| Abstract Submission No. | ABS-4.1-0221 |
| Title of Abstract | Gravity Modeling for Crustal Structure in the Kumaun Himalaya: Implications for Seismogenesis |
| Authors | Shubham Yadav*, Mahak Singh Chauhan, Abhey Ram Bansal, B. Nageswara Rao |
| Organisation | CSIR-NGRI |
| Address | Room No. 201, Main Building, CSIR-NGRi Hyderabad, Telangana, India Pincode: 500007 E-mail: geophysics.shubham@gmail.com |
| Country | India |
| Presentation | Poster |
| Abstract | A detailed gravity survey was carried out along a ~212 km transect extending from the Indo-Gangetic Plain (IGP) to the Main Central Thrust (MCT) zone across the Kumaun Himalaya, India. This tectonically complex and seismically active region hosts several interacting fault systems. To understand underlying crustal architecture and tectonic framework, gravity data were collected at an average station spacing of about 1.5 km and subsequently modeled. Model is constrained by incorporating results from geophysical and geological studies, power spectrum analysis, gravity separation techniques, wavelet analysis, 2D forward modeling and inversion for crustal configuration in the study area. Subject to geological complexity, spectral analysis is performed separately for the IGP and the Himalayan segments. In the Indo-Gangetic Plain (IGP), two major subsurface interfaces were interpreted at approximate depths of 5 km and 39 km, interpreted as the Indo-Cratonic Basement and the Moho discontinuity, respectively. In contrast, analysis of the Himalayan sector indicated the Moho at around 46 km depth and the Main Himalayan Thrust (MHT) near 10 km. A gravity separation approach was applied using wavelet analysis, PSO-based inversion, and regional modeling, integrated with available geological and geophysical constraints, to isolate distinct gravity components associated with the Himalayan tectonic framework. This approach successfully delineated the gravity effects from the upper crustal region, including major fault and thrust zones. The computed residual gravity anomaly highlighted major tectonic structures. Inversion of the residual gravity anomaly imaged the subsurface configuration of major faults and thrust zones. The results suggest a northward-dipping Moho, varying in depth from approximately 39 km to 46 km and the modeled Main Himalayan Thrust (MHT) exhibits a ramp geometry. The developed density model successfully outlines the crustal architecture across the Kumaun Himalaya and provides valuable insights into upper-crustal fault systems, contributing to improved understanding of seismogenesis evaluation in the region. |
| Keywords | Gravity, Power Spectrum, Forward Modeling, Inversion |