Visibility Graph Analysis of the 2003–2012 Earthquake Sequence in the Kachchh Region of Western India     

Luciano Telesca  Michele Lovallo  S. K. Aggarwal  P. K. Khan  B. K. Rastogi 《Pure and Applied Geophysics》2016,173(1):125-132

A visibility graph (VG) is a rather novel statistical method in earthquake sequence analysis; it maps a time series into networks or graphs, converting dynamical properties of the time series into topological properties of networks. By using the VG approach, we defined the parameter window mean interval connectivity time <T_c>, that informs about the mean linkage time between earthquakes. We analysed the time variation of <T_c> in the aftershock-depleted catalogue of Kachchh Gujarat (Western India) seismicity from 2003 to 2012, and we found that <T_c>: i) changes through time, indicating that the topological properties of the earthquake network are not stationary; and, ii) appeared to significantly decrease before the largest shock (M5.7) that occurred on March 7, 2006 near the Gedi fault, an active fault in the Kachchh region.  相似文献   

A numerical model for the dynamic analysis of inclined pile groups          下载免费PDF全文

Francesca Dezi  Sandro Carbonari  Michele Morici 《地震工程与结构动力学》2016,45(1):45-68

The paper presents a numerical model for the dynamic analysis of pile groups with inclined piles in horizontally layered soil deposits. Piles are modelled with Euler–Bernoulli beams, while the soil is supposed to be constituted by independent infinite viscoelastic horizontal layers. The pile–soil–pile interaction as well as the hysteretic and geometric damping is taken into account by means of two‐dimensional elastodynamic Green's functions. Piles cap is considered by introducing a rigid constraint; the condensation of the problem permits a consistent derivation of both the dynamic impedance matrix of the soil–foundation system and the foundation input motion. These quantities are those used to perform inertial soil–structure interaction analyses in the framework of the substructure approach. Furthermore, the model allows evaluating the kinematic stress resultants in piles resulting from waves propagating in the soil deposit, taking into account the pile–soil–pile interactions. The model validation is carried out by performing accuracy analyses and comparing results in terms of dynamic impedance functions, kinematic response parameters and pile stress resultants, with those furnished by 3D refined finite element models. To this purpose, classical elastodynamic solutions are adopted to define the soil–pile interaction problem. The model results in low computational demands without significant loss of precision, compared with more rigorous approaches or refined finite element models. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Sources and fate of nutrients in a subtropical reservoir   总被引：1，自引：0，他引：1  

Michele?A.?BurfordEmail author  Susanne?A.?Green  Andrew?J.?Cook  Suzanne?A.?Johnson  Jason?G.?Kerr  Katherine?R.?O’Brien 《Aquatic Sciences - Research Across Boundaries》2012,74(1):179-190

This study examined the sources and fate of nutrient inputs from two principal tributaries to the eutrophic subtropical Wivenhoe reservoir: an unregulated river and a dammed river with regular releases, during a period of declining reservoir water levels. Nutrient budgets were constructed over a period of 6 years, and combined with short-term data on nutrient concentrations and forms, and δ¹⁵N stable isotope data. Our study found that over a 6 year period, there was net retention of phosphorus (P) in the reservoir, with 60% of inputs retained. Most of the P input load came from the unregulated river, with an agricultural catchment, during periods of high flow. During one event half of the total TP load from the unregulated river in the study period was delivered in only 12 days. Much of the P was dissolved inorganic P (DIP) and was derived from high P concentrations in soils and sediments. This highlights the importance of appropriate catchment management practices to reduce P losses from terrestrial systems because retention of P in reservoir sediments reduces the availability of this nutrient for agricultural production. In contrast, there was negligible retention of nitrogen (N). The unregulated river was an important source of N derived from N fixation in the river and adjacent soils, while the source from the dammed river was mostly reprocessed N. The high retention of P relative to N is consistent with relatively higher accumulation of P in sediments.  相似文献   

Bedform effect on the reorganization of surface and subsurface grain size distribution in gravel bedded channels   总被引：1，自引：1，他引：0  

Arvind Singh  Michele Guala  Stefano Lanzoni  Efi Foufoula-Georgiou 《Acta Geophysica》2012,60(6):1607-1638

Quantification of river bedform variability and complexity is important for sediment transport modeling as well as for characterization of river morphology. Alluvial bedforms are shown to exhibit highly nonlinear dynamics across a range of scales, affect local bed roughness, and vary with local hydraulic, hydrologic, and geomorphic properties. This paper examines sediment sorting on the crest and trough of gravel bedforms and relates it to bed elevation statistics. The data analysed here are the spatial and temporal series of bed elevation, grain size distribution of surface and subsurface bed materials, and sediment transport rates from flume experiments. We describe surface topography through bedform variability in height and wavelength and multiscale analysis of bed elevations as a function of discharge. We further relate bedform migration to preferential distribution of coarse and fine sediments on the troughs and crests, respectively, measuring directly surface and subsurface grain size distributions, and indirectly the small scale roughness variations as estimated from high resolution topographic scans.  相似文献   

Texture Attribute Analysis of GPR Data for Archaeological Prospection     

Wenke Zhao  Emanuele Forte  Michele Pipan 《Pure and Applied Geophysics》2016,173(8):2737-2751

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Simplified seismic performance assessment and implications for seismic design     

Timothy J. Sullivan  David P. Welch  Gian Michele Calvi 《地震工程与工程振动(英文版)》2014,13(1):95-122

The last decade or so has seen the development of refined performance-based earthquake engineering (PBEE) approaches that now provide a framework for estimation of a range of important decision variables, such as repair costs, repair time and number of casualties. This paper reviews current tools for PBEE, including the PACT software, and examines the possibility of extending the innovative displacement-based assessment approach as a simplified structural analysis option for performance assessment. Details of the displacement-based s+eismic assessment method are reviewed and a simple means of quickly assessing multiple hazard levels is proposed. Furthermore, proposals for a simple definition of collapse fragility and relations between equivalent single-degree-of-freedom characteristics and multi-degree-of-freedom story drift and floor acceleration demands are discussed, highlighting needs for future research. To illustrate the potential of the methodology, performance measures obtained from the simplified method are compared with those computed using the results of incremental dynamic analyses within the PEER performance-based earthquake engineering framework, applied to a benchmark building. The comparison illustrates that the simplified method could be a very effective conceptual seismic design tool. The advantages and disadvantages of the simplified approach are discussed and potential implications of advanced seismic performance assessments for conceptual seismic design are highlighted through examination of different case study scenarios including different structural configurations.  相似文献   

Effect of Stress Perturbations on the Dynamics of a Complex Fault     

Michele Dragoni  Antonello Piombo 《Pure and Applied Geophysics》2015,172(10):2571-2583

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Investigating the Tsunamigenic Potential of Earthquakes from Analysis of the Informational and Multifractal Properties of Seismograms     

Luciano Telesca  Ashutosh Chamoli  Michele Lovallo  Tony Alfredo Stabile 《Pure and Applied Geophysics》2015,172(7):1933-1943

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Specific angular momentum of disc merger remnants and the λ_R-parameter     

Roland Jesseit  Michele Cappellari  Thorsten Naab  Eric Emsellem  Andreas Burkert 《Monthly notices of the Royal Astronomical Society》2009,397(3):1202-1214

We use two-dimensional kinematic maps of simulated binary disc mergers to investigate the  λ_R  -parameter, which is a luminosity-weighted measure of projected angular momentum per unit mass. This parameter was introduced to subdivide the SAURON sample of early-type galaxies in so-called fast  λ_R > 0.1  and slow rotators  λ_R < 0.1  . Tests on merger remnants reveal that  λ_R  is a robust indicator of the true angular momentum content in elliptical galaxies. We find the same range of  λ_R  values in our merger remnants as in the SAURON galaxies. The merger mass ratio is decisive in transforming fast rotators into slow rotators in a single binary merger, the latter being created mostly in an equal-mass merger. Slow rotators have a  λ_R  which does not vary with projection. The confusion rate with face-on fast rotators is very small. Mergers with a gas component form slow rotators with smaller ellipticities than collisionless merger remnants have, and are in much better agreement with the SAURON slow rotators. Remergers of merger remnants are slow rotators, but tend to have too high ellipticities. Fast rotators maintain the angular momentum content from the progenitor disc galaxy if merger mass ratio is high. Some SAURON galaxies have values of  λ _R   as high as our progenitor disc galaxies.  相似文献   

The mass of the black hole in Centaurus A from SINFONI AO-assisted integral-field observations of stellar kinematics     

Michele Cappellari  N. Neumayer  J. Reunanen  P. P. van der Werf  P. T. de Zeeuw  H.-W. Rix 《Monthly notices of the Royal Astronomical Society》2009,394(2):660-674

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