The
India or
Indian Plate is a
tectonic plate that was originally a part of the ancient continent of
Gondwanaland from which it split off, eventually becoming a major plate. About 50 to 55 million years ago, it fused with the adjacent
Australian Plate. It is today part of the major
Indo-Australian Plate, and includes the
subcontinent of
India and a portion of the basin under the
Indian Ocean.
In the late
Cretaceous Period about 90
million years ago, subsequent to the splitting off from Gondwanaland of conjoined Madagascar and India, the India Plate split from
Madagascar. It began moving north, at about 20 cm/
yr (8
in/yr)
, and began colliding with
Asia between 50 and 55 million years ago, in the
Eocene epoch of the
Cenozoic Era. During this time, the India Plate covered a distance of 2,000 to 3,000 km (1,200 to 1,900 mi), and moved faster than any other known plate. In 2007, German geologists determined that the reason the India Plate moved so quickly is that it is only half as thick as the other plates which formerly constituted Gondwanaland.
The collision with the
Eurasian Plate along the boundary between India and
Nepal formed the
orogenic belt that created the
Tibetan Plateau and the
Himalaya Mountains, as sediment bunched up like earth before a
plow.
The India Plate is currently moving northeast at 5 cm/yr (2 in/yr), while the Eurasian Plate is moving north at only 2 cm/yr (0.8 in/yr). This is causing the Eurasian Plate to deform, and the India Plate to compress at a rate of 4 mm/yr (0.15 in/yr).
2004 Indian Ocean earthquake
The 9.3
moment magnitude 2004 Indian Ocean earthquake was caused by stress in the
subduction zone where the India Plate is sliding under the
Burma Plate in the eastern Indian Ocean, at a rate of 6 cm/yr (2.5 in/yr). The
Sunda Trench is formed along this boundary where the Indo-Australian and Eurasian Plates meet.
Earthquakes in the region are either caused by
thrust-faulting, where the
faultline slips at right angles to the trench; or
strike-slip faulting, where material to the east of the faultline slips along the direction of the trench.
Like all similarly large earthquakes, the December 26, 2004 event was caused by thrust-faulting. A 100 km (60 mi) rupture caused about 1,600 km (994 mi) of the interface to slip, which moved the fault 15 m (50 ft) and lifted the sea floor several meters (yards), creating the great
tsunami.
Closeup of the boundary with the Eurasian, African and Arabian plates; the
2005 Kashmir earthquake occurred at the northern tip of the Indian plate.
2005 Kashmir earthquake
On October 8, 2005, an earthquake of magnitude 7.6 occurred near
Muzaffarabad,
Kashmir,
Pakistan killing more than 80,000 people, and leaving more than 2.5 million homeless.
See also
