JSEJournal of Seismic Exploration0963-0651AccScience Publishing10.36922/JSE025210006ArticleRegional patterns of seismic b-values variations in the Himalayan region (71.6°E – 95.5°E and 37.5°N – 26.6°N)https://geophysical-press.com/journal/JSE/34/1/10.36922/JSE025210006TiwariRam Krishna,SubediAnil,ParajuliDilip,DharelSantosh,NeupaneAnil,SubediHari,TimsinaBishow Raj,PaudyalHarihar20253412025-07-28This study conducts a detailed seismic hazard assessment of the Himalayan region. It focuses on studying how b-values, based on the Gutenberg–Richter law, vary throughout location and time. These fluctuations assist measuring tectonic stress and provide insights into the region’s seismic activity. This research focuses on five Himalayan sub-regions: Far Western, Western, Central-I, Central-II, and Eastern. It incorporates earthquake data spanning 1964 – 2023 obtained from the International Seismological Centre. The data were de-clustered using the Reasenberg method and examined by Maximum Likelihood Estimation. The results demonstrated considerable spatial variability in b-values across the Himalayan sub-regions. The Far Western Himalayas displayed the greatest b-value (0.93 ± 0.02), indicating frequent smaller earthquakes and lesser tectonic stress. In contrast, the Eastern (0.68 ± 0.02) and Central-I (0.69 ± 0.03) regions had the lowest b-values, implying more stress accumulation and a greater risk of future strong earthquakes. Temporal fluctuations, as a decrease in b-values preceding to the 2015 Gorkha earthquake (Mw 7.8) and a subsequent increase in Central-II (1.19 ± 0.03), highlighted the retention and release cycles. The Eastern Himalayas, particularly the Dhubri-Chungthang fault zone seismic gap in Bhutan, are considered a key high-risk zone. This region, with b-values ranging from 0.65 to 0.75, has remained unruptured since the 1934 Bihar-Nepal earthquake (Mw 8.4). The findings showed the influence of the continual convergence of the Indian and Eurasian plates (~20 mm/year) on strain heterogeneity. This study underlines the vital demand for intensive seismic monitoring, resilient infrastructure, and disaster readiness in low b-value areas to alleviate catastrophic risks in one of the globe’s most tectonically active regions.b-value, Gutenberg–Richter law, Himalayan region

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