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The Eastern Himalayan Syntaxis (EHS) and associated tectonic plate boundaries have caused two great earthquakes within hundred years and more than fifteen strong earthquakes (from eighteen centuries) in the foredeep Brahmaputra Basin. These earthquakes are generally considered blind, owing to the deficiency of surface rupture. Further, the lack of instrumental and historical archives elicits palaeo-seismological proxies for future seismic hazard assessment. The present study area is confined to the rapidly growing Dibrugarh City, lies on left bank of Brahmaputra and bounded by EHS in northeast, Main Frontal Thrust (MFT) in North, Naga Thrust (NT) in Southeast and Mishmi Thrust (MT) in east. This tectonically active area witnessed dreadful damages during the 1950 great Assam earthquake (Mw = 8.4), the largest continental ever recorded event. In this study, palaeoseismological evidence such as sand dyke and sand blow from different levels of the river terraces in and around Dibrugarh City has been dated using optically stimulated luminescence (OSL) methodology to understand the ages of the causative event. The optical dates from the palaeoliquefacton features indicate multiple episodic events ca. 888 ± 63 yrs, ca. 934 ± 63 yrs & ca. 989 ± 83 yrs. On the other hand, an age of ca. 11.3 ± 0.7 ka, early Holocene has been obtained from a neotectonic scarp indicates the crustal shortening time during MFT orogeny. Further, the empirical back-calculation of the complex geometry of the palaeoliquefaction feature facilitated in determining the causative earthquake magnitude and PGA, which is first of its kind from northeast of India. Back-calculation indicates, the magnitude of the earthquake might be range from 6.2-7.4Mw with PGA ~ 0.5-0.6g. The overlapping of palaeointensity lines /isoseismic lines from the empirical calculation, ESI and 1950 earthquake indicate the effect of multiple episodes of earthquake and vulnerability in Eastern Himalayan foothill areas. This study is of immense importance considering the seismic hazard potential in the eastern Himalaya and its surroundings and inadequate instrumentally recorded earthquake database.