Earthquake zones in Bangladesh

The first seismic zoning map of the subcontinent was compiled by the Geological Survey of India in 1935. The Bangladesh Meteorological Department adopted a seismic zoning map in 1972. In 1977, the Government of Bangladesh constituted a Committee of Experts to examine the seismic problem and make appropriate recommendations. The Committee proposed a zoning map of Bangladesh in the same year.
According to Bangladesh National Building Code (BNBC, 1993), Bangladesh is divided into 3 earthquake zones (Figure- 6):
Zone –1: the less risky zone. The Zone-1 comprising the southwestern part of Bangladesh (Jessore, Khulna and Barisal Districts) is seismically quiet, with an estimated basic seismic co-efficient of 0.04.
Zone–2: medium vulnerable zone. Zone-2 comprising the central part of Bangladesh (Dhaka, Rajshahi, Dinajpur Bogra, Chittagong and Noakhali Districts) represents the regions of recent uplifted Pleistocene blocks of the Barind and Madhupur Tracts, and the western extension of the folded belt.
Zone– 3: the most vulnerable zone. Zone-3 comprising the northern and eastern regions of Bangladesh (Sylhet, Mymensingh and Rangpur Districts) with the presence of the Dauki Fault system of eastern Sylhet and the deep seated Sylhet Fault, and proximity to the highly disturbed southeastern Assam region with the Jaflong thrust, Naga thrust and Disang thrust, is a zone of high seismic risk with a basic seismic co-efficient of 0.08. Northern Bangladesh comprising greater Rangpur and Dinajpur districts is also a region of high seismicity because of the presence of the Jamuna Fault and the proximity to the active east-west running fault and the Main Boundary Fault to the north in India. The Chittagong-Tripura Folded Belt experiences frequent earthquakes, as just to its east is the Burmese Arc where a large number of shallow depth earthquakes originate. In the modified zoning map, a part of Chittagong area is included to zone- 3