Page 93 - SST Class 05

not feel an earthquake with an intensity of 3 or less; while the one measuring 6 or
above can be highly destructive.

Tsunami
An earthquake occurs deep inside the earth. If it occurs
below the sea surface, it can cause the water waves to rise.

These waves are called tsunami. As a result of sudden
shaking, the seawater is shifted suddenly which results in
high tidal waves. These waves travel to the coast at a very
high speed. When they strike the coastal areas, a sudden
flood occurs and everything there can be flooded. This
results in large scale destruction. A tsunami

Volcano

It is very hot deep inside the earth. Everything is in a molten
state there. If there is a deep crack or hole in the earth’s
surface, this molten material can flow out at a high speed.
This hot molten rock is called lava . Lava is accompanied by
rock particles, hot water, gases and other chemicals. Lava is
very hot and is like a thick juice which flows like a river. As it
moves in the surrounding area, it takes everything in its A volcano
embrace. Due to it being very hot, things coming in its way can burn. Thus, it causes

destruction of life and property. When out of the earth, lava does not take a long time to
cool down and turn into solid rock. This means that anything surrounded by lava
cannot be retrieved. A massive volcano can even cause an earthquake.

Flood
An area may be covered with a very large amount of water,

such a situation is called a flood. It can occur due to a
number of causes. Rainfall is the main cause behind a flood.
Sometimes, it can occur owing to a river changing its course
or a dam getting damaged. In the seacoast, sea waves can
cause a flood.

A flood can cause destruction of life and property. It also A flood
harms in different ways. In the stagnant water, dreaded diseases can break out, such as
cholera, diarrhoea, malaria, dengue etc.

Drought

A flood occurs when it rains excessively. On the other hand, a drought occurs due to

Natural Disasters 93