The document discusses various natural disasters in India such as cyclones, floods, earthquakes, and landslides, detailing their causes, impacts, and mitigation measures. It emphasizes that while these disasters cannot be prevented, proactive measures like tree planting, construction of proper drainage, and timely warnings can help minimize their effects. The text also highlights specific challenges posed by human activities that exacerbate these natural calamities.

1. Dr. J.B. Kathiriya
Dept. of Veterinary Public Health & Epidemiology
College of Veterinary Science & A.H.,
Junagadh Agricultural University,
Junagadh-362001

2. INTRODUCTION
Natural Calamities like Cyclone, flood, earthquake, volcanoes
and Landslides are normal natural events in the formation of
earth, but they are disastrous when they strike human
settlements.
In India, natural disasters occur frequently. For example, about
260 million people are being affected by frequent floods which
occur in eight major river valleys in 40 million ha..
About ten million people are affected by cyclones in the entire
5700km long coastline of peninsular India in 9 states.
This impact of earthquake is much more than the other
disasters because about 400 million people in the seismic zones
IV and V (55% of total area of India) are being greatly affected.
About ten million people living along the entire sub Himalayan
region and Western Ghats suffer a lot due to landslides.
Since the disasters strike human settlements often in different
parts of the world, they have to learn to minimize the effects of
disasters.

3. CYCLONES
Cyclone is a large scale
air mass that rotates
around a strong center of
low atmospheric pressure.
Tropical cyclones in the
warm oceans are formed to
heat and moisture.
Sea surface temperature
should be above 260
C.
Cyclones move like a spin
(120-400 km/hr) with a
diameter of 100-1500 km.

5. Management
It is not possible to stop cyclones. But we can follow
certain measures to escape from their devastation.
The measures are as follows:
Planting of trees along coastal belts.
Construction of dams and wind breaks.
Installation of wide roads for the people to evacuate
quickly in emergencies.
Installation of better working system.
Construction of proper drainage.
Disaster prediction i.e., announcement of cyclone warning
to people would help in minimizing the impact.

7. FLOODS
Causes
It is caused by natural and human factors.
Natural Factors: Heavy and prolonged rainfall,
blocking of free flow of the rivers due to landsides and
overflowing of river banks.
Human Factors: Building activities, channel
manipulation through diversion of river course,
construction of bridges, deforestation,
changes in land use and blockage of water courses by
plastics.
Recently in Chennai, the intensity of flooding of roads
and residential colonies increased due to the
accumulation of plastics in water courses.

8. Control
The impact of flood can be minimized by the
following steps
The discharge of waste must be hastened.
The flow of water must be diverted.
The return runoff water from river must be delayed.
The flood situation must be announced to the people in
advance through media.

9. EARTHQUAKES
A sudden movement of Earth’s crust (or) a motion of the ground
surface is known as earthquake.
Earth’s crust has many tectonic plates of solid rock which slowly
move along their boundaries.
Hypocenter is a point of sudden energy release.
Epicenter is the place on the ground surface (fault lines or planes
of weakness) recording seismic waves (first movement) for the
first time.
The intensity of energy released by an earthquake is measured by
the Richter scale devised by Charles F. Richter.
Sesimometer is an instrument used to measure seismic waves.

10. Severity of an earthquake
S. No Richter Scale Severity of
Earth quake
1. Less than 4 Insignificant
2. 4-4.9 Minor
3. 5-5.9 Damaging
4. 6-6.9 Destructive
5. 7-7.9 Major
6. More than 8.9 Great

12. Causes
Natural factors: Friction due to moving of tectonic plates
creates stress which leads to fractures and causes
earthquakes.
Human factors:
Underground nuclear testing causes earth tremor.
Collection of huge amount of water behind a dam also causes
earthquake.
Pouring liquid wastes into deeper wells creates tremor.
Effects
Earthquake causes damage to buildings, roads, factories,
dams and bridges.
Water supply and electricity supply and
Telecommunication are completely disrupted.
In hilly areas, land slides occur damaging dams and
causing floods

13. Mitigation of earthquakes
By constructing earthquake resistant buildings or by
making pads or floats beneath the buildings we can
reduce the impact of earthquake.
By making wooden houses in seismic zones, the
effects of earthquake can be mitigated.

16. Tusnamis-(High Sea waves) (Japanese word)
Severe earthquakes under sea water generate high sea
waves and these are referred to as tsunami in Japanese
language.
They travel at a speed up to 1000mk/hr or more.
They rise from 15 meters to 65 meters in height at sea
shore, causing vast devastation in coastal areas.
The first Tsunami hit India in 1945, when Indians were
engaged in the war of Independence.
At that time, people did not worry about Tsunami much.
Even now there is a danger of Tsunami in the Arabian
sea.

17. People are not aware of this danger. But the animals are
capable of learning the tsunami strike in advance with
the help of their ultrasonic radiation.
Thus, they often escape from the danger. Therefore, it
is better to train sea animals as done in China, in order
to caution the human beings about tsunami in advance.
A tsunami-warning instrument is to be fixed in the Bay
of Bengal to track tsunami in advance.
Generally tsunami strikes during the beginning or
towards the end of a month. For example, tsunamis
struck on 27th
August 1883, 25th
November 1945 and 26th
December 2004. In some countries, tsunami struck in
the beginning of the month.

19. LANDSLIDES
The moving down of coherent rock of soil mass due to
gravitation is called landslide. The sudden rockslides are more
Causes
Human activities like hydroelectric Projects, dams,
construction of roads, railway lines, mines and deforestation
cause landslides.
Mitigation
Landslides can be minimized by stabilizing the slopes by
adopting the following measures:
A forestation in vulnerable areas so that vegetation
consolidates the slope materials and provides cohesion with
the help of root and also retards water flow and erosion.
Providing slope supported by wired stone blocks.
Providing concrete support at the base of slope.
Draining the surface and subsurface water.