Fault-controlled geomorphic features in Ridi-Shantipur area of Gulmi District and their implications for active tectonics

Abstract

The Lesser Himalaya is a fold-thrust belt in the Himalaya. In the Nepal Himalaya, several active faults, among which the Badi Gad Fault is one of them, are identified and mapped by many researchers in the past, However, very less study has been carried out on the existence of this fault and its extension. In the present study, an attempt was made to assess the fault and to map its extension in the region based on the geological as well as geomorphological criteria. For this purpose, a detailed geological map was prepared from Ridi to the Shantipur area in 1:25,000 scales. During the field work, several geological as well as geomorphic evidences of the existence of active fault were found, and some of them are also found under the aerial photo observation. These evidences include the presence of shear zones, clustering of large and several landslides along a confined linear zone, river course diversion, terrace tilting, fault scarps etc. In the present work, the Badi Gad Fault is traced out continuously from the Ridi to the Shantipur area and even extended far to the NW direction under aerial photo. The fault follows the moderate hills of the left bank of the present course of the Badi Gad River. Major shear zones found in the region are the Tal Khola, Aslewa, Eksingaun, Juhan, Gultung, and the Rupakot shear zones. These shear zones are represented by the wide zone of fault gauge, fault breccias, silickensides, striations and large landslides. Besides, other geomorphic evidences traced out are location of spring lines, tilted river terraces in Pul Camp and Wamitaksar area, river course diversion of the Lumdi Khola and fault scarp at Bhanjyangaun of Aslewa. Such types of fault-controlled geomorphic features are also found from the Rudrabeni-Wamitaksar areas under the aerial photos. Based on the fault controlled geomorphological study in the field and aerial photos interpretation, an attempt was made to map the Badi Gad Fault, an active strike slip fault in the region.

Landslide Susceptibility Assessment using Open-Source Data in the Far Western Nepal Himalaya: Case Studies from Selected Local Level Units

“…Landslides understanding can be improved through the accurate analysis of preconditions including physiographic conditions, climatic zones, and geologic scenario of an area that affects the terrain (Upreti, 2001). The potential sites for landslides are found at and adjacent to the adverse geological structures like active faults and brittle shear zones (Timalsina & Paudyal, 2018), axis of tight folds, abundant shear zones and deep weathering. Furthermore, evaluation of the geological, geomorphological, and hydrological situations that led to past landslides can provide valuable insights and information to precisely predict the occurrence of the future failures.…”

“…Landslide study and mitigation efforts requires proper assessment and identification of high-risk areas from several aspects (Budha et al, 2016;Ambrosi et al, 2018;Jharendra et al, 2018;Timalsina & Paudyal, 2018;Meena et al, 2021). Ghimire (2010) and Dahal et al (2012) assessed the regional distribution pattern of the landslide hazard and evaluated the susceptible areas in Siwalik hills.…”

Study of regional geological structures in Ridi-Shantipur area of Gulmi district, Lesser Himalaya, west-central Nepal

“…Mapping was carried out with specific objective to each student. Accordingly, the detail investigation of the Badi Gad Fault was carried out by Timalsina (Timalsina and Paudyal, 2018). Two major routes (i) Argelli-Ridi section and the (ii) Ridi-Rudrabeni section were selected for detail route mapping.…”

“…are recorded. The details of this study was carried out and published by Timalsina and Paudyal (2018) after this team work.…”