## 1 Introduction  
The Indo-Asia collision created the \(\sim\)2500 km-long seismically active Himalayan mountain belt (55 Ma) [1, 2]. The main frontal thrust (MFT) marks the southern boundary of this collisional zone (Figure 1). This youngest frontal thrust of the foreland fold and thrust belt of the northwestern Indian plate lacks a detailed quantitative landscape assessment to categorize the relative tectonic activity. The MFT's active growth and development are essential for understanding the mechanism of deformation and preparing for the future hazards associated with active tectonics. The geodetic data show the movement of the Indian plate at a rate of \(\sim\)35 mm/year and \(\sim\)38 mm/year in the northwestern and northeastern margin, respectively [3]. [PERSON] and [PERSON] [4] proposed that the MFT accommodates most of the present-day Himalayan deformation. The calculated deformation in the northwestern, central and eastern Himalayas are 9 \(\pm\) 3 mm/year [4, 5], 21 \(\pm\) 1.5 mm/year [6, 7], 23.4 \(\pm\) 6.2 mm/year [8],respectively. The MFT is a narrow zone with a high degree of cross-sectional taper in the central and eastern Himalayas; however, it is more than 100 km wide, with a low degree of cross-sectional taper in the western Himalayas, Pakistan [9; 10]. Moreover, the trend of regional structures shifts abruptly from NW-SE in the central and eastern Himalayas to NE-SW in Pakistan, which is attributed to an anti-clockwise rotation of the Indian plate [11]. The western Himalayas in north Pakistan extend from the Jhelum Basement Fault in the east to the Ophiolite Belt in the west [12]. The MFT in the western Himalayas was categorized as Salt and Trans Indus Ranges (TIR). The western and central Salt Range show an average of 10 and 5 mm/year of southward translation over the Punjab Foreland inferred from Interferometric Synthetic Aperture Radar (InSAR) and geodetic studies [13; 14; 15]. However, the TIR was separated by the active, transpressional Kalabagh Fault zone that shows an average displacement of 5.3 mm/year [16; 17]. [PERSON] et al. [18] and [PERSON] et al. [19] proposed that the Salt Range Formation forms the basal detachment along the MFT in the western Himalayas, and across-strike structural variations are related to basement ramping. In addition, the chronostriagraphic studies of the molasses suggest an earlier thrusting along the Salt Range Thrust (SRT) (~2.5 Ma) than the TIR (~1 Ma), indicative of active quaternary tectonics [20]. This implies that the TIR (an extension of MFT) in the western Himalayas represents the youngest collisional phase and are still undergoing active deformation [21; 22]. Figure 1: Satellite imagery showing the Himalayan arc and the southernmost youngest active thrust (MFT) with the associated historical earthquakes of a magnitude higher than seven (7) that had ruptured the surface. The across-strike structural variations are shown in the form of salient and recess. The calculated slip-rates along the MFT is also shown. The rectangular box indicates our study area in the Tank recess. Earthquake data were downloaded from the United States Geological Services (USGS). Faults were modified from Yin [1]. SRT: Salt Range Thrust, TIR: Trans Indus Ranges, KB: Katawaz Basin, WO: Waziristan Ophiolite, JBF: Jhelum Basement Fault, SFTB: Suleiman Fold–Thrust Belt, KFTB: Kirthar Fold–Thrust Belt. The TIR are sub-divided into the Surghar Ranges, Marwat-Khisor Ranges, Bhittani Ranges, and Manzai Ranges. These ranges have pronounced lateral structural variations and show compressional deformation along the salient and recess and transpressional deformation along the flanks (strike-slip faults) [10; 18]. The Marwat-Khisor salient separates the two prominent Kalabagh and Tank recesses in the TIR.