A fault in Geotectonic is a fracture along which the rocks are relatively displaced. The fracture occurs may be on a plane surface, a stricken side surface etc. It is called fault plane in section and a fault line on the surface. A fault is described by the angle and inclination of fault plane and the strike of the fault line. The angle made by fault plane with vertical is called Hade and if the angle made by fault plane with horizontal is called Dip. The fault plane usually inclined. The rocks below the fault plane, is called Foot wall and the rocks above the fault plane, is called Hanging Wall. But, obviously vertical faults have neither a foot wall nor a hanging wall.
The displacement may be of any amount in any direction. The amount is expressed in units of length. It may be a few mm to many km. The direction is described by means of two components.
Dip-slip or the component measured parallel to the dip of the fault. And
Strike slip or the component measured parallel to the strike of the fault.
The total displacement is known as ‘Net slip’.
The vertical component of the dip – slip is known as ‘Throw’and its horizontal component is known as Heave. In other word we can say that Throw is the vertical distance between foot hill and hanging wall and Heave is the horizontal distance between foot hill and hanging wall.
The displacing movements may push a block downwards, upwards and sideways. These are called Transitional movements. In these cases all straight lines on opposite side of the fault that are parallel before displacement remain parallel afterwards.
Causes Of Fault in Geotectonic :
Faults may be of tectonic or non-tectonic origin. Tectonic processes operate within the crust and upper mantle, the non-tectonic processes operates near the earth surface.
The main tectonic process responsible for faulting is horizontal tension. It causes gravity faults. Compression usually causes folds but when it become extreme thrust faults formed. These processes are complementary and are generated by sub-crustal continental currents. The some currents also cause lateral movement of two lithospheric crustal plates, forming strike slip faults.
Among the non-tectonic processes gravity is most significant. Many of the great thrust and nappes are formed by successive gravitational sliding down the original slopes. Faults may also be formed in unconsolidated sediments by sliding if the floor is inclined.
Know how volcanic activities take place in plate,