plates or classically thin plates. Details are given of the development of the elastic stiffness, geometric stiffness and consistent mass matrices of the finite strip models. The nature of the structural equations and the sophisticated procedure for their solution are discussed. Both vibrational and buckling applications of the developed analysis capability are presented and these include situations in which the corresponding mode shapes are of an overall nature and, for some of the buckling problems, of a highly localised nature.

Easter microplate dynamics

We use two‐dimensional elastic finite element analysis, supplemented by strength estimates, to investigate the driving mechanism of the Easter microplate. Modeled stresses are compared with the stress indicators compiled from earthquake focal mechanisms and structural observations. The objective is to constrain the tectonic forces that govern the Easter microplate rotation and to test the microplate driving hypothesis proposed by Schouten et al. [1993]. We infer that the mantle basal drag cannot drive the microplate rotation but opposes it, and that the asthenospheric viscosity is no more than about 1 × 1018 Pa s. At most, the basal drag comprises 20% of the force resisting microplate rotation. The outward pull of the main plates can drive the rotation by shear drag applied along the northern and southern boundaries of the microplate. However, we propose an additional driving force which arises from the strong variation of the ridge resistance force along the east and west rifts, so that the main driving torques come from the pull of the major plates acting across the narrowing and slowing rifts. This requires the strength to increase substantially toward the rift tips due to thickening of the brittle lithosphere as the spreading rate slows.

The influence of structural dimensions on crack arrest

An energy balance has been used for the prediction of toughness values required to ensure arrest in double tension crack arrest tests. The analysis required calculation of the total energy that depended on the force applied to the main plate and the effective length of the structure including the test frame. Theoretical calculations indicated that the energy release rate at crack arrest was governed by both the width and the length of the structure G s =σ 1 2/E(1/ πa+a/WL) where σ 1 is the initial stress; a is the crack length; L is the effective length that, in cylinders, is the circumference; W is the width; E is the elastic modulus. Agreement was obtained between the measured and calculated values of the gross section stress at arrest derived from the above analysis. The data were explained in terms of a static analysis so that the kinetic energy did not require consideration in the calculations. The mean dynamic fracture energy per unit area, R s, derived from small impact tests was sufficiently close to G s to enable prediction of arrest crack lengths for all materials. The agreement was improved by including an estimate of the effect of the force from the secondary crack initiation jack on the elastic energy available. From the expression G s values are higher in structures with large W and/or L dimensions. A conservative approach to crack arrest would be to ensure that, for all structural dimensions, the dynamic toughness exceeds the conventional value of G for a structure of infinite size, having no finite size factor G s =σ 1 2 πa/E.

Dynamic uplift in a transpressional regime: numerical model of the subduction area of Fiordland, New Zealand

Bending of the downgoing plate in subduction zone typically leads to an offshore peripheral bulge. This leads to dynamic uplift generated by the elastic bending of the subducted slab, and is generally enough to support the topography of the bulge in a non-isostatic manner and produce a positive gravity anomaly. The Southwest region of the South Island of New Zealand, Fiordland, is characterized by high elevation and a large positive Bouguer gravity anomaly. This combination of high topography with high Bouguer gravity argues against isostatic equilibrium and suggests an additional support mechanism. Earthquakes as deep as 150 km, a deformed Benioff zone and inferences from plate reconstructions all support a tectonic model where the eastern margin of the Australian plate is subducting beneath Fiordland and is sharply bent. This bending of the Australian plate provides the needed non-isostatic support for Fiordland topography and generates the observed gravity anomaly. Although the peripheral bulge in subduction zones is generally localized offshore, the positive gravity anomaly (Bouguer and free air) in Fiordland is onshore, close to the shoreline, and generally corresponds spatially with high elevations. Here we propose a mechanism that allows the subducted sliver of slab to be decoupled from the main Australian plate and strongly bent beneath Fiordland. We test this scenario with a finite-element model. The model allows us to study the flexural response of a subducting elastic slab bent by lateral compression into a shape similar to the one inferred from seismicity. We test how different plate geometries and plate boundary forces influence the flexural dynamic support of Fiordland topography, providing important constraints on the local plate dynamics. The model results show that for a tectonically reasonable combination of plate geometries and boundary forces, the deformation of the lithosphere produces the observed topography and gravity signature. In particular we find that the bending of the subducted Australian plate can supply the needed uplift and support for the topography of Fiordland. However, a weak area west of but nearby the Fiordland shoreline, perhaps a fault or tear, is needed to decouple the subducted sliver, confine the bulge, and localize the uplift within Fiordland.

“How to obtain earthquake ground motions for engineering designs”: by Ellis L. Krinitzsky; Elsevier Engineering Geology Paper, 65:1–16

LA-ICP-MS U–Pb zircon dating reveals that the Phu Kham adakites in the Truong Son Belt were emplaced during the Late Carboniferous (ca. 306 to 304 Ma), whereas the Puthep 1 (PUT 1) adakites in the Loei Fold Belt were formed during the Middle Triassic (ca. 244 to 241 Ma). These rock formation ages are largely coeval to Re–Os molybdenite ages (Phu Kham: ca. 304 Ma; PUT 1: ca. 246 Ma), suggesting close temporal links between adakite formation and copper–gold mineralization. New geochemical results show that the Phu Kham and PUT 1 adakites are characterized by low HREE and Y contents, but elevated LREE, Sr, Sr/Y, and La/Yb values. In addition, the two adakites have relatively high 143Nd/144Nd ratios (0.512648 to 0.512719), Mg# (Phu Kham: 37–68; PUT 1: 40–65), and Cr and Ni contents. These results are best interpreted as representing slab melts that have interacted with supra-subduction zone mantle wedge during ascent. Tectonically, the Phu Kham and PUT 1 adakites were most likely formed during the initiation of subduction of the Ailaoshan–Song Ma and the Main Paleo-Tethys ocean plates respectively. Close temporal relations between the adakite formation and the copper–gold mineralization suggest strong genetic links between the two in the mainland SE Asia region.

Local Velocities Inside the Gas Phase During Counter-Current Two-Phase Flow in a Narrow Vertical Channel

New data are reported on local axial velocities inside the gas phase in a vertical rectangular channel with an 8-mm gap between its main parallel plates, during counter-current air/water flow. Such a flow is considered to simulate, though in a simplifled manner, a single flow ‘element’ of a compact condenser. Mean local velocities, velocity spectra, turbulent intensities and other statistical information have been obtained by analysing the instantaneous velocity records of the gas phase acquired in presence of the liquid film, for relatively low gas Reynolds numbers. A computational fiuid dynamics code (CFX®) was employed to obtain the velocity profiles and the values calculated are found to be in good agreement with those obtained experimentally.The data suggest that for gas Reynolds numbers in the range of 500–1300 the gas motion resembles the behaviour of turbulent flow.

Fatigue behavior of the transverse stiffener subjected to constant amplitude loading

Objectives of this study are to examine the fatigue behavior of the transverse stiffener in comparison with other previous studies. The shape of fatigue cracks depended upon the number of crack initiation sites along the weld toe. Fatigue cracks initiated at a corner had quarter-elliptical fronts. And, the crack propagated through the thickness of the main plate until the remaining ligament eventually fractured at an average net section stress nearly equal to the tensile strength. The constant amplitude fatigue limits for the specimens tested atfmin=14 N/mm2 andfmax=290 N/mm2, were respectively predicted with the mean regression line,s=0.084,m=4.097, using by the number of run outs in percent. By changing fromfmin=14 N/mm2 tofmax=290 N/mm2, the fatigue strength decreased clearly in the finite life region and so did the lower bound fatigue limit fromFrl=110 to 83 N/mm2. For the effect of the weld type, it was also found that the excellent quality of automatic welding resulted in a large root radius at the weld toe and thus significantly increased the fatigue strength of both stiffeners from category C to B'

Italiaans op mijn bord?: een onderzoek naar de receptie van de Italiaanse keuken in België aan de hand van het maaltijdpatroon

Using qualitative methods, more specifically an analysis on the content of seven different editions of a widely used cookbook in Belgium, this article investigates how Italian food got introduced in the Belgian meal pattern. Our hypothesis was that Italian food could only be introduced in Belgium if it fitted within the Belgian meal pattern. We expected much more culinary innovation, and thus more Italian food, within the less structured parts of the meal pattern than within the more structured parts of the meal pattern. This hypothesis was confirmed. Italian food was introduced especially within the introductory (starter) and round off (dessert) parts of the main meal and within the daily evening meal. The more structured parts of the meal pattern such as the main plate of the main meal and festive evening meals were less subject to culinary innovation and Italian food only recently got introduced there.

Fatigue and static behaviour of aluminium box-stiffener lap joints

The fatigue and static behaviour of aluminium box-stiffener lap joints were investigated in this study. Finite element analysis showed that stress concentration factor (SCF) at the weld toe decreased greatly as the weld leg length increased, while the location of the greatest SCF deviated from the connecting point to the middle of the flange. It is also found that the SCF at the weld root is much less than that at the weld toe. Fatigue tests showed that weld toe cracking was the main fatigue failure mode. In addition, fatigue crack initiation site changed from the connecting point to the middle point of the flange. Weld root failure was only possible when the weld leg length was less than twice the main plate thickness (6.0 mm). The test data agree with those for toe failure given by Eurocode 9.

Western Alps geological constraints on western Tethyan reconstructions

Reconstructions of the Tethyan realm have been a matter of debate for a long time. Controversies spring usually from a lack of well constrained geological data which can be interpreted in different ways, or, from a lack of constraints on the plate tectonics framework. The western Alps region tends to escape these shortcomings due to a wealth of geological data regarding for examples the rifting and spreading of the Alpine Tethys and its closure, the formation of the Alpine orogenic wedge and accompanying foreland basins, through precise datation of these many events. The larger plate tectonic framework is also well constrained through precise positioning, at least since the Jurassic, of the main plates surrounding the western Alpine Tethys domain, such as the European and African plates, but also the Iberic and Adria micro-plates and the Alboran fragments. Therefore, the Western Alps and surrounding regions represent a key-stone for the western Tethys reconstruction. A detail account of the geological evolution along a western Swiss Alps transect is presented here and confronted to the plate tectonic models derived from a larger western Tethys data base.

On the strength of interplate coupling and the rate of back arc convergence in the central Andes: An analysis of the interseismic velocity field

We interpret the interseismic crustal velocity field of the central Andes using a simple three‐plate model in which the Andean mountain belt is treated as a rigid microplate located between the Nazca and South American (SoAm) plates. We assume that the Euler vectors associated with these plates are strictly coaxial and that the surface velocity field can be decomposed into an elastic loading field (driven by locking of the main plate boundary) and a smaller contribution associated with back arc convergence. We obtain our best fit to the geodetic velocities if the main plate boundary is fully (100%) locked between depths of ∼10–50 km and ∼8.5% of Nazca‐SoAm plate convergence is achieved in the back arc (by underthrusting of the Brazilian Shield beneath the Subandean zone).

Finite element analysis of the effect of weld geometry and load condition on fatigue strength of lap joint

Many welded lap joints are subject to fluctuating loads, and fatigue failure plays a dominant role in the failure of such structures. Based on the concepts of linear elastic fracture mechanics, the effects of weld geometry, load conditions and the boundary constraints on fatigue strength of a ferrite–pearlite steel lap joint were investigated in this paper using the finite element method. Paris's power law was used to predict the fatigue life of the joints. Various weld geometry including the leg length, flank angle and the size of lack-of-penetration were considered during the calculation of fatigue strengths. The loads include tension, bending and their combinations. It was found that the existence of a root crack has no influence on the fatigue strength of the joint, under the relevant load conditions. The existence of a toe crack is also of no influence on the fatigue strength of the joint if the applied loads, e.g. DOB>0 in this paper, produce a compressive stress field at the top region of the main plate. For a lap joint with a free transverse ( Y direction in this paper) boundary constraint at the main plate, a joint with a smaller size of lack-of-penetration, a reasonably large weld leg and smaller flank angle is recommended to be used in engineering practice, in order to obtain a higher fatigue strength. For a lap joint, with transverse fixed boundary constraint at the main plate, the fatigue strength increases with a decrease of weld size but the influence of flank angle depends on the type of load carried. It was also found that the size reduction in FE model is a significant influence on the calculated fatigue strength; the use of reduced size FE model gives a much higher overestimate of fatigue strength of the joint.

Three-dimensional analysis of syncytial-type cell plates during endosperm cellularization visualized by high resolution electron tomography.

The three-dimensional architecture of syncytial-type cell plates in the endosperm of Arabidopsis has been analyzed at approximately 6-nm resolution by means of dual-axis high-voltage electron tomography of high-pressure frozen/freeze-substituted samples. Mini-phragmoplasts consisting of microtubule clusters assemble between sister and nonsister nuclei. Most Golgi-derived vesicles appear connected to these microtubules by two molecules that resemble kinesin-like motor proteins. These vesicles fuse with each other to form hourglass-shaped intermediates, which become wide (approximately 45 nm in diameter) tubules, the building blocks of wide tubular networks. New mini-phragmoplasts also are generated de novo around the margins of expanding wide tubular networks, giving rise to new foci of cell plate growth, which later become integrated into the main cell plate. Spiral-shaped rings of the dynamin-like protein ADL1A constrict but do not fission the wide tubules at irregular intervals. These rings appear to maintain the tubular geometry of the network. The wide tubular network matures into a convoluted fenestrated sheet in a process that involves increases of 45 and 130% in relative membrane surface area and volume, respectively. The proportionally larger increase in volume appears to reflect callose synthesis. Upon fusion with the parental plasma membrane, the convoluted fenestrated sheet is transformed into a planar fenestrated sheet. This transformation involves clathrin-coated vesicles that reduce the relative membrane surface area and volume by approximately 70%. A ribosome-excluding matrix encompasses the cell plate membranes from the fusion of the first vesicles until the onset of the planar fenestrated sheet formation. We postulate that this matrix contains the molecules that mediate cell plate assembly.

Three-Dimensional Analysis of Syncytial-Type Cell Plates during Endosperm Cellularization Visualized by High Resolution Electron Tomography[W

AbstractThe three-dimensional architecture of syncytial-type cell plates in the endosperm of Arabidopsis has been analyzed at ∼6-nm resolution by means of dual-axis high-voltage electron tomography of high-pressure frozen/freeze-substituted samples. Mini-phragmoplasts consisting of microtubule clusters assemble between sister and nonsister nuclei. Most Golgi-derived vesicles appear connected to these microtubules by two molecules that resemble kinesin-like motor proteins. These vesicles fuse with each other to form hourglass-shaped intermediates, which become wide (∼45 nm in diameter) tubules, the building blocks of wide tubular networks. New mini-phragmoplasts also are generated de novo around the margins of expanding wide tubular networks, giving rise to new foci of cell plate growth, which later become integrated into the main cell plate. Spiral-shaped rings of the dynamin-like protein ADL1A constrict but do not fission the wide tubules at irregular intervals. These rings appear to maintain the tubular geometry of the network. The wide tubular network matures into a convoluted fenestrated sheet in a process that involves increases of 45 and 130% in relative membrane surface area and volume, respectively. The proportionally larger increase in volume appears to reflect callose synthesis. Upon fusion with the parental plasma membrane, the convoluted fenestrated sheet is transformed into a planar fenestrated sheet. This transformation involves clathrin-coated vesicles that reduce the relative membrane surface area and volume by ∼70%. A ribosome-excluding matrix encompasses the cell plate membranes from the fusion of the first vesicles until the onset of the planar fenestrated sheet formation. We postulate that this matrix contains the molecules that mediate cell plate assembly.

Fatigue strength of fillet welded structural steels: finite elements, strain gauges and reality

This work analyses the influence of geometry, residual welding stresses and secondary bending effects on the fatigue strength of fillet welded joints made of structural steels. Joints with main plate thicknesses ranging from 10 to 100 mm subjected both to axial and to bending load with load ratios between −1 and 0.1 were considered. The experimental results were taken from the literature and then re-analysed in terms of local stress field intensity instead of nominal stress. This approach led to the definition of a new unified scatter band valid for structural steels, similar to that defined in the past for welded joints but with new characteristic parameters. The application of the scatter band to local strain fields evaluated by numerical analyses or measured by strain gauges is also discussed.

Visual observations of flooding in narrow rectangular channels

New flooding data in a vertical rectangular channel with 5 and 10 mm gap between its main parallel plates are reported. Visual observations and fast recordings are made to determine conditions associated with the onset of flooding in the channel. For the 10 mm gap channel a combination of mechanisms, i.e., levitation and upward transportation of laterally coherent or isolated waves, and local wave bridging, appear to be responsible for triggering flooding. The critical flooding velocity is curiously nearly independent of liquid flow rate above film Reynolds number approximately 500. In the 5 mm gap channel and for small Re L, flooding occurs at the liquid entrance, whereas “massive” wave bridging, occurring above the middle of the test section, is the dominant flooding mechanism for relatively higher Re L. Predictions based on small amplitude stability analysis are in good agreement with flooding data from the latter case.

The Guide Star Catalog, Version 1.2: An Astrometric Recalibration and Other Refinements

A collaboration between the Space Telescope Science Institute (STScI) and the Astronomisches Rechen-Institut has produced an astrometric re-reduction of the Guide Star Catalog (GSC) published by Lasker et al. This version, GSC 1.2, has dramatically reduced the systematic errors present in the GSC 1.1. As shown by Taff et al., the positions in the GSC 1.1 are affected by plate-based systematic distortions that are largest at the plate edges (10 in the north and 12 in the south). In addition, Morrison et al. have shown that these positions also suffer from systematic errors which are a function of magnitude and radial distance from the plate center. This effect is small for radii under 27 from the plate center, then rapidly increases, producing an average offset of the faint stars (15 mag) versus the reference stars (10 mag) of 09 at the plate edges. Since the magnitude term was similar for the two main plate collections comprising the GSC, which were taken with different telescopes, exposure times, emulsions, and filters, we believe this effect is common to fast wide-field-of-view Schmidt plates. In this paper we report on the astrometric quality of the GSC 1.2 and present the method we developed (for large plate collections) to quantify and reduce the positional errors which are dependent on location on the plate and magnitude. Instruction for obtaining the catalog may be obtained from the STScI World Wide Web site, or the user can obtain the catalog directly from CDS (Centre de Donnees astronomiques de Strasbourg). This version of the catalog has not been installed in the HST Guide Star Selection system. Therefore this version must not be used for HST observation planning.