005626   Suresh R;Ravichandran P K;Gupta J P;Thampi S B;Kalyanasundaram S (India Meteorological Dep, , Chennai-600 001) : Optimum rain rate estimation from a pulsed doppler weather radar at Chennai. Mausam 2005, 56(2), 433-46.

A 10 cm S-band Doppler Weather Radar (DWR) has been installed as a replacement of an outlived analogue S-band radar at Cyclone Detection Radar (CDR) station, Chennai during September-October, 2001. Technical specifications and capabilities of this DWR have been briefly mentioned. The digital data obtained from this DWR have been used for the period November-December, 2001 to estimate the rain rate based on the Marshall-Palmer relationship between the radar reflectivity factor (z) and the rain rate (R). The relation z = 267R_1.345 estimates well the rain rate as measured by the self recording rain gauges located within 100 km radius from the DWR. This relationship has been tested for its operational applicability during March 2002 - December 2003 and found that the accumulated precipitation from the radar estimation was within an error of 15% from the rain gauge measured values. Information on the twenty four hours accumulated areal distribution of precipitation can be used by the water managers and operational hydrologists for the effective water management over the catchments since the error in rain rate estimation over a wider area is relatively small in comparison to point rainfall estimation.

10 ref, 29 ref

005625   Suresh R;Aravindan V;Rajesh Rao P;Bhatnagar A K (India Meteorological Dep, , Chennai-600 001) : Clear air echoes from the atmospheric boundary layer over Chennai - a study using S-band doppler weather radar. Mausam 2005, 56(2), 447-64.

During December 2002 - early April 2003, between 2345 and 0215 UTC and between 1230 and 1400 UTC covering the twilight period, radar reflectivities as high as 28-38 dBZ were measured in the atmospheric boundary layer by the Doppler Weather Radar (DWR) installed at Cyclone Detection Radar station, Chennai regularly. On analysis, it was found that these radar returns were not from precipitating clouds but from some other invisible source(s). The contributory mechanisms for this high order of reflectivity have been analysed from meteorological and non-meteorological angles. Thermodynamical parameters and potential radio refractive index have been computed and analysed. The refractive index structure constant (C_n²) has been computed from the 0000 and 1200 UTC RS/RW data as well as from the radar reflectivity data. The prevalence of convectively unstable atmosphere in the first layer adjacent to the surface (upto 350 m a.g.l) at 1200 UTC and nocturnal surface inversion at 0000 UTC contribute to the enhanced C_n² in the range of 3.58 x 10^-12 to 10^-15 m-^2/3 in the layers upto 900 m a.g.l. This sort of Bragg scattering with high C_n² could have contributed to radar reflectivity factor as high as +0.8 dBZ only. During the last three decades, there is an alarming increase in nocturnal surface inversion frequencies over Chennai presumably due to high concentration of suspended paniculate matters and respirable dust particles. The contribution by these pollutants to the radar reflectivity factor is restricted to a maximum of about - 0.9 dBZ only. Migratory birds of about eight to twelve thousand in number with 10 - 50 cm² radar cross section and possibly innumerable insects appear as sources of the enhanced reflectivity.

8 illus, 5 tables, 43 ref

005624   Srivastava R C (NO, Wat Technol Cent for East Region, Bhubaneswar-751 023) : Management of runoff recycling systems through multipurpose utilization in humid plateau areas of Eastern India. Indian Fmg 2004, 54(6), 19-20, 7.

Low and unstable yields and resource poor farmers characterize the rainfed areas of the plateau region of eastern India. The climatic water balance of the region shows that water deficit is prevalent from November to May in almost all locations. The irrigation development is poor and therefore the cropping intensity is also quite low. Due to these factors, a high per cent of population (<62>40%) is below poverty line and in absence of employment opportunities, migration of labourers take place creating serious socio-economic consequences. Rainwater harvesting has potential of being an alternate to water resource which can provide full irrigation in conjunction with rainfall in a rice-based two crop rotation. There is potential of runoff recylcing-based irrigation system meeting the evaporative demand of a two crop rotation is a particular catchment area. The water harvesting-based irrigation system has its multiple uses for horticulture, fisheries and duckery, which is a profitable proposition.

4 tables

005623   Sridharan S;Muthuchami A (Regional Meteorological Cent, , Chennai) : Statistical study of excess and deficient rainfalls over Jalpaiguri. Mausam 2005, 56(2), 485-95.

^ssc7 illus, 2 tables, 3 ref

005622   Sinha Y B (Director (Exploration), Oil & Nat Gas Corporation, Dehradun) : Leveraging knowledge base in hydrocarbon exploration in India - key driver for bridging demand-supply gap. J Geophys 2005, 26(1), 3-10.

Exploration & production sector, traditionally, is a knowledge-based industry. In the current context in India, as one target new objectives in established sectors and venture into logistically difficult & geologically ancient areas on one hand and the cost intensive deep water domains on the other, leveraging the emerging knowledge base assumes importance and becomes focus for a collective approach. This conference, with its focal theme of "Petroleum Exploration in India-Emerging knowledge base" will therefore provide the most appropriate platform, at the present juncture, as the Country is taking a giant step forward, in its endeavor to expand the E&P horizon to the new frontiers, envisioning enhancement in domestic supply. Reports few essential components of the available knowledge base in hydrocarbon exploration.

9 illus

005621   Sinha S (Indian Inst of Trop Meteorology, , Pune-411 008) : Representative scales of LASPEX wind data. Mausam 2005, 56(2), 401-4.

In this study, an attempt is made to identify the appropriate scales for the wind data over the stations covered in the LASPEX experiment, which can be considered to represent the large-scale wind pattern, representative of the whole area, covered by the field experiment. The divergence field was chosen for this purpose. The mean of the latitudes and longitudes of all the five stations was calculated and this represented the latitude and longitude respectively, of the central point. The wind components at each of the five stations were arbitrarily represented by a trigonometric function of wavelength and distance from the central point, which was considered as the origin. The divergence values at each station were computed and the mean value over all the stations was found. The same values of winds were used to compute the large scale divergence field over the area, by applying the method devised by Yanai et al. (1973). It was seen that for wavelengths greater than 2830 km, the ratio of the two divergences was greater than 0.9, suggesting that this was the limiting value of the wavelength which can be considered as representative of the entire area.

3 illus, 2 ref

005620   Singh Y P;Pathak R K;Nath K K (Geophysics Dep, Oil India Limited, Duliajan, Assam-786 602) : Estimation of porosity using principal component and stefwise multiple regression analysis of seismic attributes - a case study. J Geophys 2005, 26(2), 69-78.

A scheme for estimation of porosity from 3-D seismic attributes and well data is described. The methodology mills to find best statistical relationship for estimation of porosity from available well data and seismic attributes extracted from 3-D seismic volume. Principal Component Analysis (PCA) of extracted seismic attributes creates a new series of independent attributes (PC attributes). Forward stepwise multiple regression analysis derives optimum set of attributes from larger set of attributes, which also justify the efficacy of seismic and PC attribute sets. Like reliability of the derived relationship is estimated using cross validation criteria. The validation error, which is the average error for all the hidden wells, is used as a measure of the likely prediction error when the relationship is applied over the area away from wells. The scheme has been tested on the real data set from one of the oil fields in Upper Assam India, The prediction/validation error observed with PC attributes is lower than that of the same derived from seismic attributes. For nonlinear transformed sets or PC and seismic attributes, the prediction validation error reduces significantly from one observed with linear sets of PC and seismic attributes respectively. The prediction/validation error was lowest in case of nonlinear transformed set of PC attributes, this establishes that the porosity map for entire study area calculated by using nonlinear transformed PC attributes would be most accurate. The data reduction and other computational advantages associated with PC attributes make it a favorable solution for accurate porosity estimation.

11 illus, 3 tables, 11 ref

005619   Singh R P;Patel R P;Rajesh Singh;Singh R N (Atmospheric Res Lab Phys Dep, Banaras Hindu Univ, Varanasi-221 005) : Lightning produced nitrogen oxides in the lower atmosphere. Indian J Radio Space Phys 2005, 34(4), 248-54.

Nitrogen oxides are dominant constituents of the atmospheric lower regions namely, troposphere and stratosphere. Lightning phenomenon plays an important role in governing the odd nitrogen oxides in the lower atmosphere and hence in global change process. Studies made by different workers on the lightning produced nitrogen oxides and other related phenomena have been reviewed. Studies in this direction are very sparse in India. Besides the ground based, balloon-borne and satellite-borne measurements, aircraft measurements in India and elsewhere are essential for providing global information. In order to make reliable measurements the experimental site should be in remote areas free from heavy industrial pollution, so that the contaminations due to direct influence of anthropogenic activities are avoided.

6 illus, 1 table, 47 ref

005618   Singh P K;Mittal S K;Manjeet Singh;Sharma B K (Geo Scientific Instrument Div, Cent Scientific Instruments Organisation, Sector 30C, Chandigarh-160 030, Email: skmskm1@rediffmail.com) : Design of high power pump source of eye safe laser for geo-scientific application. Indian J pure appl Phys 2005, 43(7), 517-21.

The design consideration of high power diode laser at wavelength of 980 nm as pump source for erbium doped glass eye safe laser at wavelength 1.54 μm is presented. The design of high power laser requires precise control of waveguide dimensions, material and doping profile of layers. The maximum optical power is proportional to transverse optical spot size. The transverse optical spot size and threshold current density have been calculated with transverse waveguide thickness. The effect of current spreading on threshold current density is calculated. The geo-scientific application of eye safe laser is also presented.

5 illus, 1 table, 21 ref

005617   Singh D;Rama Rao Y V;Bhatia R C;Srivastav S K;Prasad S;Mukharjee S R (Indian Meteorological Dep, , New Delhi-110 003) : Operational use of improved profiles by using neural network technique derived from NOAA satellites microwave data in NWP model over Indian region. Mausam 2005, 56(2), 357-66.

Reports that temperature and moisture profiles retrieved from NOAA-16 ATOVS data over Indian region have been used in regional NWP model for the impact study. The operational NWP system of India Meteorological Department is based on a Limited Area Analysis and Forecasting System (LAPS), which consists of real time processing of data received on Global Telecommunication System (GTS), objective analysis by 3-D multivariate optimum interpolation (OI) scheme and a multi-layer primitive equation model. Several experiments were performed using temperature and moisture profiles retrieved from NOAA-16 ATOVS data. Using this data several experiments were undertaken to examine the impact of these data sets on some of the important weather syrtems such as monsoon depression, active monsoon conditions during monsoon 2003. The preliminary studies reveal that these additional data have a positive impact on rainfall prediction of the limited area model. Results of specific cases of impact studies are presented.

10 illus, 7 ref

005616   Singh C;Bandyopadhyay B K (Indian Meteorological Dep, , New Delhi-110 003) : Decaying characteristics of severe cyclonic storms after landfall over east coast of India. Mausam 2005, 56(2), 395-400.

Severe tropical cyclones are responsible for large casualties and considerable damage to property and agricultural crop. After the landfall, the main damages from cyclones are due to strong wind. An attempt has been made to study the nature of decay of wind speed of tropical cyclones after landfall for the period 1990-2003. It is found that the maximum wind speed decreased exponentially after landfall. A severe cyclonic storm decay to cyclonic storm within 6 to 9 hours after landfall where as very severe cyclonic storm decay to severe cyclonic storm within 6 hours and to cyclonic storm within 15 hours after the landfall. The mean decay rate is found to be 0.46 for the first 6 hours and 0.59 for the subsequent 6 hours.

5 illus, 4 tables, 5 ref

005615   Shrivastava P K;Neelam Singh (Dep of Phys, Government Model Sci Coll, Rewa-486 001, Email: pankaj_in_2001@rediffmail.com) : Solar longitudinal distribution of solar flares in association with Forbus decreases. Indian J Radio Space Phys 2005, 34(3), 175-8.

Solar flares are complex transient excitation of the solar atmosphere above magnetically active region of the solar surface. In the study major solar flare events have been utilized to study their longitudinal frequency distribution in eastern and western hemisphere of the sun. A statistical study has been done to derive their association with Sudden Storm Commencements (SSCs) and Forbush decreases (Fds) for the period of solar cycle 22 (1986 to February, 1996) and recent period of solar cycle 23 (March, 1996 to August, 2003). It has been noted that large number of solar flares in the solar western hemisphere are found to be associated with Forbush decreases. It is found for solar cycle 22 that the number of solar flares (Fd associated) that occurred in western hemisphere is larger as compared to that in eastern hemisphere. Number of SSC associated solar flares are also found to be larger in the solar western hemisphere.

1 illus, 1 table, 18 ref

005614   Sethi N K;Pandey V K (Radio and Atmospheric Sci Div, Natn Phys Laboratory, Dr K S Krishnan Road, New Delhi-110 012) : TEC derived from incoherent scatter measurements during solar maximum and their comparison with IRI-2001 model. Indian J Radio Space Phys 2005, 34(3), 184-90.

The diurnal and seasonal variations of the total electron content (TEC), derived from high resolution electron density profiles measured with the Arecibo (18.4°N, 66.7°W, dip 50°N) incoherent scatter radar, are examined during high sunspot activity period (1989-90). Median values of TEC are then obtained at each hour during different seasons and compared with those obtained from the latest available International Reference Ionosphere (IRI-2001) model. The diurnal variations of TEC show more or less similar trend during all the seasons (i.e. maximum around daytime and minimum around midnight) with the largest values of TEC during equinox. The variability of TEC is larger at night than by day during all the seasons. Comparison of the diurnal variation of the observed median values of TEC with those predicted by the IRI model reveals, in general, similar trend during all the seasons and at all local times except during winter, when the IRI exhibits diurnal peak of TEC at around 0900 hrs LT, and the observed median peak occurs at around 1400 hrs LT. Discrepancies between the IRI and the median values exceed 40% during nighttime for winter and equinox. However, during daytime, they are less than 20% for all the seasons, except winter morning hours. The TEC peak content increases by a factor of around 4 from solar minimum (1975-1976) to solar maximum (1989-1990).

5 illus, 22 ref

005613   Samui R P;Chattopadhyay N;Sable J P; Karthikeyan K;Balachandran P V (NO, India Meteorological Dep, Pune-411 005) : Weather based forewarning of green jassid attack on kharif rice and operational crop protection at Pattambi, Kerala. Mausam 2005, 56(2), 405-16.

The feasibility of meteorological forewarning of green jassid attack has been made using entomological and meteorological data for a period of 15 years from 1987- 2001 recorded daily at Pattambi in Kerala. Stepwise multiple regression technique is used in this study for developing forewarning models. The study revealed that maximum and minimum temperature, morning and afternoon relative humidity, bright sunshine hours and weekly totals of rainfall have profound effect on the development of green jassid at their successive generations on kharif rice crop. Weather based multiple regression models for the peak infestation period for each of the generations of the pest were developed using data for the period 1987-99 and validated using observed meteorological as well as pest data for 2000-01. Based on the findings of this study pest weather calendar for green jassid of kharif rice was prepared. This calendar would be useful for early warning and operational rice crop protection from green jassid attack.

6 illus, 2 tables, 6 ref

005612   Roy Bhowmik S K;Joardar D;Rama Rao Y V;Hatwar H R (India Meteorological Dep, , New Delhi) : Initialization of monsoon onset vortex from the use of MSMR surface wind. Mausam 2005, 56(2), 477-81.

^ssc4 illus, 1 table, 7 ref

005611   Rao U N;Sarkar A;Mohan M (Meteorology and Oceanography Grp, Space Applic Cent ISRO, Ahmedabad-380 015) : Theoretical Z-R relationship for precipitating systems using Mie scattering approach. Indian J Radio Space Phys 2005, 34(3), 191-6.

Making use of Mie scattering formulation from the classical electromagnetic theory, backscattering efficiency and radar reflectivity have been derived for a wide range of rain rates. The coefficients of Z-R (Z = radar reflectivity factor, R = rain rate, mm/h) relationships have been theoretically computed for 2.84 GHz (used in coastal Doppler radars), 13.8 GHz (used in the space-borne precipitation radar on-board TRMM satellite) and also 35.5 GHz (to be used in the forthcoming Global Precipitation Mission Radar). The Mie scattering results were compared with those obtained in the Rayleigh approximation. Analyses have been carried out for the well known Marshall-Palmer and Log-normal dropsize distributions. The theoretical approach allows for any other dropsize distribution of precipitating system and operating radar frequency.

5 illus, 2 tables, 18 ref

005610   Rama Rao Y V;Kar S C;Vijaya Kumar T S V;Kalsi S R;Hatwar H R;Roy Bhowmik S R (India Meteorological Dep, , New Delhi-110 003) : Improvements in the weather prediction over the Indian region using regional spectral model. Mausam 2005, 56(2), 343-56.

Florida State University Regional Spectral Model (FSURSM) has been installed at India Meteorological Department, New Delhi and test runs have been made. A suitable-changd in the model code were made to use analysis and forecast fields as initialiand boundary conditions, for the model from the global T-80 model run at the National Centre for Medium Range Weathet Forecasting (NCMRWF) The resolution of the regional spectral model is 0.75" transform grid, which is equivalent, to the resolution of. a T-170 global model. The model has been integrated for 3 days and studies undertaken to jest the performance of the regional model in respect of some of the major weather events that oceurrcd during, December 2002 and February 2003. Using initial analyses from ECMVW and NGMRWF the impact of initial fields on model forecast is also investigated. The case studies show that the forecasts from forecast from the regional spectral model are reasonably close to the observed features. The intensity and movement of model simulated systems are good agreement with the observations.

9 illus, 18 ref

005609   Rajasekhar R P;Mishra D C (Natn Geophys Res Inst, , Hyderabad) : Archean-proterozoic collision tectonics across Chota Nagpur granite gneissic complex and singhbhum craton: based on gravity studies integrated with geological information. J Geophys 2005, 26(2), 85-91.

Gravity data of Chota Nagpur Granite Gneissic Complex (CGGC) and Singhbhum craton in the eastern part of Satpura Mobile Belt (8MB) are analysed for crustal structure and their role in the evolution of this region. The two phases of lower crustal rocks in Chota Nagpur Granite Gneissic Complex (CGGC) related to 1.6 Ga and 1.0 Ga are associated with gravity highs. The gravity highs related to lower crustal rocks in this section are extensions of similar gravity highs from central India related to same rock types of pre and post sausar orogeny. The gravity lows of Central Indian Shear (CIS) in central past of SMB extends eastward as gravity lows of almost same order associated with South Purulia Shear Zone (SPSZ). The gravity modelling along a profile constrained from seismic section and gravity model along an adjoining profile across central part of SMB suggest high density rocks in upper crust associated with SPSZ as thrusted lower crustal rocks and crustal thickening under Singhbhum craton. The gravity highs of Singhbhum craton are related to high density mafic rocks of Chandil and Dalma-Dhanjori volcanics, which show affinity to island arc type magmatism. This tectonic setting suggest a Proterozoic collision between Bundelkhand craton to the north and Singhbhum craton to the south with South Purulia Shear Zone (SPSZ) as suture as has been suggested in case of CIS in central part of SMB. Thrusting and southward subduction during collision gave rise to lower crustal rocks of CGGC and subduction related magmatism of Chandil and Dalma -Dhanjori volcanics of Singhbhum craton.

4 illus, 21 ref

005608   Prabhakaran Nayar S R;Sreehari C V;Shibu S; Devassia C V;Subba Rao K S V;Mohankumar S V (Dep of Phys, Univ of Kerala, Trivandrum-695 581, Email: srp@md2.vsnl.net.in) : Multi-frequency HF Doppler radar observations of vertical plasma drift preliminary results. Indian J Radio Space Phys 2005, 34(4), 233-42.

A multi-frequency HF Doppler radar system suitable for ionospheric F-region vertical drift studies has been installed at the magnetic equatorial station, Trivandrum, India (8.33°N, 77°E, dip 0.4°N). The speciality of the system is the usage of three frequencies (2.5 MHz, 3.5 MHz and 4.5 MHz) in a nearly simultaneous manner, which gives F-region vertical plasma drifts at three successively higher altitudes over the sounding station. The radar is mainly used to study the nocturnal vertical drift characteristics such as pre-reversal enhancement, onset of spread-F, short-period fluctuations, etc. An equinoctial maximum in pre-reversal enhancement of vertical drift is noted. Characteristics of short-period fluctuations are studied. Preliminary results of multi-frequency sounding are presented.

8 illus, 1 table, 32 ref

005607   Mahajan K K;Dwivedi A K (Radio & Atmos Sci Div, Natn Phys Laboratory, New Delhi-110 012) : Solar EUV flux during sunspot cycles 21, 22 and 23-correlation with proxy indiees and real time prediction. Indian J Radio Space Phys 2005, 34(3), 153-60.

Langmuir probe on the Pioneer Venus Orbiter measured the total solar EUV flux during large portions of sunspot cycles 21 and 22, while CELIAS/Solar EUV Monitor (SEM) on the Solar and Heliospheric Observatory (SOHO) measured this flux in the spectral ranges 26-34 nm and 0.1-50 nm during the whole of sunspot cycle 23. Daily values of these EUV fluxes are studied in relation to various often-used proxy indices to identify a single index which has the highest correlation coefficient with the observed values during all the three sunspot cycles. It is observed that no single index exhibits this feature. However, almost all the proxy indices averaged over one-half or more solar rotations show a high degree of correlation with the daily EUV flux. Further, the solar magnetic field is found to exhibit somewhat better correlation and it is recommended that this index averaged over three previous solar rotations may be used for real time prediction of solar EUV flux.

9 illus, 3 tables, 14 ref

005606   Kotal S D;Roy Bhowmik S K;Bandyopadhyay B K; Awadhesh Kumar;Hatwar H R (Indian Meteorological Dep, , New Delhi) : Some upper air circulation and thermal features in relation to the onset of south-west monsoon over Kerala. Mausam 2005, 56(2), 481-5.

^ssc3 illus, 12 ref

005605   Kayal J R (Geol Surv of India, , 27, J L Nehru Road, Kolkata) : Seismotectonics of India with special reference to Northeast region. J Geophys 2005, 26(1), 51-7.

3 illus, 27 ref

005604   Kathiroli S;Rao D V;Rama Chandra Murthy P S (Natn Inst of Ocean Technol, , Chennai) : High resolution seismic surveys - gulf of cambay. J Geophys 2005, 26(2), 79-84.

The preliminary subbottom and side scan surveys carried out in the Gulf of Cambay recorded a few N-S structural trends. For obtaining better definition of these structural trends, high resolution seismic surveys were carried out along 23 E-W trending lines across the Gulf. While a lot of literature is available on the tectonic movements and sea level changes in the basin during Tertiary, not much is understood on the Quanternary tectonics/neotectonics of the gulf. The study has thrown some light on the neotectonics of the region in the recent past with the seismic sections depicting the area to have undergone intense folding and faulting. The layers are sheared and conspicuously absent with several features of faulting at surface and subsurface. In all, 8 major lineaments are demarcated with majority of them trending NW-SE direction. Several focal centers for the fault mechanism have been identified. Due to active neotectonism associated with these focal centers, continuity of the subsurface layers is affected and often discontinuities in the eastern side. Several vertical faults, often having less than a meter displacement, are identified.

13 illus, 4 ref

005603   Kane R P (NO, , ) : Total solar irradiance (TSI) and terrestrial climate. Mausam 2005, 56(2), 3495-8.

^ssc2 illus, 11 ref

005602   Kane R P (Instituto Nacional de Pesquisas Espacias- INPE, , C P 515, 12245-970-Sao Jose dos Campos, SP, Brazil) : Spectral characteristics and ENSO relationship of the parana river streamflow. Mausam 2005, 56(2), 367-74.

A spectral analysis of the Parana river stream flow for 1904-1999 for 3 seasons indicated a periodicity of -8.5 years in all seasons, with extra periodicities at <126>17, <126>5, <126>3.7 and <126>2.8 (QBO) years in JFMA months, at <126>29, <126>13, <126>4.7, <126>3.7, <126>2.4 and <126>2.1 (QBO) years in MAMJ months, and at <126>27 and <126>3.4 years (no QBO) in SOND months. El Ninos were associated with positive anomalies (floods) of the stream flow, with lags of few months. Pacific SST anomalies were of the same peak magnitude in the giant El Nino events of 1982 and 1997, but the stream flow anomalies were much larger in 1983 as compared to 1997. The rise and fall of the stream flow anomalies was oscillatory with peak separation of <126>5 months.

5 illus, 1 table, 15 ref

005601   Kane R P (NO, Instituto Nacional de Pesquisa Espaciais, Sao Jose dos Campos, Sao Paulo, Brazil, Email: kane@dage.inpe.br) : Cosmic ray variations during density extremes in solar wind. Indian J Radio Space Phys 2005, 34(3), 171-4.

A comparison of the variations of the cosmic ray neutron monitor intensities with variations of geomagnetic disturbance D_st and (number) densities N of interplanetary plasma observed near the Earth during June-August 1979 and May 1999 (intervals when N was abnormally low) has been presented. It showed that cosmic ray variations were very loosely related to D_st variations (variations often out-of-phase by several days, and magnitudes not proportional) and had no relationship with plasma densities N (low or high).

2 illus, 10 ref

005600   Kane R P (NO, Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos, SP, Brazil, Email: kane@laser.inpe.br) : Hysteresis and non-linearity between solar EUV and 10.7 cm fluxes. Indian J Radio Space Phys 2005, 34(3), 161-70.

It has been reported in literature that for values of the solar 2800 MHz radio flux (10.7 cm, F10) exceeding 200, solar EUV values show saturation effects. This aspect was examined using EUV data obtained by the AE-E satellites during 1977-1981 and the SEM/SOHO satellite data from 1996 onwards up to date. It was noticed that the saturation effects were not always seen in sequences of days when F10 exceeded 200. In both of these data sets, near solar maximum, there were slight differences in the evolution of the EUV and F10. Either their peaks were slightly displaced and/or their evolution profiles were different, the F10 remaining steady for several months after peaking (flat peak), while the EUV started decreasing soon after peaking, indicating probable 'hysteresis' loops.

11 illus, 2 tables, 35 ref

005599   Jegannathan G;Satyamurthy P;Sathyanarayanan L (NO, Atom Miner Directorate of Explor and Research, Bangalore-560 072) : Low energy gamma-ray spectrometry - a technique for estimation of high grade uranium in geological samples. Indian J pure appl Phys 2005, 43(7), 494-502.

Low Energy Gamma-Ray Spectrometry (LEGS) has been proved to be a rapid technique for analyzing high-grade uranium in geological samples. From the low energy portion between (40-400 keV) of the gamma-ray spectrum of uranium and thorium series, the contents of uranium, its daughter radium (eq), and thorium are determined. This gives significant information about the geochemical anomalies. A standard gamma ray spectrometer with a 1_3/4 x 2 well type Nal (Tl) gamma detector constitutes the instrumentation requirements of this technique. Sample weighing about a few grams in a glass vial is used for analysis. A detailed study on the contribution of uranium daughter's energies in gamma spectrum of uranium has made the system more efficient for analyzing high grade (20%) uraniferous samples. Minimum personal exposure and an excellent correlation of uranium values with the chemical results have made this technique a versatile one in high-grade uranium exploration programme. Problems faced by the conventional methods that is Beta-Gamma and High Energy Gamma-Ray Spectrometry used for determining the contents of uranium and thorium in high-grade uraniferous geological samples and the advantage of this technique over them have been dealt with.

16 illus, 7 tables, 2 ref

005598   Ghude S D;Jain S L;Arya B c;Bajaj M M (Radio and Atmospheric Sci Div, Natn Phys Laboratory, New Delhi-110 012, Email: sachinghide@mail.nplindia.ernet.in) : Comparison of total column water vapour measured at New Delhi, Maitri (Antarctica), Leh and Hanle. Indian J Radio Space Phys 2005, 34(4), 264-8.

Measurement of total column water vapour made over Maitri (70.44°S, 11.45°E), Antarctica, using MICROTOPS-II sun-photometer during 2002 showed that the monthly average concentration of water vapour varied from 0.67 cm to 0.18 cm. Water vapour concentration was found varying significantly with season and time of the day. The measurements carried out during 1997, 2002 and 2003 during voyage from Delhi to Antarctica revealed that the concentration of water vapour decreases with increasing latitudes. Water vapour concentration was also found to be in correlation with corresponding temperature. The water vapour over Antarctica was also compared with that over Delhi as well as with high altitude stations, Leh (34°15'N, 77°56'E, 3.311 km amsl), and Hanle (32°47'N, 78°58'E, 4.50 km amsl), which showed that the concentration of water vapour at Leh, Hanle and Maitri is of same order and very low compared to that over Delhi.

8 illus, 11 ref

005597   Eulandaivelu E;Sridharan S;Ramanan S R (Regional Meteorological Cent, , Chennai-600 006) : The effect of atmospheric blocking high and ridges on weather over Maitri, East Antarctica. Mausam 2005, 56(2), 375-84.

The Indian Antarctic station, Maitri is often experiencing continuous blizzard over a week with strong surface winds and surface temperature anomalies due to atmospheric blocking during winter and spring seasons of Antarctica. One such case during the last week of August 2000 and another case in mid-July 1996 are studied. There is more blocking activity in winter and spring months. The influence of blocking high on weather parameters during the study period is also presented.

8 illus, 1 table, 22 ref

005596   Chandra M;Srivastava A K;Singh V;Tiwari D N; Painuly P K (Geodata Processing and Interpretation Cent, Oil and Nat Gas Corportion Limited, Dehradun) : Neural networks and their applications in lithostratigraphic interpretation of seismic data for reservoir characterization. J Geophys 2005, 26(1), 11-25.

An attempt has been made to give a brief introduction of neural networks and their way of working. The neural network classifications based on training methods in unsupervised and supervised category have been described. Unsupervised neural networks analysis presumes no prior knowledge of the object to be classified and neural network looks for pattern itself during seismic facies classification. In supervised analysis, reservoir properties are predicted away from the boreholes in inter-well regions after establishing the relation between multi-seismic attributes and well log data. The effectiveness of these neural network techniques in interpretation has been demonstrated through a real data example. In study area, a series of thin clastic reservoirs are sandwiched between coal and shale layers and are discrete in nature. These multi-pay sands having thickness from 2m to 8m are the main hydrocarbon producers. Severe lateral lithological variation has affected the porosity distribution in these reservoirs. Low porosity zones are found devoid of hydrocarbons.

19 illus, 1 table, 13 ref

005595   Birbal Singh;Kushwah V;Vikram Singh;Tomar M (Dep of Electron & Commun Engng, Fac of Engng & Technology, Bichpuri, Agra-283 105) : Simultaneous ULF/VLF amplitude anomalies observed during moderate earthquakes in Indian region. Indian J Radio Space Phys 2005, 34(4), 221-32.

A three-component search coil magnetometer to monitor ultra low frequency (ULF) magnetic field emissions (frequency = 0.01-30 Hz) and an Absolute phase and amplitude data logger (AbsPAL) to monitor the phase and amplitude variation of very low frequency (VLF) 19.8 kHz fixed frequency NWC (Australia) transmitter signals have been installed at Bichpuri, Agra (Geograph Lat. 27.2°N, Long. 78°E) in India and regular simultaneous observations have been taken since 1 Aug. 2002. The analysis of the nighttime VLF amplitude data has been carried out for the initial period of nine months between 1 Aug. 2002 and 30 Apr. 2003 and it is seen that the amplitude decreased abnormally by 1-10 dB from normal nighttime daily averages on six days during the whole period under consideration. The results of ULF data analysis show that the background magnetic field amplitudes of the three components, which are usually low, in the range of 0.03-0.30 nT are enhanced to the range of 0.26-0.96 nT, either on the same days or within ± 2 days of the decrease in amplitude of the VLF signal. The possible causes for the observed ULF/VLF amplitude anomalies are examined and it is found that they are caused by moderate seismic activities that occurred along the VLF propagation path in the region. The statistical analysis of the data using mean and standard deviation around the mean is carried out, which supports the results satisfactorily.

11 illus, 1 table, 24 ref

005594   Bhattacharya S N;Srivasta S k;Prakash R; Dattatrayam R S;Arora S K;Bansal B K (India Meteorological Dep, , Lodi Road, New Delhi) : Configuration of an optimum seismological network for India. Mausam 2005, 56(2), 465-72.

India Meteorological Department (IMD) is the nodal agency of Government of India responsible for monitoring seismicity in and around the country. IMD maintains the national seismological network consisting of 47 permanent observatories, in addition to some observatories in northern India for special studies. A 16-element VSAT-based digital telemetry system for close monitoring of seismicity in and around Delhi is also in operation. In addition to IMD, several state/central government organizations, universities and R&D institutions are also operating seismological observatories in various parts of the country. Some of these observatories in the Peninsular shield region have been upgraded in the recent past with state-of-the-art digital broadband seismograph systems, in addition to opening 10 such new digital broadband stations. Makes an attempt to assess the magnitude threshold of routinely detecting and locating earthquakes occurring any where in the country with the existing IMD network. Using the seismic wave attenuation characteristics in the Himalayan and Peninsular shield regions, estimate epicentral distance up to which a regional earthquake of given magnitude can be detected and located as well. The minimum number of observatories required for uniform azimuthal coverage and accurate determination of hypocentral parameters has also been taken into consideration. An optimum seismological network configuration has been worked out based on the above inputs. It is found from the analysis that the existing IMD network is capable of detecting and locating earthquakes of magnitude 3.5 and above occurring in the mainland of the country, except for a few pockets in Rajasthan, Gujarat, Arunanchal Pradesh and J&K. An attempt has also been made to show that regional earthquake monitoring capability would largely improve by suitably upgrading and integrating the existing seismological observatories operated by various other agencies together with setting up a number of new observatories in the instrumental gap areas.

8 illus, 11 ref

005593   Bhagat D K U R (Regional Meteorological Cent, , Mumbai-411 005) : Balance of kinetic energy in the field of mid-tropospheric cyclone. Mausam 2005, 56(2), 473-500.

^ssc1 illus, 2 table, 23 ref

005592   Bhadram C V V;Amatya B V S;Pant G B;Krishna Kumar K (Meteorological Cent, , Airpot, Hyderabad) : Heat waves over Andhra Pradesh : A case study of summer 2003. Mausam 2005, 56(2), 385-94.

Temperature data of pre-monsoon months for major stations in Andhra Pradesh for long period (1901-2002) have been analysed to identify the variations in maximum temperature. Analysis of short period temperature data (1986-2002) has shown increase in the frequency of severe heat waves and also duration of heat wave spells during the last decade. Since the severe heat waves during May-June 2003 over Andhra Pradesh have claimed many lives, a detailed study of all meteorological parameters associated with such heat waves has been made and the results are discussed. Human comfort indices - Heat Index (HI), Thom's Discomfort Index & Webbs' Comfort Index computed in respect of coastal stations have clearly reflected the severity of heat waves.

8 illus, 3 tables, 8 ref

005591   Behera L (Natn Geophys Res Inst, , Hyderabad-500 007, Email: laxmidhar@ngri.res.in) : Crustal imaging of the Mahanadi delta and its tectonic significance. J Geophys 2005, 26(2), 117-32.

Crustal imaging of the Mahanadi delta by modeling both wide-angle seismic and Bouguer gravity data indicates the presence of widespread volcanic activity occurred during Early Cretaceous along the rift zones. This volcanic activity corresponds to the breakup of greater India from east Gondwana (e.g., present Antarctica and Australia). The crustal model derived has velocities of 6.0, 6.5, 6.0, 7.0, and 7.5 km/s with estimated densities of 2.7, 2.8, 2.65, 2.9, and 3.05 g/cm3, respectively for different layers. The presence of mid-crustal low-velocity (6.0 km/s) and low-density (2.65 g/cm³) zone with Moho upwarping or crustal thinning and emplacement of <126> 10 km thick high-velocity (7.5 km/s) and high-density (3.05 g/cm³) material at the base of the crust strongly suggests basaltic underplating probably due to the Kerguelen hot spot activity and indicates a typical rift-related evolution of the delta. The rifting stages have a close correlation with the different sedimentation phases of the lower and upper Gondwana deposits in the Mahanadi delta. The volcanic activities are synchronous with <126> 117 Ma Rajmahal volcanism in India and the Lambert graben of East Antarctica and are closely associated with the Gondwana breakup in the India Antarctica sector.

7 illus, 3 tables, 54 ref

005590   Bawiskar S M;Chipade M D;Majumdar V R;Bhide U V;Singh S S (Indian Inst of Trop Meteorology, , Pune-411 008) : Contrasting features of wave number one during northern summer monsoon seasons of 1997 and 2002. Mausam 2005, 56(2), 337-42.

Temporal and spatial variations of the energetics of the lower tropospheric zonal wave number one are compared for monsoon 2002 (a recent drought year) and monsoon 1997 (a normal monsoon year). Fourier technique is used to calculate momentum transport, kinetic energy and wave to wave interaction. Daily global grid point NCEP wind (u & v) data at 850 hPa for 153 davs (1 Mav to 30 September are considered. Daily and weekly variations of the energetics of wave number one indicate that as long as the momentum transport or kinetic energy of wave number one around 10° N is strong, the rainfall is better and vice-versa. The amplitude of wave number one was almost half during 2002 as compared to that of during 1997, which resulted into less transport of momentum and meager supply of kinetic energy throughout the monsoon season of 2002. The significant release of kinetic energy by wave number one may have played a vital role in triggering five intense systems during 1997 whereas the weak supply of kinetic energy may have failed to trigger a single system during monsoon 2002.

6 illus, 25 ref

005589   Baranwal M;Pathak B;Syiem S M (Geophysics Div, Geol Surv of India North East Region, Shillong) : Preliminary first level seismic microzonation of Guwahati. J Geophys 2005, 26(1), 27-33.

First level microzonation map of Guwahati has been prepared based on amplification of ground motion, slope of exposed rocks, shape and constituents of overburden material inferred from geophysical surveys. The map reflects local ground conditions. For map preparation liquefaction and amplification of ground motion has been emphasised, as they are most important earthquake hazards. Microzonation maps generally are prepared at 3 levels. Level-I map is basic amplification susceptibility map. It shows soil units grouped on the basis of their relative susceptibility to amplification, geologic and geotechnical data and uses a relative susceptibility descriptor based on soil categories. The map shows susceptibility of the ground to amplification of seismic motions relative to firm ground or rock motions at the same location. The soil profiles have been categorised in terms of their susceptibility to amplification. Where bedrock is very deep, the soil susceptibility categories of the uppermost 35 m of soil profile that generally has the greatest influence on amplification has been considered. The soil susceptibility categories defined according to soil type, thickness and stiffness has been taken as the basis for defining mapping units. Considering these factors map has been prepared which depicts the thickness of soils above bedrock based on geophysical results. The resistivity surveys carried out in the area have been analysed. The seismic studies carried out show that Vs ranges from 166 to 330 m/s and corresponding amplification ratios varies from 3.1 to 2.2. The damage ratio (DR) calculated from these values were found to be 0.2 and 0.05. The Rayleigh wave propagating through hard ground is magnified as it enters a two-layered ground with a soft surface layer. In the portions near to rock exposures this type of configuration prevails, hence magnification may be predominant. Rayleigh wave propagation relative to basin configuration has been taken to account for preparation of the map.

5 illus, 2 tables, 9 ref

005588   Ashwani Kumar;Sarma A D (Defence Electron Res Laboratory, , Candrayangutta, P O Kesavgiri, Hyderabad-500 005, Email: ad-sarma@yahoo.com) : Wide band single-fed parasitically excited microstrip patch antenna for GPS. Indian J Radio Space Phys 2005, 34(3), 179-83.

As a part of the modernization of GPS system, a second civil signal at L2 (1227.45 MHz) and a third new civil signal at L5 (1176.45 MHz) will be added to future GPS satellites in addition to existing civil signal at L1 (1575.42 MHz) frequency. A wide band, compact, low profile, parasitically excited microstrip antenna design is presented to cover L2 and L5 frequencies. The proposed antenna design has a perfect square patch, which is parasitically excited by a nearly square patch fed at single point. Good impedance matching and circularly polarized radiation patterns have been obtained over wide frequency band by using bandwidth-enhancing techniques. The gain of the antenna is found to be more than 5.5 dB.

8 illus, 11 ref

005587   Asfahani J;Tlas M (NO, Atom Energy Commn, P O Box 6091, Damascus, Syria) : A constrained nonlinear inversion approach to quantitative interpretation of self-potential anomalies caused by cylinder and sphere-like structures. J Geophys 2005, 26(2), 109-15.

A new and simple technique based on constrained nonlinear programming concept has been proposed in this paper to interpret quantitatively the self-potential SP anomalies caused by vertical and horizontal cylinders, and sphere-like structures. A constrained nonlinear model has been formulated in an attempt to describe the geophysical problem related to the structures considered here. This model has been then solved by the Frank-Wolfe algorithm in order to estimate the geophysical parameters of the sphere and cylinder such as the depth of the target z, the polarization angle q, and the electric dipole moment k. This algorithm is chosen for being robust and also its application to SP data converges rapidly towards the optimal estimation of parameters. This new constrained nonlinear programming technique has been first tested on theoretical models with random noise, where very close agreement has been obtained between assumed and evaluated parameters. The validity of this proposed new method is tested on a practical field example taken from Turkey, where available SP data existed that has been previously analyzed by different approaches. The agreement is good between the results obtained by the present study and those by other approaches. The relative advantages of the proposed technique are discussed and demonstrated.

2 illus, 3 tables, 20 ref

005586   ananda Reddy R (Geol Surv of India, , Hyderabad) : Integration of satellite imagery, geophysical and geochemical data sets for gold mineralisation in northern part of Hutti-Maski greenstone belt, Karnataka, India. J Geophys 2005, 26(2), 93-107.

The utility of integrated satellite imagery, Bouguer gravity and magnetic maps along with geochemical data in deciphering the structural fabric of the northern part of Hutt-Maski supracrustal greenstone belt in relation to the occurrence of gold prospects, concealed geological features and identification of target areas are presented in this paper. Gravity map clearly brought out the disposition of the horse shoe shaped schist belt as a distinct gravity high and also the presence of internal granitoids associated with the shear/fracture/alteration zones as lows/low nosings. Residual gravity lows associated with known gold mineralisation correlate well with magnetic highs. Geochemical analysis of mineralized zones indicate intensive chemical changes associated with wall rock alteration in the region of residual gravity lows. Some of the lineaments identified from IRS imagery also corroborate well with the shear zones associated with gold mineralisation. A narrow corridor of gravity 'high' immediately south of Hutti mines indicate the extension of the schist belt, suggestive of continuity of Hutti lodes further south. Modelling of gravity data indicates that the schist belt has a depth of about 3km. Based on integrated analysis of the available data, new target areas for gold mineralisation are identified in the northern part of Hutti-Maski greenstone belt.

7 illus, 2 tables, 12 ref

005585   Acharyya S K (Dep of Geol Sci, Jadavpur Univ, Kolkata) : Geology and tectonics of NE India. J Geophys 2005, 26(1), 35-49.

The NE Himalaya and the Indo-Burma mountain belts are linked and veer round the prolongation of the Shillong-Mikir continental promontory to form the "Eastern Himalayan Syntaxis". Marine to paralic facies early Palaeogene sediments interbanded with the Abor Volcanics are exposed beneath the up MBT at the core of the Siang Window developed close to the syntaxis. These sediments are also exposed intermittently in thrust slivers in the MBT zone along the frontal belt. A few domal windows have developed north of the frontal belt. These and the Siang windows may have been formed in a similar way. It is postulated that thickened sections of the Plaeogene sediments may be present in sub-surface at the cores of some windows. The Himalayan foreland basin had sporadic Eocene Continental Flood Basalt activity, which may be caused by deep faults that developed soon after India-Asia continental collision. The setting of the Assam shelf southeast of the Shillong-Mikir massif, is very similar to that of East-Coast of India and an oceanic margin possibly occurs close to this shelf. The Indo-Burma Range, to its cast, possibly has a continental or transitional crust foundation, which is named "Indo-Burma-Andaman" (IBA) block. The northern end of the IBA collided with the NE leading edge of the Indian continent during the Pliocene.

10 illus, 48 ref

005584   Abbady A (Phys Dep Fac of Sci, South Valley Univ Qena, Egypt) : Assessment of the natural radioactivity and its radiological hazards in some Egyptian rock phosphates. Indian J pure appl Phys 2005, 43(7), 489-93.

Radioactivity of terrestrial radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in phosphate rock samples has been measured using gamma ray spectrometry system with an HPGe detector. The samples showed fairly high mean concentrations, 410±39 Bq.kg^-1 of ²²⁶Ra, 7.9±0.95 of ²³²Th and 37.6±4 of ⁴⁰K. Mean absorbed gamma dose rate of 181.9±20 nGy.h^-1 was measured in air. Assessment of radiological hazards was made by calculating radium equivalent activities with external and internal hazard indices. The calculations showed radium equivalent activity ranging from 317 to 520 Bq.kg^-1 and external and internal hazard indices ranging from 0.4 to 0.7 and 0.1 to 0.4, respectively. The results of the analysis have been found to be in a good agreement with the data obtained by others.

2 illus, 1 table, 14 ref

004628   Trivedi S P (Tata Institute of Fundamental Research, , Homi Bhabha Road, Mumbai-400 005) : Accelerating universes in string theory. Curr Sci 2005, 88(7), 1125-32.

Authors review recent constructions of deSitter universes and inflationary universes in string theory. The constructions are based on flux vacua in string theory which lead to controlled moduli stabilization and supersymmetry breaking. The emerging picture is that of a complicated landscape with many different vacua. This is likely to be quite important for future developments in string theory.

3 illus, 59 ref

004627   Tripati S;Vora K H (Marine Archaeology Centre, National Institute Institute of Oceanography, Dona Paula-403 004) : Maritime heritage in and around Chilika lake, Orissa; geological evidence for its decline. Curr Sci 2005, 88(7), 1175-81.

Chilika (also Chilka) lake is the largest brackish water body in India. Archaeological explorations and excavations around the Chilika lake region have brought to light the habitational remains of the Neolithic-Cha- lcolithic period onwards, datable to the 3rd millennium BC. The archaeological findings embody the fact that well-known ports of the bygone era such as Manika-patna on Chilika coast, Palur on the extreme south and Che-li-ta-lo had close contacts with Africa, Ceylon, China and Southeast Asian countries. Further, a text of the 10th century AD mentions about the maritime activities of the lake and ships, which used to ply to the Southeast Asian countries from Chilika. Similarly, Soran, Nairi, Pathara and other villages around the lake have had glorious navigational traditions. The ports located around Chilika lake had played a significant role in spreading the Indian culture to other countries. However, subsequent changes in the regime caused the formation of sand bars, spits and altered sedimentation pattern, which eventually caused a decline in maritime activities in the Chilika region.

5 illus, 1 table, 30 ref

004626   Thangadurai N;Srinivasalu S;Jonathan M P; Rajeshwara Rao N;Santhosh Kumar R (Department of Geology, Anna University, Chennai-600 025, Email: ponmozhisrini2001@yahoo.com) : Pre-tsunami chemistry of sediments along the inner continental shelf off Ennore, Chennai, southeast coast of India. Indian J Mar Sci 2005, 34(3), 274-8.

Inner continental shelf off Ennore hosts sediment carrying several minor metals of both natural and anthropogenic origin from the Korttalaiyar River through Ennore Creek. The sediments are mostly sandy silt and silty sand. The CaCO₃ and organic matter contents in the sediment are very low (<126>2.1% and <126>0.9%, respectively). The correlation matrix exhibits poor correlation between these components and minor metals indicating an insignificant role of CaCO₃ and organic matter in enriching minor metals. The minor metals exhibit strong mutual positive association (R <62> 0.6 at 95% confidence level). The geographical distribution of the elements shows higher concentration in northern part of the study area when compared with their concentrations in the southern part. In view of the recent M9-tsunami effect on the coastal sediment of this region, the investigation provides immediate pre-tsunami minor metal distribution levels. This in turn will provide a reference for studying sediment re-distribution due to high energy tsunami tidal waves in the study region.

4 illus, 2 tables, 16 ref

004625   Subramani T;Elango L;Srinivasalu S;Morikio T (Civil Engng Dep, Gov Coll of Engng, Salem-636 011) : Geological setting and groundwater chemistry in Chithar river basin, Tamil Nadu, India. Indian Mineralogist 2005, 39(2), 108-19.

Basement in Chithar River basin consists of quartzite, calc-granulite, crystalline limestone, charnockite and biotite gneiss. Granitic intrusions, quartz veins, pegmatite and pyroxene granulite dykes are observed in some places. Charnockites and gneisses, the major rock types in the area, are greatly involved in the weathering processes. Mineralogically charnockites are composed of quartz, plagioclase feldspars and orthopyroxenes with garnet and biotite as minor constituents. The study of structural and tectonic history of this region indicates several episodes of deformation, which caused repeated folds, faults, joints and fracture systems. Thre major soil types namely, black cotton, deep red and red sandy soils were observed. Alteration of soda feldspar (albite) and potash feldspars (orthoclase and microcline), which are common in the biotite gnesiss occurring in the study area, is greatly responsible for the contribution of Na⁺ and K⁺ ions to grondwater. Calcic-plagioclase feldspars, pyroxenes and amphiboles are the common calcium and magnesium bearing minerals in silicate rocks of the study area, which contribute Ca²⁺ and Mg²⁺ ions to the groundwater by weathering. Sulphate ions have resulted from the weathering of disseminated pyrite mineralization in crystalline limestone. Groundwater in this region is moderately saline and low sodium class. The abundance of the major ions in groundwater is in the following order: Na⁺³ Ca²⁺ Mg²⁺ <62> K⁺ = Cl^-≥ HCO^-₃ ≥SO^2-₄ <62> NO₃^- <62> CO^2-₃ groundwater in the study area can be used for irrigation on almost all types of soil with little danger of exchangeable sodium.

7 illus, 2 tables, 14 ref

004624   Singh R P (Department of Civil Engineering, Indian Institute of Technology, Kanpur-208 016, Email: rsingh3@gmu.edu) : Future earthquakes and other natural hazards: impact on people living in the ganga basin. Curr Sci 2005, 88(7), 1025.

004623   Senthil Nathan D;Sreedhar A K (Earth Sci Dep, Pondicherry Univ, Pondicherry-605 014, Email: senthilom@rediffmail.com ) : Beach sands of Pondicherry and Mahe coasts - a comparative study. Indian Mineralogist 2005, 39(2), 120-30.

Major heavy minerals occurring in Pondicherry beach sands are pyroxene, hornblende, zircon, garnet and spinel. In Mahe beach, the dominant heavy minerals are muscovite, silimanite, kyanite, spinel and garnet. Texturally, Pondicherry beach sediments are moderate to well sorted, symmetrical to coarse skewness and meso to platy kurtic. In Mahe region, beach sands show moderate to very well sorting and lepto to platy kurtic. The sediments of Pondicherry region have been derived mainly from charnockite-biotite-hornblende gneisses with pegmatite and granite. In Mahe region source rocks would be charnockitebiotite-hornblende gneiss and khondalite. Textural parameters of the sediments reveal that Mahe beach is experiencing comparatively high energy environment than Pondicherry beach.

5 illus, 2 tables, 17 ref

004622   Seetharamaiah J;Farooqui A;Suryabhagavan K V; Nageswara Rao K (Delta Studies Insitute, Andhra University, Visakhapatnam-530 017, Email: seetharamaiah_2004@rediffmail.com) : Evolution of Iskapalli lagoon in Penner delta region, east coast of India - A sedimentological and palynological approach. Indian J Mar Sci 2005, 34(3), 267-73.

Holocene evolution of the Iskapalli lagoon has been reconstructed through land form mapping, vibracore lithology and foraminiferal analysis, supplemented by radiocarbon dating. The characteristics: texture, boundary surfaces and the palynological assemblages of the lagoon sediments obtained from two cores indicate three distinct sediment units. The lower part of the core (Unit I) consisting of highly (<62>85%) oxidized coarse sand mixed with shells, moderate bioturbation, high concentration of Spiniferites, Casuarina, fungal spores and algal cysts together with terrestrial herbaceous taxa and sub-parallel laminations suggests deposition in a sandy river mouth bar environment under strong wave influence. The middle part of the core (Unit II) comprising high silty to sandy mud, and parallel laminations together with Protoperidinium sp., Rhizophora and Avicennia indicated low energy lagoonal environment analogous to the modern lagoonal conditions. The upper part of the cores (Unit III) consisting of well sorted fine sands with abundant terrestrial taxa are considered to be wind blown sands. The oxidized condition of the distributary mouth bar sediments of Unit I and the occurrence of fine sediments of Unit II suggest the lagoon had witnessed at least one cycle of sea level fall and rise during the Late Holocene between 2000 yr BP and 1500 yr BP.

4 illus, 26 ref