Seismotectonic map of Bangladesh and surrounding regions showing epicenters of earthquakes (declustered catalogue) from 1762 to 2016. The tectonic features are from Steckler et al. (2016) and Kayal et al. (2012). The background digital elevation model (DEM) is from global multi-resolution terrain elevation data 2010 (GMTED 2010) of USGS. Simplified geological map of Bangladesh modified from Alam et al. (1990) is superimposed on the seismotectonic map occurred on unidentified and uncharacterized faults (Petersen etal. 2014). The model is based on the likelihoods that future large damaging earthquakes may occur near past small and moderate earthquakes (Frankel 1995). The background seismicity model is prepared using historical seismicity pattern to account for the random earthquakes of the whole study regions. In the present study, the background seismicity model repre-sents earthquakes from Mw 4.5 to 7.5. As earthquake magnitude less than Mw 4.5 has no engineering significance (no damage to structures) (Baker 2013), the minimum magni-tude is fixed as Mw 4.5 for these seismic sources. The maximum magnitude is set as Mw 7.5 for this seismic source, as the maximum magnitude of the historical earthquakes that occurred in uncharacterized and unidentified faults of Bangladesh was Mw 7.1 (1918 Srimangal Earthquake).

The systematic records of earthquakes that occurred in Bangladesh and the surrounding regions are not available in Bangladesh. In the present study, the earthquake catalog of these regions is compiled from the catalogs of different international sources and pub-lished studies. The sources of earthquake records are (1) USGS Comprehensive catalog from 1908 to October 26, 2016; (2) International Seismological Center (ISC)—Global Earthquake Model (GEM) catalog from 1903 to September 20, 2013; (3) Global Cen-troid Moment Tensor (CMT) catalog from 1976 to June 26, 2015. The records of his-torical earthquakes are collected from the published studies of Szeliga etal. (2010) and Ambraseys and Douglas (2004). Earthquake records of different sources are compiled, reformatted, and stored chronologically to prepare a composite, uniform earthquake catalog.

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