An earthquake is a sudden shaking or trembling of the Earth's crust due to the sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are caused by the movement of tectonic plates and volcanic eruptions. Earthquakes can result in devastating effects like loss of lives and property from building collapses, economic impacts from infrastructure damage, landslides, and tsunamis. Safety measures during an earthquake include dropping, covering, and holding on if inside, and staying away from buildings if outside.

1. PHYSICS ACTIVITY -
EARTHQUAKES

2. WHAT IS AN EARTHQUAKE ?
An earthquake (also known as a quake) is a sudden shaking or trembling of
the Earth’s crust which lasts for a very short time.
It is due to the sudden release of energy in the Earth’s crust that creates
seismic waves (shock waves).
BEFORE AN EARTHQUAKE AFTER AN EARTHQUAKE
Images from an earthquake which occured in Italy in 2016
BY-SAATHVIK M.

3. CAUSES OF EARTHQUAKES
MOVEMENT OF
TECTONIC
PLATES
The outermost layer of the earth is not in one piece,it is made up of a
number of separate slabs or plates of rocks called tectonic plates.
These plates float around in semi-molten magma, and as they collide,
move apart or slide over one another, these cause vibrations/seismic
waves.
VOLCANIC
ERUPTIONS
It is the cause of earthquake which occurs due to explosion of hot
gases. They cause sudden displacement of lava within or beneath the
conduit of the volcano. This results in vibrations across the Earth’s
surface resulting in earthquakes.
BY-SAATHVIK M.

4. IMPACTS OF EARTHQUAKES
Earthquake is an unpredictable natural disaster and can result
in devastating effects. Following are its impacts-
1)LOSS OF LIVES AND DESTRUCTION OF
PROPERTY-
● The seismic waves generated from earthquakes cause
buildings to shake and collapse. The collapse of these
structures which are made from heavy material leads to
loss of lives and damage to structures.
● Soil liquefaction i.e mixing of groundwater and sand or
soil during the earthquake tremors may occur and cause
the ground to become very soft resulting in a building to
lean or sink into the ground.
SOIL LIQUEFACTION
COLLAPSE OF BUILDINGS
BY-PRANYA BATRA

5. IMPACTS OF EARTHQUAKES
2)ECONOMIC IMPACT-
● Earthquakes cause large-scale devastation to infrastructures
and governments have to spend a large amount of money to
rebuild destroyed buildings.It also causes the spending of
the funds to distribute medicine and food to victims.
3)LANDSLIDES-
● Tremors, particularly in mountainous places, can result in
slope instability and failure, resulting in debris falling down
the slope and creating landslides.
4)TSUNAMIS-
● Tsunamis are caused by large earthquakes on the sea floor
when slabs of rock move past each other suddenly, causing
the overlying water to move.
LANDSLIDES
TSUNAMIS
BY-PRANYA BATRA

6. SAFETY MEASURES
1) DROP. COVER.
HOLD ON
● DROP down onto your
hands and knees.
● COVER your head and
neck underneath a
sturdy table or counter.
● HOLD ON to your
shelter.
2)IF INSIDE,REMAIN
INSIDE
● Stay away from hanging
objects/glass/any fixtures
that can collapse.
● If available, take
something to shield your
head and neck from
falling debris.
3)IF OUTSIDE, REMAIN
OUTSIDE
● Go to an open area away
from trees, telephone
poles, and buildings.
● The greatest danger from
falling debris is outside
doorways and close to
outer walls of buildings.
BY-PRANYA BATRA

7. Seismology – The study of earthquakes
Seismology is the scientific study of earthquakes and the generation and propagation of elastic
waves through the Earth or other planetary bodies. A recording of Earth motion as a function of
time, created by a seismograph is called a seismogram. A seismologist is a scientist working in
basic or applied seismology.
Seismologists study earthquakes by looking at the
damage that was caused and by using
seismometers. A seismometer is an instrument
that records the shaking of the Earth's surface
caused by seismic waves. The term seismograph
usually refers to the combined seismometer and
recording device. The record of the ground
motion at a measuring station as a function of
time is called seismogram
BY-SAUMYA JHA

8. Richter Scale
The richter scale is a logarithmic scale that calculates earthquakes size by measuring ground
motion on seismograph. Richter scale, quantitative measure of an earthquake’s magnitude, devised
in 1935 by American seismologists Charles F. Richter and Beno Gutenberg. Although modern
scientific practice has replaced the original Richter scale with other, more-accurate scales, the
Richter scale is still often mentioned erroneously in news reports of earthquake severity as the
catch-all name for the logarithmic scale upon which earthquakes are measured.
The earthquake with the biggest recorded
magnitude was the Great Chilean Earthquake. It
had a magnitude of 9.5 on the Richter scale and
occurred in 1960. Around 6,000 people died
because of the earthquake. No earthquake has
ever hit 10+ on the Richter Scale.
BY-SAUMYA JHA

9. QUIZ TIME
? What is an earthquake ?
? What are the causes of an earthquake ?
? Name any 3 impacts of an earthquake.
? What are the safety measures that should be adopted during an earthquake
(while outside and inside) ?
? The record of the ground motion at a measuring station as a function of time
is called _______
? Define the term elastic waves.
? Name the earthquake with the biggest magnitude and the year it occurred.
? In which year was the Richter scale devised and by whom ?

10. THANK YOU !