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Neotectonic character of Son-Narmada geo-fracture and its implication on SCR earthquakes in central India: A geomorphic and InSAR approach.
  • Srijan Srivastava,
  • Dipanjan Bhattacharjee,
  • Anupam Chattopadhyay
Srijan Srivastava
University of Delhi,University of Delhi

Corresponding Author:[email protected]

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Dipanjan Bhattacharjee
Indira Gandhi National Tribal University
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Anupam Chattopadhyay
University of Delhi
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Apparently stable central Indian craton has been experiencing a number of micro-seismicity in and around the pristine Son-Narmada-South fault (SNSF), possibly because of creep along some reactivated or unidentified fracture planes. Drainage network being highly susceptible to even subtle active tectonics, a reconnaissance study of the area has been carried out using river morphometric analysis. Thereafter, a Principal Scattering Interferometry time series (PSInSAR-TS) analysis (Hooper et al 2004, 2007) was performed to precisely locate the surface-tip of the slip plane. And finally, the fracture geometry and orientation of the slip vector was enumerated by integrating PSINSAR with morphometric analysis. Generally, drainages respond to block uplift with abrupt incision and thereby making a very narrow channel width. However, delineating such incision from the standard Width-Depth ratio from DEM based studies becomes difficult, because of its coarser resolution. Therefore, considering rectangular channel flow for a stable river, the expected width was compared with the actual width of the river measured from high resolution Sentinel II images following the relation modified after Finnegan et al., 2005; which states that W =KA^(2/3)S^(-3/16), where the constant K depends on the rectangular channel geometry, manning constant and rainfall in the area, A is upper catchment area and S is slope of the river reaches. A NE-SW trending zone of narrower channel width was identified with this procedure which was interpreted as a result of block uplift, later confirmed from the rate of uplift preliminarily calculated using an expression derived from basic stream-power equation: U=K(((Z(a)-Z(o))/Χ)^n) (A^m), where the uplift (U) is a function of erodibility (K), river catchment area (A) and chi (χ) value as per Perron and Royden 2012. PSInSAR-TS analysis of the area delineated an average net-slip rate of 11mm/year along a number of NE-SW trending south dipping oblique slip reverse faults, with sinistral strike slip components, arranged in enechelon pattern and are softly linked to each other with jogs accommodating movements in normal sense. Lastly, the fault geometry was confirmed by comparing the deformation map generated from the InSAR technique with the field evidence and previous studies.