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Why do earthquakes happen here?
The Indian
subcontinent lies upon the Indian Plate.
This plate is moving northward at about 5
centimetres per year and in doing so, collides with the Eurasian
Plate. Upon the Eurasian Plate lie the Tibet plateau &
central Asia. Due to this mammoth
collision, the Himalayas are thrust higher and very many earthquakes are generated
in the process. This is the cause of earthquakes from the
Himalayas to the Arakan Yoma. The same process, though involving
the Indian Plate and the Burmese Micro-plate results in
earthquakes in the Andaman & Nicobar Islands. Sometimes
earthquakes of different
magnitudes occur within the Indian
Plate, in the peninsula and in adjoining parts of the
Arabian
Sea or the Bay of Bengal. These arise due to localized
systems of forces in the crust sometimes associated with
ancient geological structures such as in the Rann of Kachchh.
Inter-Plate Earthquakes
(Plate boundary Earthquakes)
Most earthquakes occur along narrow zones that
follow the edges of tectonic plates. These
events are known as "Inter-Plate"
or "Plate Boundary" earthquakes. These earthquakes are the direct result of the
interaction
between two or more tectonic plates. There are two
prominent bands of Inter-Plate earthquakes. One stretches from the
western Mediterranean, covering southern Europe and north
Africa, extending through the Middle East and terminating in the
Himalayas. The second band forms a circle around the Pacific Rim,
including Kamchatka in Russa, Japan, the Philippines, Indonesia,
the South Pacific island nations and New Zealand in the west. In
the east it includes, Alaska, California and the Pacific
North-west in the U.S., western Canada, Central America and the
South American countries of
Colombia, Ecuador, Peru and Chile. This circum Pacific belt is
also often referred to as the "Ring of Fire".
Intra-Plate Earthquakes
(Mid Plate Earthquakes)
Sometimes earthquakes occur far away
from plate boundaries. These earthquakes are very infrequent but
are capable of releasing just as much energy in a single
earthquake as an earthquake of similar size along at plate
boundary. These arise due to localized systems of forces in the
crust sometimes associated with ancient geological structures such as in the Rann of Kachchh.
Seismic activity of this nature contributes 1% of the annual
seismic energy release globally. All earthquakes in peninsula
India falls within this category. Mid-plate earthquakes have also
occurred in the central Indian Ocean, in the central & eastern United States, eastern Canada,
Brazil, northern Europe, Australia, Hawaii and western parts of
the African continent. |
