Synoptic Scale Disturbances on the Monsoon Trough and Associated Rainfall Activity (1997-2002)

Panchawagh N.V.

Spatial and temporal variability of rainfall over India is remarkable in the southwest monsoon season during the period 1997 to 2002. For the first five years monsoon rainfall is normal for India. However, the year 2002 resulted into a drought year. A break phase was observed over India during July 1998. The regional circulation over India showed unusual features during monsoon 2002, viz., a one-month delay in onset of monsoon over northwest India, a break-like situation over India in July 2002 and absence of depressions/storms over Bay of Bengal in the season. The transient disturbances like low pressure areas, monsoon depressions and cyclonic storms showed large variability in their frequency, location of formation etc. and thereby affected the rainfall activity extensively through organized cumulus clouds. Hence, the space-time variability of rainfall activity over the Indian region has been studied for the period from 1 June to 30 September, 1997-2002. The study shows that the day to day rainfall activity over central parts of India was influenced by the transient disturbances. While moving across the monsoon trough region, some of them kept a more southerly track of movement and reached into anomalous heavy rainfall for subdivisions like Madhya Pradesh, Gujarat region, Vidarbha etc. in the active phase of monsoon. Monsoon circulation weakened subsequent to such events leading to development of monsoon breaks. The eastward moving troughs in mid-latitude westerly flow during June 2002 affected the part of the westward moving monsoon system and suppressed their further intensification.

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Integration of Geo information Technology and Survey Analysis for Development in Mitigation Study against Earthquake: A Case Study for Esfahan Iran

Pirasteh Saied, Mahmoodzadeh Amir and Mahtab Alam

The modern space-based remote sensing, spatial science (i.e. geo information technologies) has opened up efficient means for tectonic studies and evaluation of earthquake risk and mitigation strategy. The areas affected by earthquake are large and generally confined to plate boundaries. Fault rupture and associated surface deformation, damage due to ground shaking can be observed using remote sen­sing. The recognition of fault displacements using geo information technology for study in Esfahan has bro­ught more care for rehabilitation and vulnera­bility. The compiled seismocity map with field checks and lab analysis for buildings beside remote sensing and GIS techniques shows that Esfahan may be affected by 5-6 Richters earthquakes. This study reve­als that the infrastructure of Esfahan in some places should be rehabilitated and should be made more resistant against future earthquakes, especially for those historical bui­ldings, bridges and etc. which go back to 400 years.

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New Geochronological Data on the Continental Alkaline Flood Basalts of the Bamoun Plateau: Evidence of an Early Alkaline Volcanism of the Cameroon Volcanic Line

Moundi Amidou, Konfor Njilah Isaac , Ghogomu Richard Tanwi and Wokwenmendam Pauline Nguet

The Bamoun Plateau is one of the volcanic districts of the Cameroon Volcanic Line (CVL). It comprises two types of continental flood basalts: transitional basalts found in the western half, not studied in this paper, and alkaline basalts in the East. This paper presents new petrographical (olivine and clinopyroxene phenocryst basalt in the northern area at Foumban and in the southern area at Koutaba), mineralogical (diopside, hedengbergite and Na-augite), geochemical (low ratios Y/Nb, Zr/Nb, Ba/Nb with very high ratios LaN/YbN and CeN/YbN) and geochronological data (K-Ar) of the alkaline basalts. Sr87/Sr86 (0.70345) and 143Nd/144Nd (0.51287), mineralogical and geochemical data are similar to those of the CVL. However, the Lutetian age (46 Ma) of two of the basalts from Koutaba and Foumban are higher than those of transitional (44 Ma) or alkaline (42 Ma) basalts from Bangou (Bamileke Plateau, CVL). These data reset the time span and indicate that the volcanism of the Bamoun Plateau could be­long to the early alkaline volcanic events of the CVL.

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Relationship between Cyclonic storms and Geomagnetic storms

Joshi Indira Sudhir

Cosmic ray fluxes, modulated by solar wind, can influence storm intensity which has been examined recently by Tinsley et al9,10. The relationship is explained through changes to the rate of freezing of super cooled water droplets by ionization processes occurring in high-level storm clouds. Keeping this hypothesis in view and previous research on the relationship between extraterrestrial factors and the intensification of winter cyclones, a study has been undertaken to examine the relation between the geomagnetic storm activity and cyclonic storm activity.

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World Trade Center Disaster: Innovations for Improved Fire Safty in Buildings

Kodur V.K.R.

The September 11th terrorist incidents have caused colossal destruction and significant damage to a number of buildings in the World Trade Centre (WTC) vicinity in New York City. The twin towers of the WTC though suffered significant damage from the impact of the planes withstood the impact. However, the severe fires that followed the impact brought down the twin towers. In addition a number of other buildings, including WTC 7, suffered full or partial collapse, or significant damage as a result of fires. Thus, fire issues played a major part in the collapse of the twin towers and other WTC buildings. In this paper a brief overview of the factors leading to the collapse of the Twin Towers is presented. The overall damage to the buildings and infrastructure is review­ed and discussed. Finally the various innovations that are needed to address issues for improved building performance under fire conditions are highlighted.

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Tectonics and Seismology of North-East India and Adjoining Areas

Das P. K.

North-east India and its adjoining areas consist of some major active tectonic zones which control the seismicity of this region. Tectonic analysis of the eastern Himalayan mobile belt and the Meghalaya plateau with its surroundings indicates that seismicity in these zones is caused by movements along many N-S and NW-SE cross faulty/fractures lying to the Himalayan thrust front and cutting across the Meghalaya Plateau. In the Mishmi block, strike-slip motion is predominant along NW-SE, trending faults. In the eastern Himalayan zone, MBF and MCT are two important thrusts. Similar level of seismicity is depicted from the Dauki fault delimiting the southern boundary of the Meghalaya plateau. The Indo-Burmese Arc reveals a well defined Benioff zone with segregation of strike-slip, thrust and normal fault along the subducting zone. So it is observed that many types of faults and thrusts are the major tectonic features of the area and are responsible for some large and great earthquakes occurred in this region. So this region requires a very intensive seismological observational plan for future studies.

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