Lg Wave Attenuation in the Isparta Angle and Anatolian Plateau (Turkey)     

Sakir Sahin  Xueyang Bao  Niyazi Turkelli  Eric Sandvol  Ugur Teoman  Metin Kahraman 《Pure and Applied Geophysics》2013,170(3):337-351

We estimate Lg wave attenuation using local and regional seismic phases in the Isparta Angle and the Anatolian Plateau (Turkey). The Isparta Angle (IA) is a tectonically active zone forming the boundary between the African Plate and the Anatolian Plateau, and is currently undergoing N–S extensional deformation. The Anatolian Plateau contains many intra-continental faults including the North Anatolian Fault Zone and the East Anatolian Fault Zone as well as the Menderes Massif. A large waveform data set was compiled from a variety of local and regional seismic networks including 121 digital seismic stations (broad-band and short period) between 1999 and 2008 spanning the IA, the Anatolian Plateau and Azerbaijan. The data set was used to determine the nature of Lg wave propagation and characterize the nature of seismic attenuation within the crust of these regions. Lg waveforms were used to calculate the frequency-dependent Lg-Q _o and Lg- $ \eta $ . A wide range of Lg-Q _o values was obtained between ~52 ± 6 and 524 ± 227. Low Lg-Q _o values (~90–155) are calculated towards the north of IA, Iskenderun Gulf and its vicinity, Bingöl-Karl?ova, Izmit and its vicinity. Lg-Q _o values are especially low (<90) along the Menderes Massif and the Aksehir-Simav Fault Zones. This may be due to intrinsic attenuation of Lg associated with the partially molten crust and young volcanism. The high Lg-Q _o values (~350) are probably caused by the crust not being subject to large amounts of extensional deformation like the Antalya Gulf and apparently being thick enough to support Lg propagation. Relatively higher values along the border of this subduction zone and plate boundary might be related to the Taurus Mountain belts and Bitlis-Zagros Suture Zone. The lateral frequency dependency Lg- $ \eta $ is also consistent with high tectonic activity in this region.  相似文献   

Submerged macrophytes avoiding a negative feedback in reaction to hydrodynamic stress     

Jonas Schoelynck  Dieter Meire  Kris Bal  Kerst Buis  Peter Troch  Tjeerd Bouma  Patrick Meire  Stijn Temmerman 《Limnologica》2013,43(5):371-380

In most aquatic ecosystems, hydrodynamic conditions are a key abiotic factor determining species distribution and aquatic plant abundance. Recently, local differences in hydrodynamic conditions have been shown to be an explanatory mechanism for the patchy pattern of Callitriche platycarpa Kütz. vegetation in lowland rivers. These local conditions consists of specific areas of increased shear zones, resulting in additional plant stress and erosion of the sediment on the one hand and local decreased shear zones resulting in zones favourable to plant growth and sedimentation of bed material on the other hand. In this study, the process of this spatial plant-flow-sedimentation interaction has been illustrated quantitatively by in situ flume measurements. By disturbing the incoming discharge on a single patch in such flume, we have quantified the behaviour and influence of a C. platycarpa patch under normal field conditions (base flow). Additionally, the behaviour of a C. platycarpa patch under different conditions of hydrodynamic stress has been examined in a laboratory flume. Indeed, flexible, submerged macrophytes are capable to adapt patch dimensions with changing stream velocities. At times of modest hydrodynamic stress, the species takes a position near the water surface and optimises its leaf stand, thereby maximising its photosynthetic capacity. At times of peak discharge, the patch will bend down towards the river bed and become more confined and streamlined, as such averting the stream velocity and diminishing the risk of breaking or being uprooted.In this paper, the processes of local hydrodynamic conditions on the patch and the patch’ intriguing life strategy of avoiding negative feedback was shown.  相似文献   

Origin and ascent history of unusually crystal-rich alkaline basaltic magmas from the western Pannonian Basin     

M. Éva Jankovics  Gábor Dobosi  Antal Embey-Isztin  Balázs Kiss  Tamás Sági  Szabolcs Harangi  Theodoros Ntaflos 《Bulletin of Volcanology》2013,75(9):1-23

The last eruptions of the monogenetic Bakony-Balaton Highland Volcanic Field (western Pannonian Basin, Hungary) produced unusually crystal- and xenolith-rich alkaline basalts which are unique among the alkaline basalts of the Carpathian–Pannonian Region. Similar alkaline basalts are only rarely known in other volcanic fields of the world. These special basaltic magmas fed the eruptions of two closely located volcanic centres: the Bondoró-hegy and the Füzes-tó scoria cone. Their uncommon enrichment in diverse crystals produced unique rock textures and modified original magma compositions (13.1–14.2 wt.% MgO, 459–657 ppm Cr, and 455–564 ppm Ni contents). Detailed mineral-scale textural and chemical analyses revealed that the Bondoró-hegy and Füzes-tó alkaline basaltic magmas have a complex ascent history, and that most of their minerals (～30 vol.% of the rocks) represent foreign crystals derived from different levels of the underlying lithosphere. The most abundant xenocrysts, olivine, orthopyroxene, clinopyroxene, and spinel, were incorporated from different regions and rock types of the subcontinental lithospheric mantle. Megacrysts of clinopyroxene and spinel could have originated from pegmatitic veins/sills which probably represent magmas crystallized near the crust–mantle boundary. Green clinopyroxene xenocrysts could have been derived from lower crustal mafic granulites. Minerals that crystallized in situ from the alkaline basaltic melts (olivine with Cr-spinel inclusions, clinopyroxene, plagioclase, and Fe–Ti oxides) are only represented by microphenocrysts and overgrowths on the foreign crystals. The vast amount of peridotitic (most common) and mafic granulitic materials indicates a highly effective interaction between the ascending magmas and wall rocks at lithospheric mantle and lower crustal levels. However, fragments from the middle and upper crust are absent from the studied basalts, suggesting a change in the style (and possibly rate) of magma ascent in the crust. These xenocryst- and xenolith-rich basalts yield divers tools for estimating magma ascent rate that is important for hazard forecasting in monogenetic volcanic fields. According to the estimated ascent rates, the Bondoró-hegy and Füzes-tó alkaline basaltic magmas could have reached the surface within hours to few days, similarly to the estimates for other eruptive centres in the Pannonian Basin which were fed by “normal” (crystal and xenoliths poor) alkaline basalts.  相似文献   

Palaeoecological background of the Upper Palaeolithic site of Ságvár,Hungary: radiocarbon-dated malacological and sedimentological studies on the Late Pleistocene environment     

Dávid Molnár  Pál Sümegi  László Makó  Péter Cseh  Christian Zeeden  Janina Nett  Frank Lehmkuhl  Tünde Törőcsik  Balázs P. Sümegi 《第四纪科学杂志》2021,36(8):1353-1363

In this paper, the authors present new palaeoecological and sedimentological results from the Upper Palaeolithic site of Ságvár, Hungary. Simple (abundance and dominance) and advanced (cluster analysis, principal component analysis, correspondence) statistical analyses of malacological results were carried out, determining eight malacological zones (MZs) and the key species of the fauna evolution in the sequence. Furthermore, an age–depth model was calculated via Bayesian modelling using new radiocarbon age data. The accumulation rate (AR) was calculated by deriving data from the age–depth model. The palaeoecological reconstruction indicated a cool/cold climate and chiefly steppe environment, with low loess ARs. Not only the vegetation cover but also the geographical setting of the sequence could have led to the low AR values. However, in the uppermost part of the sequence, during the GS 3 and GS 2.1c stadials, the reconstructed palaeoclimate indicated a warming period. Nevertheless, this contradiction is not unique in the Carpathian Basin. The settled Upper Palaeolithic hunters around 22 300 cal a bp lived in a progressively warming wooded steppe environment, hunting mainly for reindeer. Climate change might have forced them to migrate away, following the reindeer.  相似文献   

Adsorption of Brilliant Green from Aqueous Solutions onto Crosslinked Chitosan Graft Copolymers     

Bengi Özkahraman  Ayça Bal  Işıl Acar  Gamze Güçlü 《洁净——土壤、空气、水》2011,39(11):1001-1006

In this study, graft copolymerization of itaconic acid (IA) and crotonic acid (CA) onto the crosslinked chitosan beads were carried out using ammonium persulfate as initiator. Grafted chitosan beads were characterized by FT‐IR analysis and grafting percentage determination. Grafting efficiency and add‐on percentages values of grafted chitosan beads were determined as 23–29 and 32–47%, respectively. Then, equilibrium isotherms and kinetics of brilliant green adsorption onto grafted chitosan beads were investigated. The results indicated that the pseudo‐second‐order kinetic model fitted better than the data obtained from pseudo‐first‐order model for the adsorption of brilliant green onto grafted chitosan beads. The fit of data for brilliant green (BG) adsorption onto grafted chitosan beads suggested that the Langmuir model gave closer fittings than the Freundlich model.  相似文献   

Amphibole perspective to unravel pre-eruptive processes and conditions in volcanic plumbing systems beneath intermediate arc volcanoes: a case study from Ciomadul volcano (SE Carpathians)     

Balázs?KissEmail author  Szabolcs?Harangi  Theodoros?Ntaflos  Paul?R.?D.?Mason  Elemér?Pál-Molnár 《Contributions to Mineralogy and Petrology》2014,167(3):986

Ciomadul is the youngest volcano in the Carpathian–Pannonian region produced crystal-rich high-K dacites that contain abundant amphibole phenocrysts. The amphiboles in the studied dacites are characterized by large variety of zoning patterns, textures, and a wide range of compositions (e.g., 6.4–15 wt% Al₂O₃, 79–821 ppm Sr) often in thin-section scale and even in single crystals. Two amphibole populations were observed in the dacite: low-Al hornblendes represent a cold (<800 °C) silicic crystal mush, whereas the high-Al pargasites crystallized in a hot (>900 °C) mafic magma. Amphibole thermobarometry suggests that the silicic crystal mush was stored in an upper crustal storage (~8–12 km). This was also the place where the erupted dacitic magma was formed during the remobilization of upper crustal silicic crystal mush body by hot mafic magma indicated by simple-zoned and composite amphiboles. This includes reheating (by ~200 °C) and partial remelting of different parts of the crystal mush followed by intensive crystallization of the second mineral population (including pargasites). Breakdown textures of amphiboles imply that they were formed by reheating in case of hornblendes, suggesting that pre-eruptive heating and mixing could take place within days or weeks before the eruption. The decompression rim of pargasites suggests around 12 days of magma ascent in the conduit. Several arc volcanoes produce mixed intermediate magmas with similar bimodal amphibole cargo as the Ciomadul, but in our dacite the two amphibole population can be found even in a single crystal (composite amphiboles). Our study indicates that high-Al pargasites form as a second generation in these magmas after the mafic replenishment into a silicic capture zone; thus, they cannot unambiguously indicate a deeper mafic storage zone beneath these volcanoes. The simple-zoned and composite amphiboles provide direct evidence that significant compositional variations of amphiboles do not necessarily mean variation in the pressure of crystallization even if the Al-tschermak substitution can be recognized, suggesting that amphibole barometers that consider only amphibole composition may often yield unrealistic pressure variation.  相似文献   

A multi-criteria evaluation model of earthquake vulnerability in Victoria,British Columbia     

Blake Byron Walker  Cameron Taylor-Noonan  Alan Tabbernor  T’Brenn McKinnon  Harsimran Bal  Dan Bradley  Nadine Schuurman  John J. Clague 《Natural Hazards》2014,74(2):1209-1222

Researchers have recently examined the geographic variability of the vulnerability of populations to earthquakes. These studies focus mainly on the complex modelling of geophysical processes or identification of socio-economically disadvantaged populations. However, no studies to date have integrated different components of vulnerability with metrics of travel distance to hospitals and trauma centres (systemic vulnerability). We argue that this previously unaccounted component is an important conceptual and practical aspect of earthquake vulnerability. Accordingly, this paper presents a multi-criteria model for combining physical, social, and systemic components, moving towards a more comprehensive assessment of vulnerability. An analytic hierarchy process is used to produce a place-specific index of social vulnerability, which we combine with soil liquefaction and amplification index and a road network model for access to hospitals and trauma services. Using a geographic information system, we implemented this model for the Greater Victoria region (483 km², 2011 population: 345,000) in British Columbia, Canada. Clustering of total vulnerability was found in outlying areas, highlighting the importance of access to trauma centres. We conclude by identifying challenges in measuring earthquake vulnerability and advocate integration of systemic vulnerability components in natural hazards research.  相似文献   

Temporal analysis of thermal bioclimate conditions between Kolkata (India) and its three neighbouring suburban sites     

Bal  Sourabh  Matzarakis  Andreas 《Theoretical and Applied Climatology》2022,148(3-4):1545-1562

Theoretical and Applied Climatology - The study of human biometeorological conditions is becoming increasingly important in climate perception for the improvement of public health system. The...  相似文献   

Assessment of water quality for drinking and irrigation purposes: a case study of Başköy springs (Ağlasun/Burdur/Turkey)     

Fatma Aksever  Ayşen Davraz  Yaşar Bal 《Arabian Journal of Geosciences》2016,9(20):748

It is important to know the quality of water resources for drinking, domestic and irrigation in the rural area. Because, in recent times, there has been increased demand for water due to population growth and intense agricultural activities, so, hydrogeochemical investigations come into prominence for the groundwater use. The purpose of this paper is to evaluate water quality of Ba?köy springs for both drinking and irrigation purposes. The geochemical processes and quality of springs were followed as seasonal in the study area. In view of geochemical classification, springs are Ca-Mg-HCO₃ water type for both seasons. Comparison of geochemical data shows that majority of the spring samples are suitable for drinking water. On the other hand, chemical indexes of springs with various classifications were calculated for irrigation purposes. According to the classifications (electrical conductivity, total dissolved solids, total hardness, salinity hazard, percent sodium, sodium adsorption ratio, residual sodium carbonate, residual sodium bicarbonate, permeability index, potential salinity, soluble sodium percentage, magnesium ratio, and Kelly’s ratio), Ba?köy springs are suitable for irrigation purposes. However, water quality of Çaygözü spring is different the other springs due to the high electrical conductivity and total dissolved solids. Also, groundwater mineralization processes and rock–water interaction are controlled with bivariate diagrams of major elements.  相似文献   

Origin and geodynamic relationships of the Late Miocene to Quaternary alkaline basalt volcanism in the Pannonian basin,eastern–central Europe     

Szabolcs Harangi  M. Éva Jankovics  Tamás Sági  Balázs Kiss  Réka Lukács  Ildikó Soós 《International Journal of Earth Sciences》2015,104(8):2007-2032

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