This document summarizes an earthquake that occurred in Sikkim, India in 2011. It discusses the magnitude of the earthquake at 6.9 and the aftershocks that followed throughout the night. It then provides definitions and explanations of key earthquake terms like focus, epicenter, fault, body waves and surface waves. Finally, it discusses the impacts of the earthquake in Sikkim and surrounding areas, including damage to buildings and roads, relief efforts provided, and studies conducted on dams and infrastructure.

2. Presented By –
Nikhil Kulkarni BE09F01F001
Mudassir Shaikh BE09F01F003
Pirpasha Ujede BE09F01F012
Rahul Agrawal BE09F01F017

3. India is vulnerable to different
natural hazards due to its proximity
to geodynamically active locales and
unique climatic pattern.
Both these factors in different
combinations lead to the occurrence
of disasters resulting from natural
hazards like floods, earthquakes,
draught, cyclones and landslides in
different parts of the country at
frequent intervals.
It is estimated that about 60% of
landmass of the country is vulnerable
to earthquakes of different
magnitudes.

4. Sikkim experienced a major
destructive earthquake of 6.9 (Mw)
heating badly causing deaths of no
of people and d.
At least 20 aftershocks at
magnitudes of 5.7, 5.1, and 4.6 (Mw)
within 30 minutes of the initial
earthquake occurred back-to-back
throughout the night created panic
in the Gangtok.

5. Q:What is earthquake?
A:” When the edge of two pieces of the earth
grind together and cause rumbling and shaking
underneath the surface of the earth. The
shaking or trembling caused by the sudden
release of energy is earthquake. Usually it is
associated with faulting or breaking of rocks”.

6. Q:What are the causes of earthquake?
A:”The earth is divided into three main layers – a
hard outer crust, a soft middle crust, and a
center core. The outer crust is broken into
massive irregular pieces called “plates”. These
plates are moving very slowly, driven by energy
forces deep within the earth. Earthquakes
occur when these moving plates grind and
scrape against each other.”

7. What is the Elastic Rebound Theory?
Explains how energy is
stored in rocks
– Rocks bend until the
strength of the rock
is exceeded
– Rupture occurs and
the rocks quickly
rebound to an
undeformed shape
– Energy is released in
waves that radiate
outward from the
fault

8. Causes of Earthquake
Two Types aftershock and foreshock
” An aftershock is a small earthquake that
follows the main earthquake.
A foreshock is a small earthquake that often
precedes a major earthquake”.

9. Earth’s Layered Structure

10. INDO-AUSTRALIAN PLATE
Eurasian Plate

11. Map of Plate Tectonics

13. Tectonic map

14. ComPrensive

15. Focus, Epicenter, and Fault
The point within Earth’s interior where the energy
waves are produced and where faulting begins is the
focus, or hypocenter
The point on Earth’s
surface directly above
the earthquake focus
is Epicenter
Fault is fracture
in Earth where
movement has
occurred

16. Locating an Epicenter
Epicenter Location
– If information is received
from the earthquake at three
stations, then the epicenter
can be located
– A circle is drawn around each
station on a map
• The radius is equal to the
distance from the station to
the epicenter
– The point in which all three
circles intersect is the
earthquake epicenter

17. Types of Faults
” Strike-slip Fault
– Earth’s plates move sideways to one another
– Creates a shear force
– Rocks on either side of the fault surface are
moving past each other without much upward
or downward movement”.

18. Q: Where are earthquakes most prone to occur?
A: ‘’There is no technology available in any part
of the world to determine the place, time, or
magnitude, of an earthquake. However, they
are most likely to occur where the plates meet.
They are most prone to the fault line of the
plates. Because the plates are in constant
motion.

19. Q:Where Do Earthquakes Occur and
How Often?
A: 80% of all earthquakes occur in
the circum-Pacific belt
– most of these result from
convergent margin activity
– ~15% occur in the
Mediterranean-Asiatic belt
– remaining 5% occur in the
interiors of plates and on
spreading ridge centers
– more than 150,000 quakes
strong enough to be felt are
recorded each year

20. •Record seismic waves
•A drum with a sheet
of paper vibrates and
a stationary pen
marks the vibrations
on the paper
•The height of the
lines are used to
measure the energy
released from the
earthquake called the
magnitude
•The magnitude of
Sikkim Earthquake
was 6.9 on Richter
Scale
Seismograph

21. Seismograms
Seismograms
are traces of
amplified,
electronically
recorded ground
motion made by
seismographs

22. Q:What are Seismic Waves?
A: Response of material to the arrival of
energy fronts released by rupture. Two
types:
– Body waves
• P and S
– Surface waves
• R and L

23. Body Waves: P and S waves
• Body waves
– P or primary waves
• fastest waves
• travel through solids,
liquids, or gases
• compressional wave,
material movement is
in the same direction
as wave movement
– S or secondary waves
• slower than P waves
• travel through solids
only
• shear waves - move
material
perpendicular to wave
movement

24. Surface Waves: R and L waves
• Surface Waves
– Travel just below or along the ground’s surface
– Slower than body waves; rolling and side-to-
side movement
– Especially damaging to buildings

25. Shaking of earthquake

26. Sr.No. Date Time of aftershocks
Hr:Min (In IST)
Magnitude
1 18.09.2011
18 :42 5.3
2 18.09.2011
19:24 4.6
3 18.09.2011
20:35 3.0
4 19.09.2011
00:57 3.4
5 19.09.2011
03:21 3.8
Aftershocks

28. Seismicity of the world

30. •Past seismicity of the region
Historical and instrumentally recorded data on earthquakes
show that the Sikkim and adjoining area lies in a region prone
to be affected by moderate to great earthquakes in the past.
Some noteworthy earthquakes that have affected the region
are:
Cachar earthquake of 10.01.1869 (M: 7.5),
Shillong plateau earthquake of 12.06.1897 (M: 8.7),
Dhubri earthquake of 02.07.1930 (M: 7.1),
Bihar-Nepal Border earthquake of 15.01.1934 (M: 8.3),
Arunachal Pradesh – China Border earthquake of 15.08.1950
(M: 8.5),
Nepal-India Border earthquake of 21.08.1988 (M: 6.4)
Sikkim earthquake of 14.02.2006 (M: 5.7)
Bhutan earthquake of 21.09.2009 (M:6.2)

31. Earthquake Magnitudes

33. Impact
Country Deaths Injured Displaced
Damaged
Houses /
Buildings
Partially
Damaged
Buildings
Total Loss
Billion US
Dollars
India 115 184 16500 15000 3,186 22.3
China 7 136 13790 156 2960 NA
Nepal 6 25 - 4360 2800 NA
Bhutan 1 16 - 6000 - NA
Bangladesh 0 - - - - NA
Total 129 - - - - -

35. Landslides are one of the natural
hazards that affect
at least 15% of land area of our
country exceeding 0.49
million km2. Landslides of different
types occur frequently
in geodynamically active domains in
Himalaya,

36. Tremors
The strong tremor jolted buildings across northern and
eastern India, including Delhi, Uttar Pradesh,
Uttarakhand, Jharkhand, Bihar, West Bengal, Assam
and Mizoram, prompting people to run out of their
homes in panic.

37. Destruction from Earthquakes
Landslides
With many earthquakes, the greatest damage
to structures is from landslides and ground
subsidence, or the sinking of the ground triggered
by vibrations
Fire
In the San Francisco earthquake of 1906, most
of the destruction was caused by fires that
started when gas and electrical lines were cut.

38. Tsunami Movement: ~600 mph in deep water
~250 mph in medium depth water
~35 mph in shallow water
Movement of a Tsunami

39. Tsunamis
Caused by the movement of the ocean floor
– Causes a disruption in the water
– Some are so wide that a large ship can
travel over the wave without knowing
– Recent earthquake in the Indian Ocean
created a tsunamis that was 100 feet
high and moving at 500 mph

40. Nepal
The magnitude of the earthquake was
5.8Mw in the region.
Bangladesh
Earthquake was 10 km (6.2 miles) deep.

41. The Economics and Societal Impacts of EQs
Damage in Oakland, CA,
1989
• Building collapse
• Fire
• Tsunami
• Ground failure

42. Effects of EQ on Sikkim Govt.
1. The Sikkim Government has disbursed Rs 14.21 crore
(142 million Rs)
as relief among quake-hit people in Sikkim.
2. The India govt. has asked seismic experts from the
IIT-Roorkee to conduct "earthquake impact studies" at
the dam sites of state-owned NHPC Ltd and North
Eastern Electric Power Corp. Ltd (Neepco).
4.Many roads are blocked by landslides
5. Indian Prime Minister Manmohan Singh immediately
convened a meeting of the National Disaster Management
Authority Chamling to express his full support.
6. The Indian Air Force flew five cargo planes with relief
material and rescue personnel
for deployment in West Bengal and Sikkim.

43. RESCUE OPERATIONS

44. References:
Sky news
Ndtv
Google earth
Star news
www.youtube.com
www.usgs.gov

46. Thank you