Evolution of fluid geochemistry at the Turrialba volcano (Costa Rica) from 1998 to 2008   总被引：3，自引：1，他引：2  

O. Vaselli  Franco Tassi  E. Duarte  E. Fernandez  R. J. Poreda  A. Delgado Huertas 《Bulletin of Volcanology》2010,72(4):397-410

Turrialba (10°02′N, 83°45′W) is a 3,349-m high stratovolcano belonging to the Holocene “Cordillera Central” volcanic belt of Costa Rica. The summit consists of three EW-oriented craters (East, Central, and West). Since its last eruptive phase (1864–1866), the Central and West craters have displayed modest fumarolic activity, with outlet temperatures clustering around 90°C. In 2001, seismic swarms, ground deformation, and increasing fumarolic activity occurred. From 2005 to 2008, new fumarolic vents opened between and within the Central and West craters, and along the western and southwestern outer flanks of the volcanic edifice. These physical changes were accompanied by a drastic modification in the gas chemistry that can be divided in three stages: (1) hydrothermal (from 1998 to autumn 2001), characterized by the presence of H₂O, CO₂, H₂S, and, to a very minor extent, HCl and HF; (2) hydrothermal/magmatic (autumn 2001–2007), with the appearance of SO₂ and a significant increase of HCl and HF; and (3) magmatic-dominated (2007–2008), characterized by increased SO₂ content, SO₂/H₂S > 100, and temperatures up to 282°C. Accordingly, gas equilibrium in the CO₂-CH₄-H₂ system suggests a progressive evolution of the deep fluid reservoir toward higher temperatures and more oxidizing conditions. The chemical–physical modifications of Turrialba in the last decade can be interpreted as part of a cyclic mechanism controlling the balance between the hydrothermal and the magmatic systems. Nevertheless, the risk of rejuvenation of the volcanic activity cannot be excluded, and an appropriate seismic, ground deformation, and geochemical monitoring program is highly recommended. Turrialba lies at a distance of 35 and 15 km from San José and Cartago, respectively, the two largest cities in Costa Rica.  相似文献   

Space- and Time-Dependent Probabilities for Earthquake Fault Systems from Numerical Simulations: Feasibility Study and First Results     

Jordan Van Aalsburg  John B. Rundle  Lisa B. Grant  Paul B. Rundle  Gleb Yakovlev  Donald L. Turcotte  Andrea Donnellan  Kristy F. Tiampo  Jose Fernandez 《Pure and Applied Geophysics》2010,167(8-9):967-977

In weather forecasting, current and past observational data are routinely assimilated into numerical simulations to produce ensemble forecasts of future events in a process termed “model steering”. Here we describe a similar approach that is motivated by analyses of previous forecasts of the Working Group on California Earthquake Probabilities (WGCEP). Our approach is adapted to the problem of earthquake forecasting using topologically realistic numerical simulations for the strike-slip fault system in California. By systematically comparing simulation data to observed paleoseismic data, a series of spatial probability density functions (PDFs) can be computed that describe the probable locations of future large earthquakes. We develop this approach and show examples of PDFs associated with magnitude M > 6.5 and M > 7.0 earthquakes in California.  相似文献   

Trends in total ozone and the effect of the equatorial zonal wind QBO     

Marta Zossi de Artigas  Patricia Fernandez de Campra 《Journal of Atmospheric and Solar》2010,72(7-8):565-569

Trends in total column ozone have been analyzed in terms of the equatorial zonal wind. We used zonal monthly mean total ozone from Total Ozone Mapping Spectrometer (TOMS) and monthly mean zonal wind in the equatorial stratosphere at 30 hPa to define the phases of the quasi-biennial oscillation (QBO). Total column ozone trends have been assessed during the period 1979–2004, for both Hemispheres, and for each month, under three conditions considering, all the ozone dataset, ozone values during easterly phase and ozone values during westerly phase of the QBO. When the whole dataset is considered, negative trends are observed. From low to midlatitudes a zonal pattern is noticed with increasing negative values toward higher latitudes. When the data is filtered according to the QBO phase, statistically significant positive trends appear in the westerly case during January to May at low latitudes .The trend pattern in the case of the easterly phase presents more negative values.  相似文献   

Sediment budget controls on foredune height: Comparing simulation model results with field data          下载免费PDF全文

Robin Davidson‐Arnott  Patrick Hesp  Jeff Ollerhead  Ian Walker  Bernard Bauer  Irene Delgado‐Fernandez  Thomas Smyth 《地球表面变化过程与地形》2018,43(9):1798-1810

The form, height and volume of coastal foredunes reflects the long‐term interaction of a suite of nearshore and aeolian processes that control the amount of sand delivered to the foredune from the beach versus the amount removed or carried inland. In this paper, the morphological evolution of more than six decades is used to inform the development of a simple computer model that simulates foredune growth. The suggestion by others that increased steepness of the seaward slope will retard sediment supply from the beach to the foredune due to development of a flow stagnation zone in front of the foredune, hence limiting foredune growth, was examined. Our long‐term data demonstrate that sediment can be transferred from the beach to the foredune, even with a steep foredune stoss slope, primarily because much of the sediment transfer takes place under oblique rather than onshore winds. During such conditions, the apparent aspect ratio of the dune to the oncoming flow is less steep and conditions are not as favourable for the formation of a stagnation zone. The model shows that the rate of growth in foredune height varies as a function of sediment input from the beach and erosion due to storm events, as expected, but it also demonstrates that the rate of growth in foredune height per unit volume increase will decrease over time, which gives the perception of an equilibrium height having been reached asymptotically. As the foredune grows in size, an increasing volume of sediment is needed to yield a unit increase in height, therefore the apparent growth rate appears to slow. Copyright © 2018 John Wiley & Sons, Ltd.  相似文献   

Mugil curema as a PAH bioavailability monitor for Atlantic west sub-tropical estuaries     

Ana Cecília Rizzatti de Albergaria-Barbosa  Vinicius Faria Patire  Satie Taniguchi  Wellington Silva Fernandez  June Ferraz Dias  Márcia Caruso Bícego 《Marine pollution bulletin》2017,114(1):609-614

This work aimed to evaluate the use of Mugil curema as a biomonitor for polycyclic aromatic hydrocarbon (PAH) bioavailability. Fish biliary metabolites from low-contaminated (Cananéia) and contaminated (Santos) Brazilian estuaries were analysed using a high-performance liquid chromatography apparatus coupled to fluorescence detectors connected in a series. In the Cananéia and Santos estuaries, total metabolite levels ranged from 0.85 to 34.4 μg g^? 1 of bile and from 4.06 to 528 μg g^? 1 of bile, respectively. Metabolite levels were not influenced by feeding status or sexual hormones (p < 0.05), thus suggesting that M. curema is a good biomonitor for PAH bioavailability. In estuarine regions, it is possible to sample both the male and female genders of this species in any reproductive period.  相似文献   

酸洗法测定海洋沉积物有机碳和无机碳含量的致命缺陷   总被引：2，自引：0，他引：2  

凌晨  刘志飞  张靖雯  赵玉龙  张艳伟  Fernandez Adrian R. 《海洋学报(英文版)》2020,39(8):96-102

Organic and inorganic carbon contents of marine sediments are important to reconstruct marine productivity,global carbon cycle, and climate change. A proper method to separate and determine organic and inorganic carbons is thus of great necessity. Although the best method is still disputable, the acid leaching method is widely used in many laboratories because of its ease-of-use and high accuracy. The results of the elemental analysis of sediment trap samples reveal that organic and inorganic carbon contents cannot be obtained using the acid leaching method, causing an infinitely amplified error when the carbon content of the decarbonated sample is 12%±1% according to a mathematical derivation. Acid fumigation and gasometric methods are used for comparison, which indicates that other methods can avoid this problem in organic carbon analysis. For the first time, this study uncovers the pitfalls of the acid leaching method, which limits the implication in practical laboratory measurement, and recommends alternative solutions of organic/inorganic carbon determination in marine sediments.  相似文献   

The stratigraphic record of minibasin subsidence,Precaspian Basin,Kazakhstan     

Christopher A.-L. Jackson  Oliver B. Duffy  Naiara Fernandez  Tim P. Dooley  Michael R. Hudec  Martin P. A. Jackson  George Burg 《Basin Research》2020,32(4):739-763

Minibasins are fundamental components of many salt-bearing sedimentary basins, where they may host large volumes of hydrocarbons. Although we understand the basic mechanics governing their subsidence, we know surprisingly little of how minibasins subside in three-dimensions over geological timescales, or what controls such variability. Such knowledge would improve our ability to constrain initial salt volumes in sedimentary basins, the timing of salt welding and the distribution and likely charging histories of suprasalt hydrocarbon reservoirs. We use 3D seismic reflection data from the Precaspian Basin, onshore Kazakhstan to reveal the subsidence histories of 16, Upper Permian-to-Triassic, suprasalt minibasins. These minibasins subsided into a Lower-to-Middle Permian salt layer that contained numerous relatively strong, clastic-dominated minibasins encased during an earlier, latest Permian phase of diapirism; because of this, the salt varied in thickness. Suprasalt minibasins contain a stratigraphic record of symmetric (bowl-shaped units) and then asymmetric (wedge-shaped units) subsidence, with this change in style seemingly occurring at different times in different minibasins, and most likely prior to welding. We complement our observations from natural minibasins in the Precaspian Basin with results arising from new physical sandbox models; this allows us to explore the potential controls on minibasin subsidence patterns, before assessing which of these might be applicable to our natural example. We conclude that due to uncertainties in the original spatial relationships between encased and suprasalt minibasins, and the timing of changes in style of subsidence between individual minibasins, it is unclear why such complex temporal and spatial variations in subsidence occur in the Precaspian Basin. Regardless of what controls the observed variability, we argue that vertical changes in minibasin stratigraphic architecture may not record the initial (depositional) thickness of underlying salt or the timing of salt welding; this latter point is critical when attempting to constrain the timing of potential hydraulic communication between sub-salt source rocks and suprasalt reservoirs. Furthermore, temporal changes in minibasin subsidence style will likely control suprasalt reservoir distribution and trapping style.  相似文献   

Growth at moult and intermoult period in the Norway lobster Nephrops norvegicus from Galician waters     

Gonzalez-Gurriaran  E.; Freire  J.; Farina  A. C.; Fernandez  A. 《ICES Journal of Marine Science》1998,55(5):924-940

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Accumulation and effects of benzo(a)pyrene on cytochrome P450 1A in waterborne exposed and intraperitoneal injected juvenile turbot (Scophthalmus maximus)     

S. Boleas  C. Fernandez  J. Beyer  J. V. Tarazona  A. Goksyr 《Marine environmental research》1998,46(1-5)

Juvenile turbot (Scophthalmus maximus) were exposed to benzo(a)pyrene (BaP) for 14 d using a glass bead generator flow-through system. Exposure was followed by a recovery period of 16 d. The highest BaP concentration in the edible portion of the fish, 16.5 ± 4.3 μg BaP/kg, was observed on the first day. Then concentrations dropped following first-order kinetics. BaP was below detection level at the end of the experiment. A statistically significant increase in bile fluorescence was observed from day 9 until the end of the experiment, suggesting the elimination of BaP metabolites by this route. No significant differences between control and exposed fish in EROD activity and CYP1A concentration, measured by immunodetection method, were observed. Intraperitoneal injection of 2.5 mg BaP/kg in juvenile turbot induced EROD activity. Under waterborne experimental conditions, bile fluorescence was observed to be a more sensitive biomarker of BaP exposure than EROD activity and CYP1A measurement.  相似文献   

Three-dimensional modelling of crustal motions caused by subduction and continental convergence in the central Mediterranean     

Ana Maria Negredo  Roberto Sabadini  Giuseppe Bianco  & Manel Fernandez 《Geophysical Journal International》1999,136(1):261-274

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