Horizontal tectonic stresses and its implications in the Shillong Plateau and its adjoining using gravity data

North East India (NEI) is situated between the Himalayan collision arc to the north and the Indo-Burmese Ranges (IBR) to the east. The tectonic unit of the NEI, Shillong Plateau (SP), is one of the most active seismotectonic zones of the Indian subcontinent, as demonstrated by its seismicity. It is crucial to identify active faults in populated areas for human safety and the sustainable development of society. The gravity method is one of the convenient methods to delineate the shallow to deeper subsurface discontinuities, i.e., it is useful to detect active faults in the subsurface compared to other geophysical methods (e.g., Electrical, and Electromagnetic methods). In this study, detailed multilayer horizontal tectonics stress (HTS) was calculated using the approach of multi-scale decomposition of gravity anomalies data. HTS can be helpful in demarcating shallow to deep-seated tectonic structures. The tectonic features exhibit a strong correlation with the distribution of HTS at different depths. Major faults and earthquake epicentre align with areas of high stress, while stable zones correspond to regions of low stress. It means that HTS is employed to deduce the distribution and stability of faults. The high value of HTS is increased from shallow to deep depths for SP, Mikir Hills, IBR and Eastern Himalaya in the NEI region, and it varies as ~ 0.2-0.53 MPa, ~ 0.24-0.61 MPa, ~ 0.3-0.84 MPa, ~ 0.4-1.2 MPa, ~ 0.57 1.86 MPa, ~ 0.8-2.4 MPa, ~ 0.84-3.0 MPa at 4, 8, 12, 20, 40, 50, and 60 km depths, respectively. While the Brahmaputra Valley and the Surma Basin show relatively less stress, where HTS varies between ~ 0.1-0.33 MPa for 4, 8, 12, 20, 40, 50, and 60 km depths. It can be interpreted that the populated SP and Mikir Hills are highly unstable or earthquake-prone regions due to high stress.