Main Central Thrust, Himalayan Thrust and Frontal Thrust
- Thrust is a reaction force described quantitatively by Newton’s third law.
- When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that system.
- The force applied on a surface in a direction perpendicular or normal to the surface is also called thrust.
- Force, and thus thrust, is measured using the International System of Units (SI) in newtons (symbol: N), and represents the amount needed to accelerate 1 kilogram of mass at the rate of 1 meter per second per second.
- In mechanical engineering, force orthogonal to the main load (such as in parallel helical gears) is referred to as static thrust.
The Main Central Thrust (MCT)
- A major geological fault where the Indian Plate has pushed under the Eurasian Plate along the Himalaya.
- The fault slopes down to the north and is exposed on the surface in a NW-SE direction (strike).
- It is a thrust fault that continues along 2900 km of the Himalaya mountain belt.
- The generally accepted definition of the Main Central Thrust is that it is a ductile shear zone along which the High-grade Great Himalayan Crystalline complex was placed above the low-grade to unmetamorphosed Lesser Himalayan Sequence.
- However, this definition is not perfect because of many difficulties and complications defining the Main Central Thrust.
The Main Himalayan Thrust (MHT)
- A décollement under the Himalaya Range.
- This thrust fault follows a NW-SE strike, reminiscent of an arc, and gently dip towards the north, beneath the region.
- It is the largest active continental megathrust fault in the world.
- The MHT accommodates crustal shortening of India and Eurasia as a result of the ongoing collision between the Indian and Eurasian plates.
The Main Frontal Thrust (MFT)
- Also known as the Himalayan Frontal Thrust (HFT) is a geological fault in the Himalayas that defines the boundary between the Himalayan foothills and Indo-Gangetic Plain.
- The fault is well expressed on the surface thus could be seen via satellite imagery.
- It is the youngest and southernmost thrust structure in the Himalaya deformation front.
- It is a splay branch of the Main Himalayan Thrust (MHT) as the root décollement.
- It runs parallel to other major splays of the MHT; Main Boundary Thrust (MBT) and Main Central Thrust (MCT).
- The Sunda Megathrust, which extends from the Banda Islands to Myanmar is joined with the MFT.
- The fault strikes in a NW-SE direction and dips at an angle of 20° to 30° in the north.
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