TECTONIC ANALYSIS OF THE MULA RIVER BASIN, KIRTHAR FOLD BELT, PAKISTAN, USING HYPSOMETRIC INDEX

The Mula River basin is in an active tectonic region of the Kirthar fold fault belt in Western Himalayas. The presence of numerous major faults like Chaman Fault, Kirthar Frontal Fault and Bannh Fault near the study suggest complex tectonic processes in the region. The seismic record of the study area also indicates that this area is tectonically active. This makes the study area an ideal site to measure tectonic activity through geomorphic indices like hypsometric integrals (HI). For tectonic analysis of the Mula River basin, we divided the study area into 309 sub-basins. The results obtained from the HI calculations for the sub-basins led us to the classification of the study area into three classes i.e., Class 1 (0.51-0.78), Class 2 (0.37 – 0.50) and Class 3 (<0.37), where Class 1 is for the highest tectonic activity and Class 2 responds to the moderate and class 3 is for the lowest tectonic activity. We calculated the hypsometric curves to understand the geomorphological cycle of the Mula River basin. We quantified the sub-basins of the Mula River basin, inside the highly active tectonic zone of Kirthar fold and fault zone, as per their tectonic activity and found that a major portion of the study area shows low tectonic activity (44.33%), medium tectonically active and high tectonically active sub-basins are 37.86 % and 17.79 % respectively. These findings are supported by the presence of high-relief areas and known faults in the study area.