Spatio‐temporal variation in b‐value prior to the 26 November 2021 Mizoram earthquake of northeast India

Abstract

In this study, the variation in frequency magnitude distribution factor (b‐value) before the main shock has been assessed for the 26 November 2021 Mizoram earthquake (Mw 6.1) in northeast India. The study area covering the Indo‐Burma Ranges is divided into square grids of equal dimension and spatial mapping of the b‐value for each square grid has been carried out. The maximum likelihood method is implemented for the estimation of the b‐value of each grid. The epicentral location of the 26 November 2021 Mizoram earthquake (Mw 6.1) is found to be in the intermediate b‐value square grid. The temporal variation in the b‐value indicates a considerable decline in the b‐value before the occurrence of the main event. The depth‐wise variation in the b‐value suggests an antithetical relationship between the b‐value and crustal stress. The spatio‐temporal and depth‐wise fluctuation in the b‐value results have been strengthened by employing a non‐parametric Kolmogorov–Smirnov (K–S) test. Based on our study, we infer that interplate earthquakes occur mostly in the upper crust of the study region.