Tectonic relationships of Southwest Iberia with the allochthons of Northwest Iberia and the Moroccan Variscides     

José Fernando Simancas  Antonio Azor  David Martínez-Poyatos  Abdelfatah Tahiri  Hassan El Hadi  Francisco González-Lodeiro  Andrés Pérez-Estaún  Ramón Carbonell 《Comptes Rendus Geoscience》2009,341(2-3):103-113

The Iberian Massif poses a problem of relationships between its northwestern and southern parts. Suture terranes (ophiolites and high-pressure rocks) crop out in NW Iberia but only as allochthonous units, unconnected from their root zone. Sutures cropping out in SW Iberia are discussed in order to relate them to the unknown root of the NW Iberia allochthons. On the other hand, the Moroccan Variscides are very briefly presented with a view to propose their correlation with the Iberian zones. Particularly important is the transition from the Variscides to the Paleoproterozoic basement in Morocco, which is a key argument for palaeogeographic reconstructions.  相似文献   

Wavelet approximation of earthquake strong ground motion-goodness of fit for a database in terms of predicting nonlinear structural response     

Maria I. Todorovska  Hadi MeidaniMihailo D. Trifunac 《Soil Dynamics and Earthquake Engineering》2009

Reduced dimensionality representation of strong ground motion records as a superposition of a relatively small number of pulses is studied. Such representation is obtained by the expansion of velocity in orthogonal wavelet series using the Fast Wavelet Transform, and approximation by only the largest energy terms in the series. The Coiflet 5 wavelet family is used, which is orthogonal, smooth and nearly symmetric. The goodness of the approximation is examined for the EQUINFOS for USA Part I database, as representative of a large variety of strong motion records (it consists of 494 three-component records from 106 earthquakes recorded in the western US between 1933 and 1984). The goodness of fit is measured in terms of closeness of predicting several input and output characteristics of a nonlinear oscillator representing a structure: (i) energy of the input ground motion (proportional to integral of velocity squared), (ii) the peak input power, and (iii) the time of collapse of a bi-linear oscillator (considering also collapse due to dynamic instability). The results show very high degree of correlation of these characteristics as estimated from the actual record and from its approximations, even for small number of pulses (relative to the number that would represent the ground velocity exactly). Such reduced representation of strong ground motion is useful for extracting such pulses from strong motion records to study their nature, and for development of new algorithms for the synthesis of artificial earthquake strong motion records.  相似文献   

A numerical study on the 2D behavior of the single and layered clayey basins     

Hadi Khanbabazadeh  Recep Iyisan 《Bulletin of Earthquake Engineering》2014,12(4):1515-1536

In this numerical study the effects of the stratification and change in material type on the dynamic behavior of the clayey basins are investigated. For this purpose two kinds of single and double layer basin models with the total depth of 100 m and width of 2 km have been selected. The single layer basins consist of soft, medium and stiff clayey materials, while double layer basins consist of a stiff sandy sub-layer overlaid by one of the soft, medium and stiff clayey soil layer. A range of bedrock inclinations at the valley sides from slighter \(10^{\circ }\) and \(20^{\circ }\) to steeper \(30^{\circ }\) and \(40^{\circ }\) are selected. A numerical study using finite difference based nonlinear code which utilizes appropriate static and dynamic boundary conditions, and includes hysteresis damping formulation based on user defined degradation curves is conducted using real earthquake motions of different strength and frequency content. The results of the 2D analyses show the differences in dynamic behavior of single and double layer basins from the aspect of amount and position of the maximum amplification and resonance period. It was seen that the shallower lateral parts of the basins are sensitive to lower periods while inner parts are sensitive to higher periods. Among other differences, the most important difference between the behavior of single and double layer basins was seen at the resonance period of the inner parts of the basins.  相似文献   

Sensitivity analysis and application of time‐lapse full‐waveform inversion: synthetic testing and field data example from the North Sea,Norway          下载免费PDF全文

Hadi Balhareth  Martin Landrø 《Geophysical Prospecting》2016,64(5):1183-1200

Time‐lapse refraction can provide complementary seismic solutions for monitoring subtle subsurface changes that are challenging for conventional P‐wave reflection methods. The utilization of refraction time lapse has lagged behind in the past partly due to the lack of robust techniques that allow extracting easy‐to‐interpret reservoir information. However, with the recent emergence of the full‐waveform inversion technique as a more standard tool, we find it to be a promising platform for incorporating head waves and diving waves into the time‐lapse framework. Here we investigate the sensitivity of 2D acoustic, time‐domain, full‐waveform inversion for monitoring a shallow, weak velocity change (?30 m/s, or ?1.6%). The sensitivity tests are designed to address questions related to the feasibility and accuracy of full‐waveform inversion results for monitoring the field case of an underground gas blowout that occurred in the North Sea. The blowout caused the gas to migrate both vertically and horizontally into several shallow sand layers. Some of the shallow gas anomalies were not clearly detected by conventional 4D reflection methods (i.e., time shifts and amplitude difference) due to low 4D signal‐to‐noise ratio and weak velocity change. On the other hand, full‐waveform inversion sensitivity analysis showed that it is possible to detect the weak velocity change with the non‐optimal seismic input. Detectability was qualitative with variable degrees of accuracy depending on different inversion parameters. We inverted, the real 2D seismic data from the North Sea with a greater emphasis on refracted and diving waves’ energy (i.e., most of the reflected energy was removed for the shallow zone of interest after removing traces with offset less than 300 m). The full‐waveform inversion results provided more superior detectability compared with the conventional 4D stacked reflection difference method for a weak shallow gas anomaly (320 m deep).  相似文献   

Trial Embankment Analysis to Predict Smear Zone Characteristics Induced by Prefabricated Vertical Drain Installation     

Ali Parsa-Pajouh  Behzad Fatahi  Philippe Vincent  Hadi Khabbaz 《Geotechnical and Geological Engineering》2014,32(5):1187-1210

In this study, FLAC finite difference software has been adopted to simulate the performance of the ground improved using prefabricated vertical drains assisted preloading, considering smear zone characteristics. The numerical code has been applied to predict smear zone properties employing a back calculation procedure using the results of several case studies. The construction of a trial embankment is proposed as a reliable method to predict the smear zone characteristics. The proposed back calculation method is applied to estimate the minimum required degree of consolidation and consequently the minimum required preloading time, resulting in a reliable estimation of the smear zone permeability and extent. Three preloading case studies considering both conventional preloading and vacuum assisted preloading have been simulated to verify the numerical code and to conduct the parametric study using the back calculation procedure. According to the results, the properties of the smear zone can be back-calculated reliably, when at least 33 % degree of consolidation due to trial embankment construction is achieved.  相似文献   

Visible light N-TiO<Subscript>2</Subscript>-induced photodegradation of Congo red: characterization,kinetics and mechanistic study     

H. S. Wahab  H. M. Hadi 《International Journal of Environmental Science and Technology》2017,14(10):2135-2148

In this study, the photocatalytic degradation of Congo red has been investigated in N-doped TiO₂ (N-TiO₂) aqueous suspensions under visible light irradiation. Visible light-active N-TiO₂ was successfully prepared at three different weight contents (2.5, 5, and 7%) employing sol–gel method. It was able to harvest the visible irradiation with wavelength suitable for activation. X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometer, diffused reflectance UV–Vis spectroscopy, nitrogen adsorption Brunauer–Emmert–Teller, Raman spectroscopy, photoluminescence and X-ray photoelectron spectrometer were used to characterize the doped catalyst. The samples had a relatively large specific Brunauer–Emmert–Teller surface areas of about 42 m² g^?1 with average X-ray diffraction crystalline size of 52 nm and showed visible light photocatalytic activity at about 408 nm. The impacts of several operating parameters on the Congo red photodegradation process were examined. Langmuir–Hinshelwood model exhibited pseudo-first-order degradation kinetics. N-TiO₂-assisted plausible photodegradation mechanism has been suggested based on the qualitatively detected intermediate compounds.  相似文献   

Mediterranean Sea and anthropogenic influences on ambient vibration amplitudes in the low-frequency and high-frequency domains in the Algiers region     

Rabah Bensalem  Jean-Luc Chatelain  Djamel Machane  El Hadi Oubaiche  Assia Bouchelouh  Nassima Benkaci  Hakim Moulouel  Souhila Chabane  Mustapha Hellel 《Arabian Journal of Geosciences》2017,10(13):282

Ambient vibrations have been continuously recorded at Dar El Beida, about 20 km from Algiers (Algeria). This data set allows determining that, in the low-frequency domain (<1 Hz), ambient vibration sources are mainly linked to Mediterranean Sea effects, while in the high-frequency domain, they are closely related to anthropogenic activity. Climatic conditions have an influence on the ambient vibration spectral amplitudes in the low-frequency domain, which is not the case in the high-frequency domain. The limit between the low-frequency and high-frequency domain, based on natural versus anthropogenic activity, is not clear cut and lies between 1.25 and 1.50 Hz. Variations of H/V peak amplitudes in the low-frequency domain are clearly linked to the climatic conditions. In the high-frequency domain, H/V peaks are not related to climatic conditions and cannot be clearly related to anthropogenic source changes.  相似文献   

Lack of population genetic structure in the marine nematodes Ptycholaimellus pandispiculatus and Terschellingia longicaudata in beaches of the Persian Gulf,Iran          下载免费PDF全文

Narjes Sahraean  Jelle Van Campenhout  Annelien Rigaux  Hadi Mosallanejad  Frederik Leliaert  Tom Moens 《Marine Ecology》2017,38(3)

We investigated genetic diversity and population genetic structure of two common benthic nematode species, Ptycholaimellus pandispiculatus and Terschellingia longicaudata, from sandy beaches in the area of Bandar Abbas (Iran), Persian Gulf. Based upon partial mitochondrial cytochrome oxidase c subunit 1 (COI) gene data, 17 and two haplotypes were found for P. pandispiculatus and Te. longicaudata, respectively. Analysis of molecular variance did not reveal a significant population genetic structure for either species. The absence of genetic structuring indicates substantial dispersal and gene flow in our study area. To assess the species structure of Te. longicaudata at a larger geographic scale, we compared 18S rDNA and COI sequences from Iran and the Scheldt Estuary in The Netherlands to ascertain whether they truly belong to the same species. Our data confirmed previous studies that Te. longicaudata likely constitutes a complex of multiple cryptic species, with one of these species having a (near) cosmopolitan distribution.  相似文献