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941.
First Order Seismic Microzonation of Delhi,India Using Geographic Information System (GIS) 总被引:2,自引:4,他引:2
William K. Mohanty M. Yanger Walling Sankar Kumar Nath Indrajit Pal 《Natural Hazards》2007,40(2):245-260
A first order seismic microzonation map of Delhi is prepared using five thematic layers viz., Peak Ground Acceleration (PGA)
contour, different soil types at 6 m depth, geology, groundwater fluctuation and bedrock depth, integrated on GIS platform.
The integration is performed following a pair-wise comparison of Analytical Hierarchy Process (AHP), wherein each thematic
map is assigned weight in the 5-1 scale: depending on its contribution towards the seismic hazard. Following the AHP, the
weightage assigned to each theme are: PGA (0.333), soil (0.266), geology (0.20), groundwater (0.133) and bedrock depth (0.066).
The thematic vector layers are overlaid and integrated using GIS. On the microzonation theme, the Delhi region has been classified
into four broad zones of vulnerability to the seismic hazard. They are very high (> 52%), high (38–52%), moderate (23–38%)
and less ( < 23%) zones of seismic hazard. The “very high” seismic hazard zone is observed where the maximum PGA varies from
140 to 210 gal for a finite source model of Mw 8.5 in the central seismic gap. A site amplification study from local and regional earthquakes for Delhi region using Delhi
Telemetry Network data shows a steeper site response gradient in the eastern side of the Yamuna fluvial deposits at 1.5 Hz.
The ‘high’ seismic hazard zone occupies most of the study area where the PGA value ranges from 90 to 140 gal. The ‘moderate’
seismic hazard zone occurs on either side of the Delhi ridge with PGA value varying from 60 to 90 gal. The ‘less’ seismic
hazard zone occurs in small patches distributed along the study area with the PGA value less than 60 gal. Site response studies,
PGA distribution and destruction pattern of the Chamoli earthquake greatly corroborate the seismic hazard zones estimated
through microzonation on GIS platform and also establishes the methodology incorporated in this study. 相似文献
942.
Manish Kumar Kalpana Kumari AL. Ramanathan Rajinder Saxena 《Environmental Geology》2007,53(3):553-574
Punjab is the most cultivated state in India with the highest consumption of fertilizers. Patiala and Muktsar districts are
two agricultural dominated districts of Punjab located in extreme south-east and south-west of the state. This paper highlights
temporal variations of the groundwater quality and compares its suitability for irrigation and drinking purpose in these two
districts. Water samples were collected in March and September 2003, representing the pre-monsoon and post-monsoon seasons,
respectively. Water samples were analysed for almost all major cations, anions, dissolved heavy metals and turbidity. Parameters
like sodium adsorption ratio, % sodium, residual sodium carbonate, total hardness, potential salinity, Kelley’s ratio, magnesium
ratio, index of base exchange and permeability index were calculated on the basis of chemical data. A questionnaire was also
used to investigate perception of villagers on taste and odour. Comparison of the concentration of the chemical constituents
with WHO (world health organization) drinking water standards of 2004 and various classifications show that present status
of groundwater in Patiala is better for irrigation and drinking purposes except for a few locations with a caution that it
may deteriorate in near future. In Muktsar, groundwater is not suitable for drinking. Higher total hardness (TH) and total
dissolved solids at numerous places indicate the unsuitability of groundwater for drinking and irrigation. Results obtained
in this forms baseline data for the utility of groundwater. In terms of monsoon impact, Patiala groundwater shows dilution
and flushing but Muktsar samples show excessive leaching of different chemical components into the groundwater leading to
the enrichment of different anions and cations indicating pollution from extraneous sources. No clear correlation between
the quality parameters studied here and perceived quality in terms of satisfactory taste response were obtained at electrical
conductivity values higher than the threshold minimum acceptable value. 相似文献
943.
Puthusserry J. Thomas Dontireddy V. Reddy Devender Kumar Pasupuleti Nagabhushanam Balbir S. Sukhija Radhendra N. Sahoo 《Quaternary Geochronology》2007,2(1-4):278-283
Optical dating of liquefied sand structures formed during major earthquakes in Upper Assam, northeast of India, has been carried out to constrain the timing of prehistoric earthquakes in this seismically active region. The bleaching of source material and of the same material during the creation of a liquefaction feature was tested using quartz extracted from 21 samples associated with two different liquefaction structures in Upper Assam. Due to the poor sensitivity of quartz from this region, a sensitisation procedure was used in our SAR protocol to reduce the scatter in optical ages. Various internal consistency tests of the measurement protocol and the excellent reproducibility of the OSL ages indicate that the dose estimates from the quartz are accurate and the optical ages reliable. The preliminary OSL ages indicate that the liquefaction features were formed between 1430 AD and 1630 AD. This study demonstrates that using OSL, ‘direct dating’ of prehistoric earthquakes may be possible, if sand blows from liquefied dykes are preserved. 相似文献
944.
New statistical models for long-range forecasting of southwest monsoon rainfall over India 总被引:2,自引:0,他引:2
The India Meteorological Department (IMD) has been issuing long-range forecasts (LRF) based on statistical methods for the
southwest monsoon rainfall over India (ISMR) for more than 100 years. Many statistical and dynamical models including the
operational models of IMD failed to predict the recent deficient monsoon years of 2002 and 2004. In this paper, we report
the improved results of new experimental statistical models developed for LRF of southwest monsoon seasonal (June–September)
rainfall. These models were developed to facilitate the IMD’s present two-stage operational forecast strategy. Models based
on the ensemble multiple linear regression (EMR) and projection pursuit regression (PPR) techniques were developed to forecast
the ISMR. These models used new methods of predictor selection and model development. After carrying out a detailed analysis
of various global climate data sets; two predictor sets, each consisting of six predictors were selected. Our model performance
was evaluated for the period from 1981 to 2004 by sliding the model training period with a window length of 23 years. The
new models showed better performance in their hindcast, compared to the model based on climatology. The Heidke scores for
the three category forecasts during the verification period by the first stage models based on EMR and PPR methods were 0.5
and 0.44, respectively, and those of June models were 0.63 and 0.38, respectively. Root mean square error of these models
during the verification period (1981–2004) varied between 4.56 and 6.75% from long period average (LPA) as against 10.0% from
the LPA of the model based on climatology alone. These models were able to provide correct forecasts of the recent two deficient
monsoon rainfall events (2002 and 2004). The experimental forecasts for the 2005 southwest monsoon season based on these models
were also found to be accurate. 相似文献
945.
Liton Kumar SARKER M. Monowar HOSSAIN M. Anisul HAQUE 《国际泥沙研究》2007,22(3):169-179
Experiments on initiation of motion of different fractions of non-uniform sediment mixtures are reported. Four sediment mixes and reference transport method to define the threshold of bed particle movement are used in this analysis. Factors controlling the initiation of motion are analyzed. It is found that relative size of different grains with respect to a median size greatly affects the initiation of movement. The incipient motion of non-uniform sediment is very much dependent on the absolute size for coarser fractions. Considering the factors controlling the initiation of motion the experimental data sets along with the other available data yield a new relationship for the calculation of critical shear stress of non-uniform sediments. A set of equations have found that all the data points fall into a single line for the finer and for coarser fractions. 相似文献
946.
Shusaku Inoue Anil C. Wijeyewickrema Hiroyuki Matsumoto Hiroyuki Miura Priyantha Gunaratna Manoj Madurapperuma Toru Sekiguchi 《Pure and Applied Geophysics》2007,164(2-3):395-411
The December 26, 2004 Sumatra-Andaman earthquake that registered a moment magnitude (Mw) of 9.1 was one of the largest earthquakes in the world since 1900. The devastating tsunami that resulted from this earthquake
caused more casualties than any previously reported tsunami. The number of fatalities and missing persons in the most seriously
affected countries were Indonesia - 167,736, Sri Lanka - 35,322, India - 18,045 and Thailand - 8,212. This paper describes
two field visits to assess tsunami effects in Sri Lanka by a combined team of Japanese and Sri Lankan researchers. The first
field visit from December 30, 2004 – January 04, 2005 covered the western and southern coasts of Sri Lanka including the cities
of Moratuwa, Beruwala, Bentota, Pereliya, Hikkaduwa, Galle, Talpe, Matara, Tangalla and Hambantota. The objectives of the
first field visit were to investigate the damage caused by the tsunami and to obtain eyewitness information about wave arrival
times. The second field visit from March 10–18, 2005 covered the eastern and southern coasts of Sri Lanka and included Trincomalee,
Batticaloa, Arugam Bay, Yala National Park and Kirinda. The objectives of the second visit were mainly to obtain eyewitness
information about wave arrival times and inundation data, and to take relevant measurements using GPS instruments. 相似文献
947.
D.G. Kaskaoutis H.D. Kambezidis Shailesh Kumar Kharol K.V.S. Badarinath 《Atmospheric Research》2007,86(3-4):286-296
This study focuses on the determination of optical depths caused by ozone and trace gases absorption in the Chappuis band, 500–700 nm, and the contribution to the Total Minus Rayleigh Optical Depth (TMROD). The optical depths were derived using the transmission functions implemented in the SMARTS parametric model, while the Total Optical Depths (TODs) were derived by solar extinction measurements obtained in Athens during May 1995. From the data analysis it is obvious that both the ozone and trace gases contribute significantly to TMROD in the Chappuis band. More specifically, the trace gases contributions are higher for air with high pollution levels, while ozone's contribution can be significant under clear-sky conditions. Therefore, the correction in TMROD due to ozone and trace gases optical depths is necessary for an accurate determination of the Aerosol Optical Depth (AOD) in the Chappuis band. The optical depth of ozone is generally removed during the process of the AOD retrievals, since the significance of its absorption in the Chappuis band is well understood. Nevertheless, the optical depth of the trace gases (mainly NO2) is not always taken into account in the AOD retrievals, though its contribution can be significant in urban polluted atmospheres. In this respect, the present study attempts to quantify the ozone and trace gases contributions in an urban environment and to provide some new functions that help estimate the contribution of ozone to the TMROD in the Chappuis band. 相似文献
948.
Bianchi Type I magnetized Cosmological model for perfect fluid distribution is investigated. The magnetic field is due to
an electric current produced along x-axis. The distribution consists of an electrically neutral perfect fluid with an infinite electrical conductivity. To get
a determinate solution, a supplementary conditionA = BC between metric potentials is used. The behaviour of the model in presence and absence of magnetic field is also discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
949.
Fluorescence efficiencies of electrons in a large number of bands of N2 second positive and N2+ first negative groups lying in the 3000–5200 Å region are calculated. At very low pressure where quenching is negligible the present values are within 15 per cent of the experimental data of Hartmann (1968). The efficiencies are found to be independent of the impact energies greater than 200 eV which is in accordance with other theoretical and experimental results. The ratio of the total efficiencies in N2 second positive and N2+ first negative groups is 1·31 and is about 20 per cent lower than the experimental values. The efficiencies at a higher pressure equal to 600 torr are compared with the experimental data of Davidson and O'Neil (1964a). 相似文献
950.
Shailendra Kumar 《Icarus》1976,28(4):579-591
Measurements made during the Mariner 10 flybys of Mercury have shown that this planet has a tenuous atmosphere, somewhat similar to that of the Moon, which consists of at least helium and can be classified as an exosphere. The amount of helium observed can be supplied by either the accretion of only a fraction of the solar wind He2+ diffusing across the magnetopause, or from outgassing of radiogenic helium from the planetary crust. The role of solar wind in the maintenance and depletion of Mercury's atmosphere is discussed in view of the density upper limits established from Mariner 10. The argon supply rate on Mercury is probably not more than that on the Earth, but it is difficult to say whether Mercury is deficient in potassium or not on the basis of the present data. The global outgassing of CO2 and H2O from the planet interior is estimated to be at least four orders of magnitude smaller than for Earth which indicates that either Mercury is deficient in volatiles or that this planet is very inactive. 相似文献