Vol. 1(3) July 2008
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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