001145   Verma P K;Powar K B;Pardeshi R G (Department of Geology, University of Delhi, Delhi-110 007) : Calcic amphiboles and petrogenesis of the Chainnigund Gabbro, Ladakh, NW Himalayas. Himalayan Geol 1999, 20(2), 61-70.

Deals with the crystal chemical characteristics of calcic amphiboles occurring in a group of rocks of gabboric composition in the vicinity of Chainnigund, in Kargil district of Jammu & Kashmir. The area, located in the Ladakh Himalaya, is a part of the subduction related Indus-Tsangpo Suture Zone and exhibits a differentiated suite ranging from an anorthositic gabbro through gabbro and norite to hornblendite. These rocks are considered to be mafic cumulates genetically related to the adjoining Dras Volcanics. The common assemblage is plagioclase + clinopyroxene + amphibole + ilmenite. Some varieties contain orthopyroxene, while others have biotite. Electron microprobe data reveal that within the broad category of calcic amphiboles, the crystals show a range of chemical variation. The largest components are edenite and pargasite. The NaA values are usually quite close to 0.5, but when it becomes less than 0.5 then edenite becomes magnesiohornblende. There is also a large tschermakite substitution. Many amphiboles are zoned with more than two zones being present. The zoning follows the trend of fractionation. The whole-rock chemical analyses for major, trace, and rare earth elements of the gabbro point to an island-arc type of setting with an overall tholeitic affinity. A correlation of the amphibole composition with the mineral assemblages of different gabbro varieties shows that the pargisitic amphiboles tends to occur in the gabbro.

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001144   Valdiya K S;Paul S K;Tara Chandra;Bhakuni S S;Upadhyay R C (Geodynamics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakhur, Bangalore-560 064) : Tectonic and lithological characterization of Himadri (great Himalaya) between Kali and Yamuna rivers, central Himalaya. Himalayan Geol 1999, 20(2), 1-17.

Great Himalayan terrane embracing the "Central Crystalline Zone" comprises two chrust-bound lithotectonic units. The Munsiari Formation at lower structural level is made up of 1900±100 m.y. old porphyritic granite and its mylonitized variants together with retrogressive green schists resulting from metamorphism taking place in the temperature range of 250-450°C and under pressure of 3 to 6 kb. The Vaikrita Group above is constituted of high-grade metamorphics and Cambro-Ordovicin granitic gneiss towards the top. The Vaikrita has been intruded by leucocratic granites that have brought about extensive migmatization of metapelites, mainly in the upper part. Divisible into three formation (Joshimath, Pandukeshwar and Pindari). the Vaikrita metamorphic rocks developed 20±2 m.y. ago in a temperature range off 650-600°C and under pressures above 6 kb (locally up to 9 kb). The leucogranite and associated dykes and veins of pegmatite and aplite in the upper part of the Vaikrita succession, characterized by sillimanite/kyanite, garnet or cordierite and high but variable values of strontium ratio, are the products of partial melting of high-grade metamorphic rocks. Mineral isochron and mica dates indicate that this anatectic granite is 20±2 m.y. old. The emplacement of the 20±2 m.y. old anatectic granite and associated pegmatite dykes and veins was coeval with deformation....

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001143   Valdiya K S (Geodynamics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560 064) : Free access to topographical maps: coping with natural hazards, assessing development potential and monitoring environmental changes. Curr Sci 2000, 79(4), 479-80.

Appreciating that topographical maps embody a wealth of geomorphological and geographical information in a capsule form, and acknowledging that the making of geological maps is essential for the assessment and management of natural resources, planning for development, and hazard-coping endeavours, these maps should be freely available to all scientific workers. There should be no restriction on the use and publication of contour maps showing precise delineation of geomorphological-geological boundaries, the locations of deposits or reserves of natural assets, the sites of development activities, and the zones identified as prone to natural hazards.

001142   Thomas B;Kasture S V;Satyan S V (NO, Physical Research Laboratory, Ahmedabad-380 009) : Simulation of winter and summer climates with PRL atmospheric general circulation model. Mausam 1999, 50(4), 391-400.

Global, spectral Atmospheric General Circulation Model (AGCM) has been developed indigenously at Physical Research Laboratory (PRL) for climate studies. The model has six σ levels in the vertical and has horizontal resolution of 21 waves with rhomboidal truncation. The model includes smooth topography, planetary boundary layer, deep convection, large scale condensation, interactive hydrology, radiation with interactive clouds and diurnal cycle. Sea surface temperature and sea ice values were fixed based on climatological data for different calender months. The model was integrated for six years starting with an isothermal atmosphere (240°K), zero winds initial conditions and forcing from incoming solar radiation. After one year the model stabilizes. The seasonal average of various fields of the last five years are discussed. It is found that the model reproduces reasonably well the seasonal features of atmospheric circulation, seasonal variability and hemispheric differences.

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001141   Tabata H (NO, Center for Ecological Research, Kyoto 606-8502, Japan) : Himalayan uplift, plant corridors and the past climate. Himalayan Geol 1998, 19(2), 61-3.

There are two kinds of distribution discontinuity of Himalayan plants. One of them is called Sino-Himalaya gap. This distribution gap is discussed in the backdrop of the recent abrupt Himalayan uplifts reported by Chinese scientists and the present plant distribution. The formation of Himalayan corridors is also briefly discussed. The palynological study of Tetang formation in Thakhola area, the upper stream area of the present Kali Gandaki, suggests that the Himalayan corridor existed on the northern side of Annapurna-Dhaulagiri mountains at least in the early Neogene. Also discusses are the Holocene climatic changes in Nepal and their synchroneity with the western Tibet.

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001140   Srinivasan V (NO, Geological Survey of India (NER), P G R S Division, Lower Motinagar, Shillong-793 014) : Litho-stratigraphy and structure of low-grade metasedimentaries in western part of Arunachal Pradesh. Himalayan Geol 1999, 20(2), 53-60.

Eastern part of Bhutan and western part of Arunachal Pradesh reveal an interference pattern of two generations of mega folds affecting the low-grade metasedimentaries which are sandwiched between the sedimentary belt in the south and Central Crystalline in the north. Presents the stratigraphy and structure of these low-grade metasedimentaries exposed in the western part of Arunachal Pradesh. Lithostratigraphically the low-grade metasedimentaries (Proterozoic?) are broadly subdivided into three groups. These are the youngest Bichom Group (Thungsing Group in Bhutan) comprising phyllites with or without rock fragments, orthoquartizites, feldspathic quartzites and gritty quartzites; the Rupa Group comprising quartizites, phyllites and dolomites and the oldest Bomdila Group comprising steaky/augen gneiss, biotite schist and feldspathised schist. Bomdila Group is exposed in the core of E-W trending, westerly plunging Narphung antiform. This antiform is refolded into the westerly plunging Rupa synform and its complimentary Saleri antiform. Rupa Group, which overlies Bombila Group, is exposed in the core part of Rupa synform. Bichom Group, which overlies Rupa Group in the western closure of Narphung antiform in Narphung sector in Eastern Bhutan, is also exposed along its southern overturned limb.

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001139   Srikantia S V (NO, Geological Society of India, Bangalore-560 011) : Restriction on maps: a denial of valid geographic information. Curr Sci 2000, 79(4), 484-8.

Maps have always served great social, geographic, scientific, economic and historical purpose. The restrictive policy regarding dissemination of map information as practised in India is disquieting. Maps on scales larger than 1:1 M of areas 80 km wide along the external land border and coastline are restricted and cannot be accessed in normal course. There is restriction on publication and export of maps, issue of gridded copies of maps, aerial photographs and trigonometric and gravity data. The latest technological developments in the light of satellite imageries and Global Positioning System have made most of the existing restrictions anachronistic. The security of maps is a colonial legacy and should go. It is important to know that security of a country has a wider dimension and does not lie in restricting maps and toposheets. The Ministry of Defence, the authority which is insisting on map restriction, should be made to understand that the prevailing restriction has not served any purpose excepting denying the citizens of India their fundamental right to information about their land. Indian scientists should join in a chorus to get this restriction on maps removed.

001138   Singh O P (NO, Meteorological Centre, Bhubaneswar) : Multiple variability of summer sea surface temperature (SST) and evaporation over the Indian seas. Mausam 1999, 50(4), 335-42.

Utilising thirty one years' marine meteorological data from 1961-91 recorded over the north Indian Ocean the sea surface temperature (SST) and evaporation have been obtained for different regions of the Arabian Sea and the Bay of Bengal. The moving pentad averages of SST and evaporation reveal increasing tendencies of both the parameters over the Arabian Sea and that of evaporation over the Bay of Bengal during May. The changes are real and significant as revealed by the trend analysis. The spectral analysis shows that SST has a 2-3 years significant cycle and evaporation rate has a 2-5 year cycle over the Indian Seas. In addition, a significant 15-year cycle is present in the SST over the Bay of Bengal and evaporation rate over the Arabian Sea. Empirical orthogonal function analysis performed on the anomalies of SST and evaporation rate over the Arabian Sea and the Bay of Bengal reveals that the time coefficient of first EOF has an increasing tendency.

001137   Scheidegger A E (NO, Technical University, A-1040 Vienna, Austria) : Morphotectonics of the Kaliasaur slide, Garhwal Himalaya, Uttar Pradesh, India. Himalayan Geol 1999, 20(2), 105-7.

Comparison of joint orientations around the Kaliasaur slide (Garhwal Himalaya, Uttar Pradesh, India) with displacement directions within the slide shows that the joint-strikes and the displacement directions are parallel. This is a condition characteristic of slides caused by shear-or wedge-type failures in many parts of the world.

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001136   Sahni A;Kad S (Centre of Advanced Study in Geology, Panjab University, Sector-14, Chandigarh-160 014) : Evidence of the tectonic events in the foreland basin: phase relationship with Himalayan and Tibetan uplifts. Himalayan Geol 1998, 19(2), 49-53.

Palaeogene sequences in the Shimla Lesser Himalayas provide excellent evidence to document the withdrawl of the Tethys and the development of the Himalayan foreland basin. Both these processes are linked to the geodynamic and tectornic evolution of Tibet: the first suggests collision and suturing, while the latter indicates the deepening of foreland basin across a strike length extending over 1500 kms through Pakistan, India and Nepal in response to the rise of the Himalayas and Tibetan Plateau. The withdrawal of Tethys is coincident with the onset of highly oxidized red coloured sediments (Murree/Dagshai) suggesting a northerly derivation of the sediments. In the Shimla Himalayas one of the keys of understanding the geodynamic evolution of Himalayas lies in the study of Subathu, Dagshai and Kasauli formations showing contrasting sedimentary depositional environments during most of the Palaeogene. The Dagshai Formation suggests the derivation of terrigenous clastics from a northerly source and has well-developed palaeosol horizons. The palaeosols are calcic and suggest some degree of semi-aridity. In sharp contrast, the overlying Kasauli Formation represents a wetter period and is represented by grey coloured organically rich silstone, sandstone sequence showing enhanced precipitation. The boundary between the Dagshai/Kasauli Formation may prove to be significant in documenting the onset of monsoon climate in the Indian Subcontinent.

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001135   Rutter N W;Rokosh D (Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Canada T6G 2E3) : Tibetan plateau: glaciation and loess deposition. Himalayan Geol 1998, 19(2), 23-37.

Faunal and floral evidence suggest that the Tibetan Plateau has been rising since Tertiary times and reached its maximum elevation sometime during the Quaternary. Although the area is presently tectonically active, radiometric dating on structural components suggest that the Plateau was near its present height by the beginning of the Quaternary, or 2.5 Ma. The timing and extent of ice over the Tibetan Plateau is controversial. Most geological evidence suggests that there were multiple glaciations but the ice extent was limited, confined to local mountains or uplands and, in some cases, minor ice sheets. Few agree that there was a major ice sheet over the entire Plateau. The timing of glacial events is poorly known because of a lack of absolute dates. Some have speculated that the more extensive, relatively early glacial activity was, in part controlled by a lower elevation of the Plateau, allowing moisture to penetrate from the southwest. It appears that when the Tibetan Plateau reached a critical height at least 2.5 million years ago, loess deposition began in north-central China. The uplift caused, in part, a change in climate and atmospheric circulation, allowing for an almost complete record of loess deposition and soil development. The loess is sourced from deserts of north and northwest China and carried by northwest winds into the Loess Plateau.

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001134   Rautela P;Thakur V C (NO, Wadia Institute of Himalayan Geology, Dehra Dun-248 001) : Landslide hazard zonation in Kaliganga and Madhyamaheshwar valleys of Garhwal Himalaya : a GIS based approach. Himalayan Geol 1999, 20(2), 31-44.

Himalaya represents a fragile ecosystem and its fragility stems from geological history of its evolution and structural set-up of the rocks. The fragility of the terrain is often manifested in the recurring natural hazards and was highlighted in August 1998 when landslides took regional proportions and a large portion of Garhwal-Kumaun was affected. Kaliganga and Madhyamaheshwar river valleys (tributaries of Mandakini river) of Garhwal Himalaya witnessed heavy losses and the death toll in these valleys crossed one hundred mark, Madhyamaheshwar river was dammed and vast tracts of hitherto fertile terraced land was rendered unsuitable for human interventions. Landslide hazard zonation (LHZ) and risk assessment studies have been carried out in these valleys under Geographical Information System (GIS) environment employing statistical index method. Geology, structure, landuse, old slides, slope, shape of the slope, aspect and drainage are the different parameters affecting mass movement and have been considered for LHZ exercise. For risk assessment population (1991 census) has been considered the sole criteria as most infrastructure in the region is interwoven around population centres. This exercise has brought out areas and population groups that are particularly vulnerable to landslides.

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001133   Ramesh S;Ramasamy S (Sedimentology Laboratory, University of Madras, Chennai-600 025) : Palynodebris accumulation characteristics of a sediment core from the eastern part of lower Bengal Fan. Curr Sci 2000, 79(1), 24-6.

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001132   Rajendran K;Harish C M (NO, Centre for Earth Science Studies, P B No. 7250, Akkulam, Thiruvanathapuram-695 031) : Mechanism of triggered seismicity at Koyna : an evaluation based on relocated earthquakes. Curr Sci 2000, 79(3), 358-63.

Seismicity associated with the Koyna Reservoir, western Maharashtra, is unique because it is one of the few sites in the world where earthquakes of M ≥ 5.0 continue to occur three decades after the initial spurt of activity. This contrasts with most other seismogenic reservoirs where temporal patterns of seismicity are characterized by one or two peaks that taper-off with time. Persistence of moderate seismicity at Koyna is enigmatic, considering also the low seismic productivity of the peninsular shield. Temporal association of major earthquakes with annual reservoir loading has been observed for long. Reports a discernible difference between the spatial pattern of earthquakes associated with the reservoir loading and unloading. A conceptual model is proposed to explain the continued occurrence of earthquakes.

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001131   Rajeevan M;De U S;Prasad R K (NO, India Meterological Department, Shivajinagar, Pune-411 005) : Decadal variation of sea surface temperatures, cloudiness and monsoon depressions in the north Indian ocean. Curr Sci 2000, 79(3), 283-5.

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001130   Patra P K;Santhanam M S;Potty K V J;Tewari M; Rao P L S (IBM India Research Laboratory, , Block-I, Indian Institute of Technology, Delhi) : Simulation of tropical cyclones using regional weather prediction models. Curr Sci 2000, 79(1), 70-8.

Two non-hydrostatic mesoscale models, namely the Regional Atmospheric Modelling System (RAMS) and the PSU-NCAR Fifth-generation Mesoscale Model (MM5) have been used to simulate various meteorological features associated with the tropical cyclones formed over the Bay of Bengal. Some of the simulation results, such as the horizontal distributions of winds, temperature, associated rainfall, cyclone tracks, moisture convection and height of the planetary boundary layer have been presented. The results are compared with the observations to assess the capability of these models in simulating various meteorological phenomena over the Indian subcontinent and it is established that the RMS errors for predicted zonal winds U, the meridional winds V, and the temperature T are within the acceptable limits. Both the models are also able to produce the warm core structure of the tropical cyclones. Also highlight a few potential areas of research to improve the model simulations of various weather events, specific to this region.

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001129   Parkash B;Sudhir Kumar;Someshwar Rao M;Giri S C;Suresh Kumar C;Gupta S;Srivastava P (Department of Earth Sciences, University of Roorkee, Roorkee-247 667) : Holocene tectonic movements and stress field in the western gangetic plains. Curr Sci 2000, 79(4), 438-49.

Using the soil-geomorphic approach recently, distribution and degree of development of surficial soils have been used to identify four tectonic blocks - Piedmont, Upper Ganga-Yamuna, Lower Ganga-Yamuna and Ganga-Ramganga blocks in the region between the Yamuna and Ramganga rivers in the western Gangetic plains. Luminescence dating of the soils from different blocks has been used to constrain timing of block movements. For example, the Lower Ganga-Yamuna, Ganga-Ramganga and Upper Ganga-Yamuna blocks wer uplifted at 8.5ka, <126>5ka and <126>2.5 ka, respectively. Also the shifting of the Ganga River from the Upper Ganga-Yamuna block to the Ganga-Ramganga block took place at about 2.5 ka. The Ganga-Ramganga block was tilted westward at about 1 ka causing a shift of the Ganga River in that direction. Additionally, a number of smaller movements are inferred during the last 500 years or so. Holocene compression directions from west and south-west were inferred from tilting of large blocks. Further, the thickness of Tertiary sediments over the Precambrain rocks in the Gangetic plains was used for finite element modelling of the stress pattern for the region.

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001128   Pant G B;Borgaonkar H P;Rupa Kumar K (NO, Indian Institute of Tropical Meteorology, Dr Homi Bhabha Road, Pashan, Pune-411 008) : Climatic signals from tree-rings: a dendroclimatic investigation of Himalayan spruce (Picea smithiana). Himalayan Geol 1998, 19(2), 65-73.

Dendroclimatic investigation of Picea smithiana from three different sites of Western Himalaya has been carried out. The statistical analysis of ring width index chronologies prepared from about 70 tree core samples indicate high dentroclimatic potential of P. smithiana in virtue of their great age and moderately high values of common variance and signal to noise ratios. Relationship between tree growth and climate based on response function analysis reveals the strong association of pre-monsoon (March-April-May) climate (temperature and precipitation) of Shimla with tree growth. Higher temperature during pre-monsoon months greatly affect the tree growth, whereas, small amount of precipitation during the season is conducive for the growth. Calibration equations derived from this relationship show statistically significant association between reconstructed and observed climate of pre-monsoon. The reconstruction, thus, obtained has been extended beyond the instrumental record using earlier part of the tree-ring chronologies in the calibration equations. The reconstructed pre-monsoon climate of Shimla does not show any long-term trends since A.D. 1725.

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001127   Owen L A (Department of Earth Sciences, University of California, Riverside, California 92521, USA) : Timing and style of glaciation in the Himalayan. Himalayan Geol 1998, 19(2), 39-47.

Style and timing of glaciation in the Himalayan, Trans-Himalaya and adjacent mountain areas is reviewed. New dates suggest that glaciation was not synchronous throughout the region and that in the central and western Himalaya and Trans-Himalaya glaciers advanced to their maximum extent during oxygen isotopic stage 3 as compared to the northern hemisphere ice sheets that reached their maximum in oxygen isotopic stage 2. In north Tibet, however, glacial advances were in phase with the northern hemisphere ice sheets. It is suggested that temporal and spatial variations in glacial style are probably controlled by variations in the relative importance of the South Asian monsoon and westerly jetstreams ad that other factors that control glacial style such as tectonics and topography are less important.

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001126   Midya S K;Ganda S C;Sahu S N (Department of Physics, Serampore College, Hooghly-712 201) : Antarctic O3 depletion and its correlation with relative sun-spot number. Mausam 1999, 50(4), 403-6.

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001125   Majumdar T J;Mohanty K K (Marine and Water Resources Division, Remote Sensing Applications Area, Space Applications Centre (ISRO), Ahmedabad-380 015) : Detection of areal snow cover changes over Antarctica using SSM/I passive microwave data. Curr Sci 2000, 79(5), 648-51.

SSM/I (Special Sensor Microwave Imager) passive microwave data of two different months over the Antarctic subcontinent have been used to: detect the areal extent of snow cover and to monitor the changes in the snow cover in this region. Minimum accumulation of snow over Antarctica occurs in February, and hence the detection of snow cover during January and February should indicate a depletion phase. An overall 14% decrease of snow has been observed during this period. Corresponding data for accumulation/depletion of snow indicates a matching of general trend. SSM/I data, thus, can be used as a very promising tool for monitoring of snow over the Antarctic region since it is not affected by cloud cover/darkness.

001124   Lal A K;Kaushik R;Sharma B (NO, Wadia Institute of Himalayan Geology, Dehradun-248 001) : Application of geographical information system (GIS) for water shed management in Garhwal Himalaya (a case study in Ir gad and Machhlad watershed). Himalayan Geol 1999, 20(2), 87-103.

Using geographical information system (GIS) two watersheds in Garhwal Himalya viz. Ir Gad and Machhlad were studied for optimizing the present utilization of natural resource, forest distribution, landuse, slope stability, infrastructure distribution and socio-economic status. Remotely sensed data is use to make decisions and cross examine the watersheds that have contrastingly different setup, currently undergoing deforestation due to unsustainable human activities. ARC/INFO package was used for generating thematic maps and these were superimposed on different combinations for delineating the final output. The thematic maps are used for decision support and planning of the watershed. One of such remedial measure for the target area, where currently soil erosion and consequent slope instability vulnerability exists, soil conserving plants species have been recommended. The high rate of gully erosion and active river network was attributed to local geological conditions that host highly fractured and weak lithology type. The morphometric analysis has also been done to determine the role of external forces on the landform. The maximum drainage density was observed near streams actively engaged in gully erosion and underground drainage movement. Appropriate remedial measures have been proposed to ensure sustainable development of the area without altering the present agricultural and irrigation pattern.

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001123   Kulkarni A V;Philip G;Thakur V C;Sood R K; Randhawa S S;Chandra R (NO, Space Applications Centre, Ahmedabad-380 053) : Glacial inventory of the Satluj basin using remote sensing technique. Himalayan Geol 1999, 20(2), 45-52.

Glacier inventory of the Satluj basin which includes the Beas and Spiti sub-basins was carried out using Geocoded false colour composites (FCCs) of India Remote Sensing Satellite (IRS) and Landsat satellites on 1:50,000 scale. Various glacier features such as accumulation area, ablation area, transient snow line/equilibrium line, moraine-dammed lakes, deglaciated valleys and permanent snowfields were mapped based on unique reflactance characteristics. Data sheet was complied using parameters as suggested by UNESCO/TTS. Additional parameters related to deglaciated valley and morainedammed lakes, which are important for disaster management and palaeoclimatic studies, were added in the data sheet. To make full utilization of this information, a Himalayan Glacier Information System (HGIS) has been developed. The total area under glaciers and permanent snowfields was calculated to be 2697 km² in which there are 334 glaciers in the Satluj basin covering an area of nearly 1515 km² and 1987 permanent snowfields covering an area of about 1182 km². The permanent snow cover and glaciers are distributed in 169 sub basins. In all 164 deglaciated valleys could be mapped in the Satluj basin covering an area of 133 km².

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001122   Kuhle M (NO, University of Goettingen, Goldschmidtstrasse 5, D-37077, Goettingen, Germany) : New findings on the inland glaciation of Tibet from south and central west Tibet with evidences for its importance as an ice age trigger. Himalayan Geol 1998, 19(2), 3-22.

During the research trip in 1996 detailed studies on the prehistoric glaciation of the Tibetan Plateau could be carried out. Youngest historical to neoglacial ice margin positions, confirming snow line (ELA) depressions up to 100-250 m have been documented as well as moraines of the Late Glacial (Stadia from c. I-IV). Ice margin deposites of the Lace Glacial Stadium I and of the Last Glacial Maximum have not been found, which corresponds to the altitude of the Tibetan plateau lying here at an average of 4700 m asl. Instead, forms of glacial erosion were frequently met like roches moutonnees, flank polishings and glacially streamlined hills, but also high-lying erratics and transfluences, giving prove of a wide-spread ice cover of important thicknesses. The glacial ice cover documented here, contributes to the reconstruction of the Tibetan inland ice being the main factor of the relief-specific hypothesis on the development of the Ice Ages, based on the global radiation geometry: accordingly, the platectonically induced uplift of Tibet above the snow line during the early Pleistocene, has brought about a glaciation, which - owing to its high albedo - reflected the subtropical radiation energy into space, thus reducing the heating of the atmosphere. This might have triggered the Ice Ages. The repeated interglacial warming-up at intervals of 100 000 years, depends on the glacio-isostatic lowering of the inland ice areas.

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001121   Khole M;De U S (NO, Meteorological Office, Pune-411 005) : Floods and droughts in association with cold and warm ENSO events and related circulation features. Mausam 1999, 50(4), 355-64.

The aim of the study is to examine some of these features more critically. It is observed that ENSO has a modifying effect on the regional scale circulation pattern and possible interactions and/or phase-locking with the plenetary scale circulation pattern, which results into the occurrence or non-occurrence of an extreme event. Also, a qualitative analysis is carried for a period 1960-90 to assess how far the mid-season rainfall deficiency is made up at the end of the season. It is observed that even during drought years, the mid-season rainfall deficiency is made up at the end of the season for a considerable percentage of the total number of cases.

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001120   Gururajan N S;Choudhuri B K (NO, Wadia Institute of Himalayan Geology, Dehra Dun-248 001) : Ductile thrusting, metamorphism and normal faulting in Dhauliganga valley, Garhwal Himalaya. Himalayan Geol 1999, 20(2), 19-29.

Central Crystalline rocks in Dhauliganga Valley, Garhwal can be divided into two major tectonic units, namely the Lower Munsiari and the Upper Vaikrita, separated by the Main Central Thrust. The Barrovian type regional metamorphism is related to the D2 deformation which produced the regional ductile shear fabric S2 and the growth of index minerals are syn- to post-kinematic in relation to S2. The exhumation of Vaikrita Crystallines due to translation along the MCT has resulted in development of a low temperature shear foliation which has superimposed over S2. This late shearing event from NE to SW has migrated from MCT towards Munsiari Thrust during lowering of temperature conditions. However, along the MCT this foliation was overgrown by rims of garnet and staurolite indicating high temperature shearing along the MCT, affecting a narrow zone. The exhumation of Vaikrita Crystallines has resulted in decompressionand development of Malari normal fault at the interface between the crystalline and the Tethyan Martoli Formation. The decompression has induced in situ melting and granite melt thus produced has intruded the interface between the Vaikrita Crystallines and Tethyan Formation in an extensional environment. The earlier ductile extension has superposed by late high angle brittle normal faulting which affected the Malari granite. The NE diping foliation at lower levels of Vaikrita Formation become more easterly dipping in the higher structural levels; this feature alongwith east-west displaced pegmatities in the normal fault zone indicate involvement of a strike slip component.

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001119   Gupta R P;Saha A K;Arora M K;Kumar A (Department of Earth Sciences, University of Roorkee, Roorkee-247 667) : Landslide hazard zonation in a part of the Bhagirathi valley, Garhwal Himalayas, using integrated remote sensing - GIS. Himalayan Geol 1999, 20(2), 71-85.

Deals with the development of a methodology for landslide hazard zonation using integrated remote sensing - GIS approach. A part of the Bhagirathi valley, Garhwal Himalayas, has been selected as the study area. This study has utilized geological - structural maps, topographic maps, and IRS - 1C and 1D multispectral LISS II and panchromatic sensor data sets as the input data. From these input data sets, various thematic data layers generated are : landuse/landcover mao, buffer map of thrusts, buffer map of photo-lineaments, lithology, buffer map of drainge, slope angle map and relative relief map. The ordinal qualitative method of weighting-rating with respect to landslide susceptibility has been selected for data integration. This has yielded a Landslide Hazard Index (LDI)-value map, based on the distribution of which Landslide Hazard Zonation has been carried out. Field data on distribution of landslides has been used to check the validity of the remote sensing - GIS based LHZ map.

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001118   Gupta R (NO, Centre for Spatial Database Management and Solutions (CSDMS), A-13, Sector 22, Noida-201 301) : SWOT analysis of geographic information: the case of India. Curr Sci 2000, 79(4), 489-98.

Geographic information is today being extensively used in decision making processes because it has become a fundamental element to provide better understanding about one's surroundings. Sustainable development relies on the control of the consequences of public decisions regarding natural resources, people and the involved interrelationships. More importantly, geographic information is a tool of democracy, which must be used in public debate as it enables visualization of the impact of planning decisions on society and to explain the retionale behind a particular decision. Today, must of the countries are set to exploit the potential of mapping technology. The present provides a SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis of the Indian geographic information situation using the international scenario as a back-drop.

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001117   Gopinathan C K (Physiological Oceanography Division, National Institute of Oceanography, Dona Paula, Goa-403 004) : Indirect method for forecasting the annual food production of India. Curr Sci 2000, 79(1), 23-4.

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001116   De U S;Mukhopadhyay R K (NO, India Meteorological Department, Pune-411 005) : Effect of ENSO/anti ENSO on northeast monsoon rainfall. Mausam 1999, 50(4), 343-54.

Analysis revealed that ENSO years were generally associated with enhanced northeast monsoon precipitation while there was reduced precipitation during Anti ENSO years, the reduction in Anti ENSO years being significant for Tamil Nadu (at 0.1% level). for Kerala (at 1% level) and for South Peninsular India (at 1% level). Of 22 ENSO years, 18 years were found to be either flood or wet years while 11 years out of 15 Anti ENSO years were found to be either drought or dry years. During ENSO years, the Sea Surface Temperature (SST) anomalies both over the Arabian Sea and the Bay of Bengal were positive during the months October to December, while the reverse was the case during Anti ENSO years. A concurrent significant positive correlation was noted between SST over east central Arabian Sea and the Northcentral Bay regions and northeast monsoon rainfall. The cyclonic systems were observed to form relatively at lower latitudes during ENSO years as compared to those during Anti ENSO years. These systems were also found to move in a more westerly direction, hit Tamil Nadu and south Andhra coast, thus giving more rain over peninsula during ENSO years. The ridge line at 200 hPa level during ENSO years was located 3° south as compared to its location during Anti ENSO years.

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001115   Das H P;Chowdhury A;Bhagwat R S (Division of Agricultural Meteorology, , Pune-411 005) : Two layer soil moisture model for estimating crop evapotranspiration and runoff. Mausam 1999, 50(4), 375-82.

Two layer model has been proposed to estimate evapotranspiration, soil moisture storage and runoff. Soil profile has been assumed to be composed of two layers; the top layer having a fixed field capacity of 100 mm and the underlying layer having field capacity depending on the soil texture. Normal values of weekly rainfall and potential evapotranspiration have been used in the study. The model, applied to kharif and rabi seasons furnishes crop evapotranspiration period when soil in two layers reach rainfall point and surface runoff and its duration. The model developed has been applied to 41 locations representing most of the soil types found in India. The analysis revealed that lowest ET is seen over Himalayan foothills and northeast India in kharif and rabi seasons. Enough residual soil moisture is available to the crops at the end of kharif season over NE India; most of it being in the top layer. Eastern India record largest runoff of 800-1000 mm. Arid to semi-arid region in NW India does not seem to experience much runoff.

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001114   Chowdhury A;Das H P;Gaikwad S D (NO, Meteorological Office, Pune-411 005) : Determination of relative contribution of different meteorological elements on evaporation. Mausam 1999, 50(4), 365-74.

Deals with infleunce of radiation, maximum temperature, hours of bright sunshine, relative humidity and surface wind on evaporation at Calcutta, Pune and New Delhi. Daily data from 1991-94 of January, May, June, July and October have been utilized. Direct and indirect influence of the weather factors have been determined through "path analysis" and discussed. Multiple regression equations have also been developed with evaporation as the dependent variable and the above five weather parameters as independent variables. The results reveal that radiation and maximum temperature are the two most important parameters which enhance evaporation. Most of their effect is direct though in some cases their interaction with relative humidity or wind also contribute significantly to evaporation. Humidity and surface wind, generally, do not significantly contribute directly to evaporation; their effect is manifested through interaction with maximum temperature, indirectly.

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001113   Banerjee S;Nathan K K;Chandrasekharan H (NO, Indian Agricultural Research Institute, New Delhgi-110 012) : Some observations on rainfall-water table relationship in a micro-watershed near Faridabad. Ann Arid Zone 2000, 39(1), 15-20.

Study has been carried out to understand the effects of rainfall on water table fluctuation (represented by the thickness of water column in a dug well) in a degraded environment for over eight years (1991-1998). The investigated area falls in the semi-arid tract of Aravalli hill range near Anangpur village, Faridabad, Haryana. During summer months, the water table in the area declines considerably and at times, the dug wells become dry. As expected, the thickness of water column increases with the onset of monsoon. However, the rate of increase is gradual in the beginning and is more during the later two monsoon months (August-September). A time lag of about a month was observed between the rainfall and corresponding thickness of water column. Analyses of the data yielded two sets, each comprising three types of regression equations, between the rainfall and thickness of water column, with and without the lag period. The characteristics of the equations are discussed. It is envisaged that such studies may help to identify the period of excess water utilized and/or otherwise. Knowedge on these aspects is of paramount importance for water resources development and management.

001112   Banerjee R (Geological Oceanography Division, National Institute of Oceanography, Dona Paula, Goa-403 004) : Documentation on burrows in hard substrates of ferromanganese crusts and associated soft sediments from the Central Indian Basin. Curr Sci 2000, 79(4), 517-21.

Substrates of ferromanganese encrustations collected from the hummocky topography of the Central Indian Basin (CIB) (lat. 12°25' - 12°45'S, water depth between 5150 and 5300 m) are largely composed of indurated claystone and altered pumice fragments, which are extensively bioturbated. Both the ferromanganese-coated and uncoated relict burrows have been collected from the same locality. Mobile epibenthic megafauna, e.g. molluscs, echinoderms, etc. seem to be the main bioturbating organisms. The adjacent sediments on the sea floor also show numerous records of recent bioturbation activity. Thus presence of the ancient and modern burrows from the same locality on the ocean floor indicates a prolonged bioturbation activity in this part of the CIB and this may have been a continuous process, pre- and post-dating the initiation of the formation of ferromanganese oxides at this place. The intense and prolonged bioturbation activity of the benthic fauna reported here indicates that they could have facilitated the occurrence of ferromanganese nodules at the sediment-water interface.

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001111   Anil Kumar K G (School of Marine Sciences, Cochin University of Science and Technology, Cochin-682 016) : Air pollution climatology of Cochin for pollution management and abatement planning. Mausam 1999, 50(4), 383-90.

Prevailing atmospheric condition is very important in determining the dispersion and dilution and thereby the resulting concentration of air pollutants. While high wind speed and stability conditions in general favour good mixing of air pollutants, conditions like inversion and calm winds cause for the build up of pullutants. In order to understand the different favourable and unfavourable conditions, some of the atmospheric aspects of air pollution are studied for the industrial city Cochin, situated on the west coast of India. Being a coastal city, the frequency of occurrence of inversions and isothermal is not very high. Low values of mixing heights are observed in the southwest parts of the city during early morning hours. The study of spatial variation of mixing heights has revealed for the first time, that a single value of mixing height at the normal point of observation cannot be taken as representative value for the whole city.

001110   Ambraseys N;Bilham R (Department of Civil Engineering, Imperial College of Science, Technology and Medicine, London SW7 2BU, UK) : Note on the Kangra Ms = 7.8 earthquake of 4 April 1905. Curr Sci 2000, 79(1), 45-50.

Although most recent Himalaya seismic hazard studies adopt the Ms = 8.0 magnitude assigned to the 4 April 1905 Kangra earthquake in 1954 Gutenberg and Richter, subsequent investigators have proposed magnitudes in the range 7.5s<8.6. On his worksheet Gutenberg calculators a magnitude of Ms = 7.7 using data from 15 teleseismic Milne records, yet he notes inexplicably at the base of the page, M = 7.8, and in a marginal note M = 7.9, a vlaue that is rounded upwards by Gutenber and Richter to Ms = 8.0. Confirm his original analysis, but find that the inclusion of 4 additional Milne date reduces the magnitude to Ms = 7.54 ± 0.23. A more refined magnitude analysis using data from 6 stations for which may estimate station corrections confirms a Ms magnitude of 7.83 ± 0.18. The reduced magnitude for this event suggests that more of the western Himalaya plate boundary remains unruptured than hiterio supposed.

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001109   Agrawal D P;Yadava M G (NO, Physical Research Laboratory, Ahmedabad-380 009) : Comparison of proxy climatic data from Tibet and Kashmir. Himalayan Geol 1998, 19(2), 55-9.

In 1982, a workshop was held on the Late Cenozoic Palaeoclimatic Changes in Kashmir and Central Asia, at Ahmedabad. Fourteen years later, a lot of work has been done on Tibet and now it is widely recognised that, "The Tibetan Plateau plays a major role in the atmospheric circulation of the Northern hemisphere and has an especially important influence upon the Indian monsoon and the Tropical Easterly Jetstream" (Gasse & Derbyshire, 1996). Climatic change, triggered primarily by orbital parameters, in first forced by events on the Tibetan Plateau, which manifests itself on a regional scale in the initial stages; and eventually averages out globally. Now a lot more data is available from the Tibetan region, which allows us to evaluate the role of the Tibetan Plateau in climatic change. The evidence from the Kashmir region shows that the adjoining areas, like Kashmir, Ladakh, and Nepal, can also yield valuable complimentary evidence on the dynamics of climatic change during the Quaternary. The importance of the evidence of the Kashmir valley against the backdrop of the Tibetan evidence.

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000143   Wesnousky S (Center for Neotectonic Studies and Department of Geological Sciences, University of Nevada, Reno, 89557, USA) : Hazard assessment based on geology : history, principles and examples. Himalayan Geol 1999, 20(1), 113-5.

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000142   Wahid C M M;Rahman M R;Islam M N (Department of Physics, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh) : Single cell and multiple cell clouds analysed with satellite data in and around Bangladesh. Mausam 1999, 50(2), 177-80.

Multi-cell and single-cell clouds were anlaysed using Geostationary Meteorological Satellite (GMS-5) data on 6 and 13 August 1997 in and around Bangladesh. The multi-cell cloud moved NE with a speed of about 6 m/s and lasted approximately 21 hours. The single-cell cloud moved SE with a speed of about 13 m/s and lasted approximately 12 hours. Clouds move faster on oceans than on land. At the mature stage of the cloud, convective component was 40% and the rest was stratiform. The precipitable portion of the cloud was 74% and the rest was non-precipitable which differs from the reported value.

000141   Verma R K;Chauhan P K S;Mohanty W K; Purkayastha S (Center of Georesources, University of Delhi, South Campus, New Delhi-110 021) : Analysis of seismicity, maximum magnitude and acceleration for Kashmir, Punjab, Kumaun and Garhwal Himalaya region. Himalayan Geol 1999, 20(1), 123-9.

Seismic risk analysis has been carried out for Kashmir, Punjab, Kumaun and Garhwal Himalayan region using all the available seismicity data. Assuming that all events of mag. <62>4.5 (mb) have been detected (for the period 1960-1990) by the operating seismological networks. A contour map for 1° x 1° areas showing N <62>=4.5 has been prepared. This map fairly well outlines the areas which have been seismically active during this period. A maximum magnitude map for 1° x 1° area (period 1950-1990) has also been prepared.

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000140   Verma H K;Chauhan R K S (Department of Applied Geophysics, Indian School of Mines, Dhanbad-826 004) : Bio-geo indicators of groundwater studies in parts of Dhanbad town, Bihar. Indian Miner 1999, 53(3-4), 247-56.

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000139   Suresh R (NO, Civil Aviation Training College, Bamrauli, Allahabad-211 010) : Forecasting maximum and minimum temperature over airports with special relevance to aviation in flight planning. Mausam 1999, 50(2), 121-8.

Forecasting of maximum and minimum temperature for aviation and non-aviation purpose has been attempted through auto regression and by employing the method of adaptive filtering and Kalman filtering during the hot weather season (March to May) over Madras. The filtering techniques have been outlined and the results are compared with the method of climatology and persistence. The Kalman filter, using the model ouput of adaptive filtering, forecasts well the day-to-day variability of maximum and minimum temperature during hot weather season over Madras with an efficiency close to 90%. As the model performs reasonably well over Madras, a coastal station, the same has been tried over Trichy (300 km southwest of Madras), an inland airport station in Tamilnadu to ascertain its efficacy. The efficiency is better than 90% in predicting maximum and minimum temperature within an accuracy of ± 2°C.

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000138   Sukhija B S;Rao M N;Reddy D V;Nagabhushanam P;Hussain S;Chadha R K;Gupta H K (NO, National Geophysical Research Institute, Hyderabad-500 007) : Paleoseismic studies of the Shillong plateau, northeast India. Himalayan Geol 1999, 20(1), 105-12.

Paleoseismic investigations carried out in the vicinity of Chedrang Fault, Shillong plateau, northeast India, unravelled the occurrence of at least three large/major earthquakes in addition to the great Assam earthquake of 1897 (M 8.7). The seismites associated with these earthquakes comprise liquefaction of sediments, tilled and deformed beds, microfaults etc. The carbon-14 dates of organic material associated with the seismites indicate the occurrence of past seismic events around 500 ± 150, 1100 ± 200, and <62> 1500 ± 200 yr BP (before present).

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000137   Sivaji Ch (NO, Indian Institute of Geomagnetism, Colaba, Mumbai-400 005) : Monitoring of resistivity variations in Delhi-Rohtak belt. Himalayan Geol 1999, 20(1), 73-9.

Study of earth's resistivity distribution provides better insight into the earthquake processes because of its direct dependence on the porosity, fluid content and pressure and temperature conditions. An attempt has been made to monitor the subsurface resistivity changes by means of a set of telluric dipoles and DC resistivity experiments in Delhi-Rohtak area. The interstation telluric coefficients are computed and their daily variations were monitored.

000136   Singh Y;Bhatt A K;Thimmaiah M;Singh S N (NO, Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad-500 016) : Uranium mineralisation associated with Precambrian granite gneiss in Chowrdhawa and Sonarigadai areas, Bilaspur district, Madhya Pradesh. Indian Miner 1999, 53(3-4), 175-86.

Petromineralogical and geochemical studies on the uranium-mineralised granite gneiss (UMGG) from the Precambrian gneiss-supracrustals and granitoids terrain of Chowrdhawa and Sonarigadai areas, Bilaspur district, Madhya Pradesh, suggest that they are cataclasites and mylonites, consisting essentially of quartz, microcline, orthoclase, plagioclase, biotite, chlorite, hornblende with magnetite, zircon, apatite, epidote, fluorite, pyrite and chalcopyrite as accessories, along with uranium minerals which include uraninite, sooty pitchblende and autunite. Chemical data indicate highly silicic (av. 80.81 % SiO2) and metaluminous to peraluminous (mol. A/C+N+K) ratio : 0.13-1.48) nature of these gneisses; their Na2O vs K2O and CaO-Na2O-K2O plots suggest them to be granite (ss). Uranium, copper and cobalt show about 51, 3 and 5 times enrichment respectively, with reference to their corresponding 5, 12 and 3 ppm abundances in the average granite. Petrography, mutual relations of diffferent mineral phases, cataclastic texture, silicic nature and fracture-controlled uranium mineralisation indicate that the gneisses were subjected to shearing and brecciation. These processes remobilised intrinsic uranium and associated metals from the gneisses and concentrated them mostly along an east-west-trending faulted contact. The process of epigenetic yet syntectonic uranium mineralisation was accompanied by hydrothermal alterations.

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000135   Singh A K (NO, Institute of Armament Technology, Girinagar, Pune-411 025) : Estimate of ground heat flux for a seasonal snow cover. Mausam 1999, 50(2), 153-8.

Estimation of ground heat flux for two locations has been done using temperature gradient method. Effective media approach has been adopted for predicting the effective thermal conductivity of ground. For comparison, in situ measurement of effective thermal conductivity of ground had also been done by thermal probe method. The measured values of thermal conductivity are in agreement with the calculated values. The estimated values of ground heat flux have been used to evaluate the melt rate at ground-snow interface.

000134   Shekhawat M S (Department of Geology, M L Sukhadia University, Udaipur-313 002) : Note on barite mineralisation in the basal aravalli volcanics, Sakroda area, district Uadipur, Rajasthan. Indian Miner 1999, 53(3-4), 235-40.

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000133   Sharma R V (NO, Regional Meteorological Centre, Colaba, Mumbai-400 005) : Structure of the Kakinada cyclone of 6 November 1996. Mausam 1999, 50(2), 129-34.

Radar is a very powerful tool in determining the position, speed and direction of movement, horizontal and vertical extent of the cyclone. Besides, the radar observations can also be expected to provide more vital information on the shape, size and behaviour of the eye of a cyclone. These features are very important input information for cyclone forecasting, especially in assessing the intensity of the cyclone. An effort has been made here to document the above features of a cyclone that struck the east Godavari coast in November 1996. The cyclone formed over central Bay of Bengal in the afternoon of 5 November 1996 and intensified into a severe cyclonic storm with a core of hurricane winds next day. T

000132   Sharan G (Centre for Management in Agriculture, Indian Institute of Management, Ahmedabad-380 015) : Cyclones and orchards. J agric Engng 1998, 35(2), 1-10.

Presents the findings of survey of four orchards that lay in the track of cyclone that made landfall in Kandla coast of Gujarat on June 9, 1998. Forms of tree failure are illustrated. Experience of resurrecting some trees is described for devising ways to protect the trees.

000131   Saikia C;Somerville P G;Graves R W (NO, Woodward-Clyde Federal Services, 566 El Dorado Street Pasadena, CA 91101, USA) : Ground motion time histories from large Himalayan earthquakes for earthquake loss reduction in India. Himalayan Geol 1999, 20(1), 131-47.

Growth in populations together with the infrastructure and lifelines that support urban development along the foothill states has increased the vulnerability of this region to large Himalayan earthquakes. Strategic plans for urban development need to consider seismic safety so that vulnerable structures are retrofitted and new structures are built using reliable design procedures that are based on realistic estimates of the strong ground motions that will occur during future large Himalayan earthquakes. Probabilistic seismic hazard maps on both national and region scales would form a valuable basis for implementation of seismic hazard mitigation measures.

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