EARTHQUAKEBELT

IN INDIA

THREE CRICKET FANATICS PLEASE

BEFORE WE PUT ON THE BELTS

THE EARTHQUAKE XI

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

1

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.

2

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.3

FOCUS OR HYPOCENTRE

The point of origin of an earthquake below the surface of earth.

EPICENTRE

The point on the surface directly above the focus where the vibrations are felt.

MAGNITUDE

A term used to establish the size of an

earthquake, which is a measure of the

amplitude of a seismicwave and is related to the

amount of energy released

during an earthquake.  Magnitude is the total energy released by an

earthquake at its focus. The Richter

Scale is most famous to measure the

magnitude of an earthquake.

INTENSITY

Intensity is a term used to measure the

impact of earthquake. Intensity

measures the strength of shaking

produced by the earthquake at a certain location.

Intensity is determined from

effects on people, human structures,

and the natural environment.

Mercalli Scale was used to predict

intensity.

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Nowadays intensity of earthquakes are not measured. They have been replaced by magnitude.

Top 5 Earthquakes by Magnitude.

S. No.

Date Place Magnitude

1 22 May 1960 Valdivia, Chile 9.5

2 27 March 1964 Alaska, USA 9.2

3 26 December 2004

Sumatra, Indonesia 9.1

4 13 August 1862 Arica,Chile 9.0

5 26 January 1700

Cascadia, USA-Canada

9.0

5

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%

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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.7

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.

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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.

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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

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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

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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)

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EARTHQUAKES IN INDIA

EARTHQUAKE ZONES IN INDIAThere 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.

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

EARTHQUAKE ZONES IN INDIACities 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.