The Dauki fault is a major fault along the southern boundary of the Shillong Plateau that may be a source of destructive seismic hazards for the adjoining areas, including northeastern Bangladesh.[1] The fault, inferred to go through the southern margin of the Shillong Plateau, is an east–west-trending reverse fault inclined towards the north.[2]
Marking the southern margins of Shillong Plateau (which is much steeper than the northern slope at about a height of 1500 m), the prominent East-West Dauki Fault System (5–6 km wide) is the most remarkable feature of the Plateau. This fault zone forms a sharp escarpment along the southern edge of the plateau. The steep escarpment indicates vertical displacement along the Dauki Fault Zone where the Bangladesh plains subside actively. Though the Dauki Fault Zone is shown as a single fault line on the geological map of Bangladesh (1990) but the images show that it is the combination of a number of en-echelon faults trending in different directions, making the fault scraps zigzag rather than a straight line. Spread between the block faulted Palaeogene sediments of the Northern Foreland Shelf and the block faulted Piedmont deposits of Plio-Pleistocene age of the Garo Hills, the Dauki Fault is a structural unit of considerable regional importance. The northeastern part of the Bengal Basin experiences strong seismicity believed to be caused by the Dauki Fault System.[3]
The Dauki Fault, according to Evans (1964), is a tear fault (transcurrent or strike slip fault) that trends transverse to the strike of the deformed rocks of the Mikir Hills Plateaus.[4] But Murthy et al. (1969) contradicted this proposition of Evans and argued with evidence that Dauki fault has a vertical uplift to the north, causing the Mikir Hills Plateaus as an uplifted region with northward tilting. These faults are similar to upthrusts.[5]