Understanding the Seismicity Pattern Across the Eastern Himalayan Region by Means of Spatiotemporal Variations in the Seismic b ‐Value

ABSTRACT Himalayan earthquakes are triggered by the release of accumulated strain driven by tectonic forces. The different geological settings of the Himalayan Seismic belt contribute to the inhomogeneous seismicity profile of the region. In this study, we estimated the spatial and temporal variation of seismicity using a unified and homogeneous part of the seismicity record (declustered dataset of 2051 earthquakes between January 1905 and May 2026) in the entire eastern Himalaya region by using the Gutenberg‐Richter relationship. A comprehensive study on the behaviour of natural seismicity encompassing the seismic gap regions is performed. The entire area is divided into square grids of size 0.2° × 0.2°, and after that, the b ‐value associated with each square grid is calculated. The results indicate that the cyclical fluctuations of the b ‐value characterise the ongoing stress build‐up and its subsequent release. The observed low b ‐value zones mark high‐stress asperities prone to large events, whereas high b ‐values reflect complex geology. It is observed that the b ‐values decrease with depth and correlate with underlying shear‐wave velocity. The inferred correlation of b ‐values with gravity anomalies is not uniform but tectonically controlled. A close comparison between b ‐values and different faulting styles reveals that the area with the highest b ‐values exhibits normal faulting. In contrast, low b ‐values are associated with thrust faulting. We believe that this unified multi‐parametric assessment offers critical insights into seismic hazard assessment by identifying high‐risk zones, which demand urgent attention.