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<p>Himalayas are seismically very active regions of the world due to ongoing continent-continent collision between India and Eurasia. The Himalayas are known to have hosted deadliest earthquakes in the past century and considering the exponential growth of population in megacities of Gangetic plains, a proper seismic hazard evaluation is very critical in this region. In this regard, the present and past slip rates along the Himalayan Frontal Thrust (HFT) are very important for understanding the convergence pattern and recurrence intervals of major earthquakes. Although geodetically derived short-term convergence rates are consistence with geologically derived long-term slip rates, this correlation is based on selected studies of uplifted Holocene terraces reporting geologically derived slip rates in Central and North-West Himalayas. There is no such reporting of Geological uplift rates from Nahan Salient in NW Himalayas. We have identified uplifted and truncated quaternary terraces along HFT in Nahan Salient Northwest Himalayas through cartosat-I stereo data. We mapped and dated the uplifted terraces in order to understand the long-term convergence rates over Holocene time period. The vertical incision rates are then calculated with the help of OSL ages and height of terraces. Assuming the vertical uplift is due to repeated past earthquakes along HFT dipping at 30°, vertical uplift rates are calculated to be 2.6 mm/yr, which equates to a fault slip rate of 5.16 mm/yr and a horizontal shortening rate of 3 mm/yr. Along with that last tectonic activity along HFT is also bracketed using age of uplifted terraces and unfaulted capping units from an exposed section of HFT fault plane along river section. The OSL ages suggest that the HFT was active between 3.8±0.4Ka and 0.706±0.15Ka. Assuming that no deformation has occurred along HFT after 0.706±0.15Ka a slip deficit of 3.6 m has been accumulated which is sufficient to generate a large earthquake in the Nahan Salient NW Himalayas.</p>

Himachal region of Northwest Himalaya exhibits the widest structural re‐entrant in Kangra region and significant strain partitioning along the frontal and hinterland out‐of‐sequence faults. We report results of continuous GPS measurements from 10 new sites in the region and analyze them along with the previously published results to constrain the ongoing arc‐normal and arc‐parallel convergence rates at 16.5 ± 1.1 and 4–5 mm/yr respectively. Thus, the ongoing convergence is oblique by 15°–20°. The Main Himalayan Thrust (MHT) is strongly coupled up to ∼100 km from the Main Frontal Thrust but displays significant variation in coupling in the transition zone across the Kangra re‐entrant and the adjoining western salient. Joint analysis of the coupling variation, the geologically inferred MHT geometry variations and the local topographic anomaly pattern strongly suggest the possibility of a potentially active, strain accumulating segment of MBT along the southern margin of Dhauladhar ranges in Western Himachal region, which is also proposed to be influencing the long‐term topographic growth in the region. Although a general agreement is observed between the long‐term shortening rates along the active faults and the estimated geodetic convergence in this region, the ensuing discussion highlights their complex relationship in terms of temporal and spatial variability in the fault activity and elastic‐inelastic deformation. We use the fault orientation and the estimated convergence rate to geometrically constrain a mean dextral slip‐rate of 4.4–5.7 mm/yr along a recently discovered Khetpurali‐Taksal fault, which is proposed to partition the majority of ongoing arc‐parallel deformation along it.

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