Spatial variations of precursory seismic quiescence observed in recent years in the eastern part of Turkey     

Serkan Öztürk  Yusuf Bayrak 《Acta Geophysica》2012,60(1):92-118

A statistical analysis is made for the eastern part of Turkey in the beginning of 2009 by studying the phenomenon of seismic quiescence as a potential precursor of the main shocks. The results produced four areas having seismic quiescence in the beginning of 2009. These areas are observed to be centered at 39.96°N–40.69°E (around A?kale, Erzurum), 39.36°N–39.74°E (around Ovac?k, Tunceli), 39.02°N–40.52°E (including Elaz?? and Bingöl), and 38.45°N–42.94°E (Van Lake). Based on the recent results showing 5 ± 1.5 years quiescence before the occurrence of an earthquake in this region, the future earthquake would be expected between 2009.5 and 2010.5. The future earthquake occurrence may reach 2012 if we consider the standard deviation of average seismic quiescence as ±1.5 years. We have found that the M _W = 6.0 Elaz?? earthquake on 8 March 2010, followed a seismic quiescence starting about 5 years before the main shock. Thus, special interest should be given to the other regions where the seismic quiescence is observed.  相似文献   

Inversion of two-dimensional tidal open boundary conditions of M<Subscript>2</Subscript> constituent in the Bohai and Yellow Seas     

曹安州  郭筝  吕咸青 《中国海洋湖沼学报》2012,30(5):868-875

Two-dimensional tidal open boundary conditions of the M2 constituent in the Bohai and Yellow Seas(BYS) have been estimated by assimilating T/P altimeter data.During inversion,independent point(IP) strategy was used,in which several IPs on the open boundary is assumed,values at these IPs can be optimized with an adjoint method,and those at other grid points are determined by linearly interpolating the values at IPs.The reasonability and feasibility of the model are tested by ideal twin experiments.In the practical experiment(PE) after assimilation,the cost function may reach 1% or less of its initial value.Mean absolute errors in amplitude and phase can be less than 5 cm and 5°,respectively,and the obtained co-chart can show the character of the M2 constituent in the BYS.The results of the PE indicate that using only two IPs on the open boundary can yield better simulated results.  相似文献   

Morphometric and molecular data on two mitochondrial genes of a newly discovered chimaeran fish (Hydrolagus melanophasma, Chondrichthyes)     

José De La Cruz-Agüero  Francisco Javier García-Rodríguez  Víctor Manuel Cota-Gómez  Felipe Neri Melo-Barrera  Rogelio González-Armas 《Ocean Science Journal》2012,47(2):147-153

Fresh and preserved (type material) specimens of the black ghost chimaera Hydrolagus melanophasma were compared for morphometric characteristics. A molecular comparison was also performed on two mitochondrial gene sequences (12S rRNA and 16S rRNA gene sequences). While significant differences in measurements were found, the differences were not attributable to sexual dimorphism or the quality of the specimens, but to the sample size and the type of statistical tests. The result of the genetic characterization showed that 12S rRNA and 16S rRNA genes represented robust molecular markers that characterized the species.  相似文献   

Seismic stratigraphy of Lago Puyehue (Chilean Lake District): new views on its deglacial and Holocene evolution     

François Charlet  Marc De Batist  Emmanuel Chapron  Sébastien Bertrand  Mario Pino  Roberto Urrutia 《Journal of Paleolimnology》2008,39(2):163-177

Prior to the collection of a series of sediment cores, a high- and very-high-resolution reflection seismic survey was carried out on Lago Puyehue, Lake District, South-Central Chile. The data reveal a complex bathymetry and basin structure, with three sub-basins separated by bathymetric ridges, bedrock islands and interconnected channels. The sedimentary infill reaches a thickness of >200 m. It can be sub-divided into five seismic-stratigraphic units, which are interpreted as: moraine, ice-contact or outwash deposits (Unit I), glacio-lacustrine sediments rapidly deposited in a proglacial or subglacial lake at the onset of deglaciation (Unit II), lacustrine fan deposits fed by sediment-laden meltwater streams in a proglacial lake (Unit III), distal deposits of fluvially derived sediment in an open, post-glacial lake (Unit IV) and authigenic lacustrine sediments, predominantly of biogenic origin, that accumulated in an open, post-glacial lake (Unit V). This facies succession is very similar to that observed in other glacial lakes, and minor differences are attributed to an overall higher depositional energy and higher terrigenous input caused by the strong seismic and volcanic activity in the region combined with heavy precipitation. A long sediment core (PU-II core) penetrates part of Unit V and its base is dated as 17,915 cal. yr. BP. Extrapolation of average sedimentation rates yields an age of ca. 24,750 cal. yr. BP for the base of Unit V, and of ca. 28,000 cal. yr. BP for the base of Unit IV or for the onset of open-water conditions. This is in contrast with previous glacial-history reconstructions based on terrestrial records, which date the complete deglaciation of the basin as ca. 14,600 cal. yr. BP. This discrepancy cannot be easily explained and highlights the need for more lacustrine records from this region. This is the second in a series of eight papers published in this special issue dedicated to the 17,900 year multi-proxy lacustrine record of Lago Puyehue, Chilean Lake District. The papers in this special issue were collected by M. De Batist, N. Fagel, M.-F. Loutre and E. Chapron.  相似文献   

The last 500 year of sedimentation in Shkodra Lake (Albania/Montenegro): paleoenvironmental evolution and potential for paleoseismicity studies     

Aurélien van Welden  Christian Beck  Jean-Louis Reyss  Salvatore Bushati  Rexhep Koci  François Jouanne  Jean-Louis Mugnier 《Journal of Paleolimnology》2008,40(2):619-633

Lake Shkodra (northern Albania, southern Montenegro) is a large (45 km length, 15 km width) and shallow (5 m mean depth) lake, developed on a mainly karstic carbonate substratum. Its recent sedimentary fill (mixed calcareous/siliciclastic clayey silts) was analysed through short gravity cores representing five centuries of environmental archive. A combination of high resolution texture analysis (particle size), magnetic susceptibility, carbon content, and radionuclide activity profiles (²¹⁰Pb, ¹³⁷Cs, ²⁴¹Am) permitted us to detect and date environmental changes, such as the Little Ice Age and the 1962–1963 catastrophic floods. Anthropogenic influences on the watershed, such as damming of the Drin River in the late 1970s, also appear to be recorded. Impacts of known strong earthquakes (1905, 1979), however, could not be clearly detected in the sediment record. The potential of the Shkodra lacustrine archive for paleoseismic investigations on long time intervals (such as Holocene) is discussed. This paper is a preliminary contribution to Shkodra Lake’s Holocene paleolimnology.  相似文献   

Assessment of nutrient sources and paleoproductivity during the past century in Longgan Lake,middle reaches of the Yangtze River,China   总被引：3，自引：0，他引：3  

Yanhong Wu  Andreas Lücke  Sumin Wang 《Journal of Paleolimnology》2008,39(4):451-462

Total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) were determined in combination with stable isotope ratios of carbon and nitrogen (δ¹³C_Org, δ¹⁵N) in a 63 cm sediment core from Longgan Lake, located in the middle reaches of the Yangtze River, China. These geochemical and isotopic records provide a continuous history of lake productivity and trophic state of Longgan Lake since 1890. Variations of δ¹³C_Org, TOC, TN and TP indicate that primary productivity of Longgan Lake increased continuously during the last century and that the trophic state of the lake shifted from oligotrophic to mestrotrophic conditions accordingly. Anthropogenic sources of organic carbon (OC), nitrogen (N) and phosphorus (P) were distinguished from their natural background in the sediments using mass accumulation rates. Element mass accumulation rates suggested increased human activities in the lake’s catchment since 1950s, were especially the utilization of artificial fertilizers amplified the anthropogenic input of N and P into the lake. In the course of the improved availability of dissolved nutrients also primary productivity of Longgan Lake increased, resulting in an increase of the Suess-effect corrected organic carbon isotope ratios. δ¹⁵N of bulk sediments show a marked shift towards lower values around 1950 that has been attributed to the input of nitrogen from chemical fertilizers characterized by relatively depleted isotopic signatures into the lake.  相似文献   

High variability in carbon and nitrogen isotopic discrimination of tropical freshwater invertebrates     

Ana Paula C. de Carvalho  Björn Gücker  Mario Brauns  Iola G. Boëchat 《Aquatic Sciences - Research Across Boundaries》2015,77(2):307-314

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Species-related risk assessment of antibiotics using the probability distribution of long-term toxicity data as weighting function: a case study     

Conrad Marx  Viktoria Mühlbauer  Peter Krebs  Volker Kuehn 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(8):2073-2085

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Seismic behaviour of traditional timber frame walls: experimental results on unreinforced walls     

Elisa Poletti  Graça Vasconcelos 《Bulletin of Earthquake Engineering》2015,13(3):885-916

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Uncertainty estimation for operational ocean forecast products—a multi-model ensemble for the North Sea and the Baltic Sea     

Inga Golbeck  Xin Li  Frank Janssen  Thorger Brüning  Jacob W. Nielsen  Vibeke Huess  Johan Söderkvist  Bjarne Büchmann  Simo-Matti Siiriä  Olga Vähä-Piikkiö  Bruce Hackett  Nils M. Kristensen  Harald Engedahl  Ed Blockley  Alistair Sellar  Priidik Lagemaa  Jose Ozer  Sebastien Legrand  Patrik Ljungemyr  Lars Axell 《Ocean Dynamics》2015,65(12):1603-1631

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