Growing zone of active tectonic deformation in northern Haryana plains

As revealed by a new study, the piedmont zone of Haryana is actively deforming and could become a future seismic hazard zone.

• ‘Piedmont plains’ are situated at the foot of mountains or hills (Like Himalayas).
• The piedmont zone of the present study area lies in seismic zone IV in the zonation map of India.

Highlights of the study:

• The study investigated the piedmont zone between the Ghaggar and Yamuna river basins in the frontal parts of the northwest Himalaya of Haryana.
• It focused on the piedmont alluvial plains and covered parts of Panchkula, Ambala and Yamunanagar districts in Haryana and Mohali district in Punjab.
• It found that there are signs of active tectonic deformations in the piedmont alluvial plains of northern Haryana.
• This was due to the convergence between the Indian tectonic plate and Eurasian plate resulted in the lifting of the Himalayan mountain belt.
• Along with the southward movement of the deformation front, the convergence also resulted in a significant shortening of the lithosphere.
• It also suggests an active deformation is propagating further south of the Himalayan front.
• These deformations may be reaching the 10- to 25-kilometre-wide piedmont zone of the Indo-Gangetic alluvial plains.
• Tool used: Ground penetrating radar (GPR) surveys is an important tool ideally suited for obtaining high resolution profiles of the subsurface over a depth range of a few metres to several tens of metres.

Ghaggar and Yamuna river basins:

• Rivers in Haryana fall mainly within Indus and Ganga basins.
• River Ghaggar sub basin and its tributaries in the west of the state caters to the Indus basin, while river Yamuna and its tributaries in the east make up the portion of the Ganga basin.
• The Ghaggar River:
  • It rises in Shivalik hills in Solan district of Himachal Pradesh. It enters Haryana in Panchkula district.
  • Hereafter the river flows making border between Punjab and Haryana for more than 100 Km.
  • After Sirsa district the river leaves Haryana State and reaches Sri Ganga Nagar district, Rajasthan where after a certain length its course becomes untraceable.
  • Once a perennial river, it is now seasonal at best. But during the monsoons, all its tributaries are found to be in flood.

What is a fault?

• A fault is a fragmentation or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other in different directions. 
• This movement of blocks of rock can be rapid, in the form of an earthquake or may occur slowly, which is called as creep. 
• Range of a fault can be few millimeters to thousands of kilometers. Most faults produce repeated displacements over geologic time. 
• During the earthquake disaster, the rock on one side of the fault suddenly falls over with respect to the other. 
• The fault surface can be vertical, horizontal or some arbitrary angle in between.

How is a fault created?

• A new fault is formed when the stress on the rock is great enough to cause a fracture, and one wall in the fracture moves relative to the other, which is caused by compressional/tensional force by the rising magma from the mantle.

Main Himalayan Thrust:

• The Main Himalayan Thrustfollows a North West-South East strike and is a décollement beneath the Himalaya Range, and gently dips towards the north, beneath the Himalayan region.
• MHT is the largest active continental mega-thrust fault in the world.
• Deformation of the crust is also accommodated along splay structures including the;
  • Himalayan Frontal Thrust (HFT)
  • Main Boundary Thrust (MBT)
  • Main Central Thrust (MCT)