Computation of ground motion amplification in Kolkata megacity (India) using finite-difference method for seismic microzonation     

Amit Shiuly  Vinay Kumar  Jay P. Narayan 《Acta Geophysica》2014,62(3):425-450

This paper presents the ground motion amplification scenario along with fundamental frequency (F ₀) of sedimentary deposit for the seismic microzonation of Kolkata City, situated on the world’s largest delta island with very soft soil deposit. A 4th order accurate SH-wave viscoelastic finite-difference algorithm is used for computation of response of 1D model for each borehole location. Different maps, such as for F ₀, amplification at F ₀, average spectral amplification (ASA) in the different frequency bandwidth of earthquake engineering interest are developed for a variety of end-users communities. The obtained ASA of the order of 3–6 at most of the borehole locations in a frequency range of 0.25–10.0 Hz reveals that Kolkata City may suffer severe damage even during a moderate earthquake. Further, unexpected severe damage to collapse of multi-storey buildings may occur in localities near Hoogly River and Salt Lake area due to double resonance effects during distant large earthquakes.  相似文献   

Formation of radical species in photolyzed CH₄:N₂ ices     

Robert Hodyss  Heather R. Howard  Jay D. Goguen 《Icarus》2011,214(2):748-753

We report photochemical studies of thin cryogenic ice films composed of N₂, CH₄ and CO in ratios analogous to those on the surfaces of Neptune’s largest satellite, Triton, and on Pluto. Experiments were performed using a hydrogen discharge lamp, which provides an intense source of ultraviolet light to simulate the sunlight-induced photochemistry on these icy bodies. Characterization via infrared spectroscopy showed that C₂H₆ and C₂H₂, and HCO are formed by the dissociation of CH₄ into H, CH₂ and CH₃ and the subsequent reaction of these radicals within the ice. Other radical species, such as C₂, , CN, and CNN, are observed in the visible and ultraviolet regions of the spectrum. These species imply a rich chemistry based on formation of radicals from methane and their subsequent reaction with the N₂ matrix. We discuss the implications of the formation of these radicals for the chemical evolution of Triton and Pluto. Ultimately, this work suggests that , CN, HCO, and CNN may be found in significant quantities on the surfaces of Triton and Pluto and that new observations of these objects in the appropriate wavelength regions are warranted.  相似文献   

Incorporating uncertainty into the estimation of biological reference points for a spiny lobster (Panulirus penicillatus) fishery     

Yi‐Jay Chang  Chi‐Lu Sun  Yong Chen  Su‐Zan Yeh  Wei‐Chuan Chiang 《新西兰海洋与淡水研究杂志》2013,47(1):429-442

The status of a fishery is often defined as the probability of fishing mortality rate exceeding a perilous level for long‐term sustainability. Lobster stock assessments are often subject to large uncertainty in input data and high levels of natural variability in lobster life history processes, which calls for incorporating uncertainty associated with both indicator and management reference points in an evaluation of biological risk of overfishing. Using a Monte Carlo simulation approach, we evaluated the impacts of uncertainty in modelling on the determination of the status of the Taitung spiny lobster (Panulirus penicillatus) fishery (Taiwan), which has not been quantitatively determined despite its commercial importance. The commonly used biological reference points derived from the per recruit model (F _0.1 the fishing mortality rate where the slope of the curve of yield‐per‐recruit model is 10% of the maximum slope and F _4Q%, the fishing mortality rate that reduces the expected egg production for a cohort of female lobsters to 40% of that produced in the absence of a fishery of the egg‐per‐recruit model) were influenced by uncertainties associated with lobster life history and fishery parameters. A large uncertainty in the current fishing mortality rate (F _cnr) and estimates of biological reference points (F _BRPs) increased the uncertainty in determining the risk of overexploitation throughout the confidence levels of the stochastic decision‐making framework. This simulation study suggests that the target reference point of F _40% is less sensitive to the input parameters’ uncertainty than F _0.1 We suggest a further evaluation of other F‐based references points and development of biomass‐based reference points before final selection and implementation for the management of the Taitung lobster fishery.  相似文献   

Elasticity of antigorite,seismic detection of serpentinites,and anisotropy in subduction zones     

Lucile Bezacier  Bruno Reynard  Jay D. Bass  Carmen Sanchez-Valle  Bertrand Van de Moortèle 《Earth and Planetary Science Letters》2010,289(1-2):198-208

Serpentinization of the mantle wedge is an important process that influences the seismic and mechanical properties in subduction zones. Seismic detection of serpentines relies on the knowledge of elastic properties of serpentinites, which thus far has not been possible in the absence of single-crystal elastic properties of antigorite. The elastic constants of antigorite, the dominant serpentine at high-pressure in subduction zones, were measured using Brillouin spectroscopy under ambient conditions. In addition, antigorite lattice preferred orientations (LPO) were determined using an electron back-scattering diffraction (EBSD) technique. Isotropic aggregate velocities are significantly lower than those of peridotites to allow seismic detection of serpentinites from tomography. The isotropic V_P/V_S ratio is 1.76 in the Voigt–Reuss–Hill average, not very different from that of 1.73 in peridotite, but may vary between 1.70 and 1.86 between the Voigt and Reuss bonds. Antigorite and deformed serpentinites have a very high seismic anisotropy and remarkably low velocities along particular directions. V_P varies between 8.9 km s^? 1 and 5.6 km s^? 1 (46% anisotropy), and 8.3 km s^? 1 and 5.8 km s^? 1 (37%), and V_S between 5.1 km s^? 1 and 2.5 km s^? 1 (66%), and 4.7 km s^? 1 and 2.9 km s^? 1 (50%) for the single-crystal and aggregate, respectively. The V_P/V_S ratio and shear wave splitting also vary with orientation between 1.2 and 3.4, and 1.3 and 2.8 for the single-crystal and aggregate, respectively. Thus deformed serpentinites can present seismic velocities similar to peridotites for wave propagation parallel to the foliation or lower than crustal rocks for wave propagation perpendicular to the foliation. These properties can be used to detect serpentinite, quantify the amount of serpentinization, and to discuss relationships between seismic anisotropy and deformation in the mantle wedge. Regions of high V_P/V_S ratios and extremely low velocities in the mantle wedge of subduction zones (down to about 6 and 3 km.s^?1 for V_P and V_S, respectively) are difficult to explain without strong preferred orientation of serpentine. Local variations of anisotropy may result from kilometer-scale folding of serpentinites. Shear wave splittings up to 1–1.5 s can be explained with moderately thick (10–20 km) serpentinite bodies.  相似文献   

FIELDWORK AND GRAPHIC NARRATIVES     

Jeff Wilson  Jay Jacot 《Geographical review》2013,103(2):143-152

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Spatial analysis of linguistic data with GIS functions     

Jay Lee  William A. Kretzschmar Jr 《International journal of geographical information science》2013,27(6):541-560

Abstract

During the 1980s techniques for analysis of geographical patterns have been refined to the point that they may be applied to data from many fields. Quantitative spatial analysis and existing functions available in geographical information systems (GIS) enable computerized implementations of these spatial analysis methods. This paper describes the application of quantitative spatial analysis and GIS functions to analysis of language data, using the extensive files of the Linguistic Atlas of the Middle and South Atlantic States (LAMSAS). A brief review of recent development of using quantitative and statistical methods for analysing linguistic data is also included.  相似文献   

Delineating groundwater potential zones in a hard-rock terrain using geospatial tool     

Prafull Singh  Jay Krishana Thakur  Suyash Kumar 《水文科学杂志》2013,58(1):213-223

Abstract

Geospatial techniques have become one of the leading tools in the field of natural sciences for assessment, monitoring and management of natural resources, particularly in groundwater research. The paper discusses the demarcation and assessment of groundwater potential zones using geospatial techniques in the Deccan Volcanic Province of Maharashtra, India, using multi-criteria analyses. The study incorporates integration of thematic information (geomorphology, lithology, drainage density, slope and lineaments) in a GIS environment in order to identify groundwater potential zones. The methodology adopted can be used as a rapid assessment tool in groundwater exploration and is helpful in predictive groundwater resource management. Multi-criteria evaluation techniques were used to integrate all the thematic layers. Individual themes and their corresponding categories were assigned a knowledge base ranking from 1 to 5, depending on their importance for groundwater potential. Using the Raster calculator tool in Arc GIS software, all thematic maps were integrated to produce a composite groundwater potential map of the study area. The identified groundwater potential zones were classified into four classes, from excellent to poor. The generated groundwater potential zones were validated with field checks and borewell/dugwell yield data, and showed consistency with the observations.

Citation Singh, P., Thakur, J. K., and Kumar, S. (2013) Delineating groundwater potential zones in a hard-rock terrain using geospatial tools. Hydrological Sciences Journal, 58 (1), 1–11.  相似文献   

SOIL,SUBSOIL, AND FOREST COMPOSITION IN SOUTH-CENTRAL MICHIGAN,USA     

Sheridan L. Dodge  Jay R. Harman 《自然地理学》2013,34(1):85-101

Although soil texture is an important predictor of upland forest composition in southern Michigan, the relationship in some areas is weak and other environmental factors may exert stronger control on species composition. One of these may be concealed subsoil lithology where coarse-textured glaciofluvial sediments are buried beneath finer-textured till. Samples of forest composition, soil, and subsoil characteristics from 48 less-disturbed woodlots in the south-central Lower Peninsula reveal that upland oaks and hickories are predominant where the till veneer is thin and sand and gravel are relatively near the surface. Where till is relatively thick and outwash is deeply buried, woodlot composition is sugar maple-beech. In each of these cases, soil texture is unrelated to stand composition. The likely effect of buried near-surface glaciofluvial sediments is moisture stress such that xeric species dominate these drier sites. The influence of subsoil on forest geography is a significant new finding with regard to southern Michigan and has possible application elsewhere in glaciated eastern North America.  相似文献   

Application of the Ti-in-quartz thermobarometer to rutile-free systems. Reply to: a comment on: ‘TitaniQ under pressure: the effect of pressure and temperature on the solubility of Ti in quartz’ by Thomas et al.   总被引：2，自引：1，他引：1  

Jay B. Thomas  E. Bruce Watson 《Contributions to Mineralogy and Petrology》2012,164(2):369-374

The premise of the Wilson et al. comment is that the Ti-in-quartz solubility calibration (Thomas et al. in Contrib Mineral Petrol 160:743–759, 2010) is fundamentally flawed. They reach this conclusion because P–T estimates using the Ti-in-quartz calibration differ from their previous interpretations for crystallization conditions of the Bishop and Oruanui rhyolites. If correct, this assertion has far-reaching implications, so a careful assessment of the Wilson et al. reasoning is warranted. Application of the Ti-in-quartz calibration as a thermobarometer in rutile-free rocks requires an estimation of TiO₂ activity in the liquid ( (liquid–rutile); referenced to rutile saturation) and an independent constraint on either P or T to obtain the crystallization temperature or pressure, respectively. The foundation of Wilson et al.’s argument is that temperature estimates obtained from Fe–Ti oxide thermometry accurately reflect crystallization conditions of quartz in the two rhyolites discussed. We maintain that our experimental approach is sound, the thermodynamic basis of the Ti-in-quartz calibration is fundamentally correct, and our experimental results are robust and reproducible. We suggest that the reason Wilson et al. obtain implausible pressure estimates is because estimates for T and they used as input values for the Ti-in-quartz calibration are demonstrably too high. Numerous studies show that Fe–Ti oxide temperature estimates of some rhyolites are substantially higher than those predicted by well-constrained phase equilibria. In this reply, we show that when reasonable input values for T and (liquid–rutile) are used, pressure estimates obtained from the Ti-in-quartz calibration are well aligned with phase equilibria and essentially identical to melt inclusion volatile saturation pressures.  相似文献   

Overview and Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992�C2009     

H. Jay Zwally  Mario B. Giovinetto 《Surveys in Geophysics》2011,32(4-5):351-376

Mass balance estimates for the Antarctic Ice Sheet (AIS) in the 2007 report by the Intergovernmental Panel on Climate Change and in more recent reports lie between approximately +50 to ?250 Gt/year for 1992 to 2009. The 300 Gt/year range is approximately 15% of the annual mass input and 0.8 mm/year Sea Level Equivalent (SLE). Two estimates from radar altimeter measurements of elevation change by European Remote-sensing Satellites (ERS) (+28 and ?31 Gt/year) lie in the upper part, whereas estimates from the Input-minus-Output Method (IOM) and the Gravity Recovery and Climate Experiment (GRACE) lie in the lower part (?40 to ?246 Gt/year). We compare the various estimates, discuss the methodology used, and critically assess the results. We also modify the IOM estimate using (1) an alternate extrapolation to estimate the discharge from the non-observed 15% of the periphery, and (2) substitution of input from a field data compilation for input from an atmospheric model in 6% of area. The modified IOM estimate reduces the loss from 136 Gt/year to 13 Gt/year. Two ERS-based estimates, the modified IOM, and a GRACE-based estimate for observations within 1992?C2005 lie in a narrowed range of +27 to ?40 Gt/year, which is about 3% of the annual mass input and only 0.2 mm/year SLE. Our preferred estimate for 1992?C2001 is ?47 Gt/year for West Antarctica, +16 Gt/year for East Antarctica, and ?31 Gt/year overall (+0.1 mm/year SLE), not including part of the Antarctic Peninsula (1.07% of the AIS area). Although recent reports of large and increasing rates of mass loss with time from GRACE-based studies cite agreement with IOM results, our evaluation does not support that conclusion.  相似文献