Himalayan Geology, Vol. 43 (2), 2022, pp. 442-456, Printed in India
Active uplift along uncommon bending moment fault in the northern limb of Surin Mastgarh Anticline, Jammu Sub Himalaya
SHRADDHA JAGTAP1,2, ARJUN PANDEY1, R. JAYANGONDAPERUMAL1*, A.K. SHARMA2, ANIL ARAVIND1, ISHWAR SINGH1, ATUL KUMAR1
1Wadia Institute of Himalayan Geology, Dehradun-248001, India
2Department of Geology, Kumaun University, Nainital, India
*Email (Corresponding author): ramperu.jayan@gmail.com
Abstract: Ongoing Indo-Eurasia convergence leads to the generation of megathrust earthquakes that periodically rupture the Himalayan Frontal Thrust (HFT) in the form of fault or fold scarps. Identifying and assessing the seismogenic potential of the active faults is warranted because of their certainty to cause destruction in one of the most densely populated regions of the world. In Jammu, the HFT remains non-emergent for a continuous stretch of ~200 km beneath the Surin Mastgarh Anticline (SMA). We identified a ~30 km long and NW-SE oriented active fault that truncates the northern limb of the frontal Surin Mastgarh Anticline (SMA), here referred to as the Naun Fault (NF). Topographic profiles constructed using RTK-GPS across the different truncated fluvial terraces along three river valleys show a vertical offset of 1-20 m. The chronological constraints on the recent displacement obtained in this study, along with the previous studies, provide consistent uplift rates varying from ~1 mm/yr since ~54-10 ka across the Naun Fault. Further, the drainage re-organization of the Sutar Khad river across the NF dated 1413-1480 CE overlaps with the timing of the historical 1555 CE Kashmir earthquake. The study suggests that the non-emergent fault system at the Jammu Himalayan front releases a part of the interseismic strain by active uplift along the SMA by uncommon bending moment fault in the northern limb that may hold sesimogenic potential to slip during large Himalayan earthquakes.
Keyword: Active fault, Detachment fold, Bending moment fault, Earthquake, River migration, NW Himalaya.
