Piedmont zone between Ghaggar and Yamuna river basins and found signs of an active tectonic deformation
The piedmont zone of Haryana is actively deforming and could become a future seismic hazard zone, we found out in our new research. Piedmont plains are situated at the foot of mountains or hills.
In fact, the active tectonics and geodynamic framework of the area may have played a role in the extinction of the Vedic Saraswati river that once flowed through the region.
Me and my colleagues investigated the piedmont zone between the Ghaggar and Yamuna river basins in the frontal parts of the northwest Himalaya of Haryana. The study focused on the piedmont alluvial plains and covered parts of Panchkula, Ambala and Yamunanagar districts in Haryana and Mohali district in Punjab.
There are signs of active tectonic deformations in the piedmont alluvial plains of northern Haryana, as the co-authors of my study and I found.
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.
Some postulations suggest 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.
The piedmont zone of the present study area lies in seismic zone IV in the zonation map of India.
We wanted to document the tectonic geomorphology of active tectonic deformation using satellite data and validated by geophysical ground penetrating radar (GPR) surveys. GPR 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.
We used different types of multispectral satellite images, which have different resolutions and optical properties. The processed images were Resourcesat LISS-III, Landsat 4-5 TM, Landsat 8 and Cartosat-1 PAN ortho images.
The river system analysis is an important tool for studying tectonic geomorphology as it is capable of adjusting to the crustal deformation that takes place over periods of centuries to decades.
We attempted to understand the active tectonic deformation and its geometry by analysing morphometric indices in six river basins and GPR surveys in the piedmont zone of Haryana and Chandigarh.
We identified the possible locations and types of active tectonic features such as subsurface faults, lineaments and warps. The presence of geomorphic signatures such as drainage gradient anomalies, abrupt changes in river flow direction, river shifts, palaeochannels, compressed meanders and topographic breaks helped us identify the features.
The tectonically controlled evolution of the region’s landscape was further proven by characteristics like the debouching of the Ghaggar and Yamuna tributaries and seasonal streams into the piedmont zone from the Siwalik.
We found the piedmont zone has been upwarped, with a 10-12 km wide upwarped badland zone trending parallel to the Himalayan strike. The rivers have also shifted their courses in response to the upliftment in the piedmont zone and have been exhibiting a migration pattern.
A subsurface blind fault may have led to the upliftment in the distal part of the piedmont zone. Abandoned channels and small abandoned tributaries helped us infer the evidence of the paleoflow.
We conducted GPR surveys and profiles obtained at Sandhay and Sadaqpur villages in Haryana based on the spatial co-occurrence of geomorphic anomalies. By visual interpretation of 2D GPR profiles (radargrams), we identified sub-surface signatures to confirm active tectonic features.
In 2D radargrams, folded (upwarped) sediment layers are found to be thrust over northerly dipping fault plane at several locations.
We concluded that the piedmont alluvial zone of the Himalayan foreland basin is actively deforming. Paleoseismic investigations through trenching are also needed to understand stress partitioning in the region.
Further, ground based SAR interferometry approach could provide invaluable insights about the deformation rate and strain accumulation in the area.
The study was published in the Geomatic, Natural Hazards and Risk journal. The journal is an international publication and publishes research on geospatial-remote sensing techniques applied to risk management and early warning of natural hazards.
Researchers from Kurukshetra University, Indian Institute of Technology (Indian School of Mines), Dhanbad and Indian Institute of Remote Sensing, Dehradun were involved in this study.
Harsh Vats works with the Department of Geophysics, Kurukshetra University, Kurukshetra, India and Geosciences Department, Indian Institute of Remote Sensing, Indian Space Research Organization, Dehradun, India
Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth
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