Evaluation of Relative Active Tectonics and the Spatial Distribution of Landslides in the Yamne Valley (Arunachal Pradesh), Northeastern Himalaya, India

ABSTRACT The Yamne Valley, located in the southern part of the Eastern Syntaxial Bend (ESB) in Arunachal Himalaya, is seismically active and results in significant tectonic movements that shape the rugged terrain. The landscape is defined by steep slopes and fragile rock formations, continuously being uplifted by tectonic forces. The active tectonics and continuous rainfall in this region have significantly affected drainage patterns and landforms, leading to increased hillslope processes and the initiation of landslides. In this study, we have assessed the active tectonics in the region utilising ALOS PALSAR (12.5 m resolution) digital elevation model (DEM), geomorphic parameters (asymmetry factor, basin shape index, hypsometric integral, stream‐length gradient, stream sinuosity, channel steepness index and valley floor width to valley height ratio) and various morphometric parameters. Subsequently, an index of relative active tectonics (iRAT) map was created exhibiting very high, high, moderate, and low areas of relative tectonics. The distribution of landslides in the area aligns with the prepared iRAT map, indicating the clustering of landslides in the areas having very high and high relative active tectonics, particularly between the Main Central Thrust (MCT) and Tiding Thrust (TT). Thus, quantitative geomorphometry may serve as a valuable tool for identifying potentially active zones susceptible to slope failures, thereby guiding decision‐makers in regional planning and efforts to mitigate landslide hazards, particularly in the Yamne Valley, supporting infrastructure and tourism activities.