Neotectonic evidences of some major rivers of North East India

The neotectonic activity of some parts of the Assam–Arakan Basin in North East India has been studied through drainage patterns, anomalies and morphotectonics to determine the recent deformation in the area that serves as the input for any seismic hazard assessment. Various drainage anomalies like annular drainage pattern, compressed meanders, paleochannels, and knick points in the river courses reveal the presence of neotectonic activity in the area, which is also confirmed by topographic profiles and seismic sections. The present study reveals that active subsurface structures like the Rudrasagar High, Geleki Low, Geleki High and Jorhat Fault have direct influence on the development and modification of the river systems courses. The morphometric and morphotectonic studies of drainage basins flowing through the Belt of Schuppen and Dauki Fault show strong influence of tectonics. The tectonic activities of the Bomdila and Kopili Faults are studied through neotectonics and seismotectonics, supplemented by gravity data. Seismicity is fairly intense in both the areas and both faults have influences in modifying the drainage alignments of the region. Occurrence of bils/swamps and develop­ment of knicks, presence of tectonic scarps, disturbed and folding in beds on the river banks and intense seismic activity in the region reveal neotectonic activity.