Comparative Analysis of Seismic Hazard Parameters in India: A Dual-Scale Approach

Seismic hazard evaluation is a cornerstone of disaster risk management, particularly in tectonically active regions. This study focuses on the Indian subcontinent (60°–100°E, 0°–40°N), a region characterized by high seismicity and complex tectonic interactions. By employing two different earthquake catalogs, namely, the conventional moment magnitude (Mw) scale catalog and the newly developed generalized moment magnitude (Mwg) scale catalog, this study evaluates key seismicity parameters, such as the Gutenberg-Richter a and b-values and the magnitude of completeness (Mc) through ZMAP analysis in MATLAB. Comprehensive declustering was performed using an established algorithm to ensure that only independent seismic events were analyzed. The catalogs were then homogenized using newly developed magnitude conversion equations derived through the improved general orthogonal regression (IGOR) approach. For the Mw catalog, the initial dataset of 1,15,564 events was reduced to 71,972 independent events post-declustering, corresponding to a 38% removal of dependent events. The Mwg catalog showed improved performance, retaining 80,243 independent events, representing a 31% reduction. The b-value for the Mw catalog was found to be 0.74, with an Mc of 4.20, while the Mwg catalog exhibited a higher b-value of 0.78 and a lower Mc of 3.80, indicating better sensitivity to smaller magnitude events. Additionally, the a-value for the Mw and Mwg catalogs was found to be 7.23 and 7.41, respectively. These results underscore the Mwg scale’s improved ability to isolate independent events, enhance completeness, and reflect regional seismicity more reliably, making it a more effective tool for seismic hazard assessment in the Indian context.