Seismotectonic regionalization of the Red Sea area and its application to seismic risk analysis     

Roberto Pedone  Paolo Lombardo  Dimitris Diamantidis 《Natural Hazards》1992,5(3):233-247

A seismological evaluation of the Red Sea margin is presented in this contribution based on the concept of seismotectonic regionalization. The geology and the tectonic structure are critically reviewed to define regions of homogeneous seismicity in the study area, and available seismicity data are implemented to estimate the seismic parameters of the region. The results of the study are applied to evaluate the seismic hazard of an offshore platform site.  相似文献   

Western Palaearctic palaeoenvironmental conditions during the Early and early Middle Pleistocene inferred from large mammal communities,and implications for hominin dispersal in Europe     

Ralf-Dietrich Kahlke  Nuria García  Dimitris S. Kostopoulos  Frédéric Lacombat  Adrian M. Lister  Paul P.A. Mazza  Nikolai Spassov  Vadim V. Titov 《Quaternary Science Reviews》2011,30(11-12):1368-1395

Large-scale fluctuations in global climate and resulting changes in ecology had a profound effect on human evolution and dispersal. Though hominin remains are scarce, studies focussing on the more abundant records of fossil land mammal communities can contribute greatly to our knowledge of the palaeoenvironmental circumstances that influenced and directed the global spread of hominins. To produce a comprehensive and accurate account of the evolution of western Palaearctic habitat diversity between 2.6 and 0.4 Ma BP, information generated from large mammal communities from 221 key sites has been included in this study.The palaeoecological conditions of the western Palaearctic during the Early and early Middle Pleistocene were principally controlled by the following key factors: (1) a widespread trend of temperature decrease, (2) the periodicity of the global temperature record, (3) the intensity of single climatic stages, (4) the temporal pattern of climatic variation, (5) geographical position, and (6) the distribution of continental water resources. A general picture of the evolution of western Palaearctic habitat diversity saw the replacement of extensive forested terrain by an alternating sequence of varied savannah-like and forested habitats during the 2.6–1.8 Ma span, as well as an alternation between different types of predominantly open habitats between 1.8 and 1.2 Ma. Both of these processes were governed by 41 ka temperature periodicity. During the 1.2–0.9 Ma time span, irregular climatic fluctuations were more common and habitat variability increased. The subsequent 0.9–0.4 Ma interval, a period controlled by 100 ka periodicity, was by comparison more stable, with longer climatic cycles alternating between open and forested landscapes. During the entire Early and early Middle Pleistocene, assemblages of large mammal communities reveal a distinct trend of decreasing continentality between Eastern and South-Eastern Europe on the one hand, and South-Western and North-Western Europe on the other. This trend was due to the effect of the Atlantic Ocean, while in Southern Europe the relatively low continentality was balanced by influences from the Mediterranean Sea.When plotted against evidence of hominin occurrence, the data on western Palaearctic habitat diversity inferred from large mammal communities indicate clear environmental stimuli for the earliest human dispersal in Europe. These are: (1) a wide range of habitats, implying a high diversity of resources; (2) mild climates with low seasonality, implying a lack of strong environmental fluctuations. Around 1.8 Ma at the latest, hominins of African origin entered the western Palaearctic for the first time, taking advantage of the diversity of habitats and resources, particularly along large river systems. Their subsequent westward spread between 1.7 and 1.3 Ma was restricted to Mediterranean-influenced areas, which offered a high variability of habitats and relatively low seasonality. The increase in environmental diversity, which occurred from 1.2 Ma onwards, opened up South-Eastern and Eastern Europe for hominin occupation. According to the available records, North-Western and Central Europe were initially colonized during late Early to early Middle Pleistocene interglacials, when these regions experienced periods of low seasonality and considerable habitat diversity.  相似文献   

Soil–foundation–structure interaction and vulnerability assessment of the Neoclassical School in Rhodes,Greece     

Anna Karatzetzou  Dimitris Pitilakis  Meta Kržan  Vlatko Bosiljkov 《Bulletin of Earthquake Engineering》2015,13(1):411-428

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Use of rubberised backfills for improving the seismic response of integral abutment bridges     

Sotiris Argyroudis  Anastasia Palaiochorinou  Stergios Mitoulis  Dimitris Pitilakis 《Bulletin of Earthquake Engineering》2016,14(12):3573-3590

Reuse of the 1.5 billion waste tyres that are produced annually is a one of the major worldwide challenges, as waste tyres are toxic and cause pollution to the environment. In recognition of this problem, this paper introduces the reuse of tyres, in the form of derived aggregates in mixtures with granulated soil materials, as previous studies indicated the potential benefits of these materials in the seismic performance of structures. The objective of the present research study is to investigate whether use of rubberised backfills benefits the seismic response of Integral Abutment Bridges (IABs) by enhancing soil-structure interaction (SSI) effects. Numerical models including typical integral abutments on surface foundation with nonlinear conventional backfill material and its alternative form as soil-rubber mixtures are analysed and their response parameters are compared. The research is conducted on the basis of parametric analysis, which aims to evaluate the influence of different rubber-soil mixtures on the dynamic response of the abutment-backfill system under various seismic excitations, accounting for dynamic soil-abutment interaction. The results provide evidence that the use of rubberised backfill leads to reductions in the backfill settlements, the horizontal displacements of the bridge deck, the residual horizontal displacements of the top of the abutment and the pressures acting on the abutment, up to 55, 18, 43 and 47 % respectively, with respect to a conventional backfill comprising of clean sand. Small change in bending moments and shear forces on the abutment wall is also observed. Therefore, rubberised backfills offer promising solution to mitigate the earthquake risk, towards economic design with minimal damage objectives for the resilience of transportation networks.  相似文献   

Inclusion of P–Δ effect in displacement‐based seismic design of steel moment resisting frames     

Aristidis V. Asimakopoulos  Dimitris L. Karabalis  Dimitri E. Beskos 《地震工程与结构动力学》2007,36(14):2171-2188

A procedure for treating the P– Δ effect in the direct displacement‐based seismic design of regular steel moment resisting frames with ideal elastoplastic material behaviour is proposed. A simple formula for the yield displacement amplification factor as a function of ductility and the stability coefficient is derived on the basis of the seismic response of an inelastic single degree‐of‐freedom system taking into account the P– Δ effect. Extensive parametric seismic inelastic analyses of plane moment resisting steel frames result in a simple formula for the dynamic stability coefficient as a function of the number of stories of a frame and the column to beam stiffness ratio. Thus, the P– Δ effect can be easily taken into account in a direct displacement‐based seismic design through the stability coefficient and the yield displacement amplification factor. A simple design example serves to illustrate the application of the proposed method and demonstrate its merits. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Chernobyl reactor accident consequences on small atmospheric ions concentration above Athens     

Dimitris A. Retalis 《Pure and Applied Geophysics》1987,125(4):669-678

In the present study the variation in small ion concentration (SIC), positive and negative, above Athens (=37°58.3N, =23°43E,h=107 m) after Chernobyl reactor accident is examined.SIC started to increase importantly at the National Observatory of Athens (N.O.A) since 3 May 1986 and reached its highest mean daily values on Monday, 5 May. These maximum values were 4 times the normal for positive ions and 5 times the normal for negative ions. Correlation coefficients were calculated between SIC and radionuclides I-131, Cs-137, Ru-103 and outdoor exposure rate.  相似文献   

Neotectonic evolution of northwestern-continental Greece     

Dr. Theodor Doutsos  Dr. Nikolaos Kontopoulos  Dr. Dimitris Frydas 《International Journal of Earth Sciences》1987,76(2):433-450

The post-Miocene sedimentary and structural evolution of NW-continental Greece changes from west to east.In the west, along the Ionian coast, the tectonic activity of the Mio-Pliocene marine sedimentation is reflected in olisthostromes and intrafoliated folds. During the emergence of the area at the Pliocene/Pleistocene boundary, low angle thrusting, dissolution cleavage and open NNW to NNE trending folds, were developed. This horizontal shortening is the result of active plate convergence between the Apulian plate and the Aegean plate. Subsequent vertical movements continuing till the precent, produces mainly NNW and ENE directed faults.In the east, between the Ionian coast and Pindus thrust, nonmarine sedimentation began, in the middle Pliocene, on a folded and partially eroded substratum. Long fault bounded intramountaneous basins formed during general uplift and extension in three directions: NNW, ENE and WNW. Extension in both areas, resulting from NNW and ENE faults, is interpreted in terms of the action of upwelling convective currents induced by the Hellenic subduction. As the Aegean back arc extension migrated slowly westwards, the whole study area was gradually affected by WNW trending grabens.

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Zusammenfassung Spätmiozäne Sedimentationsprozesse sowie strukturelle Entwicklung ändern sich in NW kontinental-Griechenland in E-W Richtung.An der Ionischen Küste wurden während der spätmiozänen Absenkung des Sedimentationsraumes mächtige Olisthostrome und intrafoliale Falten gebildet. An der Grenze des Plio/Pleistozäns wurden flache überschiebungen, Lösungsschieferung und NNW bis NNE streichende, geöffnete Falten entwickelt. Diese tektonische Strukturen sind das Ergebnis aktiver Plattenkonvergenz zwischen der apulischen lithosphären-Platte und der ägäischen Platte. Während der postorogenen Aufhebung sind NNW und ENE streichende Verwerfungen entstanden.Im mittleren Pliozän wurden im Raum zwischen Ionischem Meer und der Pindos überschiebung auf dem gefalteten und teilweise erodierten Untergrund vorwiegend limnisch-terrestrische Sedimente abgelagert. Während der postorogenen Ausweitung sind Absenkungsräume in NNW- und ENE Richtung entstanden. Sie sind vermutlich das Ergebnis von Konvektionsströmungen innerhalb der Asthenosphäre, die durch die Hellenische Subduktion hervorgerufen wurden.Die Krustenausdehnung im ägäischen »back-arc basin« hat sich kontinuierlich gegen Westen verlagert, so da\ West-Griechenland zusätzlich von WNW streichenden Grabenstrukturen weitgehend deformiert ist.

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Résumé La partie nord-occidentale de la Grèce continentale montre, d'est en ouest, une modification des processus sédimentaires et structuraux.A l'ouest, le long de la cÔte ionienne, la sédimentation marine subsidente tardi-miocène s'est accompagnée de puissants olisthostromes et de plis intrafoliaux. La limite Pliocène-Pleistocène a vu se développer des charriages peu inclinés et des plis ouverts NNE à NNW accompagnés d'une schistosité de dissolution. Ce raccourcissement horizontal est le résultat de la convergence des plaques apulienne et égéenne. Il a été suivi de mouvements subséquents verticaux, encore actifs aujourd'hui, responsables de failles de directions NNW et ENE.Plus à l'est, entre la cÔte ionienne et le charriage du Pinde, une sédimentation continentale s'est installée, au Pliocène moyen, sur le substratum plissé et partiellement érodé. Au cours du soulèvement post-orogénique, des bassins intramontagneux de grabens se sont formés selon trois directions: NNW, ENE et WNW. Les deux premières sont interprétées comme le résultat de courants de convection induits dans l'asthénosphère par la subduction hellénique. Les grabens WNW seraient en relation avec le déplacement progressif vers l'ouest de la zone d'extension crustale du bassin d'arrière-arc égéen.

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Impact of Tropospheric Ozone on Summer Climate in China     

Shu Li  Tijian Wang  Prodromos Zanis  Dimitris Melas  Bingliang Zhuang 《Acta Meteorologica Sinica》2018,32(2):279-287

The spatial distribution, radiative forcing, and climatic effects of tropospheric ozone in China during summer were investigated by using the regional climate model RegCM4. The results revealed that the tropospheric ozone column concentration was high in East China, Central China, North China, and the Sichuan basin during summer. The increase in tropospheric ozone levels since the industrialization era produced clear-sky shortwave and clear-sky longwave radiative forcing of 0.18 and 0.71 W m^–2, respectively, which increased the average surface air temperature by 0.06 K and the average precipitation by 0.22 mm day^–1 over eastern China during summer. In addition, tropospheric ozone increased the land–sea thermal contrast, leading to an enhancement of East Asian summer monsoon circulation over southern China and a weakening over northern China. The notable increase in surface air temperature in northwestern China, East China, and North China could be attributed to the absorption of longwave radiation by ozone, negative cloud amount anomaly, and corresponding positive shortwave radiation anomaly. There was a substantial increase in precipitation in the middle and lower reaches of the Yangtze River. It was related to the enhanced upward motion and the increased water vapor brought by strengthened southerly winds in the lower troposphere.  相似文献   

Ca(OH)2 Pre‐Treated Bentonite for Phosphorus Removal and Recovery From Synthetic and Real Wastewater          下载免费PDF全文

Giorgos Markou  Dimitris Mitrogiannis  Vassilis Inglezakis  Koenraad Muylaert  Nikolaos Koukouzas  Nikolaos Tsoukalas  Efstratios Kamitsos  Dimitrios Palles  Ioannis Baziotis 《洁净——土壤、空气、水》2018,46(2)

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Last glacial geomorphologic records in Mt Chelmos,North Peloponnesus,Greece     

Kosmas Pavlopoulos  Aris Leontaritis  Constantin D. Athanassas  Chara Petrakou  Dimitris Vandarakis  Kosnstantinos Nikolakopoulos  Leonidas Stamatopoulos  Katherina Theodorakopoulou 《山地科学学报》2018,15(5):948-965

This study deals with the analysis of the glacial processes that have affected the relief of Mt Chelmos in northern Peloponnesus, Greece during middle and Late Pleistocene. The goal was to compile a combined geomorphological-geological map of the study area which would enable the chronological stratification of the glacial landforms cropping up on Mt. Chelmos. Chronological stratification was further aided by optically stimulated luminescence (OSL) dating. The map served as the basis upon which the reconstruction and discussion on the phases of the Middle-Late Quaternary paleoclimatic history of Mt. Chelmos have been made. A sophisticated semiautomated method was first used to analyze the Digital Elevation Model (DEM), combined with Aster, Quickbird and ALOS imagery in order to identify glacial and periglacial, as well as karstic features. Then, these features along with other nonrecognizable features from the remote-sensing images were documented in the field. In this way, several glacial landforms were identified, such as moraines and cirques, indicating extended glaciation phases during the middle and Late Pleistocene. Additionally, a ground moraine located at an altitude of 1900-2050 m, within the Spanolakos glacial valley, was dated using the OSL-dating method. The resulting ages indicate a phase of glacier advance/stabilization during MIS-5b (89-86 ka), which is in consistence with pollenrecord evidence from Greece and the Mediterranean.  相似文献