Spatio-temporal analysis of b-value prior to 28 April 2021 Assam Earthquake and implications thereof

Here, we report a Spatio-temporal analysis of the frequency magnitude distribution earthquakes (b-value) before 28th April 2021 (Mw 6.4) earthquake event observed in northeast India. To esti- mate average b-value for study region, data set 750 events with Mw ≥ 3.9 is extracted from homogenous part catalog (1950-2021) documented by United States Geological Survey (USGS) and International seismological center (ISC) region. For spatial disparities b-value, whole region subdivided into 16 square grids dimension 1o×1o calculated each subsection. In congruence other studies, this work yields b-values ranging 0.66 to 1.25. After calculation grid, it that grid epicentral location (6.4) has low b-value. Accordingly, correlation aberrant pattern between focal depth have been comprehensively explored. It sig- nificantly dips within range ~15-35 km which implicates high-stress accumulation crustal homogeneity. The depth-wise variation infers antithetical relationship stress. Mostly interplate are region; thereby hinting at intense seismicity upper crust.