4. Earthquake may simply expressed as a momentary
shock experienced by the earth at a particular location
and time.
Earthquake may be technically defined as the vibrations
induced in the earth’s crust due to internal or external
causes that give a shock to a part of the crust and all
things existing on it
5. The study of
earthquakes is of
special significance to
civil engineer because
it will help him predict
the occurrence of
earthquake and also
design and provide
such structures that will
afford protection during
earthquake.
6. The greek word for earthquake is
Seism and therefore the term
seismic is associated with
earthquakes.
The science dealing with the study
of earthquakes is called
seismology
The word seismic is used to
qualify anything related to
earthquake such as seismic
intensity, seismic zoning, seismic
waves etc.
7. INTENSITY MAGNITUDE
FOCUS OR
HYPOCENTRE
Intensity is a term
The point of origin used to measure the A term used to establish
of an earthquake impact of the size of an earthquake,
below the surface of earthquake. Intensity which is a measure of the
earth. measures the amplitude of a seismic
strength of shaking wave and is related to the
EPICENTRE produced by the amount of energy
earthquake at a released
The point on the
certain location. during an
surface directly
Intensity is earthquake. Magnitude is
above the focus
determined from the total energy released
where the vibrations
effects on by an earthquake at its
are felt. focus. The Richter Scale
people, human
structures, and the is most famous to
natural environment. measure the magnitude of
Mercalli Scale was an earthquake.
used to predict
intensity.
8. Nowadays intensity of earthquakes are not measured.
They have been replaced by magnitude.
Top 5 Earthquakes by Magnitude.
S. Date Place Magnitude
No.
1 22 May 1960 Valdivia, Chile 9.5
2 27 March 1964 Alaska, USA 9.2
3 26 December Sumatra, Indonesia 9.1
2004
4 13 August 1862 Arica,Chile 9.0
5 26 January 1700 Cascadia, USA- 9.0
Canada
9. An earthquake may be caused by the following natural and artificial
sources.
NATURAL SOURCES
Tectonic Plates Movement 90%
Faults in Rocks (Elastic Rebound Theory) 6%
Volcanic Explosions 1%
ARTIFICIAL SOURCES
Explosion 1%
Mine Collapse 1%
Reservoir Failure 1%
10. SEISMIC WAVES
The energy released during earthquake travels to the
earth in form of waves.
The waves are called as
P-Waves
S-Waves
L-Waves (Rayleigh Waves & Love Waves)
P-Waves & S-Waves are called as body waves.
L- Waves are also called as surface waves.
11. The seismic waves are very useful as follows
They were used to establish the internal structure of the earth.
They are used to calculate the magnitude of earthquake. Richter Scale
is based upon the amplitude of the seismic waves.
They are also used to locate the epicentre of earthquakes.
They are also used for groundwater and other explorations.
12. Isoseismal Lines – Hypothetical line passing through places of same
earthquake intensity. They are also used to measure epicentre.
Seismograph – An instrument used to record ground movements
caused by earthquakes, explosions or other vibrations.
Seismic Zone - A seismic zone is a region in which the rate
of seismic activity remains fairly consistent. People often use the
term “seismic zone” to talk about an area with an increased risk
of seismic activity. Seismic hazard zones” is another term used.
13. The effects of earthquakes
Loss of Life
Building Collapse
Ignition of Fire
Ground Failure and Rupture
Landslides and Avalanches
Floods and Tidal Sources
Tsunami
Change in Soil and Rock Properties
14. WORLD SEISMIC ZONES
or EARTHQUAKE HOTSPOTS
Based on seismicity, the three most happening earthquake hotspots
in the world are
1. PACIFIC RING OF FIRE
2. ALPIDE BELT
3. MID ATLANTIC RIDGE
15.
16.
17.
18. EARTHQUAKES IN INDIA
The major earthquakes in India are
2004 Sumatra Earthquake (9.1)
1934 Bihar Earthquake (8.7)
1950 Assam (Shillong Plateau) Earthquake (8.7)
1897 Assam (Tibetian Plateau) Earthquake (8.5)
2005 Kashmir Earthquake (7.6)
2001 Gujarat(Kutch) Earthquake (7.1)
20. EARTHQUAKE ZONES IN INDIA
There are five seismic zones named as I to V based on Modified Mercalli
Scale (MM Scale) as details given below:
Zone V: Covers the areas liable to seismic intensity IX and above on MM
Scale. This is the most severe seismic zone and is referred here as Very
High Damage Risk Zone.
Zone IV: Gives the area liable to MM VIII. This, zone is second in severity to
zone V. This is referred here as High Damage Risk Zone.
Zone III: The associated intensity is MM VII. This is termed here as
Moderate Damage Risk Zone.
Zone II: The probable intensity is MM VI. This zone is referred to as Low
Damage Risk Zone.
Zone I: Here the maximum intensity is estimated as MM V or less. This zone
is termed here as Very Low Damage Risk Zone.
21.
22.
23. EARTHQUAKE ZONES IN INDIA
Zone V: Kashmir, Punjab, the western and Central Himalayas, the North-
East Indian region and the Rann of Kutch fall in this zone.
Zone IV: Indo-Gangetic basin and the capital of the country(Delhi, Jammu)
and Bihar fall in Zone 4.
Zone III: The Andaman and Nicobar Islands, parts of Kashmir, Western
Himalayas, Western Ghats fall under this zone
Zone II: Other parts of India namely Hyderabad, Lakshadweep, Orissa etc.
Zone I : No
24. EARTHQUAKE ZONES IN INDIA
Cities and Zones
• Zone III :- Ahemdabad, Vadodara, Rajkot, Bhavnagar, Surat,Mumbai,
Agra, Bhiwandi, Nashik, Kanpur Pune, Bhubneshwar, Cuttack, Asansol,
Kochi, Kolkata, Varanasi, Bareilly, Lucknow, Indore, Jabalpur, Vijaywada,
Dhanwad, Chennai, Coimbatore, Manglore, Kozhikode ,Trivandrum.
• Zone IV :- Dehradun, New Delhi, Jamunanagar, Patna, Meerut, Jammu,
Amristar,Jalandhar.
• Zone V:- Guwahati and Srinagar.
