The relationship between length and width of plutons within the crustal-scale Cobequid Shear Zone, northern Appalachians, Canada     

Ioannis K. Koukouvelas  Georgia Pe-Piper  David J. W. Piper 《International Journal of Earth Sciences》2006,95(6):963-976

The lengths and widths have been measured for 69 component bodies of composite plutons along the Cobequid Shear Zone. Plutons on major fault strands, those with mylonite zones >0.1 km wide, exhibit evidence of multiple intrusion of magma batches. Small plutons along short faults in stepover zones appear related to rapid emplacement of magma in bodies 1.5–4 km long by 0.1–2 km wide. Such small plutons show low enrichment in incompatible elements in older component bodies, but increasing amounts in younger bodies as a result of progressive magma expulsion from crystal mush during crystallization and shear-enhanced compaction in fault zones. Wider plutons generally occur along longer fault strands accommodating more strain and penetrating deeper into the crust and show enrichment in incompatible elements. The width of the mylonitic fault zone is about 15% of the width of these plutons. The length-to-width ratio of component bodies and composite plutons varies between 2 and 11. The best-fit line describing these data has a slope of 1.056, which implies scaling behavior between plutonism and tectonic processes. Scalar properties of plutonic bodies are similar to those of faults, but scalar relationships observed in component bodies do not apply to composite plutons.  相似文献   

Chaos in cuspy triaxial galaxies with a supermassive black hole: a simple toy model     

Henry E. Kandrup  Ioannis V. Sideris 《Celestial Mechanics and Dynamical Astronomy》2002,82(1):61-81

This paper summarises an investigation of chaos in a toy potential which mimics much of the behaviour observed for the more realistic triaxial generalisations of the Dehnen potentials, which have been used to model cuspy triaxial galaxies both with and without a supermassive black hole. The potential is the sum of an anisotropic harmonic oscillator potential, ${\text{V}}_{\text{0}} = \frac{1}{2}\left( {a^2 x^2 + b^2 y^2 + c^2 z^2 } \right)$ , and aspherical Plummer potential, ${\text{V}}_{\text{P}} = M_{BH} /\sqrt {r^2 + \varepsilon ^2 } $ , with $r^2 = x^2 + y^2 + z^2$ . Attention focuses on three issues related tothe properties of ensembles of chaotic orbits which impact on chaotic mixing and the possibility of constructing self-consistent equilibria:(1) What fraction of the orbits are chaotic? (2) How sensitive are the chaotic orbits, that is, how large are their largest (short time) Lyapunov exponents? (3) To what extent is the motion of chaotic orbits impeded by Arnold webs, that is, how 'sticky' are the chaotic orbits? These questions are explored as functions of the axis ratio a: b: c, black hole mass M _BH, softening length ε, and energy E with the aims of understanding how the manifestations of chaos depend onthe shape of the system and why the black hole generates chaos. The simplicity of the model makes it amenable to a perturbative analysis. That it mimics the behaviour of more complicated potentials suggests that much of this behaviour should be generic.  相似文献   

Contents Volume 82     

Henry E. Kandrup  Ioannis V. Sideris 《Celestial Mechanics and Dynamical Astronomy》2002,82(4):419-420

Volume Contents

Contents Volume 82  相似文献   

The egion fault, earthquake-related and long-term deformation, Gulf of Corinth, Greece   总被引：1，自引：0，他引：1  

Ioannis K. Koukouvelas   《Journal of Geodynamics》1998,26(2-4)

On 15 July 1995, the Egion earthquake (Ms = 6.2) occurred in the vicinity of Egion, west-central Greece. Macroseismic observations along the 12 km long E-W trending Egion fault represent short-term or earthquake-related deformation characterized by fairly straight E-W trending surface ruptures with small displacements that mimic the Egion fault geologic offsets and segmentation. Hanging wall converging slip vectors along the Egion fault are clearly related to fault motions at depth. Furthermore, peak accelerations of the built-up area of Egion amount to 0.54 g, that is double the estimated peak acceleration of the Egion coastal area, showing thus close relation between fault trace and attenuation of the ground motion.The Egion fault, with a total geological throw of 200 m and dips to the north at about 55 °, accommodating active tectonic deformation of the Egion area. Its morphotectonic expression reflects long-term deformation in competition with the 1995 earthquake related deformation. The Egion fault is controlling the geomorphic evolution of the Egion area as follows: 1) The fault is defining the evolution of fan-deltas (offshore) and the Meganitas river alluvial plain (onshore). 2) The hanging-wall's greatest subsidence is observed, at the Egion bay, at the central portion of the fault. The Egion bay is located at the central part of the fault showing a strong relationship between the long term slip-rate ratio and the recent coastal morphology. The subsidence gradient or the tectonic activity along the fault is defined by the valley-floor width to valley height index (V_f) of small rivers draining the fault scarp. The Meganitas river course is tilted, when crosses the Egion fault trace, towards the area with the highest subsidence along the fault. 3) Stream incision is more important than slope recession at areas close to the fault trace.All these observations suggest that the Egion fault, which probably hosted the last earthquake, are geomorphically controlling the evolution of a 15 km-long by 5 km-wide zone, fairly similar in dimensions to the surface length of the fault.  相似文献   

Probable evidence for periodicities in global seismic energy release     

Ioannis Liritzis  Theodoros M. Tsapanos 《Earth, Moon, and Planets》1993,60(2):93-108

A complete data set of globally distributed shallow (h , 60 Km) earthquakes have been used for first time to test the possible existence of periodicities in the seismic energy release. Only main shocks of magnitude,M 7.0 were considered, which occurred in the whole Earth during 1898–1985. These magnitudes are converted in seismic energy, which is released during the occurrence of earthquakes, through Bath's formula. The detection of such kind of periodicities is important in seismology, because these patterns may lead to the prediction of large earthquakes. Statistical techniques, such as Maximum Entropy (ME), and two Fourier approaches, the Fast Fourier Transform (FFT) and Power Spectrum (PS) of truncated subrecords of the whole time series have been applied to examine the possible existence of such periodicities in seismic energy release. Furthermore, the even-spacing technique is used to validate our results and a type-curve has been constructed for the data set.The results exhibit a network of periodicities with predominant periods at 3(±0.5), 4.5, 6.5, 8–9, 14–20, and 31–34 years. Some periods were occasionally interrupted. The latter implies that our time-series is not stationary, in that, the spectral peaks drift when the data are viewed through different time windows. The fact that the signal is weak and embedded in less accurate older data could contribute to this effect. The question of stability/validity of the apparently cyclic behaviour of the annual global seismic energy release, is one which requires further investigation.  相似文献   

Organization of Emergency Response After a Major Disaster Event in an Urban Area with the Help of an Automatic Vehicle Location and Control System   总被引：3，自引：0，他引：3  

Paraskevas Savvaidis  Konstantinos Lakakis  Ioannis Ifadis 《GPS Solutions》2002,5(4):70-79

The quick response of civil authorities after a major disaster event in an urban area is essential for the reduction of damages and impacts to human lives. One of the first critical problems to be solved at the very early stages of response is the optimum management of emergency vehicles and real time knowledge of the accessibility of the road network. In this article the concept of using a number of emergency vehicles as sensors for monitoring the traffic conditions in an urban area after a major disaster event is described. The fleet management system used for this taks is working with ral time DGPS. The system makes use of existing vehicle fleets in the urban area, rapidly collecting data and covering the whole road network. It records travel times with the help of the GPS system for every road segment driven through by each vehicle sensor, thus providing a digital time database from which traffic parameters can be also computed. It can be used for real time monitoring of traffic conditions under disaster or emergency situations where all the previously available data become invalid or unreliable. ? 2002 Wiley Periodicals, Inc.  相似文献   

Use of non-linear localization for isolating structures from earthquake-induced motions     

Alexander F. Vakakis  Anthony N. Kounadis  Ioannis G. Raftoyiannis 《地震工程与结构动力学》1999,28(1):21-36

The dynamic response due to earthquake-induced excitations of multi-storey buildings simulated by a cantilever (with attached concentrated masses) supported on a flexible foundation, is reconsidered when stiffness non-linearities are included. To this end, a suitable non-linear spring-mass device is placed between the ground and the mass of the foundation, which under certain conditions can absorb a significant amount of seismic energy over a large frequency range, thus drastically reducing the seismic response of the foundation. This is achieved by the stiffness non-linearity that gives rise to a localization phenomenon, according to which motions generated by external disturbances remain passively localized close to the point of seismic excitation instead of ‘spreading’ to the entire structure. The implications of these findings to the design of earthquake-resistant structures are discusssed. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Probing the Quiet Solar Atmosphere from the Photosphere to the Corona     

Ioannis Kontogiannis  Costis Gontikakis  Georgia Tsiropoula  Kostas Tziotziou 《Solar physics》2018,293(4):56

We investigate the morphology and temporal variability of a quiet-Sun network region in different solar layers. The emission in several extreme ultraviolet (EUV) spectral lines through both raster and slot time-series, recorded by the EUV Imaging Spectrometer (EIS) on board the Hinode spacecraft is studied along with \(\mbox{H}\upalpha\) observations and high-resolution spectropolarimetric observations of the photospheric magnetic field. The photospheric magnetic field is extrapolated up to the corona, showing a multitude of large- and small-scale structures. We show for the first time that the smallest magnetic structures at both the network and internetwork contribute significantly to the emission in EUV lines, with temperatures ranging from \(8\times 10^{4}~\mbox{K}\) to \(6\times 10^{5}~\mbox{K}\). Two components of transition region emission are present, one associated with small-scale loops that do not reach coronal temperatures, and another component that acts as an interface between coronal and chromospheric plasma. Both components are associated with persistent chromospheric structures. The temporal variability of the EUV intensity at the network region is also associated with chromospheric motions, pointing to a connection between transition region and chromospheric features. Intensity enhancements in the EUV transition region lines are preferentially produced by \(\mbox{H}\upalpha\) upflows. Examination of two individual chromospheric jets shows that their evolution is associated with intensity variations in transition region and coronal temperatures.  相似文献   

Finite element analysis of damage and failure of reinforced concrete members under earthquake loading          下载免费PDF全文

Mohammadreza Moharrami  Ioannis Koutromanos 《地震工程与结构动力学》2017,46(15):2811-2829

This paper presents a three‐dimensional analysis framework, based on the explicit finite element method, for the simulation of reinforced concrete components under cyclic static and dynamic loading. A recently developed triaxial constitutive model for concrete is combined with a material model for reinforcing steel which can account for rupture due to low‐cycle fatigue. The reinforcing bars are represented with geometrically nonlinear beam elements to account for buckling of the reinforcement. The strain penetration effect is also accounted for in the models. The modeling scheme is used in a commercial finite element program and validated with the results of experimental static and dynamic tests on reinforced concrete columns and walls. The analyses are supplemented with a parametric study to investigate the impact of several modeling assumptions on the obtained results.  相似文献   

Cost-effective analysis technique for the design of bridges against strike-slip faulting     

Athanasios Agalianos  Max Sieber  Ioannis Anastasopoulos 《地震工程与结构动力学》2020,49(11):1137-1157

The paper studies the performance of a typical overpass bridge, with continuous deck and monolithic pier-deck connections, subjected to strike-slip faulting. A three-dimensional (3D) finite element (FE) model of the entire bridge–foundation–abutment–soil system is developed, accounting for soil, structure and geometric nonlinearities. Soil behaviour is simulated with a thoroughly validated strain softening constitutive model. The concrete damaged plasticity (CDP) model is implemented for piers, accounting for the interaction between axial force N , bending moment M , shear force Q and torsion T (NMQT ); the model is validated against experimental results from the literature. The location of the fault rupture is parametrically investigated, confirming the vulnerability of indeterminate structural systems to large tectonic deformation. The deck is shown to sustain both in-plane and out-of-plane bending moments, as well as torsion; the piers are subjected to biaxial bending, shear and torsion. The response is highly dependent on the location of the fault rupture, emphasizing the need to develop cost-effective modelling techniques. Four such techniques are developed (with and without decoupling) and comparatively assessed using the detailed 3D FE model as benchmark. The best prediction is achieved by a coupled model, which includes the bridge superstructure, detailed 3D modelling of the soil-foundation system only for the pier directly affected by the fault, and nonlinear springs representing the foundations of all other piers. The proposed technique offers a computationally efficient means to parametrically analyse long multispan bridges subjected to faulting, for which full 3D FE modelling is impractical.  相似文献