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Earthquake
India has witnessed
some of the most devastating earthquakes during the
last century like the one in Kangra (1905), Bihar-Nepal
(1934) and in Assam (1950). In the recent past, earthquakes
have caused havoc in Uttarkashi (1991), Latur (1993),
Jabalpur (1997), Chamoli (1999) and in Bhuj (2001).
On 26th January 2001, India
experienced one of the worst earthquakes in recent
times. Measuring 6.9 on the Richter scale, the earthquake
caused incalculable damage not just to its epicenter,
Bhuj but also to other towns of the district of Kutch
and to about 500 villages out of the total of 900
villages. The reported damage to property in Gujarat
was about Rs.21, 000crore and the number of human
lives lost were about 14,000. Of these, more than
500 deaths were reported from Ahmedabad, situated
at a distance of about 350 kms from Bhuj. In the same
city, close to 150 multi-storied buildings crumbled
down. Cities far away from the epicenter, like Surat,
too reported damage to property.
Cyclones
Cyclones in India generally strike the East Coast;
some of the Arabian Sea Cyclones strike the west coast
of India as well mainly the Gujarat and North Maharashtra
coast. Out of the storms that develop in the Bay of
Bengal, over 58 percent approach or cross the east
coast in October and November.
India has a very long coastline of 8041 km, large
parts of which are vulnerable to cyclone.
Floods
The rapid and durable recovery which
does not reproduce the original vulnerable conditions
The country receives an annual precipitation of 400
million - hectare meters. Of the annual rainfall,
75% is received during four months of monsoon (June-
September) and, as a result, almost all the rivers
carry heavy discharge during this period. The flood
hazard is compounded by the problems of sediment deposition,
drainage congestion and synchronization of river floods
with sea tides in the coastal plains. The area vulnerable
to floods is 40 million hectares and the average area
affected by floods annually is about 8 million hectares.
The average annual total damage to crops houses public
utilities during the period 1953- 1995 was about Rs.9720
million.
The Table below depicts the average annual loss in
the 1953 onwards.
Drought
Drought is a temporary reduction
in water or moisture availability significantly below
the normal or expected amount for a specific period.
This condition occours either due to inadequacy of
rainfall, or lack or irrigation facilities, under-exploitation
or deficient availability for meeting the normal crop
requirements in the context of the agro-climatic conditions
prevailing in any particular area. This has been scientifically
computed as Moisture index (M I). There is a drought
in jaisalmer (Average rainfall 200 mm) if rainfall
is not sufficient to grow grass an paltry coarse-grains,
whereas in Bolangir or Koraput (Orissa-rainfall above
1000 mm) there is a drought if there is not enough
rainfall for bringing the paddy crop to maturity
Landslides
Landslides are simply defined as
the mass movement of rock, debris or earth down a
slope and have come to include a broad range of motions
whereby falling, sliding and flowing under the influence
of gravity dislodges earth material. They often take
place in conjunction with earthquakes, floods and
volcanoes. At times, prolonged rainfall causing heavy
block the flow or river for quite some time. The formation
of river blocks can cause havoc to the settlements
downstream on it's bursting.
In the hilly terrain of India including the Himalayas,
landslides have been a major and widely spread natural
disaster the often strike life and property and occupy
a position of major concern
One of the worst tragedies took place at Malpa Uttarkhand
(UP) on 11th and 17th August 1998 when nearly 380
people were killed when massive landslides washed
away the entire village. This included 60 pilgrims
going to Lake Mansarovar in Tibet. Consequently various
land reform measures have been initiated as mitigation
measures.
The two regions most vulnerable to landslides are
the Himalayas and the Western Ghats. The Himalayas
mountain belt comprise of tectonically unstable younger
geological formations subjected to severe seismic
activity. The Western Ghats and nilgiris are geologically
stable but have uplifted plateau margins influenced
by neo- tectonic activity. Compared to Western Ghats
region, the slides in the Himalayas region are huge
and massive and in most cases the overburden along
with the underlying litho logy is displaced during
sliding particularly due to the seismic factor.
Avalanches
Snow cover on a slope tends to slide down the slope
because of gravity. Conditions affecting stability
include the gravitational force component of the snow
and resisting forces, such as the frictional resistance
of the slope or the anchoring effect of shrubs. In
general, avalanches are caused when this balance is
lost and when the forces exceed the resistance. Avalanches
are rarely observed closely since they normally occur
during a short time period of one or two minutes.
Major Causes - Major causes of avalanches can be classified
into fixed (prime factors) and variable factors (exciting
factors), such as weather conditions and the weight
of the snow cover, Avalanches occur when these factors
are combined. The types and scale of avalanches can
differ depending on the combination of these various
factors and their scale. Major prime factors and exciting
factors are shown in the following table.
Forest Fires
The most
common hazard in forests is forests fire. Forests
fires are as old as the forests themselves. They pose
a threat not only to the forest wealth but also to
the entire regime to fauna and flora seriously disturbing
the bio-diversity and the ecology and environment
of a region. During summer, when there is no rain
for months, the forests become littered with dry senescent
leaves and twinges, which could burst into flames
ignited by the slightest spark. The Himalayan forests,
particularly, Garhwal Himalayas have been burning
regularly during the last few summers, with colossal
loss of vegetation cover of that region.
Pest Infestation
Food losses due to pests, disease,
wild animals, insects and weeds are considerable.
It is estimated that 35% of word crop production is
lost in spite of pesticide and other control programs.
The primary pests are insects, disease and weeds.
Losses due to birds and wild animals are low compared
to these. A pest may be defined as any living organism
or plant causing harm or damage to people, their animals,
crops or possessions. The important pests are those,
which lead to loss of crop yield or quality, resulting
in loss of profits to the farmers and reduced stocks
for subsistence or export.
Tsunami
A tsunami is a giant wave caused by an underwater
earthquake or volcanic eruption. This animation shows a hypothetical
tsunami in the Pacific Northwest of the United States.
Energy from
the quake creates the initial wave, which splits into two -- one wave
moves out into the ocean while the other heads toward the shore. Most
tsunamis do not create giant breaking waves on shore. Instead, they
generate very fast and strong tides that make sea level rise quickly.
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