What is an earthquake? When earth
quake – quake? Kind of but with that quake – quake it cause (crack – crack) and
destruction of living and non –living beings .so let’s dive into the meaning of
it. It is a natural event that cause by a sudden release of energy in the earth’s
lithosphere which generates waves that travels in all directions and results in
shaking of the earth. The release of energy occurs along a faults that caused
by a sharp break of the crustal rocks or slide of plates.
The point from where the energy
release inside the earth is called the focus or hypocentre of an
earthquake. After that the energy travels in all directions and reaches the
surface, the point which is nearest and perpendicular to the focus is known as epicentre
it is the first one to experience the waves.
An instrument called “seismograph”
records the waves reaching the surface. Earthquake waves are basically of two
types –body waves and surface waves. Body waves are caused due
to the release of energy at the focus which moves in all directions travelling
through the body of the earth. After the body waves reach the surface it
interacts with the surface rocks and generate new set of waves called surface waves.
These waves move along the surface,
their velocity changes as they change the medium. The denser the medium, the
higher is the velocity .Their direction also changes because of the reflection
or refraction.
There are two types of body waves – P
and S – waves. The P –waves are the first to arrive at the surface. These are
also called ‘primary waves’. They travel through gaseous, liquid and solid
materials. P –waves vibrate parallel to the direction of the waves. They are
similar to sound waves. S –waves arrive at the surface with some time lag. They
can only travel in solid medium which helped scientists to understand the
interior of the earth. The direction of vibration of S –waves is perpendicular
to the wave direction in the vertical plane. Then the surface waves are the
last to report on seismograph. These waves are more destructive than others
because they cause displacement of rocks and hence the collapse of structure
occurs.
Measuring
Earthquake
The measurements occur according to
the magnitude or intensity of the shock. The magnitude scale is known as the Richter scale. The intensity measuring
scale is known as Mercalli scale.
Earthquake safety precautions
1. Keep clear windows –glass may get
shatter from the shaking.
2. If you are outside, move away from
the buildings which can collapse. Stay in an open area where there are no
buildings, trees or electrical connections.
3. Never stand under an object that
can fall on top of you like cupboard, large bookcase.
4. If you are at school, work or any
shopping mall don’t take elevator take stairs.
Be safe, be happy.
By: Shivani Awasthi (FullFry)
