Seismic Zoning


        Seismic Zoning 
It can be defined as dividing a country or region into smaller
zones on the basis of their seismicity or earthquake activity.
It depends on :
a) The detail study of the earthquake that have occurred in past,
their characteristics like magnitude, intensity and damage.
b) The tectonic feature of the place which could cause an
earthquake in future.
Tectonic feature of India
India lies at the north- western end of the Indo- Australian plate.
On this plate, India, Australia, a major part of the Indian Ocean
and other smaller countries are located.
This plate is colliding against other neighbouring plates.
3 major tectonic plates of India are
a) Northern Himalayas
b) Plains of the Ganges and other rivers
c) The Peninsular Region
Northern Himalayas
The Himalayan Ranges comprises of highly seismic zone which is
very unstable.
All along the foothills of Himalayas, stretching from Kashmir to
Assam is a long thrust fault known as Great Boundary Fault.
This fault is highly prone to earthquake and marked as highly
seismic zone.
Plains of the Ganges and other rivers
Leaving aside the zones of Great Boundary Fault other region of
Himalayan belt and Indo Gangetic plain are moderately seismic
zones.
This zone is made of alluvial deposits which are laid into a great
depression present in front of Himalayan ranges.
Moderate earthquake are common in this region.
Peninsular India
This part comes under Poorly Seismic Region.
Peninsular India consists of ancient rocks.
Very small earthquake occur in this area .
Seismic zone map of India (IS: 1893-1970)
▪ Seismic zone map of India is divided into 5 zones- I, II, III,
IV, V
▪ Zone I- Poorly seismic zone
▪ Zone V- Highly seismic zone
Revised Seismic zone map of India (IS: 1893(part 1)-2002)
▪ The revised seismic zone map now divides India into 4 seismic
zones- II, III, IV, V
▪ Among the metropolitan cities, Delhi is in Seismic Zone IV
▪ Mumbai, Kolkata and Chennai are in Seismic Zone III.
▪ Major cities of Punjab such as Amritsar, Jalandhar and
Ludhiana are in Zone IV.

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