Seismic status in Bangladesh

Abstract

Seismic status in Bangladesh has been investigated using earthquake data recorded by the global network of USGS during 1980 to 2016. Seismicity parameters such as magnitude completeness Mc, b-value and a-value are being estimated. It has observed that the overall b-value in and around Bangladesh is of 0.84 which is seemed to be seismically active zone. As, reliable b-value assessment can lead to better seismic hazard analysis, reliable magnitude of completeness Mc can lead to b-value assessment of an area, this work has dealt and estimated magnitude of completeness Mc using various techniques for the whole region for a reliable estimation. Estimated Mc is obtained to be around 3.9-4.7, which lead to b-value of 0.93. Spatial variations of Mc  and b-value have been investigated for 1^ox1^o horizontal and vertical rectangular regions for the study area between 18-29°N and 84-95°E. Estimated Mc and b-value along with b-value are then averaged for the common regions in the pair of horizontal and vertical regions. Results are then being presented in the form of maps. The findings resemble as, the Mc is low at the border line of N-W Bangladesh, and a line from Cox’s bazaar to Sylhet through Hill tracts. Remain parts belong to the Mc value of 4.1-4.2, thus the b-value obtained is varying from 0.68 to 1.2, where, the value is higher at region in Chittagong and Barisal division that extends toward north through part of Dhaka to Sylhet and lower at Rajshahi, Rangpur and part of Khulna division, while a-value is varying from 5.0 to 7.2 mostly from west to east.

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