A 5.1 Richter magnitude earthquake struck Andaman Islands here on Saturday, India Meteorological Department (IMD) confirmed.According to IMD, the epicentre of the earthquake was almost 129 km from Mayabunder, a town in the northern part of the Andaman and Nicobar island, which has a total population of less than a lakh.The earthquake hit the island at 16:559 IST at a depth of 10 km.No casualties have been reported so far.Authorities are, however, assessing the damage caused by the tremors.